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Drug overview for PACERONE (amiodarone hcl):
Generic name: AMIODARONE HCL (A-mee-OH-da-rone)
Drug class: Antiarrhythmic - Class III
Therapeutic class: Cardiovascular Therapy Agents
Amiodarone hydrochloride is considered to be predominantly a class III antiarrhythmic agent, but the drug also appears to exhibit activity in each of the 4 Vaughn-Williams antiarrhythmic classes, including some class I (membrane-stabilizing) antiarrhythmic action.
Amiodarone appears to be effective in the management of a wide variety of ventricular as well as supraventricular arrhythmias+. Because of amiodarone's potentially life-threatening adverse effects and the management difficulties associated with its use, the drug previously was not considered a first-line antiarrhythmic but generally was reserved for use in life-threatening ventricular arrhythmias. The drug also was used infrequently for the suppression or prevention of any type of arrhythmia and only when conventional antiarrhythmic therapy was considered ineffective or was not tolerated.
However, amiodarone generally appears to exhibit greater efficacy and a lower incidence of proarrhythmic effects than class I or other class III antiarrhythmic drugs and therefore has become a mainstay in the management of various tachyarrhythmias, including expert recommendations for advanced cardiovascular life support (ACLS), despite labeling that continues to recommend more limited use. In addition, although no antiarrhythmic agent given routinely during cardiac arrest has been shown to increase survival to hospital discharge, amiodarone has been shown to increase short-term survival to hospital admission relative to lidocaine or placebo. Amiodarone should be used only by clinicians who are familiar with and have access to, either directly or through referral, the use of all currently available modalities for the management of recurrent life-threatening ventricular arrhythmias and who have access to appropriate evaluative and monitoring procedures, including continuous ECG monitoring and electrophysiologic techniques for evaluating the patient in both ambulatory and hospital settings.
Generic name: AMIODARONE HCL (A-mee-OH-da-rone)
Drug class: Antiarrhythmic - Class III
Therapeutic class: Cardiovascular Therapy Agents
Amiodarone hydrochloride is considered to be predominantly a class III antiarrhythmic agent, but the drug also appears to exhibit activity in each of the 4 Vaughn-Williams antiarrhythmic classes, including some class I (membrane-stabilizing) antiarrhythmic action.
Amiodarone appears to be effective in the management of a wide variety of ventricular as well as supraventricular arrhythmias+. Because of amiodarone's potentially life-threatening adverse effects and the management difficulties associated with its use, the drug previously was not considered a first-line antiarrhythmic but generally was reserved for use in life-threatening ventricular arrhythmias. The drug also was used infrequently for the suppression or prevention of any type of arrhythmia and only when conventional antiarrhythmic therapy was considered ineffective or was not tolerated.
However, amiodarone generally appears to exhibit greater efficacy and a lower incidence of proarrhythmic effects than class I or other class III antiarrhythmic drugs and therefore has become a mainstay in the management of various tachyarrhythmias, including expert recommendations for advanced cardiovascular life support (ACLS), despite labeling that continues to recommend more limited use. In addition, although no antiarrhythmic agent given routinely during cardiac arrest has been shown to increase survival to hospital discharge, amiodarone has been shown to increase short-term survival to hospital admission relative to lidocaine or placebo. Amiodarone should be used only by clinicians who are familiar with and have access to, either directly or through referral, the use of all currently available modalities for the management of recurrent life-threatening ventricular arrhythmias and who have access to appropriate evaluative and monitoring procedures, including continuous ECG monitoring and electrophysiologic techniques for evaluating the patient in both ambulatory and hospital settings.
DRUG IMAGES
PACERONE 200 MG TABLET
PACERONE 100 MG TABLET
PACERONE 400 MG TABLET
The following indications for PACERONE (amiodarone hcl) have been approved by the FDA:
Indications:
Life-threatening ventricular tachycardia
Prevention of ventricular fibrillation
Ventricular fibrillation
Professional Synonyms:
Life-threatening increased ventricular rate
Life-threatening ventricular polycardia
Life-threatening ventricular tachyarrhythmia
Life-threatening ventricular tachysystole
Life-threatening VT
V Fib
Ventricular fibrillation prophylaxis
VF prophylaxis
Indications:
Life-threatening ventricular tachycardia
Prevention of ventricular fibrillation
Ventricular fibrillation
Professional Synonyms:
Life-threatening increased ventricular rate
Life-threatening ventricular polycardia
Life-threatening ventricular tachyarrhythmia
Life-threatening ventricular tachysystole
Life-threatening VT
V Fib
Ventricular fibrillation prophylaxis
VF prophylaxis
The following dosing information is available for PACERONE (amiodarone hcl):
A uniform and optimal dosage schedule for amiodarone hydrochloride has not been established. Amiodarone is a highly toxic drug, and the lowest effective dosage should be used to minimize the risk and occurrence of adverse effects. Dosage of amiodarone hydrochloride must be carefully adjusted according to individual requirements and response, patient tolerance, and the general condition and cardiovascular status of the patient.
Clinical and ECG monitoring of cardiac function, including appropriate ambulatory ECG monitoring (e.g., Holter monitoring) and/or programmed electrical stimulation (PES), as appropriate, is recommended during therapy with the drug. When dosage adjustment is necessary, the patient should be monitored closely for an extended period of time because of the long and variable elimination half-life of amiodarone and the difficulty in predicting the length of time required to attain a new steady-state plasma concentration of the drug. When feasible, monitoring of plasma amiodarone concentrations may be helpful in evaluating patients who are not responding to the drug or who experience unexpectedly severe toxicity.
Monitoring of plasma amiodarone concentrations may also be useful in identifying patients whose concentrations are unusually low and who might benefit from an increase in dosage or those whose concentrations are unusually high in whom dosage reduction might minimize the risk of adverse effects.
Patients should be advised not to double the next dose if a dose is missed.
Although amiodarone dosage requirements generally appear to be similar in geriatric and younger adults, relatively high dosages should be used with caution in geriatric patients since they may be more susceptible to bradycardia and conduction disturbances induced by the drug. In addition, some manufacturers state that dosage in general for geriatric patients should be selected carefully, usually starting at the low end of the dosage range, because these individuals frequently have decreased hepatic, renal, and/or cardiac function and concomitant disease and drug therapy.
For the management of life-threatening ventricular arrhythmias, loading doses of amiodarone hydrochloride are required to ensure an antiarrhythmic effect without waiting several months. The loading-dose phase of therapy should be performed in a hospital setting. Close monitoring of patients is necessary, especially until the risk of recurrent ventricular tachycardia or fibrillation has abated.
Upon initiating amiodarone therapy in patients receiving other antiarrhythmic agents, an attempt should be made to gradually discontinue the other antiarrhythmic agents.
In adults, oral amiodarone hydrochloride loading dosages of 800-1600 mg daily generally are required for 1-3 weeks (and occasionally for longer periods of time) until an initial therapeutic response occurs. Some clinicians have used oral loading dosages exceeding 1600 mg daily or IV+ loading-dose regimens. Clinicians should consult published protocols for specific information on oral loading-dose regimens using dosages greater than 1600 mg daily or on IV loading-dose regimens.
If an IV loading-dose regimen is used, oral therapy should be initiated as soon as possible after an adequate response is obtained and IV amiodarone therapy gradually eliminated. If adverse effects become excessive during the loading-dose phase of therapy, a reduction in dosage is recommended. Elimination of recurrent ventricular tachycardia and recurrent ventricular fibrillation as well as reduction in VPCs and total ventricular ectopic beats usually occur within about 1-3 weeks.
When adequate control of ventricular arrhythmias is achieved or adverse effects become prominent, the dosage of amiodarone hydrochloride should be reduced to 600-800 mg daily for about 1 month and then reduced again to the lowest effective maintenance dosage, usually 400 mg daily. Further cautious reductions in maintenance dosage (e.g., to 200 mg daily) may be possible in some patients. Adequate maintenance dosages generally range from less than 400 mg daily up to 600 mg daily.
Because absorption and elimination of amiodarone are variable, adjustment of maintenance dosage is difficult, and it is not unusual to require dosage reductions or temporary withdrawal or discontinuance of the drug.
For the management of life-threatening ventricular arrhythmias, the recommended starting dose of IV amiodarone hydrochloride over the first 24 hours is approximately 1000 mg. The amiodarone hydrochloride dose for the first rapid loading infusion is 150 mg administered at a rate of 15 mg/minute (i.e., over 10 minutes); the initial infusion rate should not exceed 30 mg/minute. The slow loading phase of the infusion is 360 mg of amiodarone hydrochloride administered at a rate of 1 mg/minute (i.e., over 6 hours).
The first maintenance phase of the infusion is 540 mg of amiodarone hydrochloride administered at a rate of 0.5 mg/minute (i.e., over 18 hours). The first 24-hour dose of amiodarone hydrochloride may be individualized for each patient; however, in controlled clinical trials, mean daily dosages exceeding 2.1
g were associated with an increased risk of hypotension.
After the first 24 hours, the maintenance infusion rate of 0.5 mg/minute (i.e., 720 mg over 24 hours) should be continued; however, the rate of the maintenance infusion may be increased to achieve effective arrhythmia suppression. In the event of breakthrough episodes of ventricular fibrillation or hemodynamically unstable ventricular tachycardia, supplemental amiodarone hydrochloride infusions of 150 mg administered at a rate of 15 mg/minute (i.e., over 10 minutes) may be given.
Based on experience from clinical trials of IV amiodarone hydrochloride, a maintenance infusion of up to 0.5 mg/minute can be administered with caution for 2-3 weeks, regardless of the patient's age, renal function, or left ventricular function. The manufacturer states that there is limited experience in patients receiving parenteral amiodarone hydrochloride for longer than 3 weeks.
For cardiac arrest secondary to pulseless ventricular tachycardia or ventricular fibrillation, experts recommend an initial adult loading dose of amiodarone hydrochloride of 300 mg, given by rapid IV or IO+ injection; an additional dose of 150 mg may be considered.
Pediatric dosage of oral amiodarone hydrochloride has not been established, and dosage may vary considerably. For the management of ventricular and supraventricular arrhythmias in children+, some clinicians have recommended oral amiodarone hydrochloride loading dosages of 10-15 mg/kg daily or 600-800 mg/1.73 m2 daily for approximately 4-14 days and/or until adequate control of cardiac arrhythmias is achieved or adverse effects become prominent.
Dosage of the drug is then reduced to 5 mg/kg daily or 200-400 mg/1.73 m2 for several weeks. If possible, dosage is then reduced gradually to the lowest effective level.
Children younger than 1 year of age appear to require higher loading and maintenance dosages of amiodarone hydrochloride than older children when dosage of the drug is calculated on the basis of body weight, but not on the basis of body surface area.
The manufacturer states that pediatric dosage of IV amiodarone hydrochloride has not been established. For the management of refractory ventricular fibrillation or pulseless ventricular tachycardia+ during pediatric resuscitation, the recommended amiodarone hydrochloride IV or IO+ dose is 5 mg/kg as a rapid bolus injection. Some experts recommend that if adequate control of cardiac arrhythmia is not achieved, the dose may be repeated twice (maximum single dose of 300 mg) up to a total dosage of 15 mg/kg.
If used for the management of wide-complex tachycardias or SVT in pediatric patients who are not in cardiac arrest, an IV amiodarone hydrochloride dose of 5 mg/kg is recommended (infused slowly over 20-60 minutes depending on the urgency). Alternative methods of dosing IV amiodarone hydrochloride (e.g., loading dose of 5 mg/kg given in 5 divided doses of 1 mg/kg, with each incremental dose infused over 5-10 minutes) may be considered in order to minimize pediatric exposure to the plasticizer DEHP.
Patients whose arrhythmias have been controlled successfully with IV amiodarone hydrochloride may be switched to oral therapy. The manufacturer states that since there are some differences in the safety and efficacy profiles of the oral and IV preparations of amiodarone, clinicians should review the prescribing information for oral amiodarone when switching from IV to oral therapy. The optimal dose of oral amiodarone hydrochloride will depend on the dose and duration of IV therapy, as well as the bioavailability of the oral drug.
The manufacturer suggests that for patients receiving a daily dose of 720 mg of amiodarone hydrochloride IV (assuming an infusion rate of 0.5 mg/minute) for less than 1 week, 1-3 weeks, or longer than 3 weeks, the initial daily oral amiodarone hydrochloride dose should be 800-1600, 600-800, or 400 mg of the drug, respectively. These recommendations are made on the basis of a comparable total body amount of amiodarone hydrochloride delivered by IV and oral routes, taking into consideration the drug's oral bioavailability of 50%. When switching from IV to oral amiodarone hydrochloride therapy, clinical monitoring is recommended, particularly for geriatric patients.
Routine reduction of amiodarone hydrochloride dosage in patients with renal impairment does not appear to be necessary, although the risk of excessive accumulation of iodine and possible resultant thyroid effects should be considered.
The effects of hepatic impairment on the elimination of amiodarone have not been evaluated. Because the drug is extensively metabolized, probably in the liver, some clinicians caution that dosage reduction is probably warranted in patients with substantial hepatic impairment. Dosage reduction or discontinuance of amiodarone may be necessary in patients who develop evidence of hepatotoxicity during therapy with the drug.
Clinical and ECG monitoring of cardiac function, including appropriate ambulatory ECG monitoring (e.g., Holter monitoring) and/or programmed electrical stimulation (PES), as appropriate, is recommended during therapy with the drug. When dosage adjustment is necessary, the patient should be monitored closely for an extended period of time because of the long and variable elimination half-life of amiodarone and the difficulty in predicting the length of time required to attain a new steady-state plasma concentration of the drug. When feasible, monitoring of plasma amiodarone concentrations may be helpful in evaluating patients who are not responding to the drug or who experience unexpectedly severe toxicity.
Monitoring of plasma amiodarone concentrations may also be useful in identifying patients whose concentrations are unusually low and who might benefit from an increase in dosage or those whose concentrations are unusually high in whom dosage reduction might minimize the risk of adverse effects.
Patients should be advised not to double the next dose if a dose is missed.
Although amiodarone dosage requirements generally appear to be similar in geriatric and younger adults, relatively high dosages should be used with caution in geriatric patients since they may be more susceptible to bradycardia and conduction disturbances induced by the drug. In addition, some manufacturers state that dosage in general for geriatric patients should be selected carefully, usually starting at the low end of the dosage range, because these individuals frequently have decreased hepatic, renal, and/or cardiac function and concomitant disease and drug therapy.
For the management of life-threatening ventricular arrhythmias, loading doses of amiodarone hydrochloride are required to ensure an antiarrhythmic effect without waiting several months. The loading-dose phase of therapy should be performed in a hospital setting. Close monitoring of patients is necessary, especially until the risk of recurrent ventricular tachycardia or fibrillation has abated.
Upon initiating amiodarone therapy in patients receiving other antiarrhythmic agents, an attempt should be made to gradually discontinue the other antiarrhythmic agents.
In adults, oral amiodarone hydrochloride loading dosages of 800-1600 mg daily generally are required for 1-3 weeks (and occasionally for longer periods of time) until an initial therapeutic response occurs. Some clinicians have used oral loading dosages exceeding 1600 mg daily or IV+ loading-dose regimens. Clinicians should consult published protocols for specific information on oral loading-dose regimens using dosages greater than 1600 mg daily or on IV loading-dose regimens.
If an IV loading-dose regimen is used, oral therapy should be initiated as soon as possible after an adequate response is obtained and IV amiodarone therapy gradually eliminated. If adverse effects become excessive during the loading-dose phase of therapy, a reduction in dosage is recommended. Elimination of recurrent ventricular tachycardia and recurrent ventricular fibrillation as well as reduction in VPCs and total ventricular ectopic beats usually occur within about 1-3 weeks.
When adequate control of ventricular arrhythmias is achieved or adverse effects become prominent, the dosage of amiodarone hydrochloride should be reduced to 600-800 mg daily for about 1 month and then reduced again to the lowest effective maintenance dosage, usually 400 mg daily. Further cautious reductions in maintenance dosage (e.g., to 200 mg daily) may be possible in some patients. Adequate maintenance dosages generally range from less than 400 mg daily up to 600 mg daily.
Because absorption and elimination of amiodarone are variable, adjustment of maintenance dosage is difficult, and it is not unusual to require dosage reductions or temporary withdrawal or discontinuance of the drug.
For the management of life-threatening ventricular arrhythmias, the recommended starting dose of IV amiodarone hydrochloride over the first 24 hours is approximately 1000 mg. The amiodarone hydrochloride dose for the first rapid loading infusion is 150 mg administered at a rate of 15 mg/minute (i.e., over 10 minutes); the initial infusion rate should not exceed 30 mg/minute. The slow loading phase of the infusion is 360 mg of amiodarone hydrochloride administered at a rate of 1 mg/minute (i.e., over 6 hours).
The first maintenance phase of the infusion is 540 mg of amiodarone hydrochloride administered at a rate of 0.5 mg/minute (i.e., over 18 hours). The first 24-hour dose of amiodarone hydrochloride may be individualized for each patient; however, in controlled clinical trials, mean daily dosages exceeding 2.1
g were associated with an increased risk of hypotension.
After the first 24 hours, the maintenance infusion rate of 0.5 mg/minute (i.e., 720 mg over 24 hours) should be continued; however, the rate of the maintenance infusion may be increased to achieve effective arrhythmia suppression. In the event of breakthrough episodes of ventricular fibrillation or hemodynamically unstable ventricular tachycardia, supplemental amiodarone hydrochloride infusions of 150 mg administered at a rate of 15 mg/minute (i.e., over 10 minutes) may be given.
Based on experience from clinical trials of IV amiodarone hydrochloride, a maintenance infusion of up to 0.5 mg/minute can be administered with caution for 2-3 weeks, regardless of the patient's age, renal function, or left ventricular function. The manufacturer states that there is limited experience in patients receiving parenteral amiodarone hydrochloride for longer than 3 weeks.
For cardiac arrest secondary to pulseless ventricular tachycardia or ventricular fibrillation, experts recommend an initial adult loading dose of amiodarone hydrochloride of 300 mg, given by rapid IV or IO+ injection; an additional dose of 150 mg may be considered.
Pediatric dosage of oral amiodarone hydrochloride has not been established, and dosage may vary considerably. For the management of ventricular and supraventricular arrhythmias in children+, some clinicians have recommended oral amiodarone hydrochloride loading dosages of 10-15 mg/kg daily or 600-800 mg/1.73 m2 daily for approximately 4-14 days and/or until adequate control of cardiac arrhythmias is achieved or adverse effects become prominent.
Dosage of the drug is then reduced to 5 mg/kg daily or 200-400 mg/1.73 m2 for several weeks. If possible, dosage is then reduced gradually to the lowest effective level.
Children younger than 1 year of age appear to require higher loading and maintenance dosages of amiodarone hydrochloride than older children when dosage of the drug is calculated on the basis of body weight, but not on the basis of body surface area.
The manufacturer states that pediatric dosage of IV amiodarone hydrochloride has not been established. For the management of refractory ventricular fibrillation or pulseless ventricular tachycardia+ during pediatric resuscitation, the recommended amiodarone hydrochloride IV or IO+ dose is 5 mg/kg as a rapid bolus injection. Some experts recommend that if adequate control of cardiac arrhythmia is not achieved, the dose may be repeated twice (maximum single dose of 300 mg) up to a total dosage of 15 mg/kg.
If used for the management of wide-complex tachycardias or SVT in pediatric patients who are not in cardiac arrest, an IV amiodarone hydrochloride dose of 5 mg/kg is recommended (infused slowly over 20-60 minutes depending on the urgency). Alternative methods of dosing IV amiodarone hydrochloride (e.g., loading dose of 5 mg/kg given in 5 divided doses of 1 mg/kg, with each incremental dose infused over 5-10 minutes) may be considered in order to minimize pediatric exposure to the plasticizer DEHP.
Patients whose arrhythmias have been controlled successfully with IV amiodarone hydrochloride may be switched to oral therapy. The manufacturer states that since there are some differences in the safety and efficacy profiles of the oral and IV preparations of amiodarone, clinicians should review the prescribing information for oral amiodarone when switching from IV to oral therapy. The optimal dose of oral amiodarone hydrochloride will depend on the dose and duration of IV therapy, as well as the bioavailability of the oral drug.
The manufacturer suggests that for patients receiving a daily dose of 720 mg of amiodarone hydrochloride IV (assuming an infusion rate of 0.5 mg/minute) for less than 1 week, 1-3 weeks, or longer than 3 weeks, the initial daily oral amiodarone hydrochloride dose should be 800-1600, 600-800, or 400 mg of the drug, respectively. These recommendations are made on the basis of a comparable total body amount of amiodarone hydrochloride delivered by IV and oral routes, taking into consideration the drug's oral bioavailability of 50%. When switching from IV to oral amiodarone hydrochloride therapy, clinical monitoring is recommended, particularly for geriatric patients.
Routine reduction of amiodarone hydrochloride dosage in patients with renal impairment does not appear to be necessary, although the risk of excessive accumulation of iodine and possible resultant thyroid effects should be considered.
The effects of hepatic impairment on the elimination of amiodarone have not been evaluated. Because the drug is extensively metabolized, probably in the liver, some clinicians caution that dosage reduction is probably warranted in patients with substantial hepatic impairment. Dosage reduction or discontinuance of amiodarone may be necessary in patients who develop evidence of hepatotoxicity during therapy with the drug.
No enhanced Administration information available for this drug.
| DRUG LABEL | DOSING TYPE | DOSING INSTRUCTIONS |
|---|---|---|
| PACERONE 100 MG TABLET | Maintenance | Adults take 1 tablet (100 mg) by oral route 2 times per day |
| PACERONE 200 MG TABLET | Maintenance | Adults take 1 tablet (200 mg) by oral route once daily |
| PACERONE 400 MG TABLET | Maintenance | Adults take 1 tablet (400 mg) by oral route once daily |
| DRUG LABEL | DOSING TYPE | DOSING INSTRUCTIONS |
|---|---|---|
| AMIODARONE HCL 200 MG TABLET | Maintenance | Adults take 1 tablet (200 mg) by oral route once daily |
| AMIODARONE HCL 100 MG TABLET | Maintenance | Adults take 1 tablet (100 mg) by oral route 2 times per day |
| AMIODARONE HCL 400 MG TABLET | Maintenance | Adults take 1 tablet (400 mg) by oral route once daily |
The following drug interaction information is available for PACERONE (amiodarone hcl):
There are 19 contraindications.
These drug combinations generally should not be dispensed or administered to the same patient. A manufacturer label warning that indicates the contraindication warrants inclusion of a drug combination in this category, regardless of clinical evidence or lack of clinical evidence to support the contraindication.
| Drug Interaction | Drug Names |
|---|---|
| Selected Antiarrhythmics/Quinidine SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Amiodarone inhibits quinidine metabolism via CYP3A4, leading to increased serum levels of quinidine.(2) In addition to additive or synergistic effects on the QTc interval, quinidine may inhibit CYP2D6-mediated hydroxylation of propafenone, which results in decreased propafenone clearance.(16,17) Concurrent use may result in additive or synergistic effects on the QT interval. CLINICAL EFFECTS: Concurrent amiodarone may result in an increase in the pharmacologic effects of quinidine due to elevated serum levels. The QTc interval may be prolonged and result in life-threatening arrhythmias, including torsades de pointes. Concurrent quinidine may result in elevated levels and effects of propafenone.(16,17) Concurrent use of quinidine and other antiarrhythmics may result in unpredictable and/or additive effects, including QT prolongation and torsades de pointes. PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(10) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increased systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(10) The effects of quinidine on propafenone levels may not be clinically significant in poor metabolizers(17) because poor metabolizers have a genetically-determined lack of the isoenzyme inhibited by quinidine.(18) PATIENT MANAGEMENT: The Australian manufacturer of amiodarone states that concurrent use of agents known to cause torsades de pointes, such as quinidine, is contraindicated.(3) The US manufacturer of amiodarone states that the concurrent use of QT prolonging drugs should be avoided.(4) If concurrent therapy is warranted, patients should be monitored for increased quinidine levels and signs of quinidine toxicity. Cardiac function should also be monitored. The dosage of quinidine may need to be adjusted. The US manufacturer of amiodarone recommends that the dosage of quinidine be reduced by one-third during concurrent amiodarone.(4) One study recommends that the dosage of quinidine be reduced by 30-50% when amiodarone is added to therapy.(2) The Australian manufacturer of disopyramide states that the concurrent use of other antiarrhythmics, such as Class I, II, III, or IV is contraindicated.(11) The manufacturer of dofetilide states that Class I or Class III antiarrhythmic agents should be withheld for at least three half-lives prior to initiating dofetilide. Dofetilide has been administered to patients previously treated with amiodarone when amiodarone levels were below 0.3 mg/L or amiodarone had been withdrawn for at least 3 months.(12) The manufacturer of ibutilide states that Class IA or III antiarrhythmics should not be used concomitantly with ibutilide or within 4 hours post-infusion.(13) The manufacturer of propafenone states that concurrent use of Class IA and III Antiarrhythmics is not recommended and these agents should be withheld for at least 5 half-lives prior to dosing with propafenone.(16) If alternatives are not available and concurrent therapy is deemed medically necessary, obtain serum calcium, magnesium, and potassium levels and monitor ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In patients receiving concurrent amiodarone and quinidine, elevated serum levels and prolonged QT interval have been reported.(1,5-9) In a study in 11 patients, the addition of amiodarone to quinidine therapy resulted in an increase in quinidine levels by 32% and quinidine toxicity in seven patients. The increase in quinidine levels was seen as early as 24 hours after the addition of amiodarone.(2) Because combinations of antiarrhythmics are not well researched and concurrent use may result in unpredictable effects, the Australian manufacturer of disopyramide states that the concurrent use of other antiarrhythmics, such as quinidine, is contraindicated.(11) Because of the risk of adverse effects, the manufacturer of dofetilide states that Class I or Class III antiarrhythmic agents should be withheld for at least three half-lives prior to initiating dofetilide.(12) In clinical trials, Class IA and III antiarrhythmics were withheld for 5 half-lives prior to the administration of ibutilide and for 4 hours after.(13) In separate clinical trials, concomitant use of ibutilide with amiodarone resulted in significantly prolonged QTc intervals.(14,15) In a study in 11 patients with frequent ventricular arrhythmias who had not responded to treatment with quinidine sulfate alone, the addition of propafenone resulted in a significantly greater mean suppression suppression of baseline premature ventricular contractions (PVCs) than quinidine alone. Patients on propafenone alone required a higher dose to achieve significant suppression of PVCs when compared to concurrent quinidine and propafenone. It was not determined if this suppression was a result of changes in the propafenone plasma concentration or a synergistic effect of the two antiarrhythmics.(19) In another study in seven extensive metabolizer prototypes, the addition quinidine to propafenone resulted in a more than 2-fold increase in the steady-state propafenone plasma concentration, a decrease in the 5-hydroxypropafenone concentration and a reduction in the oral clearance of propafenone. In the same study, two patients who were found to be poor metabolizer phenotypes showed no change in the plasma concentrations of propafenone or its active metabolite with concomitant quinidine administration.(17) Quinidine, at a low dose, may improve efficacy of propafenone by inhibition of CYP P-450-2D6 isozyme. Propafenone 300 mg to 450 mg/day was administered to 60 patients with history of paroxysmal atrial fibrillation for a period of eight weeks resulting in 62% symptomatically controlled. Nineteen refractory patients were randomized in a double-blind fashion to receive either a higher dose of propafenone (450 to 675 mg/d) or standard propafenone dose plus low-dose quinidine (150 mg/d). After the eight week study period, serum levels recorded propafenone levels at 259 and 336 mg/d, respectively, not found to be significantly different. However, the higher dose of propafenone resulted in greater gastrointestinal side effects compared to the addition of low-dose quinidine combination.(20) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
NUEDEXTA, QUINIDINE GLUCONATE, QUINIDINE SULFATE |
| Selected Protease Inhibitors/Amiodarone SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Ritonavir-boosted nirmatrelvir(1) or tipranavir(2); ritonavir-boosted or unboosted indinavir(3); or nelfinavir (4) may inhibit the metabolism of amiodarone at CYP3A4. CLINICAL EFFECTS: The concurrent administration of amiodarone with ritonavir-boosted nirmatrelvir(1) or tipranavir(2); ritonavir-boosted or unboosted indinavir(3); or nelfinavir (4) may result in increased levels, clinical effects, and toxicity of amiodarone. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The concurrent administration of amiodarone with ritonavir-boosted nirmatrelvir(1) or tipranavir(2); ritonavir-boosted or unboosted indinavir(3); or nelfinavir (4) is contraindicated by the manufacturers of these drugs. DISCUSSION: Indinavir has been shown to inhibit CYP3A4. Therefore, the manufacturer of indinavir states that the concurrent administration of indinavir with amiodarone, which is metabolized by CYP3A4, is contraindicated.(3) Nelfinavir has been shown to inhibit CYP3A4. Therefore, the manufacturer of nelfinavir states that the concurrent administration of nelfinavir with amiodarone, which is metabolized by CYP3A4, is contraindicated.(4) Protease inhibitors linked to this monograph include: indinavir, nelfinavir, nirmatrelvir, and tipranavir. Ritonavir is always used with another protease inhibitor as a pharmacokinetic booster and is captured as part of the protease inhibitor regimen. |
APTIVUS, PAXLOVID, VIRACEPT |
| Pimozide/Selected Antiarrhythmics SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Concurrent use may possibly result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent use may result in prolongation of the QTc interval, which may result in potentially life-threatening arrhythmias.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Concurrent therapy with pimozide and Class IA and III antiarrhythmics should be avoided. The manufacturer of pimozide states that concurrent therapy with agents that prolong the QTc interval is contraindicated.(1) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Pimozide has been shown to prolong the QTc interval. Therefore, the manufacturer of pimozide states that concurrent therapy with agents that prolong the QTc interval is contraindicated because of the risk of additive effects on the QTc interval.(1) No other clinical documentation is available. One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
PIMOZIDE |
| Dofetilide/Class Ia And Class III Antiarrhythmics SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Dofetilide has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of dofetilide with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: Renal impairment may increase risk for excessive QTc prolongation as dofetilide is primarily renally eliminated. To prevent increased serum levels and risk for ventricular arrhythmias, dofetilide must be dose adjusted for creatinine clearance < or = to 60 mL/min.(1) The risk of QT prolongation may be increased by reduced creatinine clearance, female gender, larger doses of sotalol, and a history of cardiomegaly or congestive heart failure.(1-2) Risk may also be increased in patients with cardiovascular disease (e.g. myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: Class Ia or Class III antiarrhythmic agents should be withheld for at least three half-lives prior to initiating dofetilide. Dofetilide has been administered to patients previously treated with amiodarone when amiodarone levels were below 0.3 mg/L or amiodarone had been withdrawn for at least 3 months.(1) The manufacturer of propafenone states that Class Ia or Class III antiarrhythmic agents should be withheld for at least 5 half-lives prior to initiating propafenone.(2) If concurrent therapy is deemed medically necessary, obtain serum calcium, magnesium, and potassium levels and monitor ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Because of the risk of adverse effects, Class Ia or Class III antiarrhythmic agents should be withheld for at least three half-lives prior to initiating dofetilide. Dofetilide has been administered to patients previously treated with amiodarone when amiodarone levels were below 0.3 mg/L or amiodarone had been withdrawn for at least three months.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(4) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
DOFETILIDE, TIKOSYN |
| Ziprasidone/Selected QT Prolonging Agents SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Ziprasidone has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of ziprasidone with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: Bradycardia, hypokalemia, hypomagnesemia, and the presence of congenital prolongation of the QT interval may increase the risk of torsades de pointes and/or sudden death.(1) The risk of QT prolongation or torsade de pointes may also be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes), hypocalcemia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction.(3) PATIENT MANAGEMENT: The manufacturer of ziprasidone states under contraindications that ziprasidone should not be used with other drugs that prolong the QT interval such as dofetilide, sotalol, quinidine, other Class Ia and III anti-arrhythmics, mesoridazine, thioridazine, chlorpromazine, droperidol, pimozide, sparfloxacin, gatifloxacin, moxifloxacin, halofantrine, mefloquine, pentamidine, arsenic trioxide, levomethadyl acetate, dolasetron mesylate, probucol or tacrolimus.(1) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2) |
GEODON, ZIPRASIDONE HCL, ZIPRASIDONE MESYLATE |
| Droperidol/QT Prolonging Agents SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Droperidol has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of droperidol with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: Congestive heart failure, bradycardia, use of a diuretic, cardiac hypertrophy, hypokalemia, hypomagnesemia, age over 65 years, alcohol abuse, and the use of agents such as benzodiazepines, volatile anesthetics, and intravenous opiate may predispose patients to the development of prolonged QT syndrome.(1) Risk may also be increased in patients with other cardiovascular diseases (e.g. myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypocalcemia, or female gender.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The manufacturer of droperidol states under precautions drug interactions that drugs known to have the potential to prolong the QT interval should not be used together with droperidol.(1) DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
DROPERIDOL |
| Propafenone/Selected Class IA And III Antiarrhythmics SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Concurrent use of propafenone with other Class IA or III antiarrhythmics may result in additive or synergistic effects on the QTc interval.(1) In addition to additive or synergistic effects on the QTc interval, concurrent amiodarone and propafenone may affect conduction and repolarization.(1) CLINICAL EFFECTS: Concurrent use of propafenone with other Class IA and III antiarrhythmics may result in prolongation of the QTc interval and life-threatening cardiac arrhythmias. In addition to these effects, concurrent amiodarone may affect conduction and repolarization.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increased systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The manufacturer of propafenone states that concurrent use of Class IA and III Antiarrhythmics is not recommended and these agents should be withheld for at least 5 half-lives prior to dosing with propafenone.(1) If alternatives are not available and concurrent therapy is deemed medically necessary, obtain serum calcium, magnesium, and potassium levels and monitor ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Two studies evaluated the safety of adding ibutilide to propafenone for cardioversion. Although positive clinical results were observed, ten patients reported significant bradycardia and one patient experienced torsades de pointes.(4,5) A study assessed the use of propafenone in patients with amiodarone-resistant ventricular tachycardia. Two cases reported suppressed ventricular tachycardia after the addition of propafenone to amiodarone. Four cases reported worsening of spontaneous tachycardia with combined administration, and one case degenerated to ventricular fibrillation. The combination may be useful but is often associated with undesirable, significant side-effects. The combination may be limited to patients without severely depressed left ventricular function and a reduced probability of inducing ventricular tachycardia.(6) |
PROPAFENONE HCL, PROPAFENONE HCL ER |
| Ibutilide/Class IA and III Antiarrhythmics SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Concurrent use of ibutilide with Class IA or III antiarrhythmics may result in additive or synergistic effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent use of ibutilide with Class IA or III antiarrhythmics may result in life-threatening ventricular arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The manufacturer of ibutilide states that Class IA or III antiarrhythmics should not be used concomitantly with ibutilide or within 4 hours post-infusion.(1) If concurrent therapy is deemed medically necessary, obtain serum calcium, magnesium, and potassium levels and monitor ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In clinical trials, Class IA and III antiarrhythmics were withheld for 5 half-lives prior to the administration of ibutilide and for 4 hours after.(1) In separate clinical trials, concomitant use of ibutilide with amiodarone resulted in significantly prolonged QTc intervals.(2,3) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
CORVERT, IBUTILIDE FUMARATE |
| Disopyramide/Class Ia and III Antiarrhythmics SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Disopyramide has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of disopyramide with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation may be increased by reduced creatinine clearance, female gender, larger doses of sotalol, and a history of cardiomegaly or congestive heart failure.(1) Risk may also be increased in patients with cardiovascular disease (e.g. myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The Australian manufacturer of disopyramide states that the concurrent use of other antiarrhythmics, such as Class I, II, III, or IV is contraindicated.(1) If concurrent therapy is deemed medically necessary, obtain serum calcium, magnesium, and potassium levels and monitor ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Because combinations of antiarrhythmics are not well researched and concurrent use may result in unpredictable effects, the Australian manufacturer of disopyramide states that the concurrent use of other antiarrhythmics, such as Class I, II, III, or IV is contraindicated.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
DISOPYRAMIDE PHOSPHATE, NORPACE, NORPACE CR |
| Artemether-Lumefantrine/QT Prolonging Agents SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Concurrent use of artemether-lumefantrine and agents known to prolong the QT interval may result in additive or synergistic effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent administration may result in prolongation of the QTc interval and life-threatening cardiac arrhythmias, including torsades de pointes. PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The UK manufacturer of artemether-lumefantrine states that the use of artemether-lumefantrine in patients taking drugs that are known to prolong the QTc interval is contraindicated. These agents include class IA and III antiarrhythmics; neuroleptics; antidepressive agents; some macrolides, fluoroquinolones, imidazole and triazole antifungals; terfenadine; astemizole; and cisapride.(1) The US manufacturer of artemether-lumefantrine states that the use of artemether-lumefantrine should be avoided in patients taking drugs that are known to prolong the QTc interval. These agents include class IA and III antiarrhythmics; neuroleptics; antidepressive agents; some macrolides, fluoroquinolones, imidazole and triazole antifungals; terfenadine; astemizole; and cisapride.(2) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
COARTEM |
| Dronedarone/QT Prolonging Agents SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Concurrent use of dronedarone and agents known to prolong the QT interval may result in additive or synergistic effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent administration may result in prolongation of the QTc interval and life-threatening cardiac arrhythmias, including torsades de pointes. PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The US manufacturer of dronedarone states that the use of drugs or herbal products that are known to prolong the QTc interval is contraindicated. These agents include phenothiazine anti-psychotics, tricyclic antidepressants, certain oral macrolide antibiotics, and Class IA and III antiarrhythmics.(1) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
MULTAQ |
| Lovastatin (Greater Than 40 mg); Simvastatin (Greater Than 20 mg)/Amiodarone SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Amiodarone may inhibit the metabolism of lovastatin(1) and simvastatin(2-5) by CYP3A4. CLINICAL EFFECTS: Concurrent use of amiodarone(1) with certain HMG CoA reductase inhibitors may increase the risk of rhabdomyolysis. PREDISPOSING FACTORS: The risk for myopathy or rhabdomyolysis may be greater in patients 65 years and older, inadequately treated hypothyroidism, renal impairment, carnitine deficiency, malignant hyperthermia, or in patients with a history of myopathy or rhabdomyolysis. Patients with a SLCO1B1 polymorphism that leads to decreased function of the hepatic uptake transporter OATP1B1 may have increased statin concentrations and be predisposed to myopathy or rhabdomyolysis. PATIENT MANAGEMENT: The US manufacturers of lovastatin(1) and amiodarone(6) recommend that the dose of lovastatin not exceed 40 mg daily in patients receiving concurrent amiodarone unless the potential benefit outweighs the increased risk of myopathy. The US manufacturers of simvastatin(2-5) and amiodarone(6) recommend that the dose of simvastatin not exceed 20 mg daily in patients receiving concurrent amiodarone unless the potential benefit outweighs the increased risk of myopathy. DISCUSSION: Rhabdomyolysis has been reported with concurrent amiodarone and simvastatin.(6) In a case report, a 63 year-old male developed rhabdomyolysis 4 weeks after starting simvastatin therapy and 2 weeks after starting amiodarone.(7) In a clinical trial, myopathy was been reported in 6% of patients receiving concurrent simvastatin (80 mg) and amiodarone.(3) In a randomized, cross-over study in 12 healthy subjects, subjects received amiodarone (400 mg daily) with either simvastatin (40 mg) or pravastatin (40 mg). Amiodarone increase simvastatin area-under-curve (AUC) by 73%, maximum concentration (Cmax) by 100%, and half-life by 48%. There were no significant effects on pravastatin pharmacokinetics.(8) In a case report, a 72 year-old male developed rhabdomyolysis 10 weeks after starting amiodarone (200 mg daily) therapy and 6 weeks after starting simvastatin (80 mg daily).(9) In a retrospective review of patients receiving amiodarone, the rate of adverse events in combination with a statin was 1.0%, 0.7%, and 0.4% for simvastatin, atorvastatin, and pravastatin, respectively. The most commonly reported adverse effect was muscle soreness, which was present in 77% of reports and was found more often in older male patients.(10) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
ALTOPREV, EZETIMIBE-SIMVASTATIN, FLOLIPID, LOVASTATIN, SIMVASTATIN, VYTORIN, ZOCOR |
| Fingolimod/Class IA and III Antiarrhythmic Agents SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Initiation of fingolimod has a negative chronotropic effect leading to a mean decrease in heart rate of 13 beats per minute (bpm) after the first dose. The first dose has also been associated with heart block.(1-4) CLINICAL EFFECTS: The heart rate lowering effect of fingolimod is biphasic with an initial decrease usually within 6 hours, followed by a second decrease 12 to 24 hours after the first dose. Symptomatic bradycardia and heart block, including third degree block, have been observed. Bradycardia may be associated with an increase in the QTc interval, increasing the risk for torsades de pointes. The cause of death in a patient who died within 24 hour after taking the first dose of fingolimod was not conclusive, however a link to fingolimod could not be ruled out. PREDISPOSING FACTORS: Pre-existing cardiovascular or cerebrovascular disease (e.g. heart failure, ischemic heart disease, history of myocardial infarction, history of torsades de pointes, congenital long QT syndrome, stroke, or heart block), severe untreated sleep apnea, a prolonged QTc interval prior to fingolimod initiation, factors associated with QTc prolongation (e.g. hypokalemia, hypomagnesemia, bradycardia, female gender, advanced age), or concomitant treatment with Class IA or III agents may increase risk for cardiovascular toxicity due to fingolimod. Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(5) PATIENT MANAGEMENT: US, Canada and UK manufacturer information states Class Ia or Class III antiarrhythmics are contraindicated and should not be co-administered with fingolimod.(1-4) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. After the first dose of fingolimod, heart rate decrease may begin within an hour. Decline is usually maximal at approximately 6 hours followed by a second decrease 12 to 24 hours after the first dose. The second dose may further decrease heart rate, but the magnitude of change is smaller than the first dose. With continued, chronic dosing, heart rate gradually returns to baseline in about one month.(1,2) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: After the first dose of fingolimod, heart rate decrease may begin within an hour. Decline is usually maximal at approximately 6 hours followed by a second decrease 12 to 24 hours after the first dose. The second dose may further decrease heart rate, but the magnitude of change is smaller than the first dose. With continued, chronic dosing, heart rate gradually returns to baseline in about one month.(1,2) Antiarrhythmic agents linked to this monograph are disopyramide, procainamide, quinidine, amiodarone, dofetilide, dronedarone, ibutilide and sotalol. |
FINGOLIMOD, GILENYA, TASCENSO ODT |
| Anagrelide/QT Prolonging Agents SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Concurrent use of anagrelide with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of anagrelide with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of anagrelide states that anagrelide should not be used in patients taking medications known to prolong the QT interval.(1) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a thorough QT study, dose-related QT changes were observed with anagrelide. The maximum mean change in QTcI (95% CI) in comparison to placebo was 7.0 (9.8) ms and 13.0 (15.7) msec following doses of 0.5 mg and 2.5mg, respectively.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
AGRYLIN, ANAGRELIDE HCL |
| Sotalol/Selected Class I & Class III Antiarrhythmic Agents SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Sotalol has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-2) CLINICAL EFFECTS: The concurrent use of sotalol with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1-2) PREDISPOSING FACTORS: The risk of QT prolongation may be increased by reduced creatinine clearance, female gender, larger doses of sotalol, and a history of cardiomegaly or congestive heart failure.(1-2) Risk may also be increased in patients with cardiovascular disease (e.g. myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The manufacturers of sotalol state Class I or Class III antiarrhythmic agents which have the potential to prolong refractoriness may cause prolongation of the QT interval and so are not recommended.(1-2) These agents should be withheld for at least 3 half-lives prior to initiation of sotalol.(2) Selected Class I or Class III antiarrhythmic agents linked to this monograph are: ajmaline, amiodarone, bretylium, dronedarone, encainide, flecainide, hydroquinidine, indecainide, moricizine, procainamide and quinidine. If concurrent therapy is deemed medically necessary, obtain serum calcium, magnesium, and potassium levels and monitor ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
BETAPACE, BETAPACE AF, SOTALOL, SOTALOL AF, SOTALOL HCL, SOTYLIZE |
| CYP3A4 Substrates that Prolong QT/Posaconazole SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Posaconazole is a strong inhibitor of CYP3A4 and may inhibit the metabolism of CYP3A4 substrates. Use of posaconazole with agents that prolong the QTc interval may result in an additive effect on the QTc interval.(1,2) CLINICAL EFFECTS: Concurrent administration may result in elevated levels of the CYP3A4 substrate and/or prolongation of the QTc interval, which may result in life-threatening cardiac arrhythmias, including torsades de pointes.(1,2) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The US manufacturer of posaconazole states that the concurrent use of agents that prolong the QTc interval that are metabolized by CYP3A4 is contraindicated.(1) The UK manufacturer of posaconazole states that CYP3A4 substrates that are known to prolong the QTc interval must not be coadministered.(2) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Posaconazole has been shown to inhibit CYP3A4. Elevated levels of CYP3A4 substrates that are known to prolong the QTc interval may have an additive effect on the QTc interval.(1,2) CYP3A4 substrates that prolong the QTc interval and that are linked to this monograph include: aclarubicin, adagrasib, amiodarone, artemether-lumefantrine, bepridil, clarithromycin, dofetilide, erythromycin, fexinidazole, levomethadyl, lonafarnib, mobocertinib, quizartinib, revumenib, savolitinib, and telithromycin. |
NOXAFIL, POSACONAZOLE |
| Lemborexant (Greater Than 5 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Inhibitors of CYP3A4 may inhibit the metabolism of lemborexant.(1) CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP3A4 may result in increased levels of and effects from lemborexant, including somnolence, fatigue, CNS depressant effects, daytime impairment, headache, and nightmare or abnormal dreams.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The maximum recommended dose of lemborexant with concurrent use of a weak CYP3A4 inhibitors should not exceed 5 mg per dose.(1) DISCUSSION: Lemborexant is a CYP3A4 substrate. In a PKPB model, concurrent use of lemborexant with itraconazole increased area-under-curve (AUC) and concentration maximum (Cmax) by 3.75-fold and 1.5-fold, respectively. Concurrent use of lemborexant with fluconazole increased AUC and Cmax by 4.25-fold and 1.75-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(1,2) |
DAYVIGO |
| Colchicine (for Cardioprotection)/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may affect the transport of colchicine, a P-gp substrate.(1,2) CLINICAL EFFECTS: Concurrent use of a P-gp inhibitor may result in elevated levels of and toxicity from colchicine. Symptoms of colchicine toxicity include abdominal pain; nausea or vomiting; severe diarrhea; muscle weakness or pain; numbness or tingling in the fingers or toes; myelosuppression; feeling weak or tired; increased infections; and pale or gray color of the lips, tongue, or palms of hands.(1,2) PREDISPOSING FACTORS: This interaction is expected to be more severe in patients with renal or hepatic impairment.(1,2) PATIENT MANAGEMENT: The manufacturer of colchicine used for cardiovascular risk reduction states that concurrent use of colchicine with P-gp inhibitors is contraindicated.(1) DISCUSSION: There are several reports of colchicine toxicity(3-5) and death(6,7) following the addition of clarithromycin to therapy. In a retrospective review of 116 patients who received clarithromycin and colchicine during the same hospitalization, 10.2% (9/88) of patients who received simultaneous therapy died, compared to 3.6% (1/28) of patients who received sequential therapy.(8) An FDA review of 117 colchicine-related deaths that were not attributable to overdose found that 60 deaths (51%) involved concurrent use of clarithromycin.(2) There is one case report of colchicine toxicity with concurrent erythromycin.(9) In a study in 20 subjects, pretreatment with diltiazem (240 mg daily for 7 days) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of colchicine (0.6 mg) by 44.2% (range -46.6% to 318.3%) and by 93.4% (range -30.2% to 338.6%), respectively.(1) In a study in 24 subjects, pretreatment with verapamil (240 mg twice daily for 7 days) increased the Cmax and AUC of a single dose of colchicine (0.6 mg) by 40.1% (range -47.1% to 149.5%) and by 103.3% (range -9.8% to 217.2%), respectively.(1) Colchicine toxicity has been reported with concurrent use of CYP3A4 and P-gp inhibitors such as clarithromycin, cyclosporine, diltiazem, erythromycin, and verapamil.(1,2) P-gp inhibitors include abrocitinib, amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daridorexant, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, schisandra, selpercatinib, sotorasib, tepotinib, tezacaftor, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(1,10,11) |
LODOCO |
| Amiodarone/Strong CYP3A4 Inhibitors that Prolong QT SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Strong CYP3A4 inhibitors that prolong the QTc interval may inhibit the metabolism of amiodarone and result in additive risk of QT prolongation. Amiodarone is a CYP3A4 substrate.(1) CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inhibitors that prolong QT may increase the levels and effects of amiodarone including additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias like torsades de pointes (TdP).(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of amiodarone states that the concurrent use of QT prolonging agents should be avoided and that the need to co-administer amiodarone with any other drug known to prolong the QTc interval must be based on a careful assessment of the potential risks and benefits of doing so for each patient. Concurrent use with CYP3A4 inhibitors should also be avoided.(1) The US manufacturer of levoketoconazole states that levoketoconazole is contraindicated with other agents that prolong the QT interval.(3) Levoketoconazole is also contraindicated in patients with a prolonged QTcF interval of greater than 470 msec at baseline, history of torsades de pointes, ventricular tachycardia, ventricular fibrillation, or long QT syndrome (including first-degree family history). Use caution in patients with other risk factors for QT prolongation including congestive heart failure, bradyarrhythmias, and uncorrected electrolyte abnormalities. Consider more frequent ECG monitoring. Prior to starting levoketoconazole, obtain a baseline ECG and correct hypokalemia or hypomagnesemia. If a patient develops QT prolongation with a QTc interval greater than 500 msec, temporarily discontinue levoketoconazole. After resolution of prolonged QTc interval, levoketoconazole may be resumed at a lower dose. If QTc interval prolongation recurs, permanently discontinue levoketoconazole.(3) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: QTc prolongation has been reported during concurrent amiodarone and azole antifungals, fluoroquinolones, and macrolide antibiotics.(1) A retrospective review of patients who received concurrent amiodarone and haloperidol over a 24 month period found 49 patients who received concurrent therapy for 381 exposures. The mean increase in QTc interval was 9.8 msec; the average change in QTc interval per patient was 23.6 msec.(3) During phase 1 and 2 studies with levoketoconazole, which excluded patients with baseline QTcF interval greater than 470 msec, 4 (2.4%) patients experienced QTcF > 500 msec, and 23 (14.7%) patients experienced change-from-baseline QTcF > 60 msec.(2) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(4) Strong inhibitors of CYP3A4 that prolong QT include: levoketoconazole.(6,7) |
RECORLEV |
There are 59 severe interactions.
These drug interactions can produce serious consequences in most patients. Actions required for severe interactions include, but are not limited to, discontinuing one or both agents, adjusting dosage, altering administration scheduling, and providing additional patient monitoring. Review the full interaction monograph for more information.
| Drug Interaction | Drug Names |
|---|---|
| Amiodarone/Coumarin Anticoagulants SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Amiodarone inhibits the CYP2C9 mediated metabolism of the S-enantiomer, and the CYP3A4 mediated metabolism of the R-enantiomer of warfarin in vivo.(1-5) Amiodarone may also inhibit the metabolism of acenocoumarol(6) and other coumarin anticoagulants. CLINICAL EFFECTS: The concurrent administration of amiodarone and a coumarin anticoagulant may result in an increase in the clinical effects of the anticoagulant and an increased risk of bleeding.(1-23) It may take several weeks of concurrent therapy before the full effects of this interaction are noted. The effect of amiodarone on anticoagulant levels may continue for several months after amiodarone is discontinued. PREDISPOSING FACTORS: Amiodarone-induced thyrotoxicosis may increase the metabolic clearance of some vitamin K-dependent clotting factors, decreasing anticoagulant requirements.(8) In patients with the CYP2C9 intermediate and extensive metabolizer genotypes, long-acting amiodarone inhibition of CYP2C9 may increase the risk of phenoconversion to the poor metabolizer phenotype.(24) Patients with CYP2C9 intermediate metabolizer genotype are expected to be the most susceptible to this interaction and conversion to the poor metabolizer phenotype. Patients with a pre-existing CYP2C9 poor metabolizer genotype would be less susceptible to this interaction. However, these patients with reduced function genotypes (e.g. CYP2C9 *1/*3, *2/*2, *2/*3, and *3/*3) have an inherently higher risk for bleeding at usual anticoagulant doses and thus generally require lower doses to achieve effective and safe anticoagulation. In addition, CYP2C9 poor metabolizers require more a prolonged time (>2 to 4 weeks) to achieve maximum INR effect for a given dosage regimen than patients without these CYP2C9 variants. PATIENT MANAGEMENT: The US manufacturer of amiodarone states that amiodarone will almost always potentiate the anticoagulant response in patients receiving coumarin anticoagulants. They recommend decreasing the anticoagulant dosage by 1/3 to 1/2 when amiodarone therapy is initiated. Although amiodarone has a long half-life, significant increases in the INR/prothrombin time may start in 3 to 4 days. Monitor INR closely and adjust anticoagulant dose until stabile.(23) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. The time of highest risk for a coumarin-type drug interaction is when the precipitant drug is initiated or discontinued. Contact the prescriber before initiating, altering the dose or discontinuing either drug. DISCUSSION: Several studies and case reports have documented the potential interaction between warfarin and amiodarone. In several studies, the dosage of warfarin had to be decreased between 32.9% and 70% to maintain satisfactory prothrombin activity.(1-5,7-12) Several case reports and retrospective chart reviews have also documented the potential interaction between amiodarone and acenocoumarol. The dosage reduction of acenocoumarol required to maintain satisfactory prothrombin activity ranged from 20% to 60%.(13-19) A case report describes a 66-year-old male with a history of recurrent atrial fibrillation. While taking both amiodarone and a low-dose warfarin therapy, prothrombin times were prolonged, INR values were increased and bleeding occurred. Both drugs were withheld, and the effect of the interaction continued for an extended period of time.(20) One study evaluated the role desethylamiodarone, the active metabolite of amiodarone, played on concurrent warfarin therapy. After analyzing 25 patients with structural heart disease and arrhythmias, it was found that the concentration of desethylamiodarone played a larger role in augmenting the INR, than the concentration of amiodarone alone. Additional examination revealed that amiodarone primarily inhibits CYP1A2 and CYP3A4, whereas desethylamiodarone primarily inhibits CYP2C9, the isozyme responsible for the metabolism of S-warfarin.(21) An observational, cohort study reviewed the interaction of amiodarone with warfarin for a period of at least one year, while evaluating the adjustments needed to achieve an INR ratio between 2 and 3. After analyzing 43 patients, baseline warfarin therapy required a mean 44% reduction in dose after seven weeks of coadministration with amiodarone. Five subjects experienced minor bleeding. For patients receiving amiodarone maintenance, warfarin dose reductions were as follows: 400 mg/d, reduce warfarin dose 40%; 300 mg/d, reduce warfarin dose 35%; 200/d, reduce warfarin dose 30%; and 100 mg/d, reduce warfarin dose by 25%. All warfarin dose reductions are approximations and must be based on aggressive INR monitoring.(22) |
ANISINDIONE, DICUMAROL, JANTOVEN, WARFARIN SODIUM |
| Amiodarone; Dronedarone/Digitalis Glycosides SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Multiple mechanisms appear to be involved in the interaction between amiodarone and digitalis glycosides. Amiodarone decreases renal and nonrenal clearance of the digitalis glycosides, reduces digitalis glycoside volume of distribution, and increases digitalis glycoside bioavailability. In addition, digitalis glycosides depress the sinus node, producing bradycardia. Dronedarone increases digoxin levels by inhibiting the P-glycoprotein transporter. Digoxin also potentiates the electrophysiologic effects of dronedarone. CLINICAL EFFECTS: Concurrent amiodarone or dronedarone may result in elevated levels of and effects from digitalis glycosides. The magnitude of the interaction between amiodarone and digitalis glycosides is dependent on the route of administration of the digitalis glycoside and proportional to the amiodarone dose and serum level. Concurrent use of dronedarone and digoxin may increase the risk of arrhythmic or sudden death. Symptoms of digoxin toxicity can include anorexia, nausea, vomiting, headache, fatigue, malaise, drowsiness, generalized muscle weakness, hallucinations, visual disturbances, and arrhythmias. PREDISPOSING FACTORS: Low body weight, advanced age, impaired renal function, hypokalemia, hypercalcemia, and/or hypomagnesemia may increase the risk of digoxin toxicity. PATIENT MANAGEMENT: If concurrent therapy is warranted, monitor serum digitalis glycoside levels and observe the patient for symptoms of digitalis toxicity. Upon adding amiodarone or dronedarone, digitalis dosages should first be decreased in anticipation of an interaction, then adjusted accordingly. The dosage of oral digitalis glycoside may need to be decreased by 30-50%, or the frequency of administration may be reduced. For IV or IM digitalis glycoside, the dosage may need to be decreased by 15-30%, or the dosing frequency may be reduced. DISCUSSION: Plasma digitalis glycoside concentrations may increase several fold after adding amiodarone to the treatment regimen. The effect appears related to the dose of amiodarone, with higher doses of amiodarone being associated with the greatest increases. A study in 12 patients controlled on digitalis found that the addition of amiodarone for arrhythmias resulted in a 75.42% increase in digitalis plasma levels at initiation of amiodarone. At the mid-point of combination therapy, digitalis serum levels were elevated by 52.1%. Three patients experienced digitalis-related toxicity. In a study in 6 healthy volunteers, a 7-day course of amiodarone increased the maximum concentration (Cmax) of a single dose of digoxin (0.50 mg) from 2.92 ng/ml to 5.87 ng/ml. Digoxin area-under-curve (AUC) increased from 30.71 ng x h/mL to 40.63 ng x h/ml. Four out of the 6 subjects showed a decrease in the time to Cmax (Tmax) of digoxin. Concurrent use of amiodarone with IV or IM digoxin increased the digoxin AUC by 40%.(28) Increased serum digitalis glycoside levels with accompanying toxicity have been reported during concomitant administration of amiodarone and digoxin, digitalis, and digitoxin. Torsades de pointes has been reported. The subjects suffered torsades de pointes within 48 hours of amiodarone loading. Concurrent dronedarone and digoxin (dosages not stated) increased digoxin exposure 2.5-fold. In the ANDROMEDA and PALLAS trials, baseline use of digoxin was associated with an increased risk of arrhythmic or sudden death in dronedarone-treated patients when compared to the use of digoxin plus placebo. In patients not taking digoxin, there was no difference in sudden risk of death between dronedarone and placebo. In the ANDROMEDA trial, baseline digoxin use was reported in 6 of 16 dronedarone patients versus 1 of 16 placebo patients who died of arrythmia. In the PALLAS trial, baseline digoxin therapy was reported in 11 of 13 patients who died of arrhythmia, versus none of the 4 patients in the placebo group who died of arrythmia. Concomitant administration of dronedarone and oral digoxin increased the digoxin AUC by 150%.(29) |
DIGITEK, DIGOXIN, DIGOXIN MICRONIZED, LANOXIN, LANOXIN PEDIATRIC |
| Amiodarone/Diltiazem; Verapamil SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concomitant use of amiodarone with diltiazem or verapamil can contribute to depressant effects on the sinus and atrioventricular node and decreased contractility which can potentiate the electrophysiologic and hemodynamic effects of amiodarone. Diltiazem and verapamil may also increase amiodarone concentrations through CYP3A4 inhibition. Therefore, the effects of these drugs on the heart may be additive.(1-2) CLINICAL EFFECTS: Life-threatening effects, including bradycardia, sinus arrest and atrioventricular blockade may occur. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Carefully monitor patients for cardiac toxicity during combined treatment with amiodarone and diltiazem or verapamil. DISCUSSION: In a single case report, a 61-year-old female patient developed sinus arrest and low cardiac output with decreased urination when amiodarone was added to her treatment regimen of diltiazem and furosemide. After discontinuing diltiazem and amiodarone, the patient was successfully treated with ventricular pacing and pressor agents. The patient was later managed successfully with furosemide and amiodarone.(3) In a study, with severe sinus node dysfunction who were all taking diltiazem, six were concomitantly taking amiodarone and/or beta-blocking agents.(4) |
CARDIZEM, CARDIZEM CD, CARDIZEM LA, CARTIA XT, DILT-XR, DILTIAZEM 12HR ER, DILTIAZEM 24HR ER, DILTIAZEM 24HR ER (CD), DILTIAZEM 24HR ER (LA), DILTIAZEM 24HR ER (XR), DILTIAZEM HCL, DILTIAZEM HCL-0.7% NACL, DILTIAZEM HCL-0.9% NACL, DILTIAZEM HCL-NACL, DILTIAZEM-D5W, MATZIM LA, TIADYLT ER, TIAZAC, TRANDOLAPRIL-VERAPAMIL ER, VERAPAMIL ER, VERAPAMIL ER PM, VERAPAMIL HCL, VERAPAMIL SR |
| Procainamide/Amiodarone SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Unknown. Proposed pharmacokinetic mechanisms for this interaction may stem from inhibition of hepatic cytochromes and/or competitive inhibition of renal elimination via active tubular secretion.(1) Pharmacodynamic effects have also been described.(1-3) Procainamide and amiodarone each increase QRS and QTc intervals; these effects may be additive. CLINICAL EFFECTS: Serum procainamide concentrations may be elevated increasing the pharmacologic and toxic effects. Increased QTc intervals may result in potentially life-threatening arrhythmias such as torsades de pointes. PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The US manufacturer of amiodarone recommends concomitant therapy be reserved for patients with life-threatening ventricular arrhythmias who are incompletely responsive to a single agent or incompletely responsive to amiodarone. If concomitant therapy is required, the dosage of procainamide should be reduced by 30 - 50% beginning several days after amiodarone is initiated.(2) Monitor the serum procainamide concentration and observe the patient for conduction disturbances, exacerbation of tachyarrhythmias and signs of procainamide toxicity.(1,2) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Concurrent administration of procainamide and amiodarone can produce increases in the half-life and serum procainamide concentration as well as an increase in the serum level of the active metabolite N-acetylprocainamide. Hypotension and arrhythmias have been reported. In some patients the dose of procainamide may need to be reduced by 20% to 25%. Electrophysiologic effects seem to be additive. One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
PROCAINAMIDE HCL |
| Thioridazine/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Thioridazine has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of thioridazine with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: Use of thioridazine in patients with reduced CYP2D6 activity (either through genetic predisposition or use of drugs that inhibit CYP2D6 activity) may increase the risk of torsades de pointes and/or sudden death in patients taking thioridazine.(1) The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. impairment in the drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The manufacturer of thioridazine states under contraindications that the use of thioridazine should be avoided in combination with other drugs that are known to prolong the QTc interval. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
THIORIDAZINE HCL, THIORIDAZINE HYDROCHLORIDE |
| Agalsidase/Amiodarone SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Amiodarone may inhibit the intracellular activity of alpha-galactosidase.(1,2) CLINICAL EFFECTS: Concurrent use of agalsidase with amiodarone may result in decreased effectiveness of agalsidase.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of agalsidase alpha in Canada(1) and the manufacturer of agalsidase beta in the United Kingdom(2) state that agalsidase should not be administered with amiodarone. DISCUSSION: Because of a theoretical risk of inhibited intracellular activity of alpha-galactosidase activity, the manufacturer of agalsidase alpha in Canada(1) and the manufacturer of agalsidase beta in the United Kingdom(2) state that agalsidase should not be administered with amiodarone. |
FABRAZYME |
| Amiodarone/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Amiodarone has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-3) CLINICAL EFFECTS: The concurrent use of amiodarone with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1-3) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(6) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(6) PATIENT MANAGEMENT: The US manufacturer of amiodarone states that the concurrent use of QT prolonging agents should be avoided and that the need to co-administer amiodarone with any other drug known to prolong the QTc interval must be based on a careful assessment of the potential risks and benefits of doing so for each patient.(3) The Australian(1) and UK(2) manufacturers of amiodarone states that concurrent use of agents known to cause torsades de pointes is contraindicated. DISCUSSION: QTc prolongation has been reported during concurrent amiodarone and azole antifungals, fluoroquinolones, and macrolide antibiotics.(3) A retrospective review of patients who received concurrent amiodarone and haloperidol over a 24 month period found 49 patients who received concurrent therapy for 381 exposures. The mean increase in QTc interval was 9.8 msec; the average change in QTc interval per patient was 23.6 msec.(4) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(5) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
ADLARITY, ARICEPT, ARSENIC TRIOXIDE, AVELOX IV, AZITHROMYCIN, CAPRELSA, CELEXA, CESIUM CHLORIDE, CHLOROQUINE PHOSPHATE, CHLORPROMAZINE HCL, CILOSTAZOL, CIPRO, CIPROFLOXACIN, CIPROFLOXACIN HCL, CIPROFLOXACIN-D5W, CITALOPRAM HBR, DASATINIB, DIFLUCAN, DISKETS, DONEPEZIL HCL, DONEPEZIL HCL ODT, E.E.S. 200, E.E.S. 400, ERY-TAB, ERYPED 200, ERYPED 400, ERYTHROCIN LACTOBIONATE, ERYTHROCIN STEARATE, ERYTHROMYCIN, ERYTHROMYCIN ESTOLATE, ERYTHROMYCIN ETHYLSUCCINATE, ERYTHROMYCIN LACTOBIONATE, ERZOFRI, ESCITALOPRAM OXALATE, FANAPT, FLECAINIDE ACETATE, FLUCONAZOLE, FLUCONAZOLE-NACL, HALDOL DECANOATE 100, HALDOL DECANOATE 50, HALOPERIDOL, HALOPERIDOL DECANOATE, HALOPERIDOL DECANOATE 100, HALOPERIDOL LACTATE, INVEGA, INVEGA HAFYERA, INVEGA SUSTENNA, INVEGA TRINZA, ISRADIPINE, LEVOFLOXACIN, LEVOFLOXACIN HEMIHYDRATE, LEVOFLOXACIN-D5W, LEXAPRO, MEMANTINE HCL-DONEPEZIL HCL ER, METHADONE HCL, METHADONE HCL-0.9% NACL, METHADONE HCL-NACL, METHADONE INTENSOL, METHADOSE, MOXIFLOXACIN, MOXIFLOXACIN HCL, NAMZARIC, PALIPERIDONE ER, PENTAM 300, PENTAMIDINE ISETHIONATE, SEVOFLURANE, SIGNIFOR, SIGNIFOR LAR, SIRTURO, SPRYCEL, TRISENOX, ULTANE, ZITHROMAX, ZITHROMAX TRI-PAK |
| Atazanavir/Amiodarone; Ajmaline; Quinidine SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Atazanavir (unboosted or boosted with cobicistat or ritonavir) may inhibit the metabolism of ajmaline, amiodarone, and quinidine at CYP3A4.(1-4) CLINICAL EFFECTS: Concurrent use of atazanavir (unboosted or boosted with cobicistat or ritonavir) with ajmaline, amiodarone, or quinidine may result in increased levels of these antiarrhythmics and serious and/or life threatening arrhthymias, including torsades de pointes.(1-4) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(5) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(5) PATIENT MANAGEMENT: The US manufacturer of atazanavir states that the coadministration of atazanavir-ritonavir with amiodarone or quinidine is contraindicated.(1) If unboosted atazanavir is used concurrently with amiodarone, use caution and perform therapeutic concentration monitoring.(1) The Canadian and UK manufacturers of atazanavir contraindicate use of atazanavir with quinidine.(2-3) The US manufacturer of atazanavir-cobicistat states that clinical monitoring is recommended when coadministered with amiodarone or quinidine.(6) The UK manufacturer of atazanavir-cobicistat states that concurrent amiodarone and quinidine are contraindicated.(7) If concurrent use is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Atazanavir is a moderate inhibitor of CYP3A4.(8) |
ATAZANAVIR SULFATE, EVOTAZ, REYATAZ |
| Ivabradine/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: QT prolongation may be exacerbated by ivabradine-induced reduction in heart rate.(1) CLINICAL EFFECTS: Concurrent use of ivabradine and agents known to prolong the QT interval may exacerbate QT prolongation.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The UK, AU, and Canadian manufacturer of ivabradine states that concurrent use with cardiovascular and non-cardiovascular QT prolonging agents should be avoided.(1,4,5) The Canadian manufacturer states that if concurrent therapy is deemed necessary, close cardiac monitoring (12-lead ECG) is required. Depending on the ECG results, ivabradine dosing may need to be decreased or stopped.(4) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2) |
CORLANOR, IVABRADINE HCL |
| Tizanidine/Selected Antiarrhythmics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Amiodarone, mexiletine, propafenone, and verapamil may inhibit the metabolism of tizanidine by CYP1A2.(1) CLINICAL EFFECTS: Concurrent use of amiodarone, mexiletine, propafenone, or verapamil may result in elevated levels of and effects from tizanidine, including hypotension, bradycardia, drowsiness, sedation, and decreased psychomotor function. PREDISPOSING FACTORS: The risk of anticholinergic toxicities including cognitive decline, delirium, falls and fractures is increased in geriatric patients using more than one medicine with anticholinergic properties.(2) PATIENT MANAGEMENT: The US manufacturer of tizanidine states that concurrent use of tizanidine with inhibitors of CYP1A2, such as zileuton, should be avoided. If concurrent use is warranted, tizanidine should be initiated with a 2 mg dose and increased in 2-4 mg steps daily based on patient response to therapy. If adverse reactions such as hypotension, bradycardia, or excessive drowsiness occur, reduce or discontinue tizanidine therapy.(1) DISCUSSION: In a study in 10 healthy subjects, concurrent fluvoxamine, another inhibitor of CYP1A2, increased tizanidine maximum concentration (Cmax), area-under-curve (AUC), and half-life (T1/2) by 12-fold, 33-fold, and 3-fold, respectively. Significant decreases in blood pressure and increases in drowsiness and psychomotor impairment occurred.(1) In a study in 10 healthy subjects, concurrent ciprofloxacin, another inhibitor of CYP1A2, increased tizanidine Cmax and AUC by 7-fold and 10-fold, respectively. Significant decreases in blood pressure and and increases in drowsiness and psychomotor impairment occurred.(1) In an open label study in 12 healthy subjects, concurrent tizanidine (single 2 mg dose) with mexiletine (50 mg, 3 times a day for one day and then 2 times for one day), increased tizanidine Cmax and AUC by 3.1-fold and 3.6-fold, respectively. Subjects were found to have significantly lower systolic and diastolic blood pressure after concurrent administration as well as drowsiness, dry mouth, or dizziness.(3) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
TIZANIDINE HCL, ZANAFLEX |
| Dabigatran/Selected P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Dabigatran etexilate is a substrate for the P-glycoprotein (P-gp) system. Inhibition of intestinal P-gp leads to increased absorption of dabigatran.(1-3) CLINICAL EFFECTS: The concurrent use dabigatran with P-gp inhibitors may lead to elevated plasma levels of dabigatran, increasing the risk for bleeding. PREDISPOSING FACTORS: Factors associated with an increased risk for bleeding include renal impairment, concomitant use of P-gp inhibitors, patient age >74 years, coexisting conditions (e.g. recent trauma) or use of drugs (e.g. NSAIDs) associated with bleeding risk, and patient weight < 50 kg.(1-4) PATIENT MANAGEMENT: Assess renal function and evaluate patient for other pre-existing risk factors for bleeding prior to initiating concurrent therapy. The US manufacturer of dabigatran states that the concurrent use of dabigatran and P-gp inhibitors should be avoided in atrial fibrillation patients with severe renal impairment (CrCl less than 30 ml/min) and in patients with moderate renal impairment (CrCl less than 50 ml/min) being treated for or undergoing prophylaxis for deep vein thrombosis (DVT) or pulmonary embolism (PE). The interaction with P-gp inhibitors can be minimized by taking dabigatran several hours apart from the P-gp inhibitor dose.(1) The concomitant use of dabigatran with P-gp inhibitors has not been studied in pediatric patients but may increase exposure to dabigatran.(1) While the US manufacturer of dabigatran states that no dosage adjustment is necessary in other patients,(1) the Canadian manufacturer of dabigatran states that concomitant use of strong P-gp inhibitors (e.g., glecaprevir-pibrentasvir) is contraindicated. When dabigatran is used for the prevention of venous thromboembolism (VTE) after total hip or knee replacement concurrently with amiodarone, quinidine, or verapamil, the dose of dabigatran should be reduced from 110 mg twice daily to 150 mg once daily. For patients with CrCl less than 50 ml/min on verapamil, a further dabigatran dose reduction to 75 mg once daily should be considered. Verapamil should be given at least 2 hours after dabigatran to minimize the interaction.(2) The UK manufacturer of dabigatran also states the use of dabigatran with strong P-gp inhibitors (e.g., cyclosporine, glecaprevir-pibrentasvir or itraconazole) is contraindicated. Concurrent use of ritonavir is not recommended. When dabigatran is used in atrial fibrillation patients and for treatment of DVT and PE concurrently with verapamil, the UK manufacturer recommends reducing the dose of dabigatran from 150 mg twice daily to 110 mg twice daily, taken simultaneously with verapamil. When used for VTE prophylaxis after orthopedic surgery concurrently with amiodarone, quinidine, or verapamil, the dabigatran loading dose should be reduced from 110 mg to 75 mg, and the maintenance dose should be reduced from 220 mg daily to 150 mg daily, taken simultaneously with the P-gp inhibitor. For patients with CLcr 30-50 mL/min on concurrent verapamil, consider further lowering the dabigatran dose to 75 mg daily.(3) If concurrent therapy is warranted, monitor patients for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Consider regular monitoring of hemoglobin, platelet levels, and/or activated partial thromboplastin time (aPTT) or ecarin clotting time (ECT). When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. DISCUSSION: When dabigatran was co-administered with amiodarone, the extent and rate of absorption of amiodarone and its active metabolite DEA were essentially unchanged. The dabigatran area-under-curve (AUC) and maximum concentration (Cmax) were increased by about 60% and 50%, respectively;(1,2) however, dabigatran clearance was increased by 65%.(1) Pretreatment with quinidine (200 mg every 2 hours to a total dose of 1000 mg) increased the AUC and Cmax of dabigatran by 53% and 56%, respectively.(1,2) Chronic administration of immediate release verapamil one hour prior to dabigatran dose increased dabigatran AUC by 154%.(4) Administration of dabigatran two hours before verapamil results in a negligible increase in dabigatran AUC.(1) Administration of sofosbuvir-velpatasvir-voxilaprevir (400/100/200 mg daily) increased the Cmax and AUC of a single dose of dabigatran (75 mg) by 2.87-fold and 2.61-fold, respectively.(5) Simultaneous administration of glecaprevir-pibrentasvir (300/120 mg daily) with a single dose of dabigatran (150 mg) increased the Cmax and AUC by 2.05-fold and 2.38-fold, respectively.(6) A retrospective comparative effectiveness cohort study including data from 9,886 individuals evaluated adverse bleeding rates with standard doses of oral anticoagulants with concurrent verapamil or diltiazem in patients with nonvalvular atrial fibrillation and normal kidney function. The study compared rates of bleeding following co-administration of either dabigatran, rivaroxaban, or apixaban with verapamil or diltiazem, compared to co-administration with amlodipine or metoprolol. Results of the study found that concomitant dabigatran use with verapamil or diltiazem was associated with increased overall bleeding (hazard ratio (HR) 1.52; 95% confidence interval (CI), 1.05-2.20, p<0.05) and increased overall GI bleeding (HR 2.16; 95% CI, 1.30-3.60, p<0.05) when compared to amlodipine. When compared to metoprolol, concomitant dabigatran use with verapamil or diltiazem was also associated with increased overall bleeding (HR, 1.43; 95% CI, 1.02-2.00, p<0.05) and increased overall GI bleeding (HR, 2.32; 95% CI, 1.42-3.79, p<0.05). No association was found between increased bleeding of any kind and concurrent use of rivaroxaban or apixaban with verapamil or diltiazem.(7) A summary of pharmacokinetic interactions with dabigatran and amiodarone or verapamil concluded that concurrent use is considered safe if CrCl is greater than 50 ml/min but should be avoided if CrCl is less than 50 ml/min in VTE and less than 30 ml/min for NVAF. Concurrent use with diltiazem was considered safe.(9) P-gp inhibitors include amiodarone, asunaprevir, belumosudil, capmatinib, carvedilol, cimetidine, conivaptan, cyclosporine, daclatasvir, danicopan, daridorexant, diosmin, erythromycin, flibanserin, fostamatinib, ginseng, glecaprevir, indinavir, itraconazole, ivacaftor, josamycin, lapatinib, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pibrentasvir, propafenone, quinidine, ranolazine, ritonavir, sotorasib, telaprevir, telithromycin, tepotinib, tezacaftor, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, voclosporin, and voxilaprevir.(1-9) |
DABIGATRAN ETEXILATE, PRADAXA |
| Topotecan/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of P-glycoprotein may increase the absorption of topotecan.(1) CLINICAL EFFECTS: The concurrent administration of topotecan with an inhibitor of P-glycoprotein may result in elevated levels of topotecan and signs of toxicity. These signs may include but are not limited to anemia, diarrhea, and thrombocytopenia.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of topotecan states that the use of topotecan and P-glycoprotein inhibitors should be avoided. If concurrent use is warranted, carefully monitor patients for adverse effects.(1) DISCUSSION: In clinical studies, the combined use of elacridar (100 mg to 1000 mg) increased the area-under-curve (AUC) of topotecan approximately 2.5-fold.(1) Oral cyclosporine (15 mg/kg) increased the AUC of topotecan lactone and total topotecan to 2-fold to 3-fold of the control group, respectively.(1) P-gp inhibitors linked to this monograph include: adagrasib, amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, bosutinib, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, cyclosporine, danicopan, daridorexant, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fostamatinib, ginseng, hydroquinidine, isavuconazonium, itraconazole, ivacaftor, josamycin, ketoconazole, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pibrentasvir/glecaprevir, pirtobrutinib, propafenone, quinidine, ranolazine, ritonavir, selpercatinib, sotorasib, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(2,3) |
HYCAMTIN |
| Amiodarone; Dronedarone/Rifampin; Rifapentine SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Rifampin and rifapentine, strong inducers of CYP3A4, may induce the metabolism of amiodarone(1) and dronedarone.(2) CLINICAL EFFECTS: Concurrent or recent use of rifampin or rifapentine may result in decreased levels and effectiveness of amiodarone(1) and dronedarone.(2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid the use of rifampin or rifapentine in patients maintained on amiodarone or dronedarone. If concurrent use is warranted, monitor patients for decreased antiarrythmic response. DISCUSSION: Concurrent rifampin has been shown to decrease levels of amiodarone and desethylamiodarone.(1) There is a case report of increased palpitations and triggering of an internal defibrillator that occurred five weeks after the addition of rifampin to amiodarone therapy.(3) Concurrent use of rifampin and dronedarone (exact dosages not stated) decreased dronedarone exposure by 80%.(2) |
PRIFTIN, RIFADIN, RIFAMPIN |
| Amiodarone/Selected Strong CYP3A4 Inducers SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Strong CYP3A4 inducers may induce the metabolism of amiodarone by CYP3A4.(1) Amiodarone may inhibit the metabolism of phenytoin.(1) CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inducers may result in decreased levels and effectiveness of amiodarone.(1) Concurrent use of amiodarone and phenytoin may also result in elevated levels of and toxicity from phenytoin.(1) PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. PATIENT MANAGEMENT: The US manufacturer of amiodarone states concurrent use with CYP3A4 inducers may decrease amiodarone serum concentrations. Consider monitoring amiodarone serum concentrations during concurrent use.(1) Monitor phenytoin levels when initiating or discontinuing amiodarone in patients maintained on phenytoin. DISCUSSION: In a study in cardiac patients, amiodarone had no effect on carbamazepine levels.(2) In a study in 5 healthy subjects, phenytoin (2-4 mg/kg/day) decreased amiodarone levels (200 mg daily) by 32% to 49%.(3) In a study in 7 healthy subject, amiodarone (200 mg daily for three weeks) increased phenytoin (5 mg/kg) area-under-curve (AUC) by 40%.(6) In a separate study in 7 healthy subjects, amiodarone (200 mg daily for 6 weeks) increased phenytoin (2-4 mg/kg/day) by 40%.(5) Concurrent use of rifampin, another potent inducer of CYP3A4, and amiodarone has been shown to decrease levels of amiodarone and desethylamiodarone.(1) Strong CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, carbamazepine, enzalutamide, lumacaftor, mitotane, phenobarbital, phenytoin and primidone.(6) |
ASA-BUTALB-CAFFEINE-CODEINE, ASCOMP WITH CODEINE, BUTALB-ACETAMINOPH-CAFF-CODEIN, BUTALBITAL, BUTALBITAL-ACETAMINOPHEN, BUTALBITAL-ACETAMINOPHEN-CAFFE, BUTALBITAL-ASPIRIN-CAFFEINE, CARBAMAZEPINE, CARBAMAZEPINE ER, CARBATROL, CEREBYX, DILANTIN, DILANTIN-125, DONNATAL, EPITOL, EQUETRO, ERLEADA, FIORICET, FIORICET WITH CODEINE, FOSPHENYTOIN SODIUM, LYSODREN, MITOTANE, MYSOLINE, ORKAMBI, PENTOBARBITAL SODIUM, PHENOBARBITAL, PHENOBARBITAL SODIUM, PHENOBARBITAL-BELLADONNA, PHENOBARBITAL-HYOSC-ATROP-SCOP, PHENOHYTRO, PHENYTEK, PHENYTOIN, PHENYTOIN SODIUM, PHENYTOIN SODIUM EXTENDED, PRIMIDONE, SEZABY, TEGRETOL, TEGRETOL XR, TENCON, XTANDI |
| Toremifene/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Toremifene has been shown to prolong the QTc interval in a dose-related and concentration-related manner.(1) Concurrent use of toremifene and agents known to prolong the QT interval may result in additive or synergistic effects on the QTc interval.(1,2) CLINICAL EFFECTS: Concurrent administration may result in prolongation of the QTc interval and life-threatening cardiac arrhythmias, including torsades de pointes.(1,2) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The US manufacturer of toremifene states that concurrent use should be avoided. If treatment with an agent known to prolong the QT interval is required, toremifene therapy should be interrupted. If it is not possible to interrupt toremifene therapy, patients should be closely monitored. Electrocardiograms (ECGs) should be obtained.(1) Consider obtaining serum calcium, magnesium, and potassium levels and correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. The UK manufacturer of toremifene states that the use of other drugs that are known to prolong the QTc interval is contraindicated. These agents include class IA and III antiarrhythmics, astemizole, bepridil, cisapride, diphemanil, erythromycin IV, halofantrine, haloperidol, mizolastine, moxifloxacin, pentamidine, phenothiazines, pimozide, sertindole, terfenadine, and vincamine IV.(2) DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
FARESTON, TOREMIFENE CITRATE |
| Quinine/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Quinine has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of quinine with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The US manufacturer of quinine states that concurrent use with agents known to prolong the QT interval should be avoided.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports. |
QUALAQUIN, QUININE HCL, QUININE SULFATE |
| Quetiapine/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The use of quetiapine in patients maintained on agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The US manufacturer of quetiapine states that concurrent use with agents known to prolong the QT interval should be avoided.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Although quetiapine was not associated with QT or QTc changes in clinical trials, QT prolongation has been reported in post-marketing reports in conjunction with the use of other agents known to prolong the QT interval.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(2) |
QUETIAPINE FUMARATE, QUETIAPINE FUMARATE ER, SEROQUEL, SEROQUEL XR |
| Radioactive Iodide/Agents that Affect Iodide SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Many compounds can affect iodide protein binding and alter iodide pharmacokinetics and pharmacodynamics.(1) CLINICAL EFFECTS: Compounds that affect iodide pharmacokinetics and pharmacodynamics may impact the effectiveness of radioactive iodide.(1) PREDISPOSING FACTORS: Compounds that affect iodide pharmacokinetics and pharmacodynamics are expected to have the most impact during therapy using radioactive iodide. Diagnostic procedures would be expected to be impacted less. PATIENT MANAGEMENT: Discuss the use of agents that affect iodide pharmacokinetics and pharmacodynamics with the patient's oncologist.(1) Because indocyanine green contains sodium iodide, the iodine-binding capacity of thyroid tissue may be reduced for at least one week following administration. Do not perform radioactive iodine uptake studies for at least one week following administration of indocyanine green.(2) The manufacturer of iopamidol states administration may interfere with thyroid uptake of radioactive iodine and decrease therapeutic and diagnostic efficacy. Avoid thyroid therapy or testing for up to 6 weeks post administration of iopamidol.(3) DISCUSSION: Many agents interact with radioactive iodine. The average duration of effect is: anticoagulants - 1 week antihistamines - 1 week anti-thyroid drugs, e.g: carbimazole, methimazole, propylthiouracil - 3-5 days corticosteroids - 1 week iodide-containing medications, e.g: amiodarone - 1-6 months expectorants - 2 weeks Lugol solution - 3 weeks saturated solution of potassium iodine - 3 weeks vitamins - 10-14 days iodide-containing X-ray contrast agents - up to 1 year lithium - 4 weeks phenylbutazone - 1-2 weeks sulfonamides - 1 week thyroid hormones (natural or synthetic), e.g.: thyroxine - 4 weeks tri-iodothyronine - 2 weeks tolbutamide - 1 week topical iodide - 1-9 months (1) |
ADREVIEW, JEANATOPE, MEGATOPE, SODIUM IODIDE I-123 |
| Lomitapide (Less Than or Equal To 30 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of lomitapide.(1) Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Thus even weak CYP3A4 inhibitors may affect lomitapide exposure (AUC, area-under-curve). CLINICAL EFFECTS: Concurrent use of a weak inhibitor of CYP3A4 may result in 2-fold increases in lomitapide levels and toxicity from lomitapide.(1) PREDISPOSING FACTORS: This interaction may be more severe in patients with hepatic impairment or with end-stage renal disease.(1) PATIENT MANAGEMENT: The maximum lomitapide dose should be 30 mg daily for patients taking concomitant weak CYP3A4 inhibitors. Due to lomitapide's long half-life, it may take 1 to 2 weeks to see the full effect of this interaction. When initiating a weak CYP3A4 inhibitor in patients taking lomitapide 10 mg daily or more, decrease the dose of lomitapide by 50%. In patients taking lomitapide 5 mg daily, continue current dose. DISCUSSION: Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Based upon interactions with stronger inhibitors, weak inhibitors of CYP3A4 are predicted to increase lomitapide area-under-curve(AUC) 2-fold.(1) Weak CYP3A4 inhibitors linked to this interaction include alprazolam, amiodarone, amlodipine, asciminib, atorvastatin, azithromycin, Baikal skullcap, belumosudil, bicalutamide, blueberry juice, brodalumab, cannabidiol, capivasertib, cilostazol, cimetidine, ciprofloxacin, chlorzoxazone, clotrimazole, cranberry juice, cyclosporine, daridorexant, delavirdine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, larotrectinib, lacidipine, lapatinib, lazertinib, leflunomide, levamlodipine, linagliptin, lurasidone, maribavir, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, vonoprazan, and zileuton.(1-3) |
JUXTAPID |
| Trazodone (Greater Than or Equal To 100 mg)/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of trazodone with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1,2) CLINICAL EFFECTS: The use of trazodone in patients maintained on agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1,2) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of trazodone states that concurrent use with agents known to prolong the QT interval should be avoided.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Trazodone has been reported to prolong the QT interval.(1) A thorough QT study in 20 subjects evaluated the effects of trazodone at doses of 20 mg, 60 mg and 140 mg. There was no evidence of QTc prolongation at the lowest trazodone dose of 20mg (mean effect on QTc of 4.5 ms 95% CI 3.7-5.3 ms), but at 60 mg and 140 mg, there was a significant effect that exceeds the E14 FDA Guidelines threshold of prolonging the QT/QTc interval by more than 5 ms. The study found a dose-dependent effect on QTc prolongation starting at 60 mg with a mean effect on QTc of 12.3 ms (95% CI 11-13.6 ms) and increasing with a 140 mg dose to a mean effect on QTc of 19.8 ms (95% CI 17.6-22.1).(3) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(4) |
RALDESY, TRAZODONE HCL |
| Selected Antiarrhythmics/Elvitegravir-Cobicistat SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Cobicistat may inhibit the metabolism of amiodarone, disopyramide, flecainide, propafenone, and quinidine.(1,2) CLINICAL EFFECTS: Concurrent use of cobicistat and amiodarone, disopyramide, flecainide, propafenone, or quinidine may result in elevated levels of these antiarrhythmics and serious and/or life-threatening effects including QT prolongation or torsades de pointes.(1,2) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The concurrent use of cobicistat and amiodarone, disopyramide, flecainide, propafenone, or quinidine should be used with caution and clinical monitoring is recommended with concomitant use.(1,2) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Cobicistat may inhibit the metabolism and increase levels of amiodarone, disopyramide, flecainide, propafenone, or quinidine.(1,2) Selected antiarrhythmics linked to this monograph include: ajmaline, amiodarone, bepridil, disopyramide, flecainide, propafenone, and quinidine. |
GENVOYA, STRIBILD |
| Selected Quinolones/Selected Class IA & III Antiarrhythmics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Unknown. Possibly additive or synergistic effects on the QTc interval.(1-7) Proposed mechanisms for this interaction may stem from quinolone inhibition of hepatic cytochromes and/or competitive inhibition of renal elimination via active tubular secretion.(2-7) Norfloxacin is a moderate CYP3A4 inhibitor. Amiodarone, disopyramide, and dronedarone are CYP3A4 substrates. CLINICAL EFFECTS: Increased QTc intervals which may result in potentially life-threatening arrhythmias such as torsades de pointes. PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(1) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(1) PATIENT MANAGEMENT: The manufacturers of gatifloxacin,(2) gemifloxacin,(3) lomefloxacin,(4), norfloxacin(5) and ofloxacin(6) state that these agents should be avoided in patients receiving Class IA and III antiarrhythmic agents. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Gatifloxacin,(2) gemifloxacin,(3) lomefloxacin,(4), norfloxacin(5) and ofloxacin(6) have the potential to prolong the QTc interval. Torsades de pointes has been reported during post-marketing surveillance in patients receiving lomefloxacin.(4) A pharmacokinetic and pharmacodynamic study evaluated the interaction between ofloxacin and procainamide. Nine healthy volunteers randomly received one dose of procainamide 1 G, including or excluding pretreatment with ofloxacin (400 mg b.i.d. for 5 doses). A 12-point EKG monitored for any pharmacodynamic abnormalities and blood urine samples evaluated for pharmacokinetic variations. The AUC and Cmax for procainamide were increased by 27% and 21% with clearance diminished by 22%.(7) |
GATIFLOXACIN SESQUIHYDRATE, OFLOXACIN |
| Amiodarone/Sofosbuvir + Selected Direct Acting Antivirals SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The exact mechanism is unknown.(1-7) CLINICAL EFFECTS: Concurrent or recent use of amiodarone with sofosbuvir plus another direct acting antiviral may result in symptomatic bradycardia, which can be life-threatening, and cardiac arrest.(1-7) PREDISPOSING FACTORS: Patients who are also receiving a beta-blocker or who have underlying cardiac comorbidities and/or advanced liver disease may be at a higher risk of developing symptomatic bradycardia.(1-7) PATIENT MANAGEMENT: Concurrent use is potentially life-threatening. The FDA advises that sofosbuvir/ledipasvir or sofosbuvir combined with another direct acting antiviral should not be combined with amiodarone(1) and the manufacturer states concurrent therapy should only be used when other alternative antiarrhythmic treatments are not tolerated or contraindicated.(2-7) The AASLD/IDSA hepatitis C guidelines state patients being treated with amiodarone should not receive sofosbuvir-based regimens due to risk of life-threatening arrhythmias. Due to the long half-life of amiodarone, the guidelines advise that persons should be off amiodarone for at least 6 months before initiating sofosbuvir. If alternatives are deemed not to be clinically appropriate and the decision is made to start sofosbuvir in this setting, continued vigilance for bradycardia should be exercised.(8) If alternative treatment options are unavailable, or if sofosbuvir is initiated in a patient in whom amiodarone was discontinued in the previous three months, counsel patients about the risk of serious symptomatic bradycardia. Patients should undergo cardiac monitoring in an in-patient setting for the first 48 hours of coadministration and should then self-monitor their heart rate (or be monitored in a doctor's office) on a daily basis for at least the first two-weeks of treatment.(1-7) Instruct patients receiving concurrent therapy (and patients in whom amiodarone was recently discontinued) to seek medical attention immediately if they develop signs of symptomatic bradycardia, which may include: near-fainting or fainting, dizziness or lightheadedness, malaise, weakness, excessive tiredness, shortness of breath, chest pains, and/or confusion or memory problems.(1-7) DISCUSSION: Nine cases of symptomatic bradycardia have been reported with sofosbuvir in combination with ledipasvir (n=3), simeprevir (n=1), or daclatasvir (n=5; marketed internationally, investigational agent in US). Seven patients were also receiving a beta-blocker. Six cases occurred within the first 24 hours of concurrent therapy, while the other cases occurred within 2-12 days of initiation of concurrent therapy. One case involved a fatal cardiac arrest and 3 required pacemaker insertion. In 3 cases, symptomatic bradycardia recurred following rechallenge with sofosbuvir. In one case, amiodarone was discontinued and sofosbuvir was re-initiated 8 weeks later with no reoccurrence of bradycardia.(1,2) |
EPCLUSA, HARVONI, LEDIPASVIR-SOFOSBUVIR, SOFOSBUVIR-VELPATASVIR, SOVALDI, VOSEVI |
| Osimertinib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Osimertinib prolongs the QTc interval.(1) Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(2,3) CLINICAL EFFECTS: The concurrent use of osimertinib with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(2,3) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: Osimertinib prolongs the QT interval. Premarket clinical trials excluded patients with a baseline QTc > or = 470 msec. In these trials 11 patients (2.7%) had increase in QTc greater than 60 msec.(1) Manufacturer recommendations: when feasible, avoid concurrent administrations of osimertinib with drugs known to prolong the QTc interval. Conduct baseline and periodic monitoring with ECGs in patients with congenital long QTc syndrome, congestive heart failure, electrolyte abnormalities (e.g. serum calcium, magnesium, and potassium), or those taking medications known to prolong the QT interval.(1) Dose adjustments (1): - If QTc is greater than 500 msec on at least 2 separate ECGs, withhold osimertinib until QTc is < 481 msec or recovery to baseline (if baseline QTc was greater than or equal to 481 msec), then resume osimertinib at 40 mg per day. - For QTc prolongation with signs or symptoms of life threatening arrhythmia, permanently discontinue osimertinib. During concomitant therapy with another QT prolonging agent, monitor patients closely for prolongation of the QT interval.(1) Obtain serum calcium, magnesium, and potassium levels and monitoring ECG at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: A retrospective review of 618 cancer patients treated with 902 administrations of tyrosine kinase inhibitors were evaluated for rate and incidence of QTc prolongation. In patients who received osimertinib, QTc prolongation was identified in 4 (25%) with 1 (25%) having Grade 1 (QTc 450-480 ms) and 1 (25%) having Grade 2 (QTc 480-500 ms). Grade 3 events occurred in 1 (25%) having QTc greater than or equal to 500 ms and 1 (25%) having QTc change greater than or equal to 60 ms. No patients had ventricular tachycardia, sudden cardiac death, or TdP.(4) In clinical studies of 1813 patients treated with osimertinib monotherapy, 1.1% of patients were found to have a QTc interval greater than 500 ms and 4.3% of patients had an increase from baseline QTc > 60 ms.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2) |
TAGRISSO |
| Pimavanserin/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Pimavanserin prolongs the QTc interval.(1) Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(2,3) CLINICAL EFFECTS: The concurrent use of pimavanserin with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(2,3) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: Avoid the use of pimavanserin in patients receiving QT prolonging agents.(1) During concomitant therapy with another QT prolonging agent, monitor patients closely for prolongation of the QT interval.(1) Obtain serum calcium, magnesium, and potassium levels and monitoring ECG at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In thorough-QT study, pimavanserin (at twice the therapeutic dose) found that the maximum mean change was 13.5 (16.6) msec. In placebo-controlled effectiveness studies, mean increases of 5-8 msec were observed with normal dosages of 37 mg daily. Sporadic QTcF values of equal to or greater than 500 msec and change from baseline values equal to or greater than 60 msec were observed at this dose as well.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2) |
NUPLAZID |
| Hydroxyzine/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of hydroxyzine with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-4) CLINICAL EFFECTS: The concurrent use of hydroxyzine with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1-4) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(5) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(5) Doses of hydroxyzine greater than 100 mg/day may also increase the risk.(1,2) PATIENT MANAGEMENT: Concurrent use of hydroxyzine with agents known to prolong the QT interval is contraindicated in Canada(1,2) and the UK.(3) The US manufacturer states that concurrent use should be approached with caution.(4) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In vitro data indicates that hydroxyzine blocks the hERG channel, which results in the potential risk of QT interval prolongation.(6) In a placebo controlled, non-thorough QT study, 10 patients in the placebo group (n=152) had a change in QT interval from baseline between 30 ms and 60 ms and one patient presented a change from baseline higher than 60 ms. In the hydroxyzine group (n=148), 14 subjects had a change in QT interval from baseline between 30 and 60 ms and were considered to have a potential risk factor for risk of QT interval prolongation and TdP due to relevant medical history, concomitant medication potentially associated with the induction of prolongation of QT interval, and/or polymedication.(6) Health Canada reviewed 61 cases of QT interval prolongation or torsades de pointes with hydroxyzine. In a majority of cases, patients had additional risk factors for QT prolongation. Three reports provided enough data for a more detailed review. Hydroxyzine was found to be either "possible" or "probably" contribution to QT prolongation/torsades in these reports.(1) The European Medicines Agency's Pharmacovigilance Risk Assessment Committee (PRAC) reviewed 190 case reports found in a search of "torsade de pointes/QT prolongation with hydroxyzine". Forty-two non-fatality cases were subdivided into torsades (n=16), QT prolongation (n=21), and ventricular tachycardia (n=5). All included risk factors for QT interval prolongation and TdP (cardiac disorders, hypokalemia, long QT syndrome, bradycardia, concomitant drugs which are known to prolong the QT interval). Dosages ranged from <= 100 mg/day (n=10), > 100 mg/day to <=300 mg/day (n=4), > 300 mg/day (n=8), overdosages (n=11), and premedication (n=9). Twenty-one cases involving fatalities had at least one risk factor for QT prolongation. The PRAC concluded that post-marketing cases of QT interval prolongation, TdP and ventricular tachycardia confirm the findings of the hERG studies suggesting that hydroxyzine blocks hERG channels. No difference in the risk of QT interval prolongation could be observed based on the indication, age of the subject, or dose.(6) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(7) |
HYDROXYZINE HCL, HYDROXYZINE PAMOATE |
| Colchicine (for Gout & FMF)/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may affect the transport of colchicine, a P-gp substrate.(1,2) CLINICAL EFFECTS: Concurrent use of a P-gp inhibitor may result in elevated levels of and toxicity from colchicine. Symptoms of colchicine toxicity include abdominal pain; nausea or vomiting; severe diarrhea; muscle weakness or pain; numbness or tingling in the fingers or toes; myelosuppression; feeling weak or tired; increased infections; and pale or gray color of the lips, tongue, or palms of hands.(1,2) PREDISPOSING FACTORS: This interaction is expected to be more severe in patients with renal and/or hepatic impairment(1,2) and in patients who receive concurrent therapy. PATIENT MANAGEMENT: The concurrent use of colchicine with P-gp inhibitors is contraindicated in patients with renal or hepatic impairment.(1-3) Avoid concurrent use in other patients, if possible.(3) In patients without renal or hepatic impairment who are currently taking or have taken a P-gp inhibitor in the previous 14 days, the dosage of colchicine should be reduced. For gout flares, the recommended dosage is 0.6 mg (1 tablet) for one dose. This dose should be repeated no earlier than in 3 days.(1,2) For gout prophylaxis, if the original dosage was 0.6 mg twice daily, use 0.3 mg daily. If the original dosage was 0.6 mg daily, use 0.3 mg every other day.(3-12) For Familial Mediterranean fever (FMF), the recommended maximum daily dose is 0.6 mg (may be given as 0.3 mg twice a day).(1,2) Patients should be instructed to immediately report any signs of colchicine toxicity, such as abdominal pain, nausea/significant diarrhea, vomiting; muscle weakness/pain; numbness/tingling in fingers/toes; unusual bleeding or bruising, infections, weakness/tiredness, or pale/gray color of the lips/tongue/palms of hands. DISCUSSION: There are several reports of colchicine toxicity(4-6) and death(7,8) following the addition of clarithromycin to therapy. In a retrospective review of 116 patients who received clarithromycin and colchicine during the same hospitalization, 10.2% (9/88) of patients who received simultaneous therapy died, compared to 3.6% (1/28) of patients who received sequential therapy.(9) An FDA review of 117 colchicine-related deaths that were not attributable to overdose found that 60 deaths (51%) involved concurrent use of clarithromycin.(2) There is one case report of colchicine toxicity with concurrent erythromycin.(10) In a study in 20 subjects, pretreatment with diltiazem (240 mg daily for 7 days) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of colchicine (0.6 mg) by 44.2% (range -46.6% to 318.3%) and by 93.4% (range -30.2% to 338.6%), respectively.(1) In a study in 24 subjects, pretreatment with verapamil (240 mg twice daily for 7 days) increased the Cmax and AUC of a single dose of colchicine (0.6 mg) by 40.1% (range -47.1% to 149.5%) and by 103.3% (range -9.8% to 217.2%), respectively.(1) Colchicine toxicity has been reported with concurrent use of CYP3A4 and P-gp inhibitors such as clarithromycin, cyclosporine, diltiazem, erythromycin, and verapamil.(1,2) P-gp inhibitors include abrocitinib, amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, danicopan, daridorexant, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, schisandra, selpercatinib, sotorasib, tepotinib, tezacaftor, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(1,11,12) |
COLCHICINE, COLCRYS, GLOPERBA, MITIGARE, PROBENECID-COLCHICINE |
| Venetoclax/Selected P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Venetoclax is a substrate for the P-glycoprotein (P-gp) system. P-gp inhibitors may lead to increased levels of venetoclax.(1) CLINICAL EFFECTS: Concurrent use of P-gp inhibitors may result in elevated levels of venetoclax, increasing the risk for tumor lysis syndrome and other toxicities.(1) PREDISPOSING FACTORS: Risk factors for tumor lysis syndrome include (1): - the ramp-up phase of venetoclax therapy when tumor burden is highest - initial magnitude of tumor burden - renal impairment The risk of venetoclax toxicities may be increased in patients with severe hepatic impairment.(1) PATIENT MANAGEMENT: Avoid P-gp inhibitors and consider alternative treatments when possible. If a P-gp inhibitor must be used, reduce venetoclax dose by at least 50%. Monitor more closely for signs of toxicity such as tumor lysis syndrome, hematologic and non-hematologic toxicities.(1) If the P-gp inhibitor is discontinued, the manufacturer of venetoclax recommends resuming the prior (i.e. pre-inhibitor) dose of venetoclax 2 to 3 days after discontinuation of the P-gp inhibitor.(1) DISCUSSION: In 11 healthy subjects, a single dose of rifampin (a P-gp inhibitor) increased venetoclax maximum concentration (Cmax) and area-under-curve (AUC) by 106% and 78%, respectively.(1) In 11 previously treated NHL subjects, ketoconazole (a strong CYP3A4 inhibitor which also inhibits P-gp and BCRP) 400 mg daily for 7 days increased the Cmax and AUC of venetoclax 2.3-fold and 6.4-fold respectively.(1) In 12 healthy subjects, coadministration of azithromycin (500 mg Day 1, 250 mg for Days 2-5) decreased venetoclax Cmax and AUC by 25% and 35%. No dosage adjustment is needed when venetoclax is coadministered with azithromycin.(1) P-gp inhibitors include: amiodarone, asunaprevir, belumosudil, capmatinib, carvedilol, cyclosporine, danicopan, daridorexant, diosmin, flibanserin, fostamatinib, ginseng, ivacaftor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tezacaftor, tepotinib, valbenazine, vemurafenib, vimseltinib, and voclosporin.(2) |
VENCLEXTA, VENCLEXTA STARTING PACK |
| Hydroxychloroquine/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Hydroxychloroquine has been observed to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of hydroxychloroquine with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of hydroxychloroquine states that hydroxychloroquine should not be administered with other agents that prolong the QT interval.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: The manufacturer states that hydroxychloroquine has been shown to prolong the QT interval;(1) however, conditions that hydroxychloroquine treats have also been associated with QT prolongation. Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3) |
HYDROXYCHLOROQUINE SULFATE, PLAQUENIL, SOVUNA |
| Inotuzumab Ozogamicin/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of inotuzumab ozogamicin with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of inotuzumab ozogamicin with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: When possible, discontinue QT prolonging agents prior to therapy with inotuzumab ozogamicin or use alternative agents during inotuzumab ozogamicin therapy.(1) When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy.(1) Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.(1) DISCUSSION: Inotuzumab ozogamicin was shown to prolong the QT interval in clinical trials. In the INO-VATE trial, 3% (4/162) of patients experienced an increase in QTc equal to or greater than 60 msec. No patients has QTc values greater than 500 msec. Grade 2 QT prolongation was reported in 1% (2/164) patients. There were no reports of Grade 3 QT prolongation or Torsade de Pointes.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
BESPONSA |
| Bosentan/Strong and Moderate CYP2C9 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Bosentan is metabolized by CYP2C9 and CYP3A4. It is also an inducer of these enzymes. With regular dosing bosentan auto-induces its own metabolism.(1) Strong and moderate CYP2C9 inhibitors may inhibit the CYP2C9 mediated metabolism of bosentan.(2) CLINICAL EFFECTS: Concurrent use of bosentan with an inhibitor of CYP2C9 may result in elevated levels of and toxicity from bosentan.(3) PREDISPOSING FACTORS: Concurrent use of bosentan, a CYP2C9 inhibitor and a CYP3A4 inhibitor (e.g. aprepitant, boceprevir, ceritinib, ciprofloxacin, clarithromycin, conivaptan, crizotinib, cyclosporine, darunavir, diltiazem, dronedarone, erythromycin, fluconazole, fosaprepitant, idelalisib, imatinib, isavuconazole, itraconazole, ketoconazole, letermovir, mibefradil, nefazodone, netupitant, nilotinib, posaconazole, ribociclib, telaprevir, telithromycin, troleandomycin, verapamil, and voriconazole)(3) could lead to blockade of both major metabolic pathways for bosentan, resulting in large increases in bosentan plasma concentrations.(3) PATIENT MANAGEMENT: Review medication list to see if patient is also receiving a CYP3A4 inhibitor (e.g. aprepitant, boceprevir, ceritinib, ciprofloxacin, clarithromycin, conivaptan, crizotinib, cyclosporine, darunavir, diltiazem, dronedarone, erythromycin, fluconazole, fosaprepitant, idelalisib, imatinib, isavuconazole, itraconazole, ketoconazole, letermovir, mibefradil, nefazodone, netupitant, nilotinib, posaconazole, ribociclib, telaprevir, telithromycin, troleandomycin, verapamil, and voriconazole). Concomitant use of both a CYP2C9 and CYP3A4 inhibitor is not recommended by the manufacturer as the combination may lead to large increases in bosentan plasma concentrations.(1) For patients stabilized on bosentan when a CYP2C9 inhibitor is initiated, monitor tolerance to concomitant therapy and adjust bosentan dose if needed. DISCUSSION: Concurrent use with CYP2C9 inhibitors has not been studied. In a study in healthy subjects, concurrent bosentan and ketoconazole, a strong CYP3A4 inhibitor, administration increased bosentan steady-state maximum concentrations (Cmax) and area-under-curve (AUC) by 2.1-fold and 2.3-fold, respectively.(2) Strong CYP2C9 inhibitors linked to this monograph include: miconazole.(3) Moderate CYP2C9 inhibitors linked to this monograph include: amiodarone, apazone, asciminib, benzbromarone, cannabidiol, nitisinone, oxandrolone, piperine, sulfaphenazole, and phenylbutazone.(3) |
BOSENTAN, TRACLEER |
| Lofexidine/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Lofexidine has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1,2) CLINICAL EFFECTS: Concurrent use of lofexidine and agents known to prolong the QT interval may exacerbate QT prolongation.(1,2) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, advanced age,(3) renal impairment, and/or hepatic impairment.(1,2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The UK manufacturer of lofexidine states that concurrent use of lofexidine and QT prolonging agents should be avoided.(1) The US manufacturer states that ECGs should be monitored in patients receiving concurrent therapy with lofexidine and agents that are known to prolong the QT interval.(2) Consider obtaining serum calcium, magnesium, and potassium levels at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a study of healthy volunteers, lofexidine 1.44 mg to 1.8 mg had a change from baseline in QTc of 14.4 msec and 13.6 msec, respectively.(2) In a dose response study, lofexidine had a mean QTc prolongation of 7.3 msec and 9.3 msec at doses of 2.16 mg/day and 2.88 mg/day, respectively.(2) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(4) |
LOFEXIDINE HCL, LUCEMYRA |
| Talazoparib/Selected P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Amiodarone, carvedilol, clarithromycin, itraconazole, and verapamil (inhibitors of P-glycoprotein) may increase the absorption of talazoparib.(1) CLINICAL EFFECTS: The concurrent administration of talazoparib with certain inhibitors of P-glycoprotein may result in elevated levels of talazoparib and signs of toxicity.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The management of this drug interaction is indication-specific. For the treatment of breast cancer, coadministration of talazoparib with the P-gp inhibitors amiodarone, carvedilol, clarithromycin, itraconazole, and verapamil should be avoided. If coadministration cannot be avoided, the dose of talazoparib should be reduced to 0.75 mg once daily when coadministered.(1) When the P-gp inhibitor is discontinued, increase the talazoparib dose (after 3-5 half-lives of the P-gp inhibitor) to the dose used prior to initiation of the P-gp inhibitor.(1) For the treatment of metastatic castration-resistant prostate cancer, monitor patients for increased adverse reactions and adjust talazoparib dose as recommended in the prescribing information for adverse reactions.(1) DISCUSSION: In patients with advanced solid tumors, coadministration of a single 0.5 mg dose of talazoparib with itraconazole increased talazoparib AUC and Cmax by 56% and 40%, respectively.(1) In clinical studies, coadministration of talazoparib with amiodarone, carvedilol, clarithromycin, itraconazole, or verapamil resulted in an approximately 45% increase in talazoparib exposure and an increase in the rate of talazoparib dose reduction.(1) P-gp inhibitors linked to this monograph include amiodarone, carvedilol, clarithromycin, itraconazole, and verapamil. |
TALZENNA |
| Glasdegib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of glasdegib with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of glasdegib with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Avoid the concurrent use of glasdegib with medications that prolong the QT interval.(1) When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If QTc prolongation develops: ---Monitor and supplement electrolytes as clinically indicated ---Review and adjust concomitant QT prolonging medications ---Interrupt glasdegib therapy for QTc interval greater than 500 ms. ---Monitor ECGs at least weekly for 2 weeks following resolution of QTc prolongation ---Follow labeling recommendations regarding restarting glasdegib.(1) DISCUSSION: In a randomized, single-dose, double-blind, 4-way cross-over, placebo- and open-label moxifloxacin-controlled study in 36 healthy subjects, the largest placebo and baseline-adjusted QTc interval change was 8 msec (90% CI: 6-10 msec) with a single 150 mg dose of glasdegib (The 150 mg single dose was used to achieve therapeutic plasma concentrations). With two-fold therapeutic plasma concentrations (achieved with a 300 mg single dose), the QTc change was 13 msec (90% CI: 11-16 msec).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
DAURISMO |
| Entrectinib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of entrectinib with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of entrectinib with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Avoid the concurrent use of entrectinib with medications that prolong the QT interval.(1) When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If QTc prolongation develops: ---Monitor and supplement electrolytes as clinically indicated ---Review and adjust concomitant QT prolonging medications ---Interrupt entrectinib therapy for QTc interval greater than 500 ms. ---Follow labeling recommendations regarding restarting entrectinib.(1) If torsade de pointes, polymorphic ventricular tachycardia, and/or signs/symptoms of serious arrhythmia occur, permanently discontinue entrectinib.(1) DISCUSSION: In clinical trials, 3.1% of patients with at least one post-baseline ECG experienced QTcF prolongation of greater than 60 msec after starting entrectinib..(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
ROZLYTREK |
| Oral Lefamulin/P-gp Inhibitors that Prolong QT SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors that prolong the QT interval may increase the absorption of lefamulin and may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of oral lefamulin with P-gp inhibitors that prolong the QTc interval may result in elevated levels of and effects from lefamulin, including potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Avoid the concurrent use of oral lefamulin with medications that prolong the QT interval and inhibit P-gp.(1) When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a thorough QT study, intravenous lefamulin increased the QTcF 13.6 msec (90% CI = 15.5 msec) and oral lefamulin increased the QTcF by 9.3 msec (90% CI = 10.9 msec).(1) Coadministration of ketoconazole (strong CYP3A4 inhibitor) with lefamulin tablets increased lefamulin maximum concentration (Cmax) and area-under-the-curve (AUC) by 165% and 58%.(1) In a study, oral lefamulin tablets administered concomitantly with and at 2 or 4 hours before oral midazolam (a CYP3A4 substrate) increased the area-under-curve (AUC) and maximum concentration (Cmax) of midazolam by 200% and 100%, respectively. No clinically significant effect on midazolam pharmacokinetics was observed when co-administered with lefamulin injection.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) P-gp inhibitors linked to this monograph include: amiodarone, azithromycin, hydroquinidine, lapatinib, osimertinib, quinidine, ranolazine, and vemurafenib.(4) |
XENLETA |
| Pazopanib/P-gp or BCRP Inhibitors that Prolong QT SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use with other agents that prolong the QTc interval and inhibit P-gp or BCRP may result in increased absorption and higher levels of pazopanib and additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of pazopanib with other agents that prolong the QTc interval and inhibit P-gp or BCRP may result in elevated levels of pazopanib, signs of toxicity, and potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of pazopanib states concurrent use of strong P-gp or BCRP inhibitors should be avoided. Use caution when pazopanib is coadministered with other drugs known to prolong the QTc interval.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Administration of 1,500 mg lapatinib, a substrate and weak inhibitor of CYP3A4, P-gp, and BCRP, with 800 mg pazopanib resulted in an approximately 50% to 60% increase in mean pazopanib area-under-curve (AUC) and maximum concentration (Cmax) compared with administration of 800 mg pazopanib alone.(1) In clinical studies, 2% (11/558) of patients receiving pazopanib experienced QT prolongation. Torsades de pointes occurred in less than 1% (2/977) of patients who received pazopanib in monotherapy studies. In a randomized clinical trial, 3 of 290 patients who received pazopanib had post-baseline QTc values between 500 and 549 msec. None of the patients receiving placebo had post-baseline QTc values greater than or equal to 500 msec.(1) A retrospective review of 618 cancer patients treated with 902 administrations of tyrosine kinase inhibitors were evaluated for rate and incidence of QTc prolongation. In patients who received pazopanib, QTc prolongation was identified in 32 (19.4%) with 18 (56.3%) having Grade 1 (QTc 450-480 ms) and 4 (12.5%) having Grade 2 (QTc 480-500 ms). Grade 3 events occurred in 3 (9.3%) having QTc greater than or equal to 500 ms and 4 (12.5%) having QTc change greater than or equal to 60 ms. Ventricular tachycardia was seen in 2 (6.3%) of patients and 1 (3.1%) patient experienced sudden cardiac death.(4) Agents that are P-gp or BCRP inhibitors that may cause QT prolongation include: amiodarone, azithromycin, dronedarone, erythromycin, hydroquinidine, lapatinib, mavorixafor, osimertinib, pacritinib, propafenone, quinidine, ranolazine, selpercatinib, and vemurafenib.(3, 5-6) |
PAZOPANIB HCL, VOTRIENT |
| Oxaliplatin/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of oxaliplatin with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of oxaliplatin with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Avoid the concurrent use of oxaliplatin in patients with congenital long QT syndrome. ECG monitoring is recommended if oxaliplatin therapy is initiated in patients with congestive heart failure, bradyarrhythmias, drugs known to prolong the QT interval, and electrolyte abnormalities.(1) When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Prescribing information for oxaliplatin states post-marketing cases of QT prolongation and ventricular arrhythmias, including fatal Torsades de Pointes, have been reported.(1) Case reports have documented QT prolongation in patients with varying cancer indications for oxaliplatin.(3-6) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(7) |
OXALIPLATIN |
| Selpercatinib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Selpercatinib prolongs the QTc interval.(1) Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(2,3) CLINICAL EFFECTS: The concurrent use of selpercatinib with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(2,3) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: Selpercatinib prolongs the QT interval. An increase in QT interval to > 500 ms was measured in 6% of patients and increase in the QT interval of at least 60 ms over baseline was measured in 15% of patients. Monitor patients at significant risk of developing QT prolongation, including patients with known long QT syndromes, clinically significant bradyarrhythmias, and severe or uncontrolled heart failure. Assess QT interval, electrolytes, and TSH at baseline and periodically during treatment. Correct hypokalemia, hypomagnesemia, and hypocalcemia prior to initiation and during treatment. Dose adjustments (1): For grade 3 QT interval prolongation, withhold selpercatinib until recovery to baseline or grade 0 or 1. Resume at a reduced dose. -1st dose reduction: For patients weighing less than 50 kg: 80 mg twice daily. For patients weighing 50 kg or greater: 120 mg twice daily. -2nd dose reduction: For patients weighing less than 50 kg: 40 mg twice daily. For patients weighing 50 kg or greater: 80 mg twice daily. -3rd dose reduction: For patients weighing less than 50 kg: 40 mg once daily. For patients weighing 50 kg or greater: 40 mg twice daily. -For grade 4 QT prolongation, discontinue selpercatinib. DISCUSSION: The effect of selpercatinib on the QT interval was evaluated in a thorough QT study in healthy subjects. The largest mean increase in QT is predicted to be 10.6 ms (upper 90% confidence interval: 12.1 ms) at the mean steady state maximum concentration (Cmax) observed in patients after administration of 160 mg twice daily. The increase in QT was concentration-dependent. Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2) |
RETEVMO |
| Relugolix/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Relugolix is a substrate of the intestinal P-glycoprotein (P-gp) efflux transporter. Inhibitors of P-gp may increase the absorption of relugolix.(1) CLINICAL EFFECTS: The concurrent administration of relugolix with an inhibitor of P-glycoprotein may result in elevated levels of relugolix and adverse effects, including hot flashes, skin flushing, musculoskeletal pain, hyperglycemia, acute renal injury, transaminitis, arrhythmias, and hemorrhage.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of relugolix states that the coadministration of relugolix with P-gp inhibitors should be avoided. If the P-gp inhibitor is to be used short-term, relugolix may be held for up to 2 weeks. If treatment with relugolix is interrupted for longer than 7 days, resume relugolix with a loading dose of 360 mg on the first day, followed by 120 mg once daily.(1) If coadministration with a P-gp inhibitor cannot be avoided, relugolix should be taken at least 6 hours before the P-gp inhibitor. Monitor the patient more frequently for adverse events.(1) DISCUSSION: Coadministration of relugolix with erythromycin (a P-gp and moderate CYP3A4 inhibitor) increased the area-under-curve (AUC) and maximum concentration (Cmax) of relugolix by 6.2-fold. Voriconazole (a strong CYP3A4 inhibitor) did not have a clinically significant effect on the pharmacokinetics of relugolix.(1) P-gp inhibitors linked to this monograph include: amiodarone, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, curcumin, cyclosporine, daclatasvir, danicopan, daridorexant, diltiazem, diosmin, dronedarone, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo, ginseng, glecaprevir/pibrentasvir, indinavir, itraconazole, ivacaftor, josamycin, ketoconazole, lapatinib, lonafarnib, mavorixafor, mibefradil, mifepristone, neratinib, osimertinib, paroxetine, pirtobrutinib, propafenone, quinidine, quinine, ranolazine, ritonavir, sarecycline, schisandra, selpercatinib, simeprevir, sotorasib, telaprevir, telithromycin, tepotinib, tezacaftor, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(2,3) |
MYFEMBREE, ORGOVYX |
| Macitentan/Dual Moderate CYP2C9 & CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Dual moderate inhibitors of CYP2C9 and CYP3A4 may inhibit the metabolism of macitentan.(1) CLINICAL EFFECTS: Concurrent use of a dual moderate inhibitor of CYP2C9 and CYP3A4 may result in elevated levels and increased effects of macitentan.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of macitentan states that use of dual moderate inhibitors of CYP2C9 and CYP3A4 should be avoided. Concomitant use of both a moderate CYP3A4 inhibitor and a moderate CYP2C9 inhibit should also be avoided.(1) DISCUSSION: Based on pharmacokinetic (PBPK) modeling, dual moderate inhibitors of CYP2C9 and CYP3A4 such as fluconazole are predicted to increase macitentan exposure by 4-fold.(1) Dual moderate inhibitors of CYP2C9 and CYP3A4 include: amiodarone and fluconazole.(2) |
OPSUMIT, OPSYNVI |
| Rimegepant/P-gp Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Rimegepant is a calcitonin gene-related peptide receptor antagonist. Rimegepant is a substrate of the P-glycoprotein (P-gp) transporter. P-gp inhibitors may significantly increase the absorption of rimegepant.(1) CLINICAL EFFECTS: The concurrent administration of rimegepant with an inhibitor of P-glycoprotein may result in elevated levels of rimegepant.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of rimegepant recommends avoiding a second dose of rimegepant within 48 hours of a first dose when used concomitantly with P-gp inhibitors.(1) DISCUSSION: Rimegepant is a substrate of P-gp. Use of P-gp inhibitors may increase the exposure of rimegepant. In a study, cyclosporine (a potent P-gp and BCRP inhibitor) increased rimegepant area-under curve (AUC) and maximum concentration (Cmax) by 1.6- and 1.4-fold, respectively. Quinidine (a potent P-gp inhibitor) similarly increased rimegepant AUC and Cmax by 1.6- and 1.7-fold, respectively. Therefore, the effect of these drug interactions were concluded to be due entirely to P-gp and not BCRP.(1) P-glycoprotein inhibitors linked to this monograph include: amiodarone, azithromycin, belumosudil, capmatinib, carvedilol, cyclosporine, danicopan, daridorexant, diosmin, flibanserin, fostamatinib, glecaprevir/pibrentasvir, lapatinib, mavorixafor, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, vemurafenib, vimseltinib, and verapamil.(1-3) |
NURTEC ODT |
| Siponimod/Select Moderate CYP2C9 Inhibitors that Prolong QT SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of CYP2C9 may inhibit the metabolism of siponimod.(1) Initiation of siponimod has a negative chronotropic effect and may increase the risk of bradycardia.(1,2) CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP2C9 may result in elevated levels of and clinical effects of siponimod, including immunosuppression and increased risk of infection.(1,2) The heart rate lowering effect of siponimod starts within an hour, and the Day 1 decline is maximal at approximately 3-4 hours. This leads to a mean decrease in heart rate of 5-6 beats per minute after the first dose. The first dose has also been associated with heart block. With continued up-titration, further heart rate decreases are seen on subsequent days, with maximal decrease from Day 1-baseline reached on Day 5-6. Symptomatic bradycardia has been observed. Bradycardia may be associated with an increase in the QTc interval, increasing the risk for torsades de pointes.(1) PREDISPOSING FACTORS: Concurrent use of a strong or moderate inhibitor of CYP3A4 may increase the effects of the interaction.(1) Concurrent use of other drugs that may decrease heart rate (e.g., beta blockers, verapamil, diltiazem, ivabradine, digoxin) may increase risk for cardiovascular toxicity due to siponimod, including QT prolongation or torsades de pointes.(1) PATIENT MANAGEMENT: Concurrent use of an inhibitor of CYP2C9 with siponimod is not recommended in patients also taking a strong or moderate inhibitor of CYP3A4.(1) Review the patient's therapy for concurrent use of strong or moderate inhibitors of CYP3A4 prior to initiating siponimod. Patients receiving concurrent treatment with a QT prolonging agent at the time siponimod is initiated or resumed should be referred to a cardiologist. Consult the prescribing information for recommendations regarding cardiac monitoring.(1) DISCUSSION: Siponimod is metabolized by CYP2C9 (79.3%) and CYP3A4 (18.5%). Concurrent use of fluconazole (a dual moderate inhibitor of CYP2C9 and CYP3A4, 200 mg at steady state) in healthy subjects with the CYP2C9*1/*1 genotype increased the area-under-curve (AUC) of siponimod (4 mg single dose) by 2-fold. Siponimod half-life increased by 50%. Fluconazole increased siponimod AUC by 2-fold to 4-fold across all CYP2C9 genotypes.(1) After the first dose of siponimod, heart rate decrease may begin within an hour. Decline is usually maximal at approximately 3-4 hours. With continued, chronic dosing, heart rate gradually returns to baseline in about 10 days.(1,2) A transient, dose-dependent decrease in heart rate was observed during the initial dosing phase of siponimod, which plateaued at doses greater than or equal to 5 mg, and bradyarrhythmic events (AV blocks and sinus pauses) were detected at a higher incidence under siponimod treatment than placebo. AV blocks and sinus pauses occurred above the recommended dose of 2 mg, with notably higher incidence under non-titrated conditions compared to dose titration conditions.(1) Selected moderate CYP2C9 inhibitors that prolong QT linked to this monograph include: amiodarone.(4) |
MAYZENT |
| Doxorubicin/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibition may increase doxorubicin cellular concentration, as well as decrease biliary or renal elimination.(1) CLINICAL EFFECTS: Increased cellular or systemic levels of doxorubicin may result in doxorubicin toxicity, including cardiomyopathy, myelosuppression, or hepatic impairment.(1) PREDISPOSING FACTORS: The interaction magnitude may be greater in patients with impaired renal or hepatic function. PATIENT MANAGEMENT: Avoid the concurrent use of P-gp inhibitors in patients undergoing therapy with doxorubicin.(1) Consider alternatives with no or minimal inhibition. If concurrent therapy is warranted, monitor the patient closely for signs and symptoms of doxorubicin toxicity. DISCUSSION: Doxorubicin is a substrate of P-gp.(1) Clinical studies have identified and evaluated the concurrent use of doxorubicin and P-gp inhibitors as a target to overcome P-gp mediated multidrug resistance.(2,3) P-gp inhibitors linked to this monograph include: amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, capmatinib, cimetidine, cyclosporine, daclatasvir, danicopan, daridorexant, diltiazem, diosmin, dronedarone, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo, ginseng, glecaprevir/pibrentasvir, hydroquinidine, istradefylline, ivacaftor, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, paroxetine, pirtobrutinib, propafenone, quercetin, quinidine, quinine, ranolazine, sarecycline, schisandra, selpercatinib, simeprevir, sofosbuvir/velpatasvir/voxilaprevir, sotorasib, tepotinib, tezacaftor, valbenazine, vemurafenib, verapamil, vimseltinib, and voclosporin.(4,5) |
ADRIAMYCIN, CAELYX, DOXIL, DOXORUBICIN HCL, DOXORUBICIN HCL LIPOSOME |
| Intravenous Lefamulin/Selected QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of lefamulin with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of lefamulin with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Avoid the concurrent use of lefamulin with other medications that prolong the QT interval.(1) When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a thorough QT study, intravenous lefamulin increased the QTcF by 13.6 msec (90% CI = 15.5 msec) and oral lefamulin increased the QTcF by 9.3 msec (90% CI = 10.9 msec).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
XENLETA |
| Eliglustat/Dual Weak CYP2D6 and CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Eliglustat is primarily metabolized by CYP2D6 and to a lesser extent by CYP3A4.(1) Amiodarone, fluvoxamine, oral contraceptives, and ranitidine weakly inhibit CYP2D6 and CYP3A4. CLINICAL EFFECTS: Concurrent use may result in elevated levels of and clinical effects of eliglustat, including prolongation of the PR, QTc, and/or QRS intervals, which may result in life-threatening cardiac arrhythmias.(1) PREDISPOSING FACTORS: If the patient has hepatic impairment or if the patient is a CYP2D6 poor metabolizer, eliglustat metabolism can be further inhibited.(1) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Prescribing information has no specific recommendation on the use of eliglustat with drugs that are weak inhibitors of both CYP2D6 and CYP3A4. In CYP2D6 poor metabolizers, coadministration with dual weak inhibitors of CYP2D6 and CYP3A4 should be avoided. In CYP2D6 extensive metabolizers with mild (Child-Pugh Class A) hepatic impairment, the dosage of eliglustat with weak inhibitors of CYP2D6 or CYP3A4 should be limited to 84 mg daily. In CYP2D6 intermediate metabolizers and CYP2D6 extensive metabolizers without hepatic impairment, no dose adjustment of eliglustat is necessary when taken with a weak CYP2D6 inhibitor or a weak CYP3A4 inhibitor.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: There is no data on the interaction between eliglustat and dual weak inhibitors of CYP2D6 and CYP3A4. Paroxetine (30 mg daily), a strong inhibitor of CYP2D6, increased eliglustat (84 mg BID) maximum concentration (Cmax) and area-under-curve (AUC) by 7-fold and 8.4-fold, respectively, in extensive metabolizers. Physiologically-based pharmacokinetic (PKPB) models suggested paroxetine would increase eliglustat Cmax and AUC by 2.1-fold and 2.3-fold, respectively, in intermediate metabolizers. PKPB models suggested ketoconazole may increase the Cmax and AUC of eliglustat (84 mg daily) by 4.3-fold and 6.2-fold, respectively, in poor metabolizers.(1) PKPB models suggested terbinafine, a moderate inhibitor of CYP2D6, would increase eliglustat Cmax and AUC by 3.8-fold and 4.5-fold, respectively, in extensive metabolizers and by 1.6-fold and 1.6-fold, respectively in intermediate metabolizers. PKPB models suggest that concurrent eliglustat (84 mg BID), paroxetine (a strong inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 16.7-fold and 24.2-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 7.5-fold and 9.8-fold, respectively.(1) PKPB models suggest that concurrent eliglustat (84 mg BID), terbinafine (a moderate inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 10.2-fold and 13.6-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 4.2-fold and 5-fold, respectively.(1) A single dose of rolapitant increased dextromethorphan, a CYP2D6 substrate, about 3-fold on days 8 and day 22 following administration. Dextromethorphan levels remained elevated by 2.3-fold on day 28 after single dose rolapitant. The inhibitory effects of rolapitant on CYP2D6 are expected to persist beyond 28 days.(5) Weak dual inhibitors of CYP2D6 and CYP3A4 include: amiodarone and ranitidine.(3,4) |
CERDELGA |
| Panobinostat/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Panobinostat has been observed to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of panobinostat with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The manufacturer of panobinostat states concurrent use agents known to prolong the QT interval are not recommended. Panobinostat should not be started in patients with a QTcF > 450 msec or clinically significant baseline ST-segment or T-wave abnormalities. If during panobinostat therapy the QTcF increases to > 480 msec, interrupt treatment and correct any electrolyte abnormalities. If QT prolongation does not resolve, permanently discontinue treatment with panobinostat.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In the randomized multiple myeloma trial, QTc prolongation with values between 451 msec to 480 msec occurred in 10.8% of panobinostat treated patients and patients with values of 481 msec to 500 msec occurred in 1.3% of patients. A maximum QTcF increase from baseline of between 31 msec and 60 msec was reported in 14.5% of patients and a maximum QTcF increase from baseline of >60 msec was reported in 0.8% of patients.(1) Pooled clinical data from over 500 patients treated with single agent panobinostat in multiple indications and at different dose levels has shown that the incidence of CTC Grade 3 QTc prolongation (QTcF >500 msec) was approximately 1% overall and 5% or more at a dose of 60 mg or higher.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3) |
FARYDAK |
| Amiodarone/Strong CYP3A4 Inhibitors that Prolong QT SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Strong CYP3A4 inhibitors that prolong the QTc interval may inhibit the metabolism of amiodarone and result in additive risk of QT prolongation. Amiodarone is a CYP3A4 substrate.(1) CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inhibitors that prolong QT may increase the levels and effects of amiodarone including additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias like torsades de pointes (TdP).(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of amiodarone states that the concurrent use of QT prolonging agents should be avoided and that the need to co-administer amiodarone with any other drug known to prolong the QTc interval must be based on a careful assessment of the potential risks and benefits of doing so for each patient. Concurrent use with CYP3A4 inhibitors should also be avoided.(1) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: QTc prolongation has been reported during concurrent amiodarone and azole antifungals, fluoroquinolones, and macrolide antibiotics.(1) A retrospective review of patients who received concurrent amiodarone and haloperidol over a 24 month period found 49 patients who received concurrent therapy for 381 exposures. The mean increase in QTc interval was 9.8 msec; the average change in QTc interval per patient was 23.6 msec.(3) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(4) Strong inhibitors of CYP3A4 that prolong QT include: adagrasib, ceritinib, clarithromycin, lonafarnib, ribociclib, telithromycin, and voriconazole.(5,6) |
CLARITHROMYCIN, CLARITHROMYCIN ER, KISQALI, KRAZATI, LANSOPRAZOL-AMOXICIL-CLARITHRO, OMECLAMOX-PAK, VFEND, VFEND IV, VOQUEZNA TRIPLE PAK, VORICONAZOLE, ZOKINVY, ZYKADIA |
| Pacritinib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Pacritinib has been observed to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of pacritinib with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The manufacturer of pacritinib states concurrent use with agents known to prolong the QT interval should be avoided. Avoid the use of pacritinib in patients with a baseline QTc > 480 msec. Correct hypokalemia prior to initiation and during therapy with pacritinib.(1) If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a 24 week clinical study, patients treatment with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3) |
VONJO |
| Quizartinib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Quizartinib has been shown to prolong the QTc interval in a dose- and concentration dependent manner. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-3) CLINICAL EFFECTS: The concurrent use of quizartinib with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1-3) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of quizartinib states that the concurrent use of QT prolonging agents should be avoided.(1) Quizartinib is only available through a restricted REMS program due to the serious risk of QT prolongation, torsades de pointes, and cardiac arrest. The manufacturer recommends monitoring as follows: -Initiate quizartinib only if the QTcF is less than or equal to 450 ms. -During induction and consolidation, monitor ECGs prior to initiation and then at minimum once weekly during treatment. -During maintenance, monitor ECGs prior to initiation and then at minimum once weekly for the first month following dose initiation and escalation and clinically therafter. Dose escalation may occur only if the QTcF is less than or equal to 450 ms. The manufacturer recommends the following dose modifications for adverse reactions: -If the QTcF is 450 ms to 480 ms (Grade 1) - Continue quizartinib dose. -If the QTcF is 481 ms to 500 ms (Grade 2) - Reduce the dose of quizartinib without interruption based on prescribing information. Resume the previous dose in the next cycle if the QTcF has decreased to less than 450 ms. -If the QTcF is greater than 500 ms (Grade 3) - Interrupt quizartinib. Resume at a reduced dose based on prescribing information when the QTcF is less than 450 ms. Maintain the dose of 26.5 mg once daily during maintenance if the QTcF is greater than 500 ms during induction or consolidation. -If recurrent QTcF is greater than 500 ms (Grade 3) - Permanently discontinue quizartinib if QTcF is greater than 500 ms despite dose reduction and correction/elimination of other risk factors. -If TdP, polymorphic ventricular tachycardia, or signs/symptoms of life-threatening arrythmia occur (Grade 4) - Permanently discontinue quizartinib. When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Quizartinib has been associated with QTc interval prolongation, Torsades de Pointes, ventricular arrhythmias, cardiac arrest, and sudden death. Quizartinib increased QTc in a dose- and concentration-dependent manner.(1) In an exposure-response analysis, quizartinib had a predicted concentration-dependent QTc prolongation of 18 to 24 ms (upper bound of 2-sided 90% CI: 21 and 27 ms) at a median steady-state Cmax dose of 26.5 mg and 53 mg during maintenance therapy.(1) In patients administered quizartinib, 2.3% of 265 patients had a QTcF greater than 500 msec and 10% of patients had a increase from baseline QTcF greater than 60 msec.(1) In patients administered quizartinib during the induction phase, torsades de pointes occurred in approximately 0.2% of patients, cardiac arrest occurred in 0.6%, including 0.4% with a fatal outcome, and 0.1% of patients experienced ventricular fibrillation.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
VANFLYTA |
| Erdafitinib/Strong CYP3A4 or Moderate CYP2C9 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Erdafitinib is metabolized by CYP3A4 and CYP2C9. Strong inhibitors of CYP3A4 or moderate inhibitors of CYP2C9 may inhibit the metabolism of erdafitinib.(1) CLINICAL EFFECTS: Concurrent use of strong CYP3A4 or moderate CYP2C9 inhibitors may increase the levels and effects of erdafitinib, including retinopathy and hyperphosphatemia.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US prescribing information states that concurrent use of erdafitinib with strong CYP3A4 inhibitors or moderate CYPC9 inhibitors should be avoided. If concurrent use cannot be avoided, monitor closely for adverse reactions and consider a dose modification based on prescribing information. If the strong CYP3A4 or moderate CYP2C9 inhibitor is discontinued, consider increasing the erdafitinib dose if patient does not have any drug-related toxicity.(1) DISCUSSION: In PKPB models, concurrent use of fluconazole (a moderate CYP2C9 and CYP3A4 inhibitor) resulted in erdafitinib mean ratios for concentration maximum (Cmax) and area-under-curve (AUC) of 121% and 148% , respectively, compared to erdafitinib alone.(1) In PKPB models, concurrent use of itraconazole (a strong CYP3A4 inhibitor and P-gp inhibitor) resulted in erdafitinib mean ratios for Cmax and AUC of 105% and 134%, respectively, compared to erdafitinib alone.(1) Strong inhibitors of CYP3A4 include: adagrasib, boceprevir, ceritinib, clarithromycin, cobicistat, idelalisib, indinavir, itraconazole, josamycin, ketoconazole, levoketoconazole, lonafarnib, lopinavir, mibefradil, mifepristone, nefazodone, nelfinavir, nirmatrelvir, paritaprevir, posaconazole, ribociclib, saquinavir, telaprevir, telithromycin, tipranavir, troleandomycin, tucatinib, and voriconazole.(2,3) Moderate inhibitors of CYP2C9 include: adagrasib, amiodarone, apazone, asciminib, benzbromarone, cannabidiol, fluconazole, miconazole, mifepristone, milk thistle, nitisinone, oxandrolone, phenylbutazone, and sulfaphenazole.(2,3) |
BALVERSA |
| Dexmedetomidine Sublingual/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Dexmedetomidine sublingual has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of dexmedetomidine sublingual with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The manufacturer of dexmedetomidine sublingual states that concurrent use should be avoided with other agents known to prolong the QTc interval.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a QT study, dexmedetomidine sublingual had a concentration dependent effect on the QT interval. The mean QTc (95% confidence interval) increased from baseline by 6 (7) msec with a 120 mcg single dose, 8 (9) msec with 120 mcg followed by 2 additional doses of 60 mcg (total 3 doses), 8 (11) msec with a single 180 mcg dose, and 11 (14) msec with 180 mcg followed by 2 additional doses of 90 mcg (total 3 doses), respectively.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
IGALMI |
| Vincristine/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may inhibit cellular efflux of vincristine.(1) CLINICAL EFFECTS: Concurrent administration of a P-gp inhibitor may result in elevated levels of and toxicity from vincristine including myelosuppression, neurologic toxicity, tumor lysis syndrome, hepatotoxicity, constipation, or bowel obstruction.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid the use of P-gp inhibitors in patients undergoing therapy with vincristine.(1) Consider alternatives with no or minimal P-gp inhibition. The manufacturer of vincristine states that concomitant use of P-gp inhibitors should be avoided.(1) The manufacturer of lopinavir/ritonavir states that patients who develop significant hematological or gastrointestinal toxicity on concomitant vincristine should temporarily hold lopinavir/ritonavir, or use alternative medications that do not inhibit CYP3A4 or P-gp.(2) DISCUSSION: Vincristine is a substrate of P-gp. Inhibitors of P-gp may increase toxicity of vincristine.(1) There are several case reports of neurotoxicity with concurrent administration of vincristine and itraconazole.(3-5) There is a case report of neurotoxicity with concurrent administration of lopinavir-ritonavir with vincristine.(6) In a prospective study in 22 children receiving various chemotherapy with prophylactic itraconazole oral solution (0.5 ml/kg per day), two children receiving vincristine developed non-alcoholic steatohepatitis (NASH) and one child developed syndrome of inappropriate anti-diuretic hormone secretion (SIADH).(7) Strong inhibitors of P-gp linked to this monograph include: abrocitinib, amiodarone, Asian ginseng (Panax ginseng), asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daridorexant, diltiazem, diosmin, dronedarone, elagolix, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo biloba, glecaprevir and pibrentasvir, isavuconazonium, ivacaftor, lapatinib, mavorixafor, milk thistle (Silybum marianum), neratinib, osimertinib, pirtobrutinib, propafenone, quercetin, quinidine, ranolazine, rolapitant, Schisandra chinensis, selpercatinib, sofosbuvir, sotorasib, tepotinib, tezacaftor, valbenazine, velpatasvir, vemurafenib, venetoclax, verapamil, vilazodone, vimseltinib, and voclosporin.(8,9) |
VINCASAR PFS, VINCRISTINE SULFATE |
| Amiodarone/Strong CYP3A4 Inducers that Prolong QT SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Strong CYP3A4 inducers may induce the metabolism of amiodarone by CYP3A4. Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-3) CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inducers may result in decreased levels and effectiveness of amiodarone and increase the risk of potentially life-threatening arrhythmias including torsades de pointes.(1-3) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. PATIENT MANAGEMENT: The US manufacturer of amiodarone states that the concurrent use of QT prolonging drugs should be avoided. The need to co-administer amiodarone with any other drug known to prolong the QTc interval must be based on a careful assessment of the potential risks and benefits of doing so for each patient.(1) The Australian(2) and UK(3) manufacturers of amiodarone states that concurrent use of agents known to cause torsades de pointes is contraindicated. The US manufacturer of amiodarone states concurrent use with CYP3A4 inducers may decrease amiodarone serum concentrations. Consider monitoring amiodarone serum concentrations during concurrent use.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Concurrent use of rifampin, another potent inducer of CYP3A4, and amiodarone has been shown to decrease levels of amiodarone and desethylamiodarone.(1) In a study in 5 healthy subjects, phenytoin (2-4 mg/kg/day) decreased amiodarone levels (200 mg daily) by 32% to 49%.(5) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing torsades de pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(6) Strong CYP3A4 inducers that prolong QT linked to this monograph include: encorafenib and ivosidenib.(7) |
BRAFTOVI, TIBSOVO |
| Amiodarone/Strong CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Strong CYP3A4 inhibitors may inhibit the metabolism of amiodarone. Amiodarone is a CYP3A4 substrate.(1) CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inhibitors may increase the levels and effects of amiodarone including QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias like torsades de pointes (TdP).(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of amiodarone states concurrent use with CYP3A4 inhibitors should be avoided.(1) If concurrent therapy is deemed medically necessary, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: QTc prolongation has been reported during concurrent amiodarone and azole antifungals, fluoroquinolones, and macrolide antibiotics.(1) A retrospective review of patients who received concurrent amiodarone and haloperidol over a 24 month period found 49 patients who received concurrent therapy for 381 exposures. The mean increase in QTc interval was 9.8 msec; the average change in QTc interval per patient was 23.6 msec.(3) Strong inhibitors of CYP3A4 include: boceprevir, cobicistat, grapefruit, idelalisib, itraconazole, josamycin, ketoconazole, mifepristone, nefazodone, telaprevir, troleandomycin, and tucatinib.(4,5) |
EVOTAZ, ITRACONAZOLE, ITRACONAZOLE MICRONIZED, KETOCONAZOLE, KORLYM, MIFEPREX, MIFEPRISTONE, NEFAZODONE HCL, PREZCOBIX, SPORANOX, SYMTUZA, TOLSURA, TUKYSA, TYBOST, ZYDELIG |
| Pralsetinib/P-glycoprotein (P-gp) Inhibitors that Prolong QT SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors that prolong the QTc interval may inhibit cellular efflux of pralsetinib and result in additive risk of QT prolongation.(1-3) CLINICAL EFFECTS: Concurrent administration of a P-gp inhibitor that prolongs QT may result in elevated levels of and toxicity from pralsetinib, including additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias like torsades de pointes (TdP).(1-3) Other toxicities include hemorrhagic events, pneumonitis, hepatotoxicity, and hypertension.(1-3) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: Coadministration of pralsetinib with a P-gp inhibitor that prolongs QT should be avoided.(1-3) If coadministration with a P-gp inhibitor that prolongs QT cannot be avoided, use with caution and reduce the dose of pralsetinib as follows: -If the current dose is 400 mg once daily, decrease the dose to 300 mg daily. -If the current dose is 300 mg once daily, decrease the dose to 200 mg daily. -If the current dose is 200 mg once daily, decrease the dose to 100 mg daily. After the inhibitor is discontinued for three to five half-lives, resume the dose of pralsetinib at the dose taken prior to initiation of the inhibitor.(1) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If the QTc interval exceeds 500 ms, interrupt pralsetinib therapy until QTc is <470 ms. Resume pralsetinib at the same dose if risk factors that cause QT prolongation an are identified and corrected. If risk factors that cause QT prolongation are not identified, resume pralsetinib at a reduced dose. Permanently discontinue pralsetinib if the patient develops life-threatening arrhythmia.(3) DISCUSSION: Coadministration of a single dose of cyclosporine 600 mg (a P-gp inhibitor) with a single pralsetinib 200 mg dose increased pralsetinib concentration maximum (Cmax) by 48% and area-under-curve (AUC) by 81%.(1) In clinical trials, QTc prolongation developed in 5.1% of patients on pralsetinib, with 2 patients (0.4%) having serious prolongation. Two patients required dose reductions or interruptions. No patients required permanent discontinuation of pralsetinib, and there was no life-threatening or fatal QT prolongation.(2) In a secondary analysis of the phase II ARROW study, ECG and plasma concentrations of 34 patients were examined. At steady state, mean change in QTc was 4.9-7.7 ms, with a greater QTc increase at higher concentrations, especially above 3,000 ng/mL. Although median minimum concentration (Cmin) is 1,150 ng/mL, there is a large interindividual variation and concentrations above 3,000 ng/mL may be expected in some patients.(2) P-glycoprotein inhibitors that prolong QT linked to this monograph include: amiodarone, azithromycin, hydroquinidine, lapatinib, mavorixafor, osimertinib, propafenone, quinidine, ranolazine, and vemurafenib.(5,6) |
GAVRETO |
| Sodium Iodide I 131/Agents that Affect Iodide SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Many compounds can affect iodide protein binding and alter iodide pharmacokinetics and pharmacodynamics.(1,2) CLINICAL EFFECTS: Compounds that affect iodide pharmacokinetics and pharmacodynamics may impact the effectiveness of radioactive iodide.(1,2) PREDISPOSING FACTORS: Compounds that affect iodide pharmacokinetics and pharmacodynamics are expected to have the most impact during therapy using radioactive iodide. Diagnostic procedures would be expected to be impacted less. PATIENT MANAGEMENT: Discuss the use of agents that affect iodide pharmacokinetics and pharmacodynamics with the patient's oncologist.(1,2) Because indocyanine green contains sodium iodide, the iodine-binding capacity of thyroid tissue may be reduced for at least one week following administration. Do not perform radioactive iodine uptake studies for at least one week following administration of indocyanine green.(3) The manufacturer of iopamidol states administration may interfere with thyroid uptake of radioactive iodine and decrease therapeutic and diagnostic efficacy. Avoid thyroid therapy or testing for up to 6 weeks post administration of iopamidol.(4) DISCUSSION: Many agents interact with radioactive iodine. The average duration of effect is: anticoagulants - 1 week antihistamines - 1 week anti-thyroid drugs, e.g: carbimazole, methimazole, propylthiouracil - 3-5 days corticosteroids - 1 week iodide-containing medications, e.g: amiodarone - 1-6 months expectorants - 2 weeks Lugol solution - 3 weeks saturated solution of potassium iodine - 3 weeks vitamins - 10-14 days iodide-containing X-ray contrast agents - up to 1 year lithium - 4 weeks phenylbutazone - 1-2 weeks sulfonamides - 1 week thyroid hormones (natural or synthetic), e.g.: thyroxine - 4 weeks tri-iodothyronine - 2 weeks tolbutamide - 1 week topical iodide - 1-9 months (1,2) |
HICON, SODIUM IODIDE I-131 |
| Givinostat/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Givinostat may prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of givinostat with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The manufacturer of givinostat states that the concurrent use of QT prolonging agents should be avoided. If concurrent use cannot be avoided, obtain ECGs prior to initiating givinostat, during concomitant use, and as clinically indicated.(1) If the QTc interval is greater than 500 ms or the change from baseline is greater than 60 ms, withhold givinostat therapy.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a QT study, the largest mean increase in QTc interval of 13.6 ms (upper confidence interval of 17.1 ms) occurred 5 hours after administration of givinostat 265.8 mg (approximately 5 times the recommended 53.2 mg dose in patients weighing 60 kg or more).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
DUVYZAT |
| Revumenib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Revumenib may prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of revumenib with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The manufacturer of revumenib states that the concurrent use of QT prolonging agents should be avoided. If concurrent use cannot be avoided, obtain ECGs prior to initiating revumenib, during concomitant use, and as clinically indicated.(1) If the QTc interval is greater than 480 ms, withhold revumenib therapy. Resume revumenib after the QTc interval drops to 480 msec or less.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In clinical trials, QTc interval prolongation was reported as an adverse event in 29% of 135 patients treated with the recommended dosage of revumenib; 12% of patients had Grade 3 QTc prolongation. Revumenib increased the QTc interval in a concentration-dependent manner. At the mean steady-state Cmax using the highest approved recommended dosage of revumenib without CYP3A4 inhibitors, QTc increase was predicted to be 27 msec (upper bound of 90% confidence interval = 30 msec). At the steady-state Cmax using the highest approved recommended dosage of revumenib with CYP3A4 inhibitors, QTc increase was predicted to be 19 msec (upper bound of 90% confidence interval = 22 msec).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
REVUFORJ |
There are 37 moderate interactions.
The clinician should assess the patient’s characteristics and take action as needed. Actions required for moderate interactions include, but are not limited to, discontinuing one or both agents, adjusting dosage, altering administration.
| Drug Interaction | Drug Names |
|---|---|
| Cyclosporine/Amiodarone SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Amiodarone may inhibit the metabolism of cyclosporine by CYP3A4. CLINICAL EFFECTS: Increased levels of cyclosporine, which may result in renal toxicity. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Monitor cyclosporine levels and renal function in patients receiving concurrent therapy. During concurrent therapy with amiodarone, cyclosporine dosages may need to be decreased by over 50%. DISCUSSION: Documentation on this interaction is limited to case reports involving ten transplant patients. In the first report, the dosage of cyclosporine required to maintain a therapeutic trough concentration of 200-250 ng/ml (measured by high-performance liquid chromatography) decreased from 5.4-5.8 mg/Kg/day to 2.3 mg/Kg/day following the addition of amiodarone. Cyclosporine clearance decreased from 0.22 L/hr/Kg to 0.1 L/hr/Kg 12 days after the addition of amiodarone. In the second report, there was a twofold increase in cyclosporine levels following the addition of amiodarone to stabilized cyclosporine therapy. A retrospective study of eight transplant patients who received concurrent therapy with cyclosporine and amiodarone reported that cyclosporine levels increased in all subjects despite a decrease in cyclosporine dosage (from 6.2 mg/Kg/day to 3.5 mg/Kg/day). |
CYCLOSPORINE, CYCLOSPORINE MODIFIED, GENGRAF, NEORAL, SANDIMMUNE |
| Selected NSAIDs/Selected CYP2C9 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The major metabolic pathway for many non-steroidal anti-inflammatory agents (NSAIDs) is CYP2C9. Inhibitors of CYP2C9 include: amiodarone, asciminib, cannabidiol, diosmin, fluconazole, ketoconazole, miconazole, nitisinone, oxandrolone, piperine, voriconazole, and zafirlukast.(1,2) CLINICAL EFFECTS: Concurrent use of NSAIDs with inhibitors of CYP2C9 may result in increased levels of and adverse effects from NSAIDs, including increased risk for bleeding. NSAIDs linked to this monograph are celecoxib, diclofenac, flurbiprofen, ibuprofen, meloxicam, naproxen, parecoxib, piroxicam and valdecoxib. PREDISPOSING FACTORS: Higher doses of either agent would be expected to increase the risk for serious adverse effects such as gastrointestinal bleeding (GIB) or renal failure. Patients who smoke, are elderly, debilitated, dehydrated, have renal impairment, or who have a history of GIB due to NSAIDs are also at increased risk for serious adverse events.(3-7) The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). PATIENT MANAGEMENT: Patients on routine NSAID therapy when an inhibitor of CYP2C9 is started should be evaluated for patient-specific risk factors for NSAID toxicity. Based upon this risk assessment, consider dose reduction of the NSAID or close monitoring for adverse effects. For a patient already receiving a CYP2C9 inhibitor when an NSAID is started, consider initiating the NSAID at a lower than usual dose, particularly when predisposing risk factors for harm are present. The manufacturer of celecoxib recommends that celecoxib be introduced at the lowest recommended dose in patients receiving fluconazole therapy.(3) The manufacturer of fluconazole states that half the dose of celecoxib may be necessary when fluconazole is added.(4) It would be prudent to follow this recommendation with other CYP2C9 inhibitors and to decrease the dose of celecoxib in patients in whom CYP2C9 inhibitors are added to celecoxib therapy. The manufacturer of diclofenac-misoprostol states that the total daily dose of diclofenac should not exceed the lowest recommended dose of 50 mg twice daily in patients taking CYP2C9 inhibitors.(5) It would be prudent to use the lowest recommended dose of other diclofenac formulations in patients taking CYP2C9 inhibitors. The manufacturer of parecoxib states that the dose of parecoxib should be reduced in those patients who are receiving fluconazole therapy.(6) It would be prudent to follow this recommendation with other CYP2C9 inhibitors. If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. DISCUSSION: The concomitant administration of celecoxib and fluconazole (200 mg daily) resulted in a 2-fold increase in celecoxib plasma concentration.(3) In vitro studies in human hepatocytes found that amiodarone inhibited diclofenac metabolism.(7) In two separate studies, single doses of diclofenac (50 mg) or ibuprofen (400 mg) were coadministered with the last dose of voriconazole (400 mg q12h on Day 1, followed by 200 mg q12h on Day 2). Voriconazole increased the mean AUC of diclofenac by 78% and increased the AUC of the active isomer of ibuprofen by 100%.(8-10) Coadministration of diosmin increased diclofenac levels by 63%.(2) Coadministration of flurbiprofen or ibuprofen with fluconazole increased the AUC of flurbiprofen by 81% and of the active ibuprofen by 82% compared with either agent alone.(4) Concurrent voriconazole increased meloxicam AUC by 47%.(11,12) The concurrent administration of fluconazole and parecoxib resulted in increases in the area-under-curve (AUC) and maximum concentration (Cmax) of valdecoxib (the active metabolite of parecoxib) by 62% and 19%, respectively.(6) In a study, single dose diclofenac (50mg) given concurrently with the last dose of voriconazole (400 mg every 12 hours on Day 1, 200 mg every 12 hours on Day 2) increased Cmax and AUC by 2.1-fold and 1.8-fold, respectively. (5) Inhibitors of CYP2C9 include: amiodarone, asciminib, cannabidiol, diosmin, fluconazole, ketoconazole, miconazole, nitisinone, oxandrolone, piperine, voriconazole, and zafirlukast.(1,2) |
ANAPROX DS, ANJESO, ARTHROTEC 50, ARTHROTEC 75, CALDOLOR, CAMBIA, CELEBREX, CELECOXIB, COMBOGESIC, COMBOGESIC IV, CONSENSI, DICLOFENAC, DICLOFENAC POTASSIUM, DICLOFENAC SODIUM, DICLOFENAC SODIUM ER, DICLOFENAC SODIUM MICRONIZED, DICLOFENAC SODIUM-MISOPROSTOL, EC-NAPROSYN, ELYXYB, FELDENE, FLURBIPROFEN, HYDROCODONE-IBUPROFEN, IBU, IBUPAK, IBUPROFEN, IBUPROFEN LYSINE, IBUPROFEN-FAMOTIDINE, INFLAMMACIN, INFLATHERM(DICLOFENAC-MENTHOL), LOFENA, LURBIPR, MELOXICAM, NAPRELAN, NAPROSYN, NAPROTIN, NAPROXEN, NAPROXEN SODIUM, NAPROXEN SODIUM CR, NAPROXEN SODIUM ER, NAPROXEN-ESOMEPRAZOLE MAG, NEOPROFEN, PIROXICAM, SUMATRIPTAN SUCC-NAPROXEN SOD, SYMBRAVO, TOXICOLOGY SALIVA COLLECTION, TRESNI, TREXIMET, VIMOVO, VIVLODEX, ZIPSOR, ZORVOLEX, ZYNRELEF |
| Selected Beta-Blockers/Amiodarone; Dronedarone SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The mechanism by which carvedilol, metoprolol, nebivolol, and propranolol and amiodarone produce severe bradycardia and hypotension is due to depressant effects on the sinus and AV node. Since these beta-blockers are cleared by CYP2D6 metabolism and amiodarone is a weak 2D6 inhibitor; amiodarone may decrease their metabolism.(1,3) Dronedarone is a moderate CYP2D6 inhibitor therefore may inhibit the metabolism of carvedilol, metoprolol, nebivolol and propranolol since these beta-blockers are cleared by CYP2D6 metabolism.(2-3) CLINICAL EFFECTS: The concurrent administration of hepatically metabolized beta-blockers with amiodarone(1) or dronedarone may result in bradycardia and hypotension.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Use low doses of beta-blockers initially. Only increase the dosage of the beta-blocker after ECG verification of good tolerability.(2) Patients receiving a concurrent therapy should be closely monitored for adverse effects, such as bradycardia and hypotension. Patients experiencing this drug interaction should have their beta-adrenergic blocking drug discontinued. Supportive therapy with sympathomimetic agents may be required. DISCUSSION: In one case report, a patient taking amiodarone developed hypotension and atropine-resistant sinus bradycardia after receiving a single dose of metoprolol. Three hours after receiving the metoprolol dose, the patient experienced dizziness, weakness, and blurred vision.(1) Another report described two patients who exhibited an interaction between amiodarone and propranolol. One patient maintained on amiodarone experienced cardiac arrest after a single oral dose of propranolol. The second patient received intravenous amiodarone followed by 2 doses of oral propranolol and developed severe bradycardia followed by ventricular fibrillation.(4) The stereoselective effect of amiodarone on the pharmacokinetics of racemic carvedilol was evaluated in 106 patients, where 52 received carvedilol monotherapy and 54 received carvedilol with amiodarone. There was no significant differences between the serum concentration to dose ratio between the 2 groups. However, there was an increase in the ratio of S-carvedilol to R-carvedilol. During amiodarone, the concentration of S-carvedilol increased from 3.03 ng/ml to 6.54 ng/ml.(5) Several studies have shown that the addition of carvedilol to congestive heart failure patients currently receiving amiodarone resulted in improved hypotension/dizziness, primary AV block, and aggravated angina.(6-8) Dronedarone increased propranolol and metoprolol (exact dosages not stated) by 1.3-fold and 1.6-fold, respectively.(2) Amiodarone increased metoprolol maximum concentration (Cmax) from 40 mcg/L to 70 mcg/L and area-under-curve (AUC) from 767 mcg x h/L to 1387 mcg x h/L after an amiodarone loading dose of 1.2 g. The interaction was noted to be more pronounced in patients with >/= 2 compared to 1 functional CYP2D6 alleles.(9) Concomitant use of dronedarone and metoprolol were studied in 49 health subjects with four differing CYP2D6 mutations. Thirty-nine were extensive metabolizers of CYP2D6 with Cmax significantly increased from baseline (134.1 ng/mL) on day 13 to 162.6 ng/mL, 195.58 ng/mL, and 180.9 ng/mL after administration of dronedarone 800 mg, 1200 mg, and 1600 mg dose, respectively.(10) |
BYSTOLIC, CARVEDILOL, CARVEDILOL ER, COREG, COREG CR, HEMANGEOL, INDERAL LA, INDERAL XL, INNOPRAN XL, KAPSPARGO SPRINKLE, LOPRESSOR, METOPROLOL SUCCINATE, METOPROLOL TARTRATE, METOPROLOL-HYDROCHLOROTHIAZIDE, NEBIVOLOL HCL, PROPRANOLOL HCL, PROPRANOLOL HCL ER, PROPRANOLOL-HYDROCHLOROTHIAZID, TOPROL XL |
| Atorvastatin; Lovastatin (Less than or Equal To 40 mg); Simvastatin (Less Than or Equal To 20 mg)/Amiodarone SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Amiodarone may inhibit the metabolism of atorvastatin,(1) lovastatin(2) and simvastatin(3-6) by CYP3A4. CLINICAL EFFECTS: Concurrent use of amiodarone(2) with certain HMG CoA reductase inhibitors may increase the risk of rhabdomyolysis. PREDISPOSING FACTORS: The risk for myopathy or rhabdomyolysis may be greater in patients 65 years and older, inadequately treated hypothyroidism, renal impairment, carnitine deficiency, malignant hyperthermia, or in patients with a history of myopathy or rhabdomyolysis. Patients with a SLCO1B1 polymorphism that leads to decreased function of the hepatic uptake transporter OATP1B1 may have increased statin concentrations and be predisposed to myopathy or rhabdomyolysis. PATIENT MANAGEMENT: Use the lowest dose of atorvastatin necessary in patients receiving concurrent amiodarone therapy.(1) The US manufacturers of amiodarone(1) and lovastatin(2) recommend that the dose of lovastatin not exceed 40 mg daily in patients receiving concurrent amiodarone unless the potential benefit outweighs the increased risk of myopathy. The US manufacturers of amiodarone(1) and simvastatin(3-6) recommend that the dose of simvastatin not exceed 20 mg daily in patients receiving concurrent amiodarone unless the potential benefit outweighs the increased risk of myopathy. DISCUSSION: Rhabdomyolysis has been reported with concurrent amiodarone and atorvastatin and simvastatin.(1) In a case report, a 63 year-old male developed rhabdomyolysis 4 weeks after starting simvastatin therapy and 2 weeks after starting amiodarone.(7) In a clinical trial, myopathy was been reported in 6% of patients receiving concurrent simvastatin (80 mg) and amiodarone.(3) In a randomized, cross-over study in 12 healthy subjects, subjects received amiodarone (400 mg daily) with either simvastatin (40 mg) or pravastatin (40 mg). Amiodarone increased simvastatin area-under-curve (AUC) by 73%, maximum concentration (Cmax) by 100%, and half-life by 48%. There were no significant effects on pravastatin pharmacokinetics.(8) In a case report, a 72 year-old male developed rhabdomyolysis 10 weeks after starting amiodarone (200 mg daily) therapy and 6 weeks after starting simvastatin (80 mg daily).(9) In a retrospective review of patients receiving amiodarone, the rate of adverse events in combination with a statin was 1.0%, 0.7%, and 0.4% for simvastatin, atorvastatin, and pravastatin, respectively. The most commonly reported adverse effect was muscle soreness, which was present in 77% of reports and was found more often in older male patients.(10) |
ALTOPREV, AMLODIPINE-ATORVASTATIN, ATORVALIQ, ATORVASTATIN CALCIUM, CADUET, EZETIMIBE-SIMVASTATIN, LIPITOR, LOVASTATIN, SIMVASTATIN, VYTORIN, ZOCOR |
| Selected Antiarrhythmics/Selected Protease Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Darunavir (coadministered with cobicistat or ritonavir)(1), fosamprenavir (with or without ritonavir),(2) lopinavir-ritonavir(3), and ombitasvir-paritaprevir-ritonavir(4) are CYP3A4 inhibitors and may decrease the metabolism of ajmaline, amiodarone, and quinidine. CLINICAL EFFECTS: Concurrent use of darunavir (coadministered with cobicistat or ritonavir)(1), fosamprenavir (with or without ritonavir),(2) lopinavir-ritonavir(3), or ombitasvir-paritaprevir-ritonavir(4) with ajmaline, amiodarone, or quinidine may result in elevated levels of these antiarrhythmics and serious and/or life-threatening arrhythmias, including torsades de pointes. PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(5) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(5) PATIENT MANAGEMENT: Darunavir (coadministered with cobicistat or ritonavir),(1) fosamprenavir (with or without ritonavir),(2) lopinavir-ritonavir,(3) and ombitasvir-paritaprevir-ritonavir(4) should be used with caution with ajmaline, amiodarone, and quinidine, along with concentration monitoring of these agents. The US Department of Health and Human Services HIV guidelines state that amiodarone should not be coadministered with darunavir or lopinavir unless benefits outweigh risks, and that quinidine should not be coadministered with protease inhibitors.(12) The Canadian and UK manufacturers of darunavir,(6,7) fosamprenavir,(8,9) and lopinavir-ritonavir(10,11) state that concurrent use of amiodarone is contraindicated. The UK manufacturers of darunavir(7) and fosamprenavir(9) state that concurrent use of quinidine is contraindicated. If used concurrently, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Darunavir and fosamprenavir are moderate inhibitors of CYP3A4. Lopinavir-ritonavir is a strong inhibitor of CYP3A4.(13) |
DARUNAVIR, FOSAMPRENAVIR CALCIUM, KALETRA, LOPINAVIR-RITONAVIR, PREZCOBIX, PREZISTA, SYMTUZA |
| Amiodarone/Fentanyl SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Fentanyl, a potent opioid with a narrow therapeutic window, is metabolized via CYP3A4. Amiodarone is a weak inhibitor of CYP3A4.(1) CLINICAL EFFECTS: Concurrent use of amiodarone may result in increased levels and toxicity of fentanyl.(2) PREDISPOSING FACTORS: Interaction effects may be magnified in patients on more than one inhibitor of CYP3A4. Heat. PATIENT MANAGEMENT: If co-administration is necessary, caution is advised when initiating or discontinuing concurrent treatment, particularly if the patient is also receiving concurrent treatment with other CYP3A4 inhibitors (e.g. systemic azole antifungals, clarithromycin, protease inhibitors).(2) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. Consider this risk when using concurrently with agents that may increase opioid drug levels.(3) Monitor for increased adverse effects such as respiratory suppression or increased sedation if amiodarone is added to existing fentanyl therapy. Patients already receiving amiodarone and newly starting on fentanyl therapy may be more sensitive to fentanyl effects and may need lower than usual doses.(2) Evaluate patients at frequent intervals and consider dose adjustments until stable drug effects are achieved. Discuss naloxone with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing naloxone to patients prescribed medicines to treat OUD or opioid analgesics (such as those taking CNS depressants) who are at increased risk of opioid overdose and when a patient has household members/close contacts at risk for accidental overdose.(4) Avoid exposing the fentanyl patch application site and surrounding area to direct external heat sources as there have been reports of overdose and death as a result of exposure to heat.(2) DISCUSSION: Studies and case reports of concomitant amiodarone and fentanyl administration focus on perioperative use. A study was performed to evaluate the combination of amiodarone and fentanyl in the operative setting.(5) This was a prospective, randomized, double-blind placebo controlled trial to evaluate the risk for hemodynamic compromise in 84 cardiac patients undergoing bypass or valve surgery. Patients were started on one of two oral amiodarone loading regimens or placebo 1 to 5 days prior to surgery. All patients received fentanyl as a component of anesthesia therapy during the procedure. Although systolic BP was lower in amiodarone patients both pre-fentanyl and post-bypass, there were no adverse events. A retrospective study compared patients who received concurrent amiodarone and fentanyl anesthesia to patients who received fentanyl alone. Patients who received concurrent amiodarone had more episodes of low systemic vascular resistance and required more hemodynamic support with intra-arterial balloon placement. In the group receiving concurrent amiodarone, 66% developed bradycardia, complete heart block, or became pacemaker-dependent compared to 17% of patients who did not receive amiodarone.(6) There are several reports of serious complications including bradycardia, hypotension, marked reduction in cardiac output, and sinus arrest in patients receiving concurrent amiodarone and fentanyl anesthesia.(7-11) A study in healthy subjects shown that the application of heat over the fentanyl patch system increased mean overall fentanyl exposure by 120% and average maximum fentanyl level by 61%.(2) |
FENTANYL, FENTANYL CITRATE, FENTANYL CITRATE-0.9% NACL, FENTANYL CITRATE-D5W, FENTANYL CITRATE-STERILE WATER, FENTANYL CITRATE-WATER, FENTANYL-BUPIVACAINE-0.9% NACL, FENTANYL-BUPIVACAINE-NACL, FENTANYL-ROPIVACAINE-0.9% NACL, FENTANYL-ROPIVACAINE-NACL |
| Amiodarone/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Amiodarone has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-3) CLINICAL EFFECTS: The concurrent use of amiodarone with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1-3) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(5) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(5) PATIENT MANAGEMENT: The Australian(1) and UK(2) manufacturers of amiodarone states that concurrent use of agents known to cause torsades de pointes is contraindicated. The US manufacturer of amiodarone states that the concurrent use of QT prolonging drugs should be avoided and that need to co-administer amiodarone with any other drug known to prolong the QTc interval must be based on a careful assessment of the potential risks and benefits of doing so for each patient.(3) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: QTc prolongation has been reported during concurrent amiodarone and fluoroquinolones and macrolide antibiotics. Agents that are linked to this monograph may have been associated with Torsades de Pointes and/or QT prolongation but at this time lack substantial evidence for causing Torsades de Pointes.(4) One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
ADVAIR DISKUS, ADVAIR HFA, AIRDUO DIGIHALER, AIRDUO RESPICLICK, ALFUZOSIN HCL ER, APOKYN, APOMORPHINE HCL, ASPRUZYO SPRINKLE, ATOMOXETINE HCL, CLOZAPINE, CLOZAPINE ODT, CLOZARIL, DANZITEN, DIPRIVAN, ELLENCE, EPIRUBICIN HCL, ERIBULIN MESYLATE, FLUTICASONE-SALMETEROL, FLUTICASONE-SALMETEROL HFA, GRANISETRON HCL, HALAVEN, ISTODAX, LAPATINIB, LENVIMA, NEXAVAR, NILOTINIB HCL, ONAPGO, ONDANSETRON HCL, ONDANSETRON HCL-0.9% NACL, PROPOFOL, RANOLAZINE ER, ROMIDEPSIN, RUBRACA, RYDAPT, SANCUSO, SEREVENT DISKUS, SORAFENIB, STRATTERA, SUSTOL, TASIGNA, TYKERB, UROXATRAL, VERSACLOZ, VIBATIV, WIXELA INHUB, XALKORI, ZELBORAF |
| Loperamide/CYP3A4; CYP2C8; P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of CYP3A4, CYP2C8, and/or P-gp may increase loperamide systemic absorption and facilitate entry into central nervous system (CNS).(1) CLINICAL EFFECTS: Concurrent use of inhibitors of CYP3A4, CYP2C8, and/or P-gp may increase levels of loperamide, resulting in respiratory depression.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Use loperamide with caution in patients receiving inhibitors of CYP3A4, CYP2C8, and/or P-gp. Consider lower doses of loperamide in these patients and monitor for adverse effects. The manufacturer of lonafarnib recommends starting loperamide at a dose of 1 mg and slowly increasing the dose as needed.(2) DISCUSSION: In a randomized, cross-over study in 12 healthy subjects, itraconazole (100 mg twice daily for 5 days - first dose 200 mg), gemfibrozil (600 mg twice daily), and the combination of itraconazole and gemfibrozil (same dosages) increased the area-under-curve (AUC) of single doses of loperamide (4 mg) by 2.9-fold, 1.6-fold, and 4.2-fold, respectively.(3) In a study of healthy subjects, lonafarnib (100 mg twice daily for 5 days) increased the AUC and maximum concentration (Cmax) of single dose loperamide (2 mg) by 299% and 214%, respectively.(3) In a study in 18 healthy males, quinidine increased the AUC of a single dose of loperamide by 2.2-fold and markedly decreased pupil size.(4) In a study in 8 healthy subjects, subjects experienced respiratory depression when a single dose of loperamide (16 mg) was administered with a single dose of quinidine (600 mg) but not when loperamide was administered alone.(6) Loperamide plasma levels increased 2-fold to 3-fold.(5) |
LOPERAMIDE |
| Tolterodine/Class IA & III Antiarrhythmics SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Concurrent use of tolterodine and Class IA or III antiarrhythmics may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent use of tolterodine and Class IA or III antiarrhythmics may result in QTc prolongation and life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congential long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, advanced age, and/or patients who are poor CYP P-450-2D6 metabolizers.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Use tolterodine with caution in patients maintained on Class IA or III antiarrhythmics.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: The effects of tolterodine on the QTc interval were studied in 45 healthy subjects. Effects were compared to moxifloxacin, a known QTc prolonging agent. Tolterodine's effect on the QTc interval correlated with tolterodine plasma concentration. There was a greater increase in QTc in patients who were CYP P-450-2D6 poor metabolizers. There has been no associated with tolterodine and torsades in the international post-marketing experience of Detrol or Detrol LA.(1) |
TOLTERODINE TARTRATE, TOLTERODINE TARTRATE ER |
| Sunitinib/Class IA & III Antiarrhythmics SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Concurrent use of sunitinib and Class IA or III antiarrhythmics may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent use of sunitinib and Class IA or III antiarrhythmics may result in QTc prolongation and life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, advanced age, use of multiple medications, and/or in patients who are taking strong CYP P-450-3A4 inhibitors.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Use sunitinib with caution in patients maintained on Class IA or III antiarrhythmics.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Sunitinib has been shown to prolong the QT interval in a dose dependent manner. Torsade de Pointes has been observed in less than 0.1% of patients receiving sunitinib.(1) A retrospective review of 618 cancer patients treated with 902 administrations of tyrosine kinase inhibitors were evaluated for rate and incidence of QTc prolongation. In patients who received sunitinib, QTc prolongation was identified in 26 (19.4%) with 16 (61.5%) having Grade 1 (QTc 450-480 ms) and 6 (23.1%) having Grade 2 (QTc 480-500 ms). Grade 3 events occurred in 1 (3.8%) having QTc greater than or equal to 500 ms and 1 (3.8%) having QTc change greater than or equal to 60 ms. Ventricular tachycardia was seen in 1 (3.8%) of patients and 1 (3.8%) patient experienced sudden cardiac death.(3) |
SUNITINIB MALATE, SUTENT |
| Everolimus/Moderate CYP3A4; P-gp Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate inhibitors of CYP3A4 and/or p-glycoprotein (P-gp) may inhibit the metabolism of everolimus.(1) CLINICAL EFFECTS: Concurrent use of moderate inhibitors of CYP3A4 and/or P-gp may result in elevated levels of and toxicity from everolimus.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If concurrent therapy with everolimus and moderate inhibitors of CYP3A4 and/or P-gp is warranted, reduce the dosage of everolimus.(1) In patients with advanced hormone receptor-positive, HER2-negative breast cancer (HR+BC); advanced pancreatic neuroendocrine tumors (PNET); or advanced renal cell carcinoma; or renal angiomyolipoma with TSC, decrease the dose of everolimus to 2.5 mg daily. An increase to 5 mg daily may be considered based on patient tolerance. If the inhibitor is discontinued, allow an elimination period of 2-3 days before increasing the dose to that used prior to the inhibitor.(1) In patients with subependymal giant cell astrocytoma with TSC, reduce the dosage of everolimus by 50% to maintain trough concentrations of 5 ng/ml to 15 ng/ml. If the patient is already receiving 2.5 mg daily, consider a dose of 2.5 mg every other day. Assess everolimus levels 2 weeks after the addition of the inhibitor. Resume the everolimus dose used prior to initiation of the inhibitor after the inhibitor has been discontinued for 3 days, and assess everolimus trough levels 2 weeks later.(1) Guidelines from the American Society of Transplantation state that protease inhibitors are contraindicated, and recommend avoiding the use of erythromycin with everolimus. If the combination must be used, lower the dose of everolimus by up to 50% upon initiation of the antibiotic and monitor levels daily.(3) DISCUSSION: In a study in healthy subjects, concurrent use of erythromycin, a moderate CYP3A4 inhibitor and a P-gp inhibitor, increased everolimus AUC and Cmax by 2.0-fold and 4.4-fold, respectively.(1) In a study in healthy subjects, concurrent use of ketoconazole, a strong CYP3A4 inhibitor and a P-gp inhibitor, increased everolimus area-under-curve (AUC) and maximum concentration (Cmax) by 3.9-fold and 15.0-fold, respectively.(1) In a study in healthy subjects, concurrent use of verapamil, a moderate CYP3A4 inhibitor and a P-gp inhibitor, increased everolimus AUC and Cmax by 2.3-fold and 3.5-fold, respectively.(1) In a study in 16 healthy subjects, concurrent use of verapamil increased everolimus Cmax and AUC by 130% and 250%, respectively.(4) Moderate CYP3A4 and/or P-gp inhibitors include: abrocitinib, amiodarone, amprenavir, aprepitant, asciminib, asunaprevir, atazanavir, avacopan, azithromycin, belumosudil, cimetidine, clofazimine, conivaptan, crizotinib, danicopan, daridorexant, delavirdine, diltiazem, diosmin, dronedarone, duvelisib, erythromycin, fedratinib, flibanserin, fluconazole, fluvoxamine, fosamprenavir, fosnetupitant, fostamatinib, imatinib, isavuconazonium, ivacaftor, ledipasvir, lenacapavir, letermovir, mavorixafor, netupitant, nilotinib, nirogacestat, pirtobrutinib, propafenone, schisandra, tepotinib, tezacaftor, tofisopam, treosulfan, vemurafenib, verapamil, vimseltinib, and voclosporin.(5-7) |
AFINITOR, AFINITOR DISPERZ, EVEROLIMUS, TORPENZ, ZORTRESS |
| Rivaroxaban/Selected P-gp and Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Amiodarone, azithromycin, brodalumab, chloramphenicol, cimetidine, cyclosporine, felodipine, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, hydroquinidine, ivacaftor, nilotinib, piperine, pirtobrutinib, quinidine, ranolazine, simeprevir, ticagrelor and tolvaptan may inhibit the metabolism of rivaroxaban by CYP3A4 and by P-glycoprotein.(1,2) CLINICAL EFFECTS: Concurrent use of an agent that is both an inhibitor of P-gp and a weak inhibitor of CYP3A4 may result in elevated levels of and clinical effects of rivaroxaban, including an increased risk of bleeding, in patients with decreased renal function.(1,2) PREDISPOSING FACTORS: Patients with decreased renal function (CrCL of 15 ml/min to 80 ml/min) may be predisposed to this interaction.(1) The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). PATIENT MANAGEMENT: The US manufacturer states no precautions are necessary with the concurrent use of these agents and rivaroxaban in patients with normal renal function.(1) It would be prudent to closely monitor concurrent use in patients with reduced renal function (CrCL of 15 ml/min to 80 ml/min). If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. DISCUSSION: Clarithromycin (500 mg twice daily) increased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of rivaroxaban by 50% and 40%, respectively.(1,2) Erythromycin (500 mg three times daily) increased the AUC and Cmax of a single dose of rivaroxaban by 30% and 30%, respectively.(1-3) In patients with mild renal impairment (CrCl of 50 ml/min to 79 ml/min) who were receiving erythromycin, rivaroxaban levels were increased 76% when compared to administration of rivaroxaban in patients with normal renal function receiving rivaroxaban alone. In patients with moderate renal impairment (CrCl of 30 ml/min to 49 ml/min) who were receiving erythromycin, rivaroxaban levels were increased 99% when compared to administration of rivaroxaban in patients with normal renal function receiving rivaroxaban alone.(1) Fluconazole increased the AUC and Cmax of a single dose of rivaroxaban by 40%% and 30%, respectively.(1) These changes are not expected to be clinically significant in patients with normal renal function.(1,2) In a case report, an 88-year-old woman with renal impairment on rivaroxaban presented with an elevated INR of 2.5 and a rivaroxaban peak plasma concentration above the upper limit of detection at >800 mcg/L (therapeutic range 58-211 mcg/L). Nothing in her medical history suggested a reason for supratherapeutic rivaroxaban levels except for a 7-week amiodarone regimen that was discontinued 3 weeks prior. This suggests the potential for amiodarone to persist in the body weeks after its use and precipitate drug-drug interactions.(4) A retrospective cohort study examined 24,943 patients aged 66 years and older with concurrent therapy of an anticoagulant, either rivaroxaban (40.0%), apixaban (31.9%), or dabigatran (28.1%), with either azithromycin or clarithromycin. The primary outcome of hospital admission with major hemorrhage within 30 days on concurrent therapy was higher in patients on clarithromycin (0.77%) compared to azithromycin (0.43%) with an adjusted hazard ratio of 1.71 (95% CI, 1.20-2.45). In a self-controlled case series, 744 major hemorrhage events were identified among 647 unique individuals taking anticoagulants who were exposed to clarithromycin. The rate of events that occurred during clarithromycin use had a significant rate ratio of 1.44 (95% CI, 1.08-1.92).(5) A propensity matched cohort evaluated the concurrent use of combined P-gp and moderate CYP3A4 inhibitors with apixaban or rivaroxaban. Combined inhibitors included amiodarone, diltiazem, erythromycin, dronedarone, and verapamil. Bleeding occurred in 26.4% of patients in the inhibitor group compared to 18.4% in the control group (hazard ratio 1.8; 95% CI 1.19-2.73; p=0.006). Although not statistically significant, patients in the inhibitor group also had a higher rate of major bleeding (15% vs 10.3%) and minor bleeding (8.9% vs 5.2%), respectively.(6) A summary of pharmacokinetic interactions with rivaroxaban and amiodarone concluded that concurrent use should be avoided if CrCl < 80 ml/min.(7) A prospective cohort study of 174 patients evaluated the concurrent use of rivaroxaban and amiodarone. The combination of rivaroxaban and amiodarone was associated with a higher incidence of bleeding events (p=0.041; HR=2.83, 95% CI 1.05-7.66) and clinically relevant non-major bleeding (p=0.021; HR=3.65, 95% CI 1.21-10.94). Concurrent use of amiodarone and rivaroxaban in non-valvular atrial fibrillation patients was an independent risk factor for increased risk of bleeding (p=0.044; OR 2.871, 95% CI 1.028-8.023).(8) P-gp and weak CYP3A4 inhibitors linked to this monograph are: amiodarone, azithromycin, belumosudil, brodalumab, chloramphenicol, cimetidine, cyclosporine, daridorexant, diosmin, flibanserin, fostamatinib, glecaprevir/pibrentasvir, hydroquinidine, istradefylline, ivacaftor, mavorixafor, nilotinib, piperine, pirtobrutinib, quinidine, ranolazine, simeprevir and tolvaptan.(9,10) |
RIVAROXABAN, XARELTO |
| Sirolimus/Amiodarone; Dronedarone SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Amiodarone and dronedarone may inhibit the metabolism of sirolimus by CYP3A4. CLINICAL EFFECTS: Concurrent use of amiodarone or dronedarone may result in elevated levels of and toxicity from sirolimus. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Monitor sirolimus levels and renal function in patients receiving concurrent therapy, especially at the initiation of amiodarone or dronedarone. The dosage of sirolimus may need adjusting. If concurrent amiodarone or dronedarone is discontinued, the dosage of sirolimus may need adjusting. The US manufacturer of sirolimus protein-bound injection (Fyarro) states a dose reduction to 56 mg/m2 is recommended when used concurrently with moderate or weak CYP3A4 inhibitors. Concurrent use with strong CYP3A4 inhibitors should be avoided.(3) DISCUSSION: There are case reports of sirolimus toxicity with both amiodarone(1) and dronedarone(2). Dronedarone is a moderate inhibitor of CYP3A4 and would be expected to increase sirolimus levels.(4) |
FYARRO, SIROLIMUS |
| Afatinib/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of P-glycoprotein (P-gp) may increase the absorption of afatinib.(1) CLINICAL EFFECTS: The concurrent administration of afatinib with an inhibitor of P-glycoprotein may result in elevated levels of afatinib and signs of toxicity. These signs may include but are not limited to worsening diarrhea, stomatitis, skin rash/exfoliation/bullae or paronychia.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of afatinib states the afatinib dose should be reduced by 10 mg if the addition of a P-glycoprotein inhibitor is not tolerated.(1) If afatinib dose was reduced due to addition of a P-gp inhibitor, resume the previous dose after the P-gp inhibitor is discontinued.(1) The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to afatinib.(2) DISCUSSION: A drug interaction study evaluated the effects of ritonavir 200 mg twice daily on afatinib exposure. Administration of ritonavir 1 hour before afatinib administration increased systemic exposure by 48%. Afatinib exposure was not changed when ritonavir was administered simultaneously with or 6 hours after afatinib dose.(1) P-glycoprotein inhibitors linked to this monograph are: amiodarone, asunaprevir, azithromycin, belumosudil, carvedilol, cimetidine, clarithromycin, cobicistat, cyclosporine, danicopan, daridorexant, diosmin, dronedarone, erythromycin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, isavuconazonium, itraconazole, ivacaftor, josamycin, ketoconazole, lapatinib, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, propafenone, quinidine, ranolazine, ritonavir, saquinavir, sofosbuvir/velpatasvir/voxilaprevir, telaprevir, tepotinib, tezacaftor, tucatinib, valbenazine, vemurafenib, verapamil, vimseltinib and voclosporin.(1-3) |
GILOTRIF |
| Nintedanib/Dual CYP3A4 & P-gp Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Nintedanib is a substrate for the P-glycoprotein (P-gp) transporter and is metabolized to a minor extent by CYP3A4. CLINICAL EFFECTS: Concurrent use of an agent that is both an inhibitor of P-gp and CYP3A4 may result in elevated levels of and clinical effects of nintedanib. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of nintedanib recommends close monitoring for nintedanib patients receiving drugs which are both P-gp and CYP3A4 inhibitors. In an interaction study ketoconazole increased exposure to nintedanib by 60%. Nintedanib therapy may need to be interrupted or the dose may need to be reduced.(1) DISCUSSION: In an interaction study coadministration with ketoconazole, a P-gp and CYP3A4 inhibitor, increased nintedanib exposure (area-under-curve, AUC) and maximum concentration (Cmax) by 1.61-fold and 1.83 fold respectively.(1) Strong CYP3A4 & P-gp inhibitors include: adagrasib, boceprevir, clarithromycin, cobicistat, grapefruit, indinavir, itraconazole, josamycin, ketoconazole, levoketoconazole, lonafarnib, lopinavir, mibefradil, mifepristone, nefazodone, nelfinavir, nirmatrelvir, paritaprevir, posaconazole, ritonavir, saquinavir, telaprevir, telithromycin, tipranavir, and tucatinib. Moderate CYP3A4 & P-gp inhibitors include: conivaptan, diltiazem, dronedarone, erythromycin, fluvoxamine, isavuconazonium, schisandra, and verapamil. Weak CYP3A4 & P-gp inhibitors include: amiodarone, azithromycin, cimetidine, cyclosporine, daclatasvir, daridorexant, diosmin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, ivacaftor, lapatinib, mavorixafor, and ranolazine.(2) |
OFEV |
| Edoxaban (Greater Than 30 mg)/Select P-gp Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Edoxaban is a substrate for P-glycoprotein (P-gp). Inhibitors of P-gp may increase intestinal absorption and decrease renal tubular elimination of edoxaban.(1,2) CLINICAL EFFECTS: Concurrent use with selected P-gp inhibitors may result in higher systemic concentrations of edoxaban which may increase the risk for bleeding.(1,2) PREDISPOSING FACTORS: Bleeding risk may be increased in patients with creatinine clearance below 50 mL per minute(1-4). Use of multiple agents which increase edoxaban exposure or affect hemostasis would be expected to increase the risk for bleeding. The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). PATIENT MANAGEMENT: Management recommendations between approving regulatory agencies (FDA or European Medicines Agency, EMA) are conflicting. EMA approved prescribing information specifically states that dosage adjustments are not required solely for concomitant use with amiodarone, quinidine, or verapamil regardless of indication.(3,4) Potential interactions with azithromycin, clarithromycin, or oral itraconazole are not described.(3) FDA approved prescribing recommendations for edoxaban are indication specific:(2) - For prevention of stroke or embolic events due to nonvalvular atrial fibrillation, no edoxaban dose adjustments are recommended during concomitant therapy with P-glycoprotein inhibitors. - For treatment of deep vein thrombosis (DVT) or pulmonary embolism (PE), the edoxaban dose should be reduced to 30 mg daily during concomitant use with azithromycin, clarithromycin, oral itraconazole, quinidine or verapamil. The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to edoxaban.(6) Monitor patients receiving anticoagulant therapy for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. anti Factor Xa inhibition) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. Discontinue edoxaban in patients with active bleeding. DISCUSSION: Edoxaban in vivo interaction studies have been performed for quinidine and verapamil. In vivo interaction studies have not been conducted for the remaining P-gp inhibitors linked to this monograph.(1,4) In an interaction study, the effect of repeat administration of quinidine (300 mg TID) on a single oral dose of edoxaban 60 mg was evaluated in healthy subjects. Both peak (Cmax) and total systemic exposure (AUC) to edoxaban and to the active M4 metabolite increased approximately 1.75-fold.(1) In an interaction study, the effect of repeat administration of verapamil (240 mg Verapamil SR Tablets (Calan SR) QD for 11 Days) on a single oral dose of edoxaban 60 mg on the morning of Day 10 was evaluated in healthy subjects. Total and peak systemic exposure to edoxaban increased 1.53-fold and 1.53-fold, respectively. Total and peak systemic exposure to the active M4 metabolite increased 1.31-fold and 1.28-fold, respectively.(1) Based upon the above results, patients in the DVT/PE trial had a 50% dose reduction (from 60 mg to 30 mg) during concomitant therapy with P-glycoprotein inhibitors. Approximately 0.5% of these patients required a dose reduction solely due to P-gp inhibitor use. This low rate of concurrent therapy was too small to allow for detailed statistical evaluation. Almost all of these patients were receiving quinidine or verapamil. In these patients, both trough edoxaban concentrations (Ctrough) used to evaluate bleeding risk, and total edoxaban exposure (AUC or area-under-curve) used to evaluate treatment efficacy, were lower than patients who did not require any edoxaban dose adjustment. In this DVT/PE comparator trial, subgroup analysis revealed that warfarin had numerically better efficacy than edoxaban in patients receiving P-gp inhibitors. Based upon the overall lower exposure to edoxaban in P-gp dose adjusted subjects, both EMA and FDA Office of Clinical Pharmacology (OCP) concluded that the edoxaban 50% dose reduction overcorrected for the difference in exposure.(1,4) Consequently, EMA recommended no edoxaban dose adjustments for patients receiving concomitant therapy with quinidine or verapamil.(3,4) A summary of pharmacokinetic interactions with edoxaban and verapamil concluded that if concurrent use is considered safe.(7) P-gp inhibitors linked to this interaction are: amiodarone, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, daclatasvir, danicopan, daridorexant, diltiazem, diosmin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, oral itraconazole, indinavir, ivacaftor, josamycin, ledipasvir, lonafarnib, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, telaprevir, telithromycin, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(8) |
SAVAYSA |
| Lesinurad/Moderate CYP2C9 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate inhibitors of CYP2C9 may inhibit the metabolism of lesinurad.(1) CLINICAL EFFECTS: Concurrent use of moderate inhibitors of CYP2C9 may result in elevated levels and toxicity from lesinurad, include nephrotoxicity.(1) PREDISPOSING FACTORS: Patients with decreased renal function (CrCl less than 60 ml/min) and patients not receiving a xanthine oxidase inhibitor may be at increased risk of nephrotoxicity.(1) PATIENT MANAGEMENT: Approach the concurrent use of lesinurad and moderate inhibitors of CYP2C9 with caution.(1) Monitor renal function in patients receiving concurrent therapy closely. Interrupt therapy and measure serum creatinine promptly in patients who report flank pain and/or nausea/vomiting. DISCUSSION: Fluconazole (200 mg daily), a moderate inhibitor of CYP2C9, increased lesinurad levels by 50%.(1) |
DUZALLO |
| Efavirenz/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Efavirenz has been observed to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of efavirenz with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) CYP2B6 genotype may also increase the risk of this interaction. Patients who are most susceptible to this interaction are patients who are CYP2B6 poor metabolizers with CYP2B6 *6/*6 allele.(3) PATIENT MANAGEMENT: The US manufacturer of efavirenz states alternatives should be considered when concurrent administration with a drug with a known risk of Torsade de Pointes or when administered to patients at higher risk of Torsade de Pointes. Limited information is available on the potential pharmacodynamic interaction between efavirenz and drugs that prolong the QT interval; however, QT prolongation has been observed with efavirenz.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: A thorough QT study was conducted in the general population in 120 healthy subjects receiving efavirenz 600 mg daily. Time-matched differences in QTc with efavirenz compared to placebo was evaluated on day 11, at 6 hours post dose. The mean change in QTc was 5.2 msec and no change in QTc was greater than 10 msec.(4) In addition to the thorough QT study, the effect of efavirenz on the QTc interval was evaluated in 58 healthy subjects based on CYP2B6 genotype. CYP2B6 polymorphism was evaluated for each patient and results were the following: 65% with *1/*1 or *1/*4 allele (wild-type metabolizers), 26% with *1/*6 allele (intermediate metabolizers) and 9% with *6/*6 allele (slow metabolizers). Subjects with 2 copies of the CYP2B6*6 allele had significantly higher efavirenz exposure at steady-state (p<0.05). At steady-state concentrations of efavirenz, patients with CYP2B6 *1/*1 or *1/*6 alleles had no change in the QTc interval (p>0.05). However, patients with CYP2B6 *6/*6 allele had an increase in QTc mean +/- SD from 406 +/- 16.4 to 423 +/- 11.8 msec (p=0.02).(3) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(5) |
EFAVIRENZ, EFAVIRENZ-EMTRIC-TENOFOV DISOP, EFAVIRENZ-LAMIVU-TENOFOV DISOP, SYMFI, SYMFI LO |
| Letermovir/Amiodarone SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Letermovir, a moderate CYP3A4 inhibitor and CYP2C8 inhibitor, may inhibit the metabolism of amiodarone at CYP3A4 and CYP2C8. CLINICAL EFFECTS: The concurrent administration of amiodarone with letermovir may result in increased levels, clinical effects, and toxicity of amiodarone. PREDISPOSING FACTORS: Concurrent use with cyclosporine. PATIENT MANAGEMENT: The US manufacturer of letermovir recommends monitoring for adverse effects and amiodarone concentrations when letermovir and amiodarone are administered concurrently. When letermovir is coadministered with cyclosporine, the combined effect on amiodarone may be similar to a strong CYP3A4 inhibitor.(1) DISCUSSION: Letermovir has been shown to inhibit CYP3A4. In a study, concomitant administration of letermovir (480 mg once daily) with the CYP3A4 substrate midazolam (1 mg single dose intravenous) increased the midazolam area under the curve (AUC) and C24hr by 1.47-fold and 2.74-fold, respectively. Concomitant administration of letermovir (480 mg once daily) with midazolam (2 mg single dose oral) increased the midazolam AUC and maximum concentration (Cmax) by 2.25-fold and 1.72-fold.(1) |
PREVYMIS |
| Trazodone (Less Than 100 mg)/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Concurrent use of trazodone with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1,2) CLINICAL EFFECTS: The use of trazodone in patients maintained on agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1,2) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of trazodone states that concurrent use with agents known to prolong the QT interval should be avoided.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Trazodone has been reported to prolong the QT interval.(1) A thorough QT study in 20 subjects evaluated the effects of trazodone at doses of 20 mg, 60 mg and 140 mg. There was no evidence of QTc prolongation at the lowest trazodone dose of 20mg (mean effect on QTc of 4.5 ms 95% CI 3.7-5.3 ms), but at 60 mg and 140 mg, there was a significant effect that exceeds the E14 FDA Guidelines threshold of prolonging the QT/QTc interval by more than 5 ms. The study found a dose-dependent effect on QTc prolongation starting at 60 mg with a mean effect on QTc of 12.3 ms (95% CI 11-13.6 ms) and increasing with a 140 mg dose to a mean effect on QTc of 19.8 ms (95% CI 17.6-22.1).(3) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(4) |
TRAZODONE HCL |
| Edoxaban (Less Than or Equal To 30 mg)/Select P-gp Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Edoxaban is a substrate for P-glycoprotein (P-gp). Inhibitors of P-gp may increase intestinal absorption and decrease renal tubular elimination of edoxaban.(1,2) CLINICAL EFFECTS: Concurrent use with selected P-gp inhibitors may result in higher systemic concentrations of edoxaban which may increase the risk for bleeding.(1,2) PREDISPOSING FACTORS: Bleeding risk may be increased in patients with creatinine clearance below 50 mL per minute(1-4). Use of multiple agents which increase edoxaban exposure or affect hemostasis would be expected to increase the risk for bleeding. The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). PATIENT MANAGEMENT: Management recommendations between approving regulatory agencies (FDA or European Medicines Agency, EMA) are conflicting. EMA approved prescribing information specifically states that dosage adjustments are not required solely for concomitant use with amiodarone, quinidine, or verapamil regardless of indication.(3,4) Potential interactions with azithromycin, clarithromycin, or oral itraconazole are not described.(3) FDA approved prescribing recommendations for edoxaban are indication specific:(2) - For prevention of stroke or embolic events due to nonvalvular atrial fibrillation, no edoxaban dose adjustments are recommended during concomitant therapy with P-glycoprotein inhibitors. - For treatment of deep vein thrombosis (DVT) or pulmonary embolism (PE), the edoxaban dose should be reduced to 30 mg daily during concomitant use with azithromycin, clarithromycin, oral itraconazole, quinidine or verapamil. The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to edoxaban.(6) Monitor patients receiving anticoagulant therapy for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. anti Factor Xa inhibition) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. Discontinue edoxaban in patients with active bleeding. DISCUSSION: Edoxaban in vivo interaction studies have been performed for quinidine and verapamil. In vivo interaction studies have not been conducted for the remaining P-gp inhibitors linked to this monograph.(1,4) In an interaction study, the effect of repeat administration of quinidine (300 mg TID) on a single oral dose of edoxaban 60 mg was evaluated in healthy subjects. Both peak (Cmax) and total systemic exposure (AUC) to edoxaban and to the active M4 metabolite increased approximately 1.75-fold.(1) In an interaction study, the effect of repeat administration of verapamil (240 mg Verapamil SR Tablets (Calan SR) QD for 11 Days) on a single oral dose of edoxaban 60 mg on the morning of Day 10 was evaluated in healthy subjects. Total and peak systemic exposure to edoxaban increased 1.53-fold and 1.53-fold, respectively. Total and peak systemic exposure to the active M4 metabolite increased 1.31-fold and 1.28-fold, respectively.(1) Based upon the above results, patients in the DVT/PE trial had a 50% dose reduction (from 60 mg to 30 mg) during concomitant therapy with P-glycoprotein inhibitors. Approximately 0.5% of these patients required a dose reduction solely due to P-gp inhibitor use. This low rate of concurrent therapy was too small to allow for detailed statistical evaluation. Almost all of these patients were receiving quinidine or verapamil. In these patients, both trough edoxaban concentrations (Ctrough) used to evaluate bleeding risk, and total edoxaban exposure (AUC or area-under-curve) used to evaluate treatment efficacy, were lower than patients who did not require any edoxaban dose adjustment. In this DVT/PE comparator trial, subgroup analysis revealed that warfarin had numerically better efficacy than edoxaban in patients receiving P-gp inhibitors. Based upon the overall lower exposure to edoxaban in P-gp dose adjusted subjects, both EMA and FDA Office of Clinical Pharmacology (OCP) concluded that the edoxaban 50% dose reduction overcorrected for the difference in exposure.(1,4) Consequently, EMA recommended no edoxaban dose adjustments for patients receiving concomitant therapy with quinidine or verapamil.(3,4) A summary of pharmacokinetic interactions with edoxaban and verapamil concluded that if concurrent use is considered safe.(7) P-gp inhibitors linked to this interaction are: amiodarone, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, daclatasvir, danicopan, daridorexant, diltiazem, diosmin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, indinavir, oral itraconazole, ivacaftor, josamycin, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, telaprevir, telithromycin, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil vimseltinib, and voclosporin.(8) |
SAVAYSA |
| Gilteritinib/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Concurrent use of gilteritinib with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of gilteritinib with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(1) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(1) PATIENT MANAGEMENT: When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. Prior to initiation of therapy with gilteritinib, obtain baseline ECG and on days 8 and 15 of cycle 1, and prior to the start of the next two subsequent cycles. If QTc prolongation develops: ---Monitor and supplement electrolytes as clinically indicated ---Review and adjust concomitant QT prolonging medications For a QTc interval greater than 500 msec: ---Interrupt gilteritinib therapy ---Resume gilteritinib therapy at 80 mg when the QTc interval returns to within 30 msec of baseline or <= 480 msec. For QTc interval increased by > 30 msec on ECG on Day 8 of cycle 1: ---Confirm with ECG on Day 9 ---If confirmed, consider dose reduction to 80 mg.(2) DISCUSSION: In the gilteritinib clinical trial, 1.4% of patients developed a QTc interval greater than 500 msec and 7% of patients had an increase QTc greater than 60 msec.(2) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
XOSPATA |
| Lacosamide/Sodium Channel Blockers; Potassium Channel Blockers SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Lacosamide may enhance the slow inactivation of voltage-gated sodium channels and may cause dose-dependent bradycardia, prolongation of the PR interval, atrioventricular (AV) block, or ventricular tachyarrhythmia.(1) CLINICAL EFFECTS: Concurrent use of lacosamide and agents that affect cardiac conduction (sodium channel blockers and potassium channel blockers) may increase the risk of bradycardia, prolongation of the PR interval, atrioventricular (AV) block, or ventricular tachyarrhythmia.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Lacosamide should be used with caution in patients on concomitant medications that affect cardiac conduction, including sodium channel blockers and potassium channel blockers.(1) If concurrent use is needed, obtain an ECG before lacosamide therapy and after lacosamide dose is titrated to steady-state.(1) Patients should be monitored closely when lacosamide is given intravenously.(1) DISCUSSION: In a clinical trial in patients with partial-onset seizures, asymptomatic first-degree atrioventricular (AV) block occurred in 4/944 (0.4%) of patient who received lacosamide compared to 0/364 (0%) with placebo.(1) In a clinical trial in patients with diabetic neuropathy, asymptomatic first-degree AV block occurred in 5/1023 (0.5%) of patients who received lacosamide compared to 0/291 (0%) with placebo.(1) Second-degree and complete AV block have been reported in patients with seizures.(1) One case of profound bradycardia was observed in a patient during a 15-minute infusion of 150 mg of lacosamide.(1) A case report of a 49 year old male with refractory complex partial and generalized seizures described the development of ventricular tachycardia four months after addition of lacosamide 400 mg/day to the existing regimen of carbamazepine, lamotrigine, clonazepam, and valproate. The patient's ECG showed first-degree AV block, posterior left fascicular block, and severe widening of the QRS complex, all of which resolved upon discontinuation of lacosamide.(2) |
LACOSAMIDE, MOTPOLY XR, VIMPAT |
| Pitolisant/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Concurrent use of pitolisant with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of pitolisant with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: Patients who are CYP2D6 poor metabolizers or on concurrent use with CYP2D6 inhibitors are at increased risk for higher systemic exposure to pitolisant and may be at increased risk of QT prolongation.(1) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.(2) DISCUSSION: In two dedicated QT prolongation studies, supra-therapeutic doses of pitolisant at 3-6 times the therapeutic dose (108-216 mg) were seen to cause mild to moderate QTc prolongation (10-13 ms). A study in patients who were CYP2D6 poor metabolizers had higher systemic exposure up to 3-fold compared to CYP2D6 extensive metabolizers.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
WAKIX |
| Tacrolimus/Moderate & Weak CYP3A4 Inhibitors that Prolong QT SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate and weak inhibitors of CYP3A4 may inhibit the metabolism of tacrolimus.(1) In addition, concurrent use of tacrolimus with agents known to prolong the QT interval may result in additive or synergistic effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent use of a CYP3A4 inhibitor may result in elevated levels of and toxicity from tacrolimus, including nephrotoxicity and neurotoxicity.(1) In addition, concurrent administration of a QT prolonging CYP3A4 inhibitor and tacrolimus may result in prolongation of the QTc interval and life-threatening cardiac arrhythmias, including torsades de pointes. PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of tacrolimus recommends frequently monitoring tacrolimus whole blood trough concentrations and reducing tacrolimus dose if needed.(1) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: The coadministration of amiodarone and tacrolimus was described in a case report of a 73-year-old kidney transplant recipient with normal renal function who was on amiodarone for years. Tacrolimus 7 mg per day was started and after 3 months, the patient was found to have a tacrolimus level of 63 ng/mL. The dose of tacrolimus was lowered to 2 mg per day, and tacrolimus levels dropped to 12.9 ng/mL.(3) In another case report, a 65-year-old man on amiodarone for 5 years started tacrolimus 3 mg twice daily status-post renal transplant. After one day, QTc was prolonged from a baseline of 440 ms to 535 ms. QTc dropped to 493 ms three days after discontinuation of amiodarone and dose reduction of tacrolimus.(4) A case report describes the interaction between azithromycin and tacrolimus in a 27-year old woman with acute myelogenous leukemia who had a bone marrow transplant. On tacrolimus 0.02 mg/kg/day IV, the patient had stable tacrolimus levels of 15.8 to 17.5 ng/mL. Three days after initiation of azithromycin 500 mg daily, tacrolimus levels rose to over 30 ng/mL.(5) In a case report, a 64-year-old kidney transplant recipient on a stable dose of tacrolimus 10 mg twice daily for 5 months was started on ranolazine 500 mg twice daily for angina. Tacrolimus levels rose from the patient's stable levels of 7 to 10 ng/mL in the previous 5 months to 17.8 ng/mL after 1 day.(6) Another case report describes a 54-year-old kidney transplant recipient on tacrolimus 3 mg twice daily with trough levels of 4.5 to 7.4 ng/mL for the previous 4 years. After he was started on ranolazine 375 mg twice daily, tacrolimus levels rose to 10.9 ng/mL and serum creatinine (Scr) rose from 1.2 to 2 mg/dL. Ranolazine was discontinued after one month, and tacrolimus levels dropped to 3.6 ng/mL, with complete reversal of renal failure.(7) A 62-year-old kidney transplant recipient on a stable dose of tacrolimus for years was started on ranolazine and titrated to 1,000 mg twice daily over one month. After 2 weeks, he experienced renal failure with Scr rising from 1.5 to 2.4 mg/dL, and tacrolimus level was elevated at 14 ng/mL. Ranolazine was discontinued and tacrolimus levels decreased to 7 ng/mL after 3 days, with Scr returning to baseline.(8) Moderate CYP3A4 inhibitors that prolong QT linked to this monograph include: ciprofloxacin, crizotinib, and nilotinib.(9) Weak CYP3A4 inhibitors the prolong QT linked to this monograph include: amiodarone, azithromycin, cilostazol, entrectinib, lapatinib, mavorixafor, osilodrostat, propofol, ranolazine, rucaparib and selpercatinib.(9) |
ASTAGRAF XL, ENVARSUS XR, PROGRAF, TACROLIMUS, TACROLIMUS XL |
| Lemborexant (Less Than or Equal To 5 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of CYP3A4 may inhibit the metabolism of lemborexant.(1) CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP3A4 may result in increased levels of and effects from lemborexant, including somnolence, fatigue, CNS depressant effects, daytime impairment, headache, and nightmare or abnormal dreams.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The maximum recommended dose of lemborexant with concurrent use of a weak CYP3A4 inhibitors should not exceed 5 mg per dose.(1) DISCUSSION: Lemborexant is a CYP3A4 substrate. In a PKPB model, concurrent use of lemborexant with itraconazole increased area-under-curve (AUC) and concentration maximum (Cmax) by 3.75-fold and 1.5-fold, respectively. Concurrent use of lemborexant with fluconazole increased AUC and Cmax by 4.25-fold and 1.75-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(1,2) |
DAYVIGO |
| Ubrogepant/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of ubrogepant.(1) CLINICAL EFFECTS: Concurrent use of ubrogepant with weak CYP3A4 inhibitors may result in an increase in exposure of ubrogepant.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when used concomitantly with weak CYP3A4 inhibitors. Initial dose of ubrogepant should not exceed 50 mg when used concomitantly with weak inhibitors of CYP3A4. A second dose may be given within 24 hours but should not exceed 50 mg when used concurrently with weak CYP3A4 inhibitors.(1) DISCUSSION: Coadministration of ubrogepant with verapamil, a moderate CYP3A4 inhibitor, resulted in a 3.5-fold and 2.8-fold increase in area-under-curve (AUC) and concentration maximum (Cmax), respectively. No dedicated drug interaction study was conducted to assess concomitant use with weak CYP3A4 inhibitors. The conservative prediction of the maximal potential increase in ubrogepant exposure with weak CYP3A4 inhibitors is not expected to be more than 2-fold.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, asciminib, azithromycin, Baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, delavirdine, dihydroberberine, diosmin, elagolix, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, maribavir, mavorixafor, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(2,3) |
UBRELVY |
| Amisulpride/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Amisulpride has been shown to prolong the QT interval. Concurrent use with QT prolonging agents may result in additive effects on the QT interval.(1) CLINICAL EFFECTS: The concurrent use of amisulpride with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Use caution when using amisulpride concurrently with other agents that can prolong the QT interval. Amisulpride may cause a dose and concentration dependent increase in the QTc interval. When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. ECG monitoring is recommended in patients with pre-existing arrhythmias or cardiac conduction disorders; electrolyte abnormalities; congestive heart failure; or in patients taking medications or with other medical conditions known to prolong the QT interval. Correct any electrolyte abnormalities.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting.(2) DISCUSSION: QT prolongation and torsades de pointes have been reported with amisulpride. In a study in 40 patients with post operative nausea and vomiting, amisulpride increased baseline QTcF by 5 msec after a 2-minute intravenous infusion of 5 mg and by 23.4 msec after an 8-minute intravenous infusion of 40 mg. Based on an exposure-response relationship, it is expected that a 10 mg intravenous infusion over 1 minute may increase the QTcF by 13.4 msec.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
BARHEMSYS |
| Osilodrostat/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Osilodrostat has been shown to prolong the QT interval. Concurrent use with QT prolonging agents may result in additive effects on the QT interval.(1) CLINICAL EFFECTS: The concurrent use of osilodrostat with agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Use caution when using osilodrostat concurrently with other agents that can prolong the QT interval and consider more frequent ECG monitoring. A dose-dependent QT interval prolongation was noted in clinical studies. Prior to initiating therapy with osilodrostat, obtain a baseline ECG and monitor for QTc interval changes thereafter. Consider temporary discontinuation of therapy if the QTc interval increases > 480 msec. When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.(2) DISCUSSION: QTc prolongation has been reported with osilodrostat. In a thorough QT study in 86 healthy patients, osilodrostat increased baseline QTcF by 1.73 msec at a 10 mg dose and 25.38 msec at a 150 mg dose (up to 2.5 times the maximum recommended dosage). The predicted mean placebo-corrected QTcF at the highest recommended dose in clinical practice (30 mg twice daily) was estimated as 5.3 msec.(1) In a clinical study, five patients (4%) were reported to have an event of QT prolongation, three patients (2%) had a QTcF increase of > 60 msec from baseline, and 18 patients (13%) had a new QTcF value of > 450 msec.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) |
ISTURISA |
| Tamoxifen/Selected Weak CYP2D6 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of CYP2D6 may inhibit the conversion of tamoxifen to endoxifen (an active metabolite of tamoxifen).(1-2) The role of endoxifen in tamoxifen's efficacy has been debated and may involve a minimum concentration level.(3-5) CLINICAL EFFECTS: Concurrent use of inhibitors of CYP2D6 may decrease the effectiveness of tamoxifen in preventing breast cancer recurrence. PREDISPOSING FACTORS: Concurrent use of weak CYP2D6 inhibitors in patients who are CYP2D6 intermediate metabolizers should be avoided. Patients who are CYP2D6 poor metabolizers lack CYP2D6 function and are not affected by CYP2D6 inhibition. PATIENT MANAGEMENT: Although data on this interaction are conflicting, it may be prudent to use alternatives to CYP2D6 inhibitors when possible in patients taking tamoxifen. The US manufacturer of tamoxifen states that the impact on the efficacy of tamoxifen by strong CYP2D6 inhibitors is uncertain and makes no recommendation regarding coadministration with inhibitors of CYP2D6.(12) The manufacturer of paroxetine (a strong CYP2D6 inhibitor) states that alternative agents with little or no CYP2D6 inhibition should be considered.(13) The National Comprehensive Cancer Network's breast cancer guidelines advises caution when coadministering strong CYP2D6 inhibitors with tamoxifen.(14) If concurrent therapy is warranted, the risks versus benefits should be discussed with the patient. DISCUSSION: Some studies have suggested that administration of fluoxetine, paroxetine, and quinidine with tamoxifen or a CYP2D6 poor metabolizer phenotype may result in a decrease in the formation of endoxifen (an active metabolite of tamoxifen) and a shorter time to breast cancer recurrence.(1-2,9) A retrospective study of 630 breast cancer patients found an increasing risk of breast cancer mortality with increasing durations of coadministration of tamoxifen and paroxetine. In the adjusted analysis, absolute increases of 25%, 50%, and 75% in the proportion of time of overlapping use of tamoxifen with paroxetine was associated with 24%, 54%, and 91% increase in the risk of death from breast cancer, respectively.(15) The CYP2D6 genotype of the patient may have a role in the effects of this interaction. Patients with wild-type CYP2D6 genotype may be affected to a greater extent by this interaction. Patients with a variant CYP2D6 genotype may have lower baseline levels of endoxifen and may be affected to a lesser extent by this interaction.(6-10) In a retrospective review, 1,325 patients treated with tamoxifen for breast cancer were classified as being poor 2D6 metabolizers (lacking functional CYP2D6 enzymes), intermediate metabolizers (heterozygous alleles), or extensive metabolizers (possessing 2 functional alleles). After a mean follow-up period of 6.3 years, the recurrence rates were 14.9%, 20.9%, and 29.0%, in extensive metabolizers, intermediate metabolizers, and poor metabolizers, respectively.(11) In October of 2006, the Advisory Committee Pharmaceutical Science, Clinical Pharmacology Subcommittee of the US Food and Drug Administration recommended that the US tamoxifen labeling be updated to include information about the increased risk of breast cancer recurrence in poor CYP2D6 metabolizers (either by genotype or drug interaction).(16-17) The labeling changes were never made due to ongoing uncertainty about the effects of CYP2D6 genotypes on tamoxifen efficacy. In contrast to the above information, two studies have shown no relationship between CYP2D6 genotype and breast cancer outcome.(18-20) As well, a number of studies found no association between use of CYP2D6 inhibitors and/or antidepressants in patients on tamoxifen and breast cancer recurrence,(21-25) though the studies were limited by problematic selection of CYP2D6 inhibitors and short follow-up. Weak CYP2D6 inhibitors include: amiodarone, chlorpromazine, citalopram, escitalopram, flecainide, methadone, panobinostat, propafenone, telithromycin, vemurafenib, and venlafaxine.(26-27) |
SOLTAMOX, TAMOXIFEN CITRATE |
| Galantamine/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Galantamine may reduce heart rate by increasing acetylcholine in the heart and increasing vagal tone. Bradycardia has been associated with increased risk of QTc interval prolongation.(1) Concurrent use of galantamine with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(2) CLINICAL EFFECTS: The use of galantamine in patients maintained on agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(2) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, advanced age or when receiving concomitant treatment with an inhibitor of CYP3A4.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The UK manufacturer of galantamine states that it should be used with caution in patients treated with drugs that affect the QTc interval.(2) If concurrent therapy is warranted, monitor ECG more frequently and consider obtaining serum calcium, magnesium, and potassium levels at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Therapeutic doses of galantamine have been reported to cause QTc prolongation in patients.(2) An 85 year old male with dementia was restarted on galantamine 8 mg daily after a 2-week treatment interruption due to a syncopal episode that occurred 3 months previously. During his prior syncopal episode, he was hypotensive and bradycardic, but QTc interval was normal. After restarting galantamine, he was found to be hypotension and bradycardiac again, and QTc interval was significantly prolonged to 503 msec, over 60 msec longer than when he was off galantamine. Galantamine was discontinued and his QTc interval returned to baseline.(4) A 47 year old schizophrenic male experienced prolongation of the QTc interval to 518 msec after galantamine was increased from 8 mg daily to 12 mg daily. Although he was also on quetiapine and metoprolol, he had been stable on his other medications. His QTc interval normalized after galantamine was stopped.(5) The European pharmacovigilance (Eudravigilance) database contains 14 reports of torsades de pointe in patients on galantamine as of October 2019.(1) A pharmacovigilance study based on the FDA Adverse Event Reporting System (FAERS) database found that, of a total of 33,626 cases of TdP/QT prolongation reported between January 2004 and September 2022, 54 cases occurred in patients on galantamine. The disproportionality analysis found a ROR = 5.12, 95% CI (3.92,6.68) and a PRR = 5.11, chi-square = 175.44.(6) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(7) |
GALANTAMINE ER, GALANTAMINE HBR, GALANTAMINE HYDROBROMIDE, ZUNVEYL |
| Ponesimod/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Ponesimod is a sphingosine 1-phosphate (S1P) receptor 1 modulator. Initiation of ponesimod has a negative chronotropic effect leading to a mean decrease in heart rate of 6 beats per minute (bpm) after the first dose. The first dose has also been associated with heart block.(1) CLINICAL EFFECTS: After a dose of ponesimod, a decrease in heart rate typically begins within an hour and reaches its nadir within 2-4 hours. The heart rate typically recovers to baseline levels 4-5 hours after administration. All patients recovered from bradycardia. The conduction abnormalities typically were transient, asymptomatic, and resolved within 24 hours. Second- and third-degree AV blocks were not reported. With up-titration after Day 1, the post-dose decrease in heart rate is less pronounced. Bradycardia may be associated with an increase in the QTc interval, increasing the risk for torsades de pointes.(1,2) PREDISPOSING FACTORS: Pre-existing cardiovascular or cerebrovascular disease (e.g. heart failure, ischemic heart disease, history of myocardial infarction, stroke, or heart block), severe untreated sleep apnea, a prolonged QTc interval prior to ponesimod initiation, factors associated with QTc prolongation, or concomitant treatment with QT prolonging agents may increase risk for cardiovascular toxicity due to ponesimod.(1) The risk of QT prolongation or torsades de pointes may also be increased in patients with a history of torsades de pointes, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of the QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Prior to initiation of ponesimod, obtain an ECG to determine if preexisting conduction abnormalities are present. Ponesimod is generally not recommended in patients who are receiving concurrent treatment with a QT prolonging agent, anti-arrhythmic drugs, or drugs that may decrease heart rate. Consultation with a cardiologist is recommended.(1) In patients with heart rate (HR) less than 55 beats per minute (bpm), first- or second-degree AV block, or history of myocardial infarction or heart failure, monitor patients for 4 hours after the first dose for signs and symptoms of bradycardia with a minimum of hourly pulse and blood pressure measurements. Obtain an ECG in these patients prior to dosing and at the end of the 4-hour observation period.(1) Additional US monitoring recommendations include: If HR is less than 45 bpm, the heart rate 4 hours post-dose is at the lowest value post-dose or if the ECG shows new onset of second degree or higher AV block at the end of the monitoring period, then monitoring should continue until the finding has resolved. If patient requires treatment for symptomatic bradycardia, second-degree or higher AV block, or QTc interval greater than or equal to 500 msec, perform continuous overnight ECG monitoring and repeat the first dose monitoring strategy for the second dose of ponesimod. Consult the prescribing information for full monitoring recommendations. If fewer than 4 consecutive doses are missed during titration: resume treatment with the first missed titration dose and resume the titration schedule at that dose and titration day. If fewer than 4 consecutive doses are missed during maintenance: resume treatment with the maintenance dosage. If 4 or more consecutive daily doses are missed during treatment initiation or maintenance treatment, reinitiate Day 1 of the dose titration (new starter pack) and follow first-dose monitoring recommendations. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: After the first dose of ponesimod, heart rate decrease may begin within the first hour. Decline is usually maximal at approximately 4 hours. With continued, chronic dosing, post-dose decrease in heart rate is less pronounced. Heart rate gradually returns to baseline in about 4-5 hours.(1) |
PONVORY |
| Ozanimod/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Ozanimod is a sphingosine 1-phosphate (S1P) receptor modulator. Initiation of ozanimod has a negative chronotropic effect leading to a mean decrease in heart rate of 13 beats per minute (bpm) after the first dose. The first dose has also been associated with heart block.(1,2) Ozanimod blocks the capacity of lymphocytes to egress from lymph nodes, reducing the number of lymphocytes in peripheral blood. The mechanism by which ozanimod exerts therapeutic effects in multiple sclerosis is unknown but may involve the reduction of lymphocyte migration into the central nervous system. CLINICAL EFFECTS: The initial heart rate lowering effect of ozanimod usually occurs within 5 hours. With continued up-titration, the maximal heart rate effect of ozanimod occurred on Day 8. Symptomatic bradycardia and heart block, including third degree block, have been observed. Bradycardia may be associated with an increase in the QTc interval, increasing the risk for torsades de pointes.(1,2) PREDISPOSING FACTORS: Pre-existing cardiovascular or cerebrovascular disease (e.g. heart failure, ischemic heart disease, history of myocardial infarction, stroke, or heart block), severe untreated sleep apnea, a prolonged QTc interval prior to ozanimod initiation, factors associated with QTc prolongation (e.g. hypokalemia, hypomagnesemia), or concomitant treatment with QT prolonging agents may increase risk for cardiovascular toxicity due to ozanimod.(1,2) The risk of QT prolongation or torsades de pointes may also be increased in patients with a history of torsades de pointes, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of the QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: Prior to initiation of ozanimod, obtain an ECG to determine if preexisting conduction abnormalities are present. Patients with preexisting cardiac conditions, significant QT prolongation (QTc >450 msec in males, >470 msec in females), concurrent Class Ia or Class III antiarrhythmics, or receiving concurrent treatment with a QT prolonging agent at the time ozanimod is initiated or resumed should be referred to a cardiologist.(1) The US recommendations state: Dose titration is recommended with initiation of ozanimod due to transient decrease in heart rate and AV conduction delays.(1) United Kingdom recommendations:(2) Due to the risk of transient decreases in HR with the initiation of ozanimod, first dose, 6-hour monitoring for signs and symptoms of symptomatic bradycardia is recommended in patients with resting HR <55 bpm, second-degree [Mobitz type I] AV block or a history of myocardial infarction or heart failure. Patients should be monitored with hourly pulse and blood pressure measurement during this 6-hour period. An ECG prior to and at the end of this 6-hour period is recommended. Additional monitoring after 6 hours is recommended in patients with: heart rate less than 45 bpm, heart rate at the lowest value post-dose (suggesting that the maximum decrease in HR may not have occurred yet), evidence of a new onset second-degree or higher AV block at the 6-hour post dose ECG, or QTc interval greater than 500 msec. In these cases, appropriate management should be initiated and observation continued until the symptoms/findings have resolved. Instruct patients to report any irregular heartbeat, dizziness, or fainting.(2,3) DISCUSSION: After the first dose of ozanimod heart rate decline is usually maximal at approximately 5 hours, returning to baseline at 6 hours. With continued, chronic dosing, maximum heart rate effect occurred on day 8.(1,2) |
ZEPOSIA |
| Triclabendazole/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Triclabendazole has been observed to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) Triclabendazole is partially metabolized by CYP1A2. Ciprofloxacin, propafenone, and vemurafenib are CYP1A2 inhibitors and may inhibit the CYP1A2 mediated metabolism of triclabendazole. CLINICAL EFFECTS: The concurrent use of triclabendazole with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Hepatic impairment and concurrent use of CYP1A2 inhibitors may raise triclabendazole levels and increase the risk of QT prolongation.(1) PATIENT MANAGEMENT: The manufacturer of triclabendazole states concurrent use with agents known to prolong the QT interval should be used with caution. Monitor ECG in patients with a history of QTc prolongation, symptoms of long QT interval, electrolyte imbalances, concurrent CYP1A2 inhibitors, or hepatic impairment. If signs of a cardiac arrhythmia develop, stop treatment with triclabendazole and monitor ECG.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a thorough QT study, a dose-dependent prolongation in the QTc interval was observed with triclabendazole. The largest placebo-corrected mean increase in QTc was 9.2 msec (upper limit of confidence interval (UCI): 12.2 msec) following oral administration of 10 mg/kg triclabendazole twice daily (at the recommended dose), and the largest placebo-corrected mean increase in QTc was 21.7 msec (UCI: 24.7 msec) following oral administration of 10 mg/kg triclabendazole twice daily for 3 days (3 times the approved recommended dosing duration).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3) |
EGATEN |
| Mavorixafor/P-gp Inhibitors that Prolong QT SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors that prolong the QT interval may increase the absorption of mavorixafor and may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent use of P-gp inhibitors that prolong the QTc interval may increase the levels and effects of mavorixafor including additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes, and sudden death.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: When used concomitantly with P-gp inhibitors, monitor more frequently for mavorixafor adverse effects and reduce the dose in 100 mg increments, if necessary, but not to a dose less than 200 mg.(1) The manufacturer of mavorixafor states the concurrent use of mavorixafor should be used with caution with other agents known to prolong the QT interval. ECG monitoring is recommended prior to initiation, during concurrent therapy, and as clinically indicated with other agents known to prolong the QTc interval.(1) If QT prolongation occurs, a dose reduction or discontinuation of mavorixafor may be required.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.(1) DISCUSSION: In a thorough QT study, a dose of mavorixafor 800 mg increased the mean QTc 15.6 msec (upper 90% confidence interval = 19.8 msec). The dose of mavorixafor was 2 times the recommended maximum daily dose.(1) In a study with healthy subjects, itraconazole 200 mg daily (a strong CYP3A4 and P-gp inhibitor) increased the exposure to single-dose mavorixafor 200 mg similar to that from single-dose mavorixafor 400 mg alone. This suggests that itraconazole increased mavorixafor exposure by about 2-fold.(1) A study in healthy volunteers found that ritonavir 100 mg twice daily (a strong CYP3A4 inhibitor and P-gp inhibitor) increased the area-under-curve (AUC) and maximum concentration (Cmax) of single-dose mavorixafor 200 mg by 60% and 39%, respectively.(3) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(4) P-gp inhibitors linked to this monograph include: amiodarone, azithromycin, hydroquinidine, lapatinib, osimertinib, quinidine, ranolazine, vemurafenib and selpercatinib.(5) |
XOLREMDI |
| Sulfonylureas/Amiodarone SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Amiodarone may decrease the metabolism of sulfonylureas by inhibiting CYP2C9. Amiodarone is a moderate CYP2C9 inhibitor.(1-5) CLINICAL EFFECTS: Increased effectiveness of the sulfonylurea which may result in clinical symptoms of hypoglycemia. PREDISPOSING FACTORS: This interaction may be more likely in patients using higher doses of amiodarone and who use amiodarone for greater than 180 days.(6) PATIENT MANAGEMENT: Closely monitor blood glucose levels during concurrent therapy. The dose of the sulfonylurea may need to be adjusted when initiating or discontinuing amiodarone therapy. DISCUSSION: In a nested case control study, concurrent use of amiodarone and sulfonylureas increased the risk of severe hypoglycemia by 56% (95% CI:0.98-2.46). In patients on sulfonylureas, amiodarone use greater than 180 days and at higher daily doses was associated with a 2.08-fold and a 2.21-fold increase in severe hypoglycemia, respectively, which was statistically significant.(6) |
DUETACT, GLIMEPIRIDE, GLIPIZIDE, GLIPIZIDE ER, GLIPIZIDE XL, GLIPIZIDE-METFORMIN, GLUCOTROL XL, GLYBURIDE, GLYBURIDE MICRONIZED, GLYBURIDE-METFORMIN HCL, PIOGLITAZONE-GLIMEPIRIDE |
| Mavacamten/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Weak CYP3A4 inhibitors may decrease the metabolism of mavacamten.(1) CLINICAL EFFECTS: Concurrent use of weak CYP3A4 inhibitors may increase the plasma levels and the incidence and severity of adverse reactions of mavacamten.(1) PREDISPOSING FACTORS: CYP2C19 poor metabolizers may experience an increased incidence or severity of adverse effects.(1) PATIENT MANAGEMENT: The UK manufacturer of mavacamten states no dose adjustment is necessary when starting mavacamten in patients on weak CYP3A4 inhibitors or in intermediate, normal, rapid, or ultra-rapid CYP2C19 metabolizers already on mavacamten and starting a weak CYP3A4 inhibitor. In poor CYP2C19 metabolizers already on mavacamten and starting a weak CYP3A4 inhibitor, reduce mavacamten 5 mg to 2.5 mg or if on 2.5 mg pause treatment for 4 weeks. If CYP2C19 phenotype is unknown, consider a mavacamten starting dose of 2.5 mg daily.(1) DISCUSSION: In a PBPK model, concomitant use of mavacamten (15 mg daily) with cimetidine 400 mg twice daily, a weak CYP3A4 inhibitor, was predicted to increase mavacamten area-under-curve (AUC) by 6% and maximum concentration (Cmax) by 4% in poor CYP2C19 metabolizers and by 3% and 2%, respectively, in both intermediate and normal CYP2C19 metabolizers.(2) Weak CYP3A4 inhibitors include: alprazolam, amiodarone, amlodipine, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, chlorzoxazone, cilostazol, ciprofloxacin, clotrimazole, cranberry, cyclosporine, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, istradefylline, ivacaftor, lacidipine, lapatinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, pazopanib, peppermint oil, propiverine, propofol, ranitidine, remdesivir, resveratrol, roxithromycin, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, and viloxazine.(4,5) |
CAMZYOS |
The following contraindication information is available for PACERONE (amiodarone hcl):
Drug contraindication overview.
No enhanced Contraindications information available for this drug.
No enhanced Contraindications information available for this drug.
There are 8 contraindications.
Absolute contraindication.
| Contraindication List |
|---|
| Bradycardia |
| Cardiogenic shock |
| Complete atrioventricular block |
| Lactation |
| Refractive keratoplasty by laser surgery |
| Second degree atrioventricular heart block |
| Sinus node dysfunction |
| Syncope due to bradycardia |
There are 17 severe contraindications.
Adequate patient monitoring is recommended for safer drug use.
| Severe List |
|---|
| Alveolar hemorrhage |
| Chronic obstructive pulmonary disease |
| Congenital long QT syndrome |
| Drug-induced hepatitis |
| Eosinophilic pneumonia |
| Hypersensitivity pneumonitis |
| Hyperthyroidism |
| Hypokalemia |
| Hypomagnesemia |
| Hypothyroidism |
| Interstitial pneumonitis |
| Optic neuritis |
| Optic neuropathy |
| Pregnancy |
| Prolonged QT interval |
| Thyrotoxicosis |
| Torsades de pointes |
There are 4 moderate contraindications.
Clinically significant contraindication, where the condition can be managed or treated before the drug may be given safely.
| Moderate List |
|---|
| Corneal deposits |
| Disease of liver |
| Invasive surgical procedure |
| Peripheral neuropathy |
The following adverse reaction information is available for PACERONE (amiodarone hcl):
Adverse reaction overview.
No enhanced Common Adverse Effects information available for this drug.
No enhanced Common Adverse Effects information available for this drug.
There are 84 severe adverse reactions.
| More Frequent | Less Frequent |
|---|---|
|
Abnormal hepatic function tests Alveolitis Hypotension Interstitial pneumonitis Pulmonary fibrosis Skin photosensitivity |
Blurred vision Cardiac arrhythmia Chronic heart failure Corneal deposits Dyschromia Hyperthyroidism Hypothyroidism Optic neuritis Optic neuropathy Prolonged QT interval Sinus bradycardia Torsades de pointes Visual halos |
| Rare/Very Rare |
|---|
|
Acute pancreatitis Acute respiratory distress syndrome Acute respiratory failure Agranulocytosis Allergic dermatitis Anaphylaxis Angioedema Aplastic anemia Atrial fibrillation Atrioventricular block Bradycardia Bronchiolitis obliterans Bronchospastic pulmonary disease Bullous dermatitis Cholestasis Cholestatic hepatitis Corneal degeneration Demyelinating disorder DRESS syndrome Dyspnea Edema Eosinophilic pneumonia Epididymitis Erythema multiforme Exfoliative dermatitis Hallucinations Heart block Hemolytic anemia Hemoptysis Hepatitis Hypersensitivity pneumonitis Hypoxia Idiopathic intracranial hypertension Injection site sequelae Kidney disease with reduction in glomerular filtration rate (GFr) Lupus-like syndrome Lymphadenopathy Malignant neoplasm of skin Myopathy Neutropenic disorder Pancytopenia Papilledema Parkinsonism Paroxysmal ventricular tachycardia Peripheral demyelinating neuropathy Peripheral neuropathy Pleural effusions Pleuritis Pulmonary edema Pulmonary hemorrhage Renal failure Rhabdomyolysis Scotomata Shock SIADH syndrome Sinus arrest Sinus node dysfunction Skin rash Stevens-johnson syndrome Thrombocytopenic disorder Thyroid carcinoma Tissue necrosis Toxic epidermal necrolysis Vasculitis Vision impairment |
There are 40 less severe adverse reactions.
| More Frequent | Less Frequent |
|---|---|
|
Anorexia Ataxia Constipation Fatigue Malaise Nausea Tremor Vomiting |
Abnormal sexual function Acute abdominal pain Dizziness Dry eye Dysgeusia Ecchymosis Flushing Headache disorder Insomnia Libido changes Paresthesia Photophobia |
| Rare/Very Rare |
|---|
|
Accidental fall Acute cognitive impairment Alopecia Back pain Bradykinesia Cough Delirium Eczema Eosinophilia Erectile dysfunction Facial edema Fever Gait abnormality Involuntary muscle movement Muscle spasm Muscle weakness Sialorrhea Sleep disorder Urticaria Xerostomia |
The following precautions are available for PACERONE (amiodarone hcl):
No enhanced Pediatric Use information available for this drug.
Contraindicated
Severe Precaution
Management or Monitoring Precaution
Contraindicated
| None |
Severe Precaution
| None |
Management or Monitoring Precaution
| None |
Reproduction studies in pregnant rats or rabbits receiving oral amiodarone hydrochloride dosages of 25 mg/kg daily (approximately 0.4 and 0.9 times, respectively, the maximum recommended human maintenance dosage of 600 mg for a 50-kg patient (calculated on the basis of body surface area)) revealed no evidence of harm to the fetus. However, in pregnant rabbits receiving oral amiodarone hydrochloride dosages of 75 mg/kg daily (approximately 2.7 times the maximum recommended human maintenance dosage of 600 mg for a 50-kg patient (calculated on the basis of body surface area)), abortions occurred in more than 90% of these rabbits. Slight displacement of the testes and an increased incidence of incomplete ossification of some skull and digital bones were reported in pregnant rats receiving oral amiodarone hydrochloride dosages of 50 mg/kg daily (approximately 0.8 times the maximum recommended human maintenance dosage of 600 mg for a 50-kg patient (calculated on the basis of body surface area)) or more.
In addition, in rats receiving oral amiodarone hydrochloride dosages of 100 mg/kg daily (approximately 1.6 times the maximum recommended human maintenance dosage of 600 mg for a 50-kg patient (calculated on the basis of body surface area) or more, or 200 mg/kg daily (approximately 1.6 or 3.2 times the maximum recommended human maintenance dosage of 600 mg for a 50-kg patient (calculated on the basis of body surface area)), reduced fetal body weight or increased incidence of fetal resorptions, respectively, were observed. Adverse effects on fetal growth and survival also were reported in 1 of 2 strains of mice receiving oral amiodarone hydrochloride dosages of 5 mg/kg daily (approximately 0.04 times the maximum recommended human maintenance dosage of 600 mg for a 50-kg patient (calculated on the basis of body surface area)). In a reproductive study in which amiodarone was administered IV to rabbits at dosages of 5, 10, or 25 mg/kg daily (approximately 0.1, 0.3, or 0.7 times the recommended maximum human dose on the basis of body surface area, respectively), maternal deaths occurred in all groups, including controls.
Embryotoxicity, as manifested by fewer full-term fetuses and increased resorptions with concomitantly lower litter weights, occurred at dosages of 10 mg/kg and greater. No evidence of embryotoxicity was observed at the 5 mg/kg dosage and no teratogenicity was observed at any dosage level tested. In a teratology study in which amiodarone was administered by continuous IV infusion to rats at dosages of 25, 50, or 100 mg/kg daily (approximately 0.4, 0.7, or 1.4 times the recommended maximum human dose on the basis of body surface area, respectively), maternal toxicity (as evidenced by reduced weight gain and food consumption) and embryotoxicity (as evidenced by increased resorptions, decreased live litter size, reduced body weights, and retarded sternum and metacarpal ossification) were observed in the group receiving 100 mg/kg daily.
Amiodarone and N-desethylamiodarone cross the placenta to a limited extent. QT prolongation and transient sinus bradycardia have been observed in neonates of a limited number of pregnant women who received the drug during the second and/or third trimester. Specific data are not available, but there are concerns that amiodarone potentially could adversely affect fetal thyroid function and overall development.
Congenital goiter/hypothyroidism and hyperthyroidism have been observed in a limited number of neonates born to women who received amiodarone during pregnancy. Amiodarone should be used during pregnancy only when the potential benefits justify the possible risks to the fetus. Women should inform their clinicians if they are or plan to become pregnant or plan to breast-feed.
If amiodarone is used during pregnancy or if the patient becomes pregnant while receiving the drug, the patient should be apprised of the potential hazard to the fetus. Women of childbearing potential should avoid becoming pregnant during amiodarone therapy. The prolonged elimination of amiodarone from the body after discontinuance of the drug should be considered when a woman of childbearing potential receiving amiodarone plans to become pregnant.
It is not known whether use of amiodarone during labor and delivery could have any immediate or delayed adverse effects on the mother or fetus. Studies in rodents have not shown any effect of the drug on duration of gestation or on parturition.
In addition, in rats receiving oral amiodarone hydrochloride dosages of 100 mg/kg daily (approximately 1.6 times the maximum recommended human maintenance dosage of 600 mg for a 50-kg patient (calculated on the basis of body surface area) or more, or 200 mg/kg daily (approximately 1.6 or 3.2 times the maximum recommended human maintenance dosage of 600 mg for a 50-kg patient (calculated on the basis of body surface area)), reduced fetal body weight or increased incidence of fetal resorptions, respectively, were observed. Adverse effects on fetal growth and survival also were reported in 1 of 2 strains of mice receiving oral amiodarone hydrochloride dosages of 5 mg/kg daily (approximately 0.04 times the maximum recommended human maintenance dosage of 600 mg for a 50-kg patient (calculated on the basis of body surface area)). In a reproductive study in which amiodarone was administered IV to rabbits at dosages of 5, 10, or 25 mg/kg daily (approximately 0.1, 0.3, or 0.7 times the recommended maximum human dose on the basis of body surface area, respectively), maternal deaths occurred in all groups, including controls.
Embryotoxicity, as manifested by fewer full-term fetuses and increased resorptions with concomitantly lower litter weights, occurred at dosages of 10 mg/kg and greater. No evidence of embryotoxicity was observed at the 5 mg/kg dosage and no teratogenicity was observed at any dosage level tested. In a teratology study in which amiodarone was administered by continuous IV infusion to rats at dosages of 25, 50, or 100 mg/kg daily (approximately 0.4, 0.7, or 1.4 times the recommended maximum human dose on the basis of body surface area, respectively), maternal toxicity (as evidenced by reduced weight gain and food consumption) and embryotoxicity (as evidenced by increased resorptions, decreased live litter size, reduced body weights, and retarded sternum and metacarpal ossification) were observed in the group receiving 100 mg/kg daily.
Amiodarone and N-desethylamiodarone cross the placenta to a limited extent. QT prolongation and transient sinus bradycardia have been observed in neonates of a limited number of pregnant women who received the drug during the second and/or third trimester. Specific data are not available, but there are concerns that amiodarone potentially could adversely affect fetal thyroid function and overall development.
Congenital goiter/hypothyroidism and hyperthyroidism have been observed in a limited number of neonates born to women who received amiodarone during pregnancy. Amiodarone should be used during pregnancy only when the potential benefits justify the possible risks to the fetus. Women should inform their clinicians if they are or plan to become pregnant or plan to breast-feed.
If amiodarone is used during pregnancy or if the patient becomes pregnant while receiving the drug, the patient should be apprised of the potential hazard to the fetus. Women of childbearing potential should avoid becoming pregnant during amiodarone therapy. The prolonged elimination of amiodarone from the body after discontinuance of the drug should be considered when a woman of childbearing potential receiving amiodarone plans to become pregnant.
It is not known whether use of amiodarone during labor and delivery could have any immediate or delayed adverse effects on the mother or fetus. Studies in rodents have not shown any effect of the drug on duration of gestation or on parturition.
Amiodarone and, to a lesser extent, N-desethylamiodarone are distributed into milk in concentrations substantially higher than concurrent maternal plasma concentrations. Nursing offspring of lactating rats receiving amiodarone have been shown to be less viable and to have reduced bodyweight gains. Because nursing may expose the infant to a substantial dose of amiodarone and its metabolite, it is recommended that nursing be discontinued during amiodarone therapy. The slow elimination of amiodarone from the body after discontinuance of the drug should also be considered.
No enhanced Geriatric Use information available for this drug.
The following prioritized warning is available for PACERONE (amiodarone hcl):
WARNING: Though this medication often gives great benefits to people with irregular heartbeat, it may rarely worsen an irregular heartbeat or cause serious (sometimes fatal) side effects. When starting treatment with this drug, your doctor may have you stay in the hospital for proper monitoring. Amiodarone may take 2 weeks or longer to have an effect in your body.
Also, this drug stays in your body for weeks to months, even after you are no longer taking it. Serious side effects may occur weeks to months after taking amiodarone. Serious side effects may include lung or liver problems. Tell your doctor right away if you notice any symptoms of lung or liver problems such as nausea/vomiting that doesn't stop, cough, shortness of breath, chest pain, coughing up blood, dark urine, severe stomach/abdominal pain, or yellowing eyes/skin.
WARNING: Though this medication often gives great benefits to people with irregular heartbeat, it may rarely worsen an irregular heartbeat or cause serious (sometimes fatal) side effects. When starting treatment with this drug, your doctor may have you stay in the hospital for proper monitoring. Amiodarone may take 2 weeks or longer to have an effect in your body.
Also, this drug stays in your body for weeks to months, even after you are no longer taking it. Serious side effects may occur weeks to months after taking amiodarone. Serious side effects may include lung or liver problems. Tell your doctor right away if you notice any symptoms of lung or liver problems such as nausea/vomiting that doesn't stop, cough, shortness of breath, chest pain, coughing up blood, dark urine, severe stomach/abdominal pain, or yellowing eyes/skin.
The following icd codes are available for PACERONE (amiodarone hcl)'s list of indications:
| Life-threatening ventricular tachycardia | |
| I47.2 | Ventricular tachycardia |
| I47.20 | Ventricular tachycardia, unspecified |
| I47.21 | Torsades de pointes |
| I47.29 | Other ventricular tachycardia |
| Prevention of ventricular fibrillation | |
| I49.01 | Ventricular fibrillation |
| Ventricular fibrillation | |
| I49.01 | Ventricular fibrillation |
Formulary Reference Tool