Zithromax

DRUG IMAGES

ZITHROMAX 250 MG Z-PAK TABLET
ZITHROMAX 200 MG/5 ML SUSP
ZITHROMAX 100 MG/5 ML SUSP
ZITHROMAX 500 MG TABLET
ZITHROMAX 1 GM POWDER PACKET
ZITHROMAX I.V. 500 MG VIAL
ZITHROMAX 250 MG TABLET

The following indications for ZITHROMAX (azithromycin) have been approved by the FDA:

Indications:
Acute bacterial otitis media
Acute exacerbation of obstructive chronic bronchitis by M. catarrhalis
Acute exacerbation of obstructive chronic bronchitis by Streptococcus pneumoniae
Acute exacerbation of obstructive chronic bronchitis due to H. flu
Acute gonococcal cervicitis
Acute gonococcal urethritis
Acute Haemophilus influenzae bacterial sinusitis
Acute Moraxella catarrhalis bacterial sinusitis
Acute Streptococcus pneumoniae bacterial sinusitis
Bacterial pneumonia
Chancroid
Chlamydia cervicitis
Chlamydia trachomatis pelvic inflammatory disease
Chlamydia trachomatis urethritis
Chlamydial pneumonia
Chronic bronchitis with bacterial exacerbation
Haemophilus influenzae acute otitis media
Haemophilus influenzae pneumonia
Legionella pneumophila pneumonia
Moraxella catarrhalis acute otitis media
Moraxella catarrhalis pneumonia
Mycoplasma hominis pelvic inflammatory disease
Mycoplasmal pneumonia
Pelvic inflammatory disease with Neisseria gonorrhea
Pharyngitis due to Streptococcus pyogenes
Pneumococcal acute otitis media
Pneumococcal pneumonia
Pneumonia due to Staphylococcus aureus
Skin and skin structure Streptococcus agalactiae infection
Skin and skin structure Streptococcus pyogenes infection
Staphylococcus aureus skin and skin structure infection
Tonsillitis due to Streptococcus pyogenes

Professional Synonyms:
Acute bacterial exacerbation of chronic bronchitis
Acute cervical gonococcal infection
Acute cervical gonorrhea
Acute cervical infection due to Neisseria gonorrhoeae
Acute exacerbation of obstructive chronic bronchitis by B. catarrhalis
Acute exacerbation of obstructive chronic bronchitis by Branhamella catarrhalis
Acute exacerbation of obstructive chronic bronchitis by Moraxella catarrhalis
Acute exacerbation of obstructive chronic bronchitis by Neisseria catarrhalis
Acute H. influenzae exacerbation of obstructive chronic bronchitis
Acute otitis media due to Diplococcus pneumoniae
Acute otitis media due to Fraenkel's Pneumococcus
Acute otitis media due to H. flu
Acute otitis media due to Haemophilus influenzae
Acute otitis media due to Hemophilus influenzae
Acute otitis media due to influenza Bacillus
Acute otitis media due to Moraxella catarrhalis
Acute otitis media due to Pfeiffer's Bacillus
Acute otitis media due to Pneumococcus
Acute otitis media due to Pneumonococcus
Acute otitis media due to Streptococcus pneumoniae
Acute sinusitis due to B. catarrhalis
Acute sinusitis due to Branhamella catarrhalis
Acute sinusitis due to diplococcus pneumoniae
Acute sinusitis due to Fraenkel's pneumococcus
Acute sinusitis due to Fraenkel's pneumonococcus
Acute sinusitis due to H. flu
Acute sinusitis due to H. influenzae
Acute sinusitis due to Haemophilus influenzae
Acute sinusitis due to Hemophilus influenzae
Acute sinusitis due to Influenza bacillus
Acute sinusitis due to M. catarrhalis
Acute sinusitis due to Moraxella catarrhalis
Acute sinusitis due to Neisseria catarrhalis
Acute sinusitis due to Pfeiffer's bacillus
Acute sinusitis due to pneumococcus
Acute sinusitis due to Streptococcus pneumoniae
Acute sinusitis from Fraenkel-Weichselbaum pneumococcus
Acute urethral gonococcal infection
Acute urethral gonorrhea
Acute urethral infection due to Neisseria gonorrhoeae
Bacterial exacerbation of chronic bronchitis
Bacterial otitis media
Cervicitis due to Chlamydia trachomatis
Chancroidal ulcer
Eaton agent pneumonia
Epidemic sore throat
Fraenkel-Weichselbaum Pneumococcus acute otitis media
H. flu pneumonia
H. influenzae pneumonia
Hemophilus influenzae pneumonia
Infection of the lungs due to Chlamydia
Influenza Bacillus pneumonia
NGU due to Chlamydia trachomatis
Nongonococcal urethritis due to Chlamydia trachomatis
Pelvic inflammatory disease due to Chlamydia trachomatis
Pelvic inflammatory disease due to Mycoplasma hominis
Pelvic inflammatory disease due to Neisseria gonorrhea
Pfeiffer's Bacillus pneumonia
Pharyngitis due to group A beta-hemolytic streptococci
Pharyngitis due to Streptococcus epidemicus
PID due to Chlamydia trachomatis
PID due to Mycoplasma hominis
Pneumonia due to B. catarrhalis
Pneumonia due to Branhamella catarrhalis
Pneumonia due to Haemophilus influenzae
Pneumonia due to M. catarrhalis
Pneumonia due to Moraxella catarrhalis
Pneumonia due to Neisseria catarrhalis
Pneumonia due to Staphylococcus pyogenes aureus
Pneumonia due to Streptococcus pneumoniae
Primary atypical pneumonia
Septic sore throat
Skin & skin soft tissue Streptococcus pyogenes infection
Skin and skin soft tissue infection due to S. agalactiae
Skin and skin soft tissue S. agalactiae infection
Skin and skin soft tissue Staphylococcus aureus infection
Streptococcal pharyngitis
Streptococcus pyogenes tonsillitis
Trachelitis due to Chlamydia trachomatis
Urethritis due to Chlamydia trachomatis
Venereal ulcer

The following dosing information is available for ZITHROMAX (azithromycin):

Dosing
Administration
ZITHROMAX
AZITHROMYCIN

Pending revision, the material in this section should be considered in light of more recently available information in the MedWatch notification at the beginning of this monograph.

Dosage of azithromycin, which is commercially available for oral and IV use as the dihydrate, is expressed in terms of anhydrous azithromycin.

Two 250-mg tablets of azithromycin are bioequivalent to one 500-mg tablet. The extended-release oral suspension is not bioequivalent to and is not interchangeable with the conventional oral suspension or tablets.

Dosage adjustment is not necessary in patients with renal impairment (glomerular filtration rate 80 mL/minute or less). However, data are limited regarding use of azithromycin in patients with severe renal impairment (glomerular filtration rate less than 10 mL/minute) and the manufacturer states that the drug should be used with caution in these patients.

The pharmacokinetics of azithromycin in patients with hepatic impairment have not been established. The manufacturer states that data are insufficient to make dosage recommendations for patients with hepatic impairment and azithromycin should be used with caution in such patients since the drug is eliminated principally via the liver. Based on results of a limited study in patients with impaired hepatic function, some clinicians state that dosage adjustments are not necessary in patients with class A or B liver cirrhosis.

No enhanced Administration information available for this drug.

Dosing information for ZITHROMAX
DRUG LABEL	DOSING TYPE	DOSING INSTRUCTIONS
ZITHROMAX 1 GM POWDER PACKET	Maintenance	Adults take 1 packet (1,000 mg) by oral route dissolved in 2 ounces of water as a single dose
ZITHROMAX 250 MG Z-PAK TABLET	Maintenance	Adults take 2 tablets (500 mg) by oral route once daily for 1 day then 1 tablet (250 mg) by oral route once daily for 4 days
ZITHROMAX 500 MG TABLET	Maintenance	Adults take 1 tablet (500 mg) by oral route once daily for 3 days
ZITHROMAX 200 MG/5 ML SUSP	Maintenance	Adults take 12.5 milliliters (500 mg) by oral route once daily for 1 day then 6.25 milliliters (250 mg) by oral route once daily for 4 days
ZITHROMAX I.V. 500 MG VIAL	Maintenance	Adults infuse 500 mg over 30 minute(s) by intravenous route once daily
ZITHROMAX 250 MG TABLET	Maintenance	Adults take 2 tablets (500 mg) by oral route once daily for 1 day then 1 tablet (250 mg) by oral route once daily for 4 days

Generic dosing information for AZITHROMYCIN
DRUG LABEL	DOSING TYPE	DOSING INSTRUCTIONS
AZITHROMYCIN 200 MG/5 ML SUSP	Maintenance	Adults take 12.5 milliliters (500 mg) by oral route once daily for 1 day then 6.25 milliliters (250 mg) by oral route once daily for 4 days
AZITHROMYCIN 250 MG TABLET	Maintenance	Adults take 2 tablets (500 mg) by oral route once daily for 1 day then 1 tablet (250 mg) by oral route once daily for 4 days
AZITHROMYCIN 500 MG TABLET	Maintenance	Adults take 1 tablet (500 mg) by oral route once daily for 3 days
AZITHROMYCIN I.V. 500 MG VIAL	Maintenance	Adults infuse 500 mg over 30 minute(s) by intravenous route once daily
AZITHROMYCIN 1 GM PWD PACKET	Maintenance	Adults take 1 packet (1,000 mg) by oral route dissolved in 2 ounces of wateras a single dose

The following drug interaction information is available for ZITHROMAX (azithromycin):

Contraindicated
Severe
Moderate

There are 10 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
Live Typhoid Vaccine/Antimicrobials 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: The antimicrobial may be active against the organism in the live-vaccine. Antimicrobial therapy may prevent the vaccine organism from replicating enough to trigger an immune response.(1) CLINICAL EFFECTS: Vaccination may be ineffective. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Do not give oral typhoid vaccine until 72 hours after the last dose of antimicrobial. If possible, to optimize vaccine effectiveness, do not start antibacterial drugs for 72 hours after the last dose of oral typhoid vaccine. A longer interval should be considered for long-acting antimicrobials, such as azithromycin.(3) DISCUSSION: Because antimicrobial therapy may prevent sufficient vaccine-organism replication to generate an immune response, the manufacturer of live-attenuated typhoid vaccine and the Centers for Disease Control (CDC) state that the vaccine should not be administered to patients receiving antimicrobial therapy.(1-3)	VIVOTIF
Pimozide/Selected Macrolide Antibiotics 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: Macrolide antibiotics may inhibit the metabolism of pimozide by CYP3A4. CLINICAL EFFECTS: Increased levels of pimozide may result in prolongation of the QT-interval, ventricular arrhythmias, and death. 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) 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.(4) PATIENT MANAGEMENT: The manufacturer of pimozide states that concurrent therapy with macrolide antibiotics and pimozide 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: The manufacturer of pimozide states that two deaths have been linked to the addition of clarithromycin to pimozide therapy. Therefore, the manufacturer of pimozide states that concurrent therapy with macrolide antibiotics and pimozide is contraindicated.(1) A study in 12 subjects found that the concurrent administration of pimozide and clarithromycin resulted in significant increases in the pimozide maximum concentration (Cmax) and area-under-curve (AUC) and decreased the clearance of pimozide. There was also a significant increase in the QTc interval when pimozide was administered with clarithromycin.(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.	PIMOZIDE
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
Disopyramide/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 disopyramide 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 torsades 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 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 and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The Australian manufacturer of disopyramide states that concurrent use with agents liable to produce torsades de pointes, including tricyclic or tetracyclic antidepressants, erythromycin, vincamine, and sultopride, is contraindicated.(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: 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.	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
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
Levoketoconazole/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: Levoketoconazole has been observed to prolong the QTc interval in a dose-dependent manner. 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 levoketoconazole 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 levoketoconazole states that levoketoconazole is contraindicated with other agents that prolong the QT interval.(1) 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.(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: During phase 1 and 2 studies, 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.(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)	RECORLEV
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

There are 61 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
Selected Anticoagulants (Vit K antagonists)/Selected Macrolide Antibiotics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Macrolide antibiotics may inhibit the metabolism of anticoagulants. CLINICAL EFFECTS: Concurrent use of a macrolide antibiotic may result in increased effects of the anticoagulant with possible elevated INR and/or bleeding. PREDISPOSING FACTORS: Poor nutrition, fever, larger macrolide doses, and older age. 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: Closely monitor INR values in patients maintained on anticoagulants in whom macrolide antibiotics are initiated or discontinued. The dose of the anticoagulant may need to be adjusted. 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: In a retrospective review comparing patients who received concurrent warfarin and azithromycin to matched controls who received only warfarin, azithromycin had no significant effects on INR values.(1) Another retrospective review compared patients who received concurrent warfarin and azithromycin to matched controls who received concurrent warfarin and felodipine. Azithromycin had no significant effects on INR values.(2) In contrast, there are several case reports of increased warfarin effects 4 to 8 days after the addition of azithromycin.(3-7) There is a case report of a patient with an INR of 8.2 after adding azithromycin to concurrent warfarin therapy. During this time, she also decreased her smoking from (1 pack/day to 2 packs/3 days).(5) There are several case reports of increased INRs after the addition of clarithromycin to warfarin therapy.(8-11) In a study in 8 patients, the addition of erythromycin base (333 mg 3 times daily for 7 days) to warfarin therapy resulted in a 9.9% increase in prothrombin time ratio from baseline (from 1.61 to 1.77). However, values were still within therapeutic range and no patient experienced adverse effects.(12) In another study in 12 healthy subjects, erythromycin (250 mg 4 times daily for 8 days) increased the clearance of a single dose of warfarin (1 mg/kg) by 14%.(13) There are several published case reports of interactions between erythromycin and warfarin(14-19) and acenocoumarol.(20) In a study in 21 healthy subjects, roxithromycin (150 mg twice daily) had no effect on warfarin pharmacokinetics or pharmacodynamics.(21) However, there has been one case report of a parietal abdominal hematoma following concurrent roxithromycin and acenocoumarol.(22) There have been several case reports of increased warfarin effects following the addition of telithromycin to therapy.(23,24)	ANISINDIONE, DICUMAROL, JANTOVEN, WARFARIN SODIUM
Digoxin, Oral/Macrolide Antibiotics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Macrolides may alter the bacterial flora in the GI tract, increasing the bioavailability of digoxin. Some macrolides may inhibit the transport of digoxin by p-glycoprotein in the intestines and kidneys. CLINICAL EFFECTS: Digoxin serum levels may be elevated (up to 2-fold), producing increased therapeutic and adverse effects. Symptoms of digoxin toxicity can include anorexia, nausea, vomiting, headache, fatigue, malaise, drowsiness, generalized muscle weakness, disorientation, hallucinations, visual disturbances, and arrhythmias. The effects of macrolides on the GI flora may persist for several months. PREDISPOSING FACTORS: The increase in serum levels is greatest with those digoxin products with the lowest bioavailability and may not be clinically significant in patients taking digoxin elixir. Low body weight, advanced age, impaired renal function, hypokalemia, hypercalcemia, and/or hypomagnesemia may increase the risk of digoxin toxicity. PATIENT MANAGEMENT: Monitor digoxin serum levels during concurrent macrolide therapy and adjust the dose as needed. The dosage of digitalis glycoside may need to be decreased by 30-50% or the frequency of administration may be reduced. DISCUSSION: In a retrospective review, azithromycin, clarithromycin, and erythromycin use were associated with a 3.7-fold, 7.9-fold, and 3.7-fold increased risk of digoxin toxicity.(1) In a retrospective review, clarithromycin prescription at 7, 14, and 30 days prior was associated with a 4.36-fold, 5.07-fold, and 2.98-fold increase in risk of hospitalization for digoxin toxicity.(2) In a clinical trial in 12 healthy males, clarithromycin (250 mg twice daily for 3 days) increased the area-under-curve (AUC) of a single oral dose of digoxin by 1.7-fold. Clarithromycin increased the AUC of intravenous digoxin by 1.2-fold.(3) In a study in 7 patients with congestive heart failure, clarithromycin therapy increased digoxin levels by 70%.(4) In a study in elderly patients taking digoxin, clarithromycin decreased digoxin renal clearance by 56-60%.(5) In a study in 9 healthy males, clarithromycin and erythromycin had no effect on levels of intravenous digoxin.(6) In a study in 3 subjects, erythromycin increased serum digoxin concentrations 2-fold.(7) Telithromycin has been shown to increase digoxin maximum concentration (Cmax) and trough levels (Cmin) by 73% and 21%, respectively.(8) Elevated digoxin levels and toxicity have been reported during concurrent therapy with azithromycin,(9) clarithromycin,(10-25) erythromycin,(26-30) josamycin,(31) roxithromycin,(32) and telithromycin.(33) Approximately 10% of the patients receiving digoxin excrete significant amounts of inactive digoxin metabolites.(7) Since bacterial flora in the GI tract are involved with the conversion of cardioactive digoxin to the inactive metabolite, administration of macrolides as well as other antibiotics may alter the bacterial flora, interfering with the conversion process. These 10% of the patients are at additional risk of elevated digoxin levels due to the drug interaction. Concomitant administration of erythromycin and digoxin caused digoxin serum concentration to increase 100%. (34)	DIGITEK, DIGOXIN, DIGOXIN MICRONIZED, LANOXIN
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.	AMIODARONE HCL, AMIODARONE HCL-D5W, NEXTERONE, PACERONE
Ziprasidone/Selected QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. 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: 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.(1,3) 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) It would be prudent to avoid the use of ziprasidone with medicines suspected of prolonging the QT 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)	GEODON, ZIPRASIDONE HCL, ZIPRASIDONE MESYLATE
Paliperidone/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Paliperidone has been shown to cause a modest increase in 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 paliperidone 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 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, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The US manufacturer of paliperidone states that the use of paliperidone should be avoided with other drugs that are known to prolong the QTc interval, including Class IA and Class III antiarrhythmics, antipsychotics, antibiotics such as gatifloxacin and moxifloxacin, or any other class of medications known to prolong the QTc interval.(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: 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)	ERZOFRI, INVEGA, INVEGA HAFYERA, INVEGA SUSTENNA, INVEGA TRINZA, PALIPERIDONE ER
Nilotinib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Nilotinib prolongs 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 nilotinib 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.(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, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The US manufacturer of nilotinib states that the use of nilotinib should be avoided with other drugs that are known to prolong the QTc interval. Should treatment with a QT prolonging agent be required, interruption of nilotinib therapy should be considered. If concurrent therapy cannot be avoided, monitor patients closely for prolongation of the QT interval and follow recommended nilotinib dosage adjustments for QT prolongation.(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. The UK manufacturer of nilotinib states that the use of nilotinib should be used with caution with other drugs that are known to prolong the QTc interval.(3) 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 nilotinib, QTc prolongation was identified in 29 (38.7%) with 1 (3.5%) having Grade 1 (QTc 450-480 ms) and 2 (7%) having Grade 2 (QTc 480-500 ms). Grade 3 events occurred in 9 (31%) having QTc greater than or equal to 500 ms and 17 (58.6%) having QTc change greater than or equal to 60 ms. No patients developed ventricular tachycardia, sudden cardiac death, or TdP.(5) 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)	DANZITEN, NILOTINIB HCL, TASIGNA
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
Quinidine; Quinine/Selected Macrolides SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Clarithromycin, erythromycin and troleandomycin may inhibit the metabolism of quinidine(1) and quinine(2) by CYP3A4. Azithromycin, clarithromycin and erythromycin have been associated with prolongation of the QT interval.(3,4) CLINICAL EFFECTS: The concurrent use of azithromycin, clarithromycin, erythromycin, or troleandomycin may result in elevated levels and effects from quinidine and quinine, including torsades de pointes.(3,4) 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. co-administration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(5) PATIENT MANAGEMENT: Concurrent use of quinidine with azithromycin, clarithromycin, erythromycin or troleandomycin should be avoided when possible. If combination therapy is required evaluate patient-specific predisposing risk factors, baseline QTc interval, and monitor as appropriate. Consider obtaining serum calcium, magnesium, and potassium levels and correct any electrolyte abnormalities. The dosage of quinidine may need to be adjusted in patients receiving erythromycin or troleandomycin. The US manufacturer of quinine states that concurrent use of erythromycin or troleandomycin should be avoided.(2) DISCUSSION: In a study in 30 healthy males, pretreatment with erythromycin (250 mg 4 times daily) decreased the total clearance, partial clearance by 3-hydroxylation, and partial clearance by N-oxidation of a single oral dose of quinidine (200 mg) by 34%, 50%, and 33%, respectively. Quinidine maximum concentration (Cmax) increased by 39%.(6) QT prolongation(7) and quinidine toxicity(8) have been reported following erythromycin administration. In a cross-over study in 10 healthy subjects, troleandomycin (500 mg every 8 hours) increased the area-under-curve (AUC) of a single oral dose of quinine sulfate (600 mg) by 87%. Quinine clearance was 45% lower and the formation clearance of 3-hydroxyquinine, quinine's main metabolite, decreased 81%.(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.	NUEDEXTA, QUALAQUIN, QUINIDINE GLUCONATE, QUINIDINE SULFATE, QUININE HCL, QUININE SULFATE
Propafenone/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Propafenone 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 propafenone 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 manufacturer of propafenone states that the use of propafenone with other 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. 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)	PROPAFENONE HCL, PROPAFENONE HCL ER
Aliskiren/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: Aliskiren is a substrate for the P-glycoprotein (P-gp) system. Inhibitors of P-gp may increase the absorption of aliskiren.(1-3) CLINICAL EFFECTS: The concurrent use of aliskiren and P-gp inhibitors may result in elevated levels of aliskiren. This may result in increased effect and toxicity of aliskiren including hypotension.(1-3) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of aliskiren states that concurrent use of itraconazole should be avoided.(1) The UK manufacturer of aliskiren states that the concurrent use of P-gp inhibitors such as itraconazole is contraindicated.(2) The US manufacturer of itraconazole states that concurrent administration of aliskiren is not recommended during and two weeks after itraconazole treatment.(4) DISCUSSION: In a study in healthy subjects, concurrent itraconazole (100 mg) increased the maximum concentration (Cmax) and area-under-curve (AUC) of aliskiren (150 mg) by 5.8-fold and 6.5-fold, respectively.(2,3) Selected P-gp inhibitors linked to this monograph include: azithromycin, belumosudil, clarithromycin, danicopan, daridorexant, fostamatinib, indinavir, itraconazole, lopinavir/ritonavir, mavorixafor, nirmatrelvir/ritonavir, pirtobrutinib, rifampin and vimseltinib.(4,5)	ALISKIREN, TEKTURNA
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
Dofetilide/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Dofetilide has been shown to prolong the QTc interval in a dose-dependent fashion. 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(TdP).(1) Agents linked to this monograph are: chloroquine, chlorpromazine, dolasetron, domperidone, haloperidol, pentamidine, probucol, and propoxyphene. 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) Risk factors for QT prolongation include: cardiovascular disease (e.g. heart failure, recent myocardial infarction, history of torsades de pointes, congenital long QT syndrome), female sex, hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, advanced age, and concurrent use of agents known to cause QT prolongation.(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 dofetilide states that the use of dofetilide with other agents known to prolong the QTc interval is not recommended.(1) Use available alternative agents whenever possible. 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. If dofetilide dose is increased or if dofetilide therapy is reinitiated after an interruption, the patient should be hospitalized for continuous ECG monitoring.(1) 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.(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.	DOFETILIDE, TIKOSYN
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
Flecainide/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Flecainide 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 flecainide with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes(TdP).(1) PREDISPOSING FACTORS: In general, 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.(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 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).(1) PATIENT MANAGEMENT: If possible, avoid the use of flecainide with other agents known to prolong the QT 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 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) 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.	FLECAINIDE ACETATE
Ibutilide/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Ibutilide has been shown to prolong the QTc interval.(1) Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(2) CLINICAL EFFECTS: The concurrent use of ibutilide with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes(TdP).(1,2) PREDISPOSING FACTORS: In general, 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: If possible, avoid the use of ibutilide with other agents known to 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: In a study in healthy volunteers, intravenous infusions of ibutilide resulted in prolongation of the QT interval that was directly correlated with ibutilide plasma concentration during and after 10-minute and 8-hour infusions.(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) 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
Procainamide/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Procainamide 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 procainamide with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes(TdP).(1) PREDISPOSING FACTORS: In general, 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.(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 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).(1) PATIENT MANAGEMENT: If possible, avoid the use of procainamide with other agents known to prolong the QT 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 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) 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
Sotalol/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. 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) 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) 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.(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 manufacturer of sotalol states that concurrent use with other agents known to prolong the QT interval is not recommended.(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. 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.	BETAPACE, BETAPACE AF, SOTALOL, SOTALOL AF, SOTALOL HCL, SOTYLIZE
Azithromycin/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Azithromycin 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 azithromycin with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes(TdP).(1,2) PREDISPOSING FACTORS: In general, 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: If possible, avoid the use of azithromycin with other agents known to prolong the QT 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: In a randomized, placebo-controlled parallel trial 116 healthy subjects received either chloroquine (1000 mg) alone or in combination with oral azithromycin (500 mg, 1000 mg, and 1500 mg once daily). Co-administration of azithromycin increased the QTc interval in a dose- and concentration- dependent manner. In comparison to chloroquine alone, the maximum mean (95% upper confidence bound) increases in QTcF were 5 (10) ms, 7 (12) ms and 9 (14) ms with the co-administration of 500 mg, 1000 mg and 1500 mg azithromycin, 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) 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, CAPRELSA, CELEXA, CESIUM CHLORIDE, CHLOROQUINE PHOSPHATE, CHLORPROMAZINE HCL, CILOSTAZOL, CIPRO, CIPROFLOXACIN, CIPROFLOXACIN HCL, CIPROFLOXACIN-D5W, CITALOPRAM HBR, DIFLUCAN, DIPRIVAN, DISKETS, DONEPEZIL HCL, DONEPEZIL HCL ODT, ESCITALOPRAM OXALATE, FLUCONAZOLE, FLUCONAZOLE-NACL, GATIFLOXACIN SESQUIHYDRATE, HALDOL DECANOATE 100, HALDOL DECANOATE 50, HALOPERIDOL, HALOPERIDOL DECANOATE, HALOPERIDOL DECANOATE 100, HALOPERIDOL LACTATE, 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, PENTAM 300, PENTAMIDINE ISETHIONATE, PROPOFOL, SEVOFLURANE, THIORIDAZINE HCL, THIORIDAZINE HYDROCHLORIDE, TRISENOX, ULTANE
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
Bedaquiline/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 bedaquiline with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The use of bedaquiline 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.(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: Bedaquiline should be used with caution in patients receiving therapy with agents that prolong the QT interval. Patients should receive a baseline electrocardiogram (ECG) before initiation, 2 weeks after initiation, during treatment as clinically indicated, and at the expected time of maximum increase of the QT interval when receiving concurrent agents that prolong the QT interval. Bedaquiline and other QT prolonging agents should be discontinued if the patient develops a clinically significant ventricular arrhythmia or a QTcF of greater than 500 msec confirmed by repeat ECGs. If a patient develops syncope, perform an ECG.(1) Also consider obtaining serum calcium, magnesium, and potassium levels at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a clinical trial, mean increases in QTc were greater in patients treated with bedaquiline than with placebo. At Week 1, bedaquiline increased QTc by an average of 9.9 msec, compared with 2.5 msec for placebo. At Week 24, bedaquiline increased QTc by an average of 15.7 msec, compared with 6.2 msec for placebo. In another clinical trial in which patients received bedaquiline with other QT prolonging agents, QT prolongation was additive and proportional to the number of QT prolonging drugs used. Patients receiving bedaquiline alone averaged a QTc increase of 23.7 msec over baseline, while patients receiving bedaquiline with at least one other QT prolonging agent averaged a QTc increase of 30.7 msec.(1) In a study, bedaquiline was coadministered with QTc prolonging agents clofazimine and levofloxacin. In the study, 5% of patients had a QTc >= 500 ms and 43% of patients had an increase in QTc >= 60 ms from baseline.(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)	SIRTURO
Ceritinib/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 ceritinib 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.(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) Patients with severe hepatic impairment (Child-Pugh C) may be at increased risk of this interaction. Ceritinib dose reduction may be warranted in severe hepatic impairment. See prescribing information for recommendations.(1) PATIENT MANAGEMENT: When possible, avoid coadministration of ceritinib with other QT prolonging agents. Obtain an electrocardiogram (ECG) and monitor serum calcium, magnesium, and potassium levels at baseline and regular intervals in patients receiving concurrent therapy with ceritinib and another agent that prolongs the QTc interval.(1) In patients who develop a QTC interval greater than 500 msec on at least 2 occasions, withhold ceritinib until the QTc interval is less than 481 msec or recovery to baseline if baseline QTc was greater than or equal to 481 msec, then resume ceritinib with a 150 mg dose reduction. If the patient develops QTc interval prolongation in combination with torsades de pointes or polymorphic ventricular tachycardia or signs/symptoms of serious arrhythmia, permanently discontinue ceritinib.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a clinical trial 3% of patients experienced a QTc interval increase over baseline greater than 60 msec. Less than 1% of patients (1 of 304) treated with ceritinib was found to have a QTc greater than 500 msec. The upper limit of the 90% confidence interval for mean QTC increase was 16 msec at ceritinib 750 mg. Data suggested that ceritinib produces concentration-dependent QTc interval prolongation.(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)	ZYKADIA
Crizotinib/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 crizotinib 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.(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: Consider periodic electrocardiogram (ECG) and electrolyte monitoring (calcium, magnesium, and potassium levels at baseline and regular intervals) in patients receiving concurrent therapy with crizotinib and another agent that prolongs the QTc interval.(1) In patients who develop a QTc greater than 500 ms on at least 2 separate ECGs, withhold crizotinib until recovery to baseline or to a QTc less than 481 ms, then resume crizotinib at reduced dose.(1) In patients who develop a QTc greater than 500 ms or greater than or equal to 60 ms change from baseline with Torsade de pointes or polymorphic ventricular tachycardia or signs/symptoms of serious arrhythmia, permanently discontinue crizotinib.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Crizotinib is associated with concentration-dependent QTc interval prolongation. In a clinical trial 2.1% of patients were found to have a QTcF greater than or equal to 500 msec and 5% of patients had an increase in QTcF by greater than or equal to 60 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 crizotinib, QTc prolongation was identified in 1 (50%) with 1 (100%) having Grade 1 (QTc 450-480 ms). No patients had a QTc change greater than or equal to 60 ms, ventricular tachycardia, sudden cardiac death, or TdP.(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)	XALKORI
Lenvatinib/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: Concurrent use of lenvatinib in patients taking other medications that prolong the QT interval may result in additive QT prolongation. QT prolongation 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, hypoalbuminemia, bradycardia, female gender, or advanced age.(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 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: Monitor electrocardiograms during concurrent therapy with lenvatinib and agents that prolong the QT interval. In a clinical trial of patients with refractory, progressive thyroid cancer, QT prolongation was reported in 9% of lenvatinib patients. Monitor and correct electrolyte abnormalities in all patients.(1) This is particularly important in lenvatinib patients as diarrhea, nausea, vomiting, and decreased appetite are common side effects which may increase the risk for electrolyte disturbances. Monitor ECG at baseline and at regular intervals. Lenvatinib dose must be withheld if the QTc exceeds 500 msec until QTc resolves to less than 480 msec or baseline. Lenvatinib must be resumed at reduced dose when QTc prolongation resolves to less than 480 ms or to baseline. Dose adjustments below are indication specific and are for patients with normal hepatic and renal function:(1) Dose Modifications in Differentiated Thyroid Cancer(DTC): - First occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose to 20 mg once daily - Second occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose to 14 mg once daily - Third occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose 10 mg once daily Dose Modifications in Renal Cell Cancer (RCC): - First occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose to 14 mg once daily - Second occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose to 10 mg once daily - Third occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose 8 mg once daily Dose Modifications in Hepatocellular Carcinoma (HCC) for Actual weight 60 kg or greater: - First occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose to 8 mg once daily - Second occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose to 4 mg once daily - Third occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose 4 mg every other day Dose Modifications in Hepatocellular Carcinoma (HCC) for Actual weight less than 60 kg: - First occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose to 4 mg once daily - Second occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline then decrease dose to 4 mg every other day - Third occurrence of QTc > 500 msec or onset of another Grade 2 or Grade 3 Adverse Reaction or Grade 4 Laboratory Abnormality: Interrupt therapy until resolved to Grade 0-1 or baseline and discontinue lenvatinib (1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a clinical trial of patients with refractory, progressive thyroid cancer, QT prolongation was reported in 9% of lenvatinib patients and 2% of placebo patients. The incidence of Grade 3 QT prolongation of > 500 msec was reported in 2% of lenvatinib patients compared with no reports in placebo patients.(1) In contrast, a single lenvatinib dose of 32 mg (1.3 times the recommended daily dose) did not prolong the QT/QTc interval in a thorough QT study performed in healthy subjects.(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 lenvatinib, QTc prolongation was identified in 9 (42.9%) with 4 (44.4%) having Grade 1 (QTc 450-480 ms) and 3 (33.3%) having Grade 2 (QTc 480-500 ms). Grade 3 events occurred in 0 (0%) having QTc greater than or equal to 500 ms and 1 (11.1%) having QTc change greater than or equal to 60 ms. Ventricular tachycardia was seen in 1 (11.1%) patient.(3)	LENVIMA
Ondansetron/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.(1-3) CLINICAL EFFECTS: The use of ondansetron in patients maintained on 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 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 in the elderly (> or = 75 years of 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 risk for QT prolongation due to ondansetron is dose and route related. Intravenous (IV) doses lead to higher peak concentrations and systemic exposure and so have a greater risk for QT prolongation compared with the same dose given orally. Faster rates of IV infusion are also associated with a greater risk for QT prolongation.(5) If concomitant therapy is needed, correct electrolyte abnormalities prior to starting therapy. Monitor closely, particularly in patients with predisposing risk factors for QT prolongation (e.g. cardiac disease, female, elderly). Electrocardiogram (ECG) monitoring should be performed in patients receiving concurrent therapy.(1-3) The Canadian manufacturer of Zofran injection has specific recommendations for use of IV ondansetron in oncology patients greater than or equal to 75 years of age (5): - all IV doses must be diluted in 50 - 100 mL of compatible fluid and infused over at least 15 minutes - initial and repeat IV doses must not exceed 8 mg. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a double-blind, randomized, placebo and positive controlled cross-over study, an ondansetron intravenous (IV) dose of 32 mg increased the maximum mean QTcF by 19.6 msec (upper limit of 90% CI: 21.5). A dose of 8mg increased the QTcF by a maximum mean of 5.8 (upper limit of 90% CI: 7.8). A dose of 16 mg was predicted to have a mean increase in QTcF of 9.1 msec (upper limit of 90% CI: 11.2).(1) QT prolongation and torsades de pointes have been reported in post-marketing reports in patients receiving ondansetron.(2-3) In a review of published reports of QT prolongation associated with ondansetron administration, 67% of patients were also receiving another medication known to prolong the QT interval.(6) In a prospective, observational study, administration of a single ondansetron IV dose of 4 mg in the emergency department increased the mean and median QTc interval by 16.2 msec (95% CI 4.2-28.2 msec; p=0.01) and 12 msec (IQR 5.5-18 msec; p<0.01), respectively. Three patients had extreme QTc prolongation. With exclusion of those 3 patients, the median QTc prolongation was 10 msec (IQR 5-15 msec; p<0.01).(7) 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.(8) 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.	ONDANSETRON HCL, ONDANSETRON HCL-0.9% NACL
Romidepsin/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Romidepsin 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 romidepsin 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, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of romidepsin states that appropriate cardiovascular monitoring, such as baseline and regular monitoring of ECG and obtaining serum calcium, magnesium, and potassium levels, should be performed if concurrent therapy with agents known to prolong the QT interval is warranted.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In two clinical trials, discontinuation of romidepsin secondary to QT prolongation occurred in at least 2% of patients.(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)	ISTODAX, ROMIDEPSIN
Sorafenib/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 sorafenib with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The use of sorafenib 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.(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: Patients receiving concurrent therapy with agents known to prolong the QTc interval should be monitored with electrocardiograms during treatment with sorafenib. Electrolytes (calcium, magnesium, and potassium) should also be monitored.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a non-randomized trial in 53 patients, sorafenib resulted in a mean change in QTc of 8.5 msec (upper bound of 90% CI: 13.3 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 sorafenib, QTc prolongation was identified in 13 (31.7%) with 5 (38.5%) having Grade 1 (QTc 450-480 ms) and 4 (30.7%) having Grade 2 (QTc 480-500 ms). Grade 3 events occurred in 2 (15.4%) having QTc greater than or equal to 500 ms and 2 (15.4%) having QTc change greater than or equal to 60 ms. No patients developed ventricular tachycardia, sudden cardiac death, or TdP.(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)	NEXAVAR, SORAFENIB
Telavancin/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Telavancin 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 telavancin 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 telavancin recommends against the use of telavancin with other drugs known to cause QT prolongation.(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 randomized, double-blind, multiple-dose, positive-controlled, placebo-controlled, parallel study in healthy subjects, the mean maximum baseline-corrected, placebo-corrected QTc prolongation was 11.6 msec and 15.1 msec for telavancin at dosages of 7.5 mg/kg and 15 mg/kg, respectively. The estimated mean maximum baseline-corrected, placebo-corrected QTc prolongation for a telavancin dosage of 10 mg/kg is 12-15 msec.(1) In studies in patients, 21% of patients receiving telavancin (214 of 1029, 10 mg/kg) and 16% of patients receiving vancomycin (164 of 1033) received concurrent QT prolonging agents. The rate of QTc prolongation greater than 60 msec was 1.5% (15 patients) in the telavancin group and 0.6% (6 patients) in the vancomycin group. Nine of the 15 telavancin subjects with QTc prolongation received concurrent QT prolongers, compared with 1 of the vancomycin patients.(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)	VIBATIV
Vemurafenib/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 vemurafenib 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.(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: Vemurafenib should not be initiated in patients taking medications known to prolong the QT interval, patients having a baseline QTc greater than 500 msec, uncorrectable electrolyte abnormalities, or known long QT syndrome is not recommended.(1) All patients receiving vemurafenib should undergo ECG testing at baseline, after 15 days of treatment, monthly during the first 3 months of treatment, and then every 3 months. If a patient's QTc exceeds 500 msec during treatment, vemurafenib should be discontinued and cardiac risk factors for QT prolongation should be controlled. Consider discontinuing other medications known to prolong the QT interval at this time. If the patient's QTc decreases below 500 msec, vemurafenib may be introduced at a lower dosage according to the current labeling recommendations. If the patient's QTc remains greater than 500 msec and increased >60 msec from pre-treatment values after controlling cardiac risk factors for prolongation, permanently discontinue vemurafenib.(1) Consider obtaining serum calcium, magnesium, and potassium levels at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Vemurafenib is associated with concentration-dependent QTc interval prolongation. In the first month of treatment, the largest mean QTc change was 12.8 msec (upper boundary of 90% CI: 14.9 msec). In the first 6 months of treatment, the largest mean QTc change was 15.1 msec (upper boundary of 90% CI: 17.7 msec).(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)	ZELBORAF
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
Cholera Vaccine Live/Selected Antibiotics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Antibiotics with activity against Vibrio cholerae may attenuate the immunization response to the live cholera vaccine.(1) CLINICAL EFFECTS: Concurrent or recent antibiotic use may make the cholera vaccine ineffective.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of live cholera vaccine states that it should not be administered to patients who have received antibiotics within 14 days prior to vaccination.(1) If antimalarial prophylaxis with chloroquine is required, administer the live cholera vaccine at least 10 days before beginning chloroquine.(1) Antibiotics linked to this monograph are: macrolides, quinolones, tetracyclines, ampicillin, cefprozil, chloramphenicol, furazolidone, sulfamethoxazole-trimethoprim, and sulfametrole-trimethoprim.(2,3) DISCUSSION: Antibiotics with activity against Vibrio cholerae may attenuate the immunization response to the live cholera vaccine, rendering the vaccine ineffective.	VAXCHORA ACTIVE COMPONENT, VAXCHORA VACCINE
Ribociclib/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 ribociclib with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of ribociclib 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 concurrent use of ribociclib with agents known to prolong the QT interval.(1) If concurrent therapy is deemed medically necessary, monitor patients closely. Obtain serum calcium, magnesium, and potassium levels and correct any electrolyte abnormalities at the beginning of each ribociclib cycle. Monitor ECG at baseline, Day 14 of the first cycle, at the beginning of the second cycle, and as necessary. If a prolonged QTc is noted, refer to ribociclib prescribing information for current dose modification and management instructions. Ribociclib may need to be interrupted, reduced, or discontinued.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Ribociclib has been shown to prolong the QTc interval in a concentration-dependent manner. At steady state, the mean increase in QTc interval exceeded 20 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)	KISQALI
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
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
Encorafenib/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 encorafenib with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of encorafenib 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 encorafenib with medications that prolong the QT interval.(1) Recommended dosage modifications for encorafenib and QTc prolongation adverse reactions include: - QTcF greater than 500 ms and less than or equal to 60 ms increase from baseline: Withhold encorafenib until QTcF less than or equal to 500 ms. Resume at reduced dose. If more than one recurrence, permanently discontinue encorafenib. - QTcF greater than 500 ms and greater than 60 ms increase from baseline: Permanently discontinue encorafenib.(1) See prescribing information for additional information regarding dose reductions.(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: Encorafenib has been associated with a dose-dependent QTc interval prolongation. Following administration of encorafenib in combination with binimetinib, the largest mean (90% CI) QTcF change from baseline was 18 ms (14-22 ms), based on central tendency analysis.(1) Following administration of encorafenib in combination with cetuximab and mFOLFOX6, an increase of QTcF >500 ms was measured in 3.6% (8/222) of patients.(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)	BRAFTOVI
Ivosidenib/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 ivosidenib with agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of ivosidenib 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 ivosidenib 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 ivosidenib therapy ---Monitor ECGs at least weekly for 2 weeks following resolution of QTc prolongation ---Follow labeling recommendations regarding restarting ivosidenib.(1) DISCUSSION: In clinical trials of ivosidenib, 9% of patients experienced a QTc interval greater than 500 msec and 14% of patients had an increased from baseline QTc interval of greater than 60 msec. Patients with a baseline QTc of equal to or greater than 450 msec without pre-existing bundle branch block, or with a history of long QT syndrome were excluded from this trial.(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)	TIBSOVO
Eliglustat/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 eliglustat. If the patient is also taking an inhibitor of CYP2D6, eliglustat metabolism can be further inhibited.(1) CLINICAL EFFECTS: Concurrent use of an agent that is a weak inhibitor of CYP3A4 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 is also taking an inhibitor of CYP2D6, is a poor metabolizer of CYP2D6, and/or has hepatic impairment, 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: The concurrent use of eliglustat with weak inhibitors of CYP3A4 in poor metabolizers of CYP2D6 should be avoided.(1) The dosage of eliglustat with weak inhibitors of CYP3A4 in extensive metabolizers of CYP2D6 with mild (Child-Pugh Class A) hepatic impairment should be limited to 84 mg daily.(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: Ketoconazole (400 mg daily), a strong inhibitor of CYP3A4, increased eliglustat (84 mg BID) maximum concentration (Cmax) and area-under-curve (AUC) by 4-fold and 4.4-fold, respectively, in extensive metabolizers. Physiologically-based pharmacokinetic (PKPB) models suggested ketoconazole would increase eliglustat Cmax and AUC by 4.4-fold and 5.4-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 fluconazole, a moderate inhibitor of CYP3A4, would increase eliglustat Cmax and AUC by 2.8-fold and 3.2-fold, respectively, in extensive metabolizers and by 2.5-fold and 2.9-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) Weak inhibitors of CYP3A4 include: alprazolam, amlodipine, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, 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, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, and vonoprazan.(3,4)	CERDELGA
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
Pazopanib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Pazopanib 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 pazopanib 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 pazopanib states that pazopanib should be avoided in patients receiving other drugs known to cause QT prolongation.(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 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 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)	PAZOPANIB HCL, VOTRIENT
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
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
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
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
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
Adagrasib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Adagrasib 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 adagrasib 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 adagrasib states that the concurrent use of QT prolonging agents should be avoided.(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 patients develop QTc prolongation >500 msec or >60 msec from baseline, withhold adagrasib until QTc interval less than 481 msec or QTc interval returns to baseline. Resume adagrasib at the next lower dose level. If patients develop torsade de pointes, polymorphic ventricular tachycardia, or signs and symptoms of serious or life-threatening arrythmia, permanently discontinue adagrasib.(1) DISCUSSION: Adagrasib has been associated with QTc interval prolongation. Adagrasib increased QTc in a concentration-dependent manner. In patients administered adagrasib 600 mg twice daily, the mean QTcF change from baseline was 18 msec. In the pooled safety population, 6% of 366 patients with at least one post-baseline ECG had an average QTc greater than 501 msec and 11% of patients had a increase from baseline QTc greater than 60 msec.(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)	KRAZATI
Fecal Microbiota Spores/Antibiotics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Fecal microbiota spores is a suspension of live bacterial spores, which may be compromised by concurrent use of antibiotics.(1) CLINICAL EFFECTS: Antibiotics may decrease the effectiveness of fecal microbiota spores.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Antibiotics should not be used concurrently with fecal microbiota spores. Antibacterial treatment should be completed for 2 to 4 days before initiating treatment with fecal microbiota spores.(1) DISCUSSION: Antibiotics may compromise the effectiveness of fecal microbiota spores.	VOWST
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
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
Lonafarnib/QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Lonafarnib 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 lonafarnib 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 lonafarnib states that the concurrent use of QT prolonging agents should be avoided. If concurrent use cannot be avoided, obtain ECGs when initiating, during concurrent use, and as clinically indicated.(1) Lonafarnib dose modification recommendation: if the QTc interval is greater than or equal to 500 msec, withhold lonafarnib until the QTc interval is less than 470 msec, then resume lonafarnib at the same dosage.(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 thorough QT study, lonafarnib 200 mg twice daily for 9 consecutive days and a single 200 mg dose on day 10 increased the mean QTc interval by 19 msec (upper bound of 90% confidence interval = 27 msec) on day 10 at 48 hours after administration of the morning dose of lonafarnib 200 mg. The maximum concentration (Cmax) on Day 10 was 2233 ng/ml, which is similar to the mean Cmax of 2695 ng/ml observed in the Hutchinson-Gilford Progeria Syndrome patient population.(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)	ZOKINVY
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
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 45 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
Etoposide/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibition may increase etoposide cellular concentration, decrease biliary or renal elimination, and increase systemic absorption of oral etoposide.(1-4) CLINICAL EFFECTS: Increased cellular or systemic levels of etoposide may result in etoposide toxicity. PREDISPOSING FACTORS: The interaction magnitude may be greater in patients receiving oral etoposide, or with impaired renal or hepatic function. PATIENT MANAGEMENT: Anticipate and monitor for increased hematologic and gastrointestinal toxicities. Adjust or hold etoposide dose when needed. In patients receiving high-dose cyclosporine therapy, etoposide dosages should be reduced by 50%.(1) Monitor for signs of etoposide toxicity. Dosages may need further adjustment. 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 etoposide.(5) DISCUSSION: In a study in 16 patients, the administration of etoposide plus cyclosporine increased etoposide area-under-curve (AUC) by 59% and half-life by 73%. Etoposide renal clearance was decreased by 38% and nonrenal clearance was decreased by 52%. White blood cell count nadir was significantly lower during concurrent therapy with cyclosporine and etoposide (1200 mm3) when compared to etoposide alone (2500 mm3). There was also a trend for higher dosages of cyclosporine to exert increased effects on etoposide, although this difference did not reach statistical significance.(1) P-gp inhibitors linked to this monograph are asciminib, asunaprevir, azithromycin, belumosudil, cimetidine, clarithromycin, cyclosporine, daridorexant, danicopan, diosmin, flibanserin, fostamatinib, glecaprevir/pibrentasvir, itraconazole, ivacaftor, josamycin, ketoconazole, lonafarnib, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, tezacaftor, tucatinib, valbenazine, vemurafenib, verapamil, vimseltinib, and voclosporin.	ETOPOPHOS, ETOPOSIDE
Lovastatin; Simvastatin (Greater Than 20 mg)/Azithromycin SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The exact mechanism is unknown. Other macrolides (e.g. erythromycin, clarithromycin) which are moderate or strong inhibitors of CYP3A4 have been shown to increase levels of the HMG-CoA reductase inhibitors (statins); however, azithromycin is a much weaker inhibitor of this isoenzyme.(1,2) FDA has classified lovastatin and simvastatin as sensitive substrates at CYP3A4. Sensitive substrates are drugs whose plasma exposure (area-under-curve or AUC) has been shown to increase > or = 5-fold when co-administered with a strong inhibitor of a specific enzyme. A weak inhibitor increases AUC of a sensitive substrate > 1.25-fold but < 2-fold. Azithromycin is classified as a weak inhibitor of CYP3A4.(1) CLINICAL EFFECTS: Concurrent therapy may result in rhabdomyolysis. Symptoms of rhabdomyolysis include muscle pain, tenderness, weakness, elevated creatine kinase levels, and reddish-brown, heme positive urine. 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: In patients with one or more predisposing risk factors for statin associated myopathy it may be prudent to suspend lovastatin or simvastatin during azithromycin therapy. Rhabdomyolysis has been reported with the combination of lovastatin or simvastatin and azithromycin. If temporary discontinuation of the HMG-CoA reductase inhibitor is not possible, patients should be instructed to report any unexplained muscle pain, tenderness, weakness, or discoloration of the urine.(3,4) DISCUSSION: A systematic screening of the World Health Organization Adverse Drug Reaction database found case reports suggestive of an interaction between azithromycin and statins. The authors found 5 lovastatin and 20 simvastatin case reports and used a disproportionality measure which found report rates were 1.88 and 3.55 times higher respectively than predicted.(5) A case report describes rhabdomyolysis in a 73 year old man with chronic renal impairment, diabetes, hypertension, gout and hyperlipidemia with regular medications which included allopurinol 100 mg daily, prednisone 5 mg daily, labetalol, bumetanide, insulin, amlodipine (a weak CYP3A4 inhibitor) and simvastatin 80 mg daily. Azithromycin 500 mg X1 day, then 250 mg daily X4 days was prescribed for acute bronchitis. One week later patient was admitted to the hospital with a 5 day history of severe weakness and pain in his arms and legs. He developed acute renal insufficiency (creatinine baseline 1.7 increased to 3.8) and rhabdomyolysis (CPK 11,240 units/L). Treatment led to resolution of symptoms in 3 weeks. Simvastatin was restarted at 40 mg daily and subsequently increased back to 80 mg daily without recurrence of symptoms.(6) A case report describes a 56 year old man receiving buspirone, nefazodone (a strong CYP3A4 inhibitor), lisinopril, aspirin and simvastatin 80 mg daily without reported problems. Azithromycin and fexofenadine were prescribed for sinusitis. He was admitted to the hospital 5 days later with a 2-3 day history of generalized back,leg, and flank pain along with coca-cola colored urine. AST, ALT and creatine kinase were 2,324, 700, and 10,738 respectively. Patient was discharged after 8 days. His simvastatin was not resumed.(7) An article reported two cases of rhabdomyolysis, one following the addition of clarithromycin to lovastatin therapy and the other following the addition of azithromycin to lovastatin therapy.(8)	ALTOPREV, EZETIMIBE-SIMVASTATIN, FLOLIPID, LOVASTATIN, SIMVASTATIN, VYTORIN, ZOCOR
Apomorphine/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Apomorphine 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 apomorphine 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 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 apomorphine states that the use of apomorphine with other agents known to prolong the QT interval should be done with caution.(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. 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)	APOKYN, APOMORPHINE HCL, ONAPGO
Ivabradine/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. 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) 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 been associated with torsades de pointes and/or QT prolongation but at this time lack substantial evidence for causing torsades de pointes.(2)	CORLANOR, IVABRADINE HCL
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
Ranolazine/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Ranolazine prolongs the QTc interval in a dose-related manner. Use with other agents that prolong the QTc interval may result in additive effects.(1) CLINICAL EFFECTS: Concurrent use of ranolazine and agents known to prolong the QTc interval may result in prolongation of the QTc interval and 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.(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, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The UK manufacturer of ranolazine states that concurrent use with agents known to prolong the QT interval should be approached with caution.(1) Patients should be instructed to inform their physician if they are receiving any drugs that prolong the QTc interval.(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: Ranolazine has been shown to prolong the QTc interval in a dose-related manner.(1,2) 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)	ASPRUZYO SPRINKLE, RANOLAZINE ER
Posaconazole/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 posaconazole 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, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The UK manufacturer of posaconazole states that posaconazole should be used with caution when given with other agents known to 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: 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)	NOXAFIL, POSACONAZOLE
Dasatinib/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 dasatinib 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 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 dasatinib states that dasatinib should be used with caution when given with other agents known to 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: 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 dasatinib, QTc prolongation was identified in 48 (41.7%) with 8 (16.7%) having Grade 1 (QTc 450-480 ms) and 15 (31.3%) having Grade 2 (QTc 480-500 ms). Grade 3 events occurred in 8 (16.7%) having QTc greater than or equal to 500 ms and 14 (29.2%) having QTc change greater than or equal to 60 ms. Ventricular tachycardia was seen in 2 (4.2%) of patients and 1 (2.1%) patient experienced TdP.(4) 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)	DASATINIB, SPRYCEL
Lapatinib/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 lapatinib 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, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The US manufacturer of lapatinib states that lapatinib should be used with caution when given with other agents known to prolong the QT interval.(1) If concurrent therapy is warranted, 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: Lapatinib is associated with concentration-dependent QTc interval prolongation. In a single-blind, placebo-controlled crossover study with lapatinib 2,000 mg every 12 hours for 3 doses, a maximum mean double delta QTcF of 8.75 ms was observed. 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)	LAPATINIB, TYKERB
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
Toremifene/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. 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, electrocardiograms (ECGs) should be obtained and patients should be closely monitored for QT prolongation.(1) Additional monitoring when concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels at baseline and regular intervals. 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
Lopinavir/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Lopinavir has been shown to prolong the QTc interval by 5 msec. 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 lopinavir 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 lopinavir states that the concurrent administration of other drugs that are known to prolong the QTc 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: In a randomized, placebo and active controlled crossover study in 39 healthy subjects designed to evaluated QTc intervals, lopinavir/ritonavir increased QTc by 5.3 msec and 15.2 msec for 400/100 mg twice daily and 800/200 mg twice daily, 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.(2)	KALETRA, LOPINAVIR-RITONAVIR
Iloperidone/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Iloperidone has been shown to prolong the QTc interval by 9 msec at dosages of 12 mg twice daily. 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 iloperidone 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 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 with concurrent use of inhibitors of CYP3A4 or CYP2D6, which metabolize iloperidone.(1,3) 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. co-administration 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 iloperidone states that the concurrent administration of other drugs that are known to prolong the QTc 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. 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) Coadministration of ketoconazole (200 mg twice daily, an inhibitor of CYP P-450-3A4) and iloperidone (12 mg twice daily) was associated with a mean QTcF increase of 19 msec from baseline, compared with an increase of 9 msec with iloperidone alone.(1) Coadministration of paroxetine (20 mg daily, an inhibitor of CYP P-450-2D6) and iloperidone (12 mg twice daily) was associated with a mean QTcF increase of 19 msec from baseline, compared with an increase of 9 msec with iloperidone alone.(1)	FANAPT
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
Clozapine/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 clozapine with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The use of clozapine 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.(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: Approach the concurrent use of clozapine and other agents that are known to prolong the QTc interval with caution.(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: Treatment with clozapine has been associated with QT prolongation as well as ventricular arrythmia, Torsades de Pointes, cardiac arrest, and sudden death.(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)	CLOZAPINE, CLOZAPINE ODT, CLOZARIL, VERSACLOZ
Voriconazole/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 voriconazole with agents known to prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent use may result in potentially life-threatening cardiac arrhythmias, including 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.(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 voriconazole states concurrent use with agents known to prolong the QT interval should be administered with caution.(1) In patients maintained on voriconazole and other agents known to prolong the QT interval, consider a baseline ECG prior to administration to assess the risk/benefit of therapy. Consider obtaining serum calcium, magnesium, and potassium levels at baseline and at regular intervals. Correct any electrolyte abnormalities prior to initiation of therapy. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: A placebo-controlled, randomized, crossover study to evaluate the effect on the QT interval of healthy male and female subjects was conducted with three single oral doses of voriconazole and ketoconazole. The placebo-adjusted mean maximum increases in QTc from baseline after 800 mg, 1200 mg, and 1600 mg of voriconazole and after ketoconazole 800 mg were all <10 msec. No subject experienced an interval exceeding the potentially clinically relevant threshold of 500 msec.(1) In a retrospective study of 2,735 patients with a prolonged QTc interval, voriconazole use was associated with an increased risk of torsades de pointes.(4)	VFEND, VFEND IV, VORICONAZOLE
Fingolimod/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Fingolimod is a sphingosine 1-phosphate (S1P) receptor modulator. 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.(1-3) Fingolimod blocks the capacity of lymphocytes to egress from lymph nodes, reducing the number of lymphocytes in peripheral blood. The mechanism by which fingolimod exerts therapeutic effects in multiple sclerosis is unknown but may involve the reduction of lymphocyte migration into the central nervous system.(1-3) 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. There is no consistent signal of increased incidence of QTc outliers, either absolute or change from baseline, associated with fingolimod treatment.(1-3) 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 fingolimod 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 fingolimod. 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.(4) 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).(4) PATIENT MANAGEMENT: Patients with a baseline QTc interval greater than or equal to 500 milliseconds should not be started on fingolimod. Patients with 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, or a prolonged QTc interval prior to fingolimod initiation should receive cardiologist consultation to evaluate the risks of fingolimod therapy. In all patients, first dose monitoring is recommended to monitor for bradycardia for the first 6 hours. Check blood pressure and pulse hourly. ECG monitoring is recommended prior to dosing and at the end of the observation period. US monitoring recommendations include additional monitoring for the following patients:(1) If heart rate (HR) is less than 45 beats per minute (bpm), the heart rate 6 hours postdose is at the lowest value postdose, 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. Continuous overnight ECG monitoring is recommended in patients requiring pharmacologic intervention for symptomatic bradycardia, some preexisting heart and cerebrovascular conditions, prolonged QTc before dosing or during 6 hours observation, concurrent therapy with QT prolonging drugs, or concurrent therapy with drugs that slow heart rate or AV conduction. Consult the prescribing information for full monitoring recommendations. United Kingdom recommendations:(3) Obtain a 12-lead ECG prior to initiating fingolimod therapy. Consult a cardiologist for pretreatment risk-benefit assessment if patient has a resting heart rate less than 55 bpm, history of syncope, second degree or greater AV block, sick-sinus syndrome, concurrent therapy with beta-blockers, Class Ia, or Class III antiarrhythmics, heart failure or other significant cardiovascular disease. Perform continuous ECG monitoring, measure blood pressure and heart rate every hour, and perform a 12-lead ECG 6 hours after the first dose. Monitoring should be extended beyond 6 hours if symptomatic bradycardia or new onset of second degree AV block, Mobitz Type II or third degree AV block has occurred at any time during the monitoring period. If heart rate 6 hours after the first dose is less than 40 bpm, has decreased more than 20 bpm compared with baseline, or if a new onset second degree AV block, Mobitz Type I (Wenckebach) persists, then monitoring should also be continued. If fingolimod treatment is discontinued for more than two weeks, the effects on heart rate and conduction could recur. Thus, first dose monitoring precautions should be followed upon reintroduction of fingolimod. 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) In a thorough QT interval study of doses of 1.25 or 2.5 mg fingolimod at steady-state, when a negative chronotropic effect of fingolimod was still present, fingolimod treatment resulted in a prolongation of QTc, with the upper boundary of the 90% confidence interval (CI) of 14.0 msec. 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 or a drug interaction with fingolimod could not be ruled out.(1)	FINGOLIMOD, GILENYA, TASCENSO ODT
Alfuzosin/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 alfuzosin with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The use of alfuzosin 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 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: Approach the concurrent use of alfuzosin and other agents that are known to prolong the QTc interval with caution.(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.(2)	ALFUZOSIN HCL ER, UROXATRAL
Pasireotide/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 pasireotide with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The use of pasireotide 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: Pasireotide should be used with caution in patients receiving therapy with agents that prolong the QT interval. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals.(1) Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In randomized, blinded, crossover study in healthy subjects, pasireotide (0.6 mg BID) increased the placebo-subtracted QTcI by 12.7 msec (95 upper CI: 14.7 msec). Supra-therapeutic doses of 1.95 mg BID increased the placebo-subtracted QTcI by 16.6 msec (95 upper CI: 18.6 msec).(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)	SIGNIFOR, SIGNIFOR LAR
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
Trazodone (Greater Than or Equal To 100 mg)/Possible 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)	RALDESY, TRAZODONE HCL
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
Azithromycin/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Azithromycin 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 azithromycin with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes(TdP).(1) PREDISPOSING FACTORS: In general, 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.(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 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).(1) PATIENT MANAGEMENT: If possible, avoid the use of azithromycin with other agents known to prolong the QT 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 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)	ATOMOXETINE HCL, ELLENCE, EPIRUBICIN HCL, GRANISETRON HCL, ISRADIPINE, OFLOXACIN, RUBRACA, RYDAPT, SANCUSO, STRATTERA, SUNITINIB MALATE, SUSTOL, SUTENT, TOLTERODINE TARTRATE, TOLTERODINE TARTRATE ER
Eribulin/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Eribulin 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 eribulin 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, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of eribulin states that patients receiving concurrent therapy with eribulin and other agents known to prolong the QT interval should receive ECG monitoring.(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: QT prolongation, independent of eribulin concentration, was observed on Day 8 of therapy but not on Day 1 in an uncontrolled open-label ECG study in 26 patients.(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)	ERIBULIN MESYLATE, HALAVEN
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 CYP2B66 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
Trazodone (Less Than 100 mg)/Possible 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
Simvastatin (Less Than or Equal To 20 mg)/Azithromycin SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The exact mechanism is unknown. Other macrolides (e.g. erythromycin, clarithromycin) which are moderate or strong inhibitors of CYP3A4 have been shown to increase levels of the HMG-CoA reductase inhibitors (statins); however, azithromycin is a much weaker inhibitor of this isoenzyme.(1,2) FDA has classified simvastatin as a sensitive substrate at CYP3A4. Sensitive substrates are drugs whose plasma exposure (area-under-curve or AUC) has been shown to increase greater than or equal to 5-fold when co-administered with a strong inhibitor of a specific enzyme. A weak inhibitor increases AUC of a sensitive substrate greater than 1.25-fold but less than 2-fold. Azithromycin is classified as a weak inhibitor of CYP3A4.(1) CLINICAL EFFECTS: Concurrent therapy may result in rhabdomyolysis. Symptoms of rhabdomyolysis include muscle pain, tenderness, weakness, elevated creatine kinase levels, and reddish-brown, heme positive urine. 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: In patients with one or more predisposing risk factors for statin associated myopathy it may be prudent to suspend simvastatin during azithromycin therapy. Rhabdomyolysis has been reported with the combination of simvastatin and azithromycin. If temporary discontinuation of the HMG-CoA reductase inhibitor is not possible, patients should be instructed to report any unexplained muscle pain, tenderness, weakness, or discoloration of the urine.(3,4) DISCUSSION: A systematic screening of the World Health Organization Adverse Drug Reaction database found case reports suggestive of an interaction between azithromycin and statins. The authors found 5 lovastatin and 20 simvastatin case reports and used a dis proportionality measure which found report rates were 1.88 and 3.55 times higher respectively than predicted.(5) A case report describes rhabdomyolysis in a 73 year old man with chronic renal impairment, diabetes, hypertension, gout and hyperlipidemia with regular medications which included allopurinol 100 mg daily, prednisone 5 mg daily, labetalol, bumetanide, insulin, amlodipine (a weak CYP3A4 inhibitor) and simvastatin 80 mg daily. Azithromycin 500 mg X1 day, then 250 mg daily X4 days was prescribed for acute bronchitis. One week later patient was admitted to the hospital with a 5 day history of severe weakness and pain in his arms and legs. He developed acute renal insufficiency (creatinine baseline 1.7 increased to 3.8) and rhabdomyolysis (CPK 11,240 units/L). Treatment led to resolution of symptoms in 3 weeks. Simvastatin was restarted at 40 mg daily and subsequently increased back to 80 mg daily without recurrence of symptoms.(6) A case report describes a 56 year old man receiving buspirone, nefazodone (a strong CYP3A4 inhibitor), lisinopril, aspirin and simvastatin 80 mg daily without reported problems. Azithromycin and fexofenadine were prescribed for sinusitis. He was admitted to the hospital 5 days later with a 2-3 day history of generalized back, leg, and flank pain along with coca-cola colored urine. AST, ALT and creatine kinase were 2,324, 700, and 10,738 respectively. Patient was discharged after 8 days. His simvastatin was not resumed.(7) An article reported two cases of rhabdomyolysis, one following the addition of clarithromycin to lovastatin therapy and the other following the addition of azithromycin to lovastatin therapy.(8)	EZETIMIBE-SIMVASTATIN, SIMVASTATIN, VYTORIN, ZOCOR
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
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
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
Siponimod/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Siponimod is a sphingosine-1-phosphate (S1P) receptor modulator. Initiation of siponimod has a negative chronotropic effect. Siponimod blocks the capacity of lymphocytes to egress from lymph nodes, reducing the number of lymphocytes in peripheral blood. The mechanism by which siponimod exerts therapeutic effects in multiple sclerosis is unknown, but may involve reduction of lymphocyte migration into the central nervous system.(1,2) CLINICAL EFFECTS: 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: 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 siponimod 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 siponimod. 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 siponimod, obtain an ECG to determine if preexisting conduction abnormalities are present.(1) Advice from a cardiologist is recommended in patients with preexisting heart and cerebrovascular conditions, prolonged QTc interval before or during the 6 hour observation, risk factors for QT prolongation, concurrent therapy with QT prolonging drugs or drugs that slow the heart rate or AV conduction.(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, first dose monitoring is recommended with hourly pulse and blood pressure to monitor for bradycardia for the first 6 hours. ECG monitoring is recommended prior to dosing and at the end of the observation period.(1) Additional US monitoring recommendations include: If HR is less than 45 bpm, the heart rate 6 hours postdose is at the lowest value postdose 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. Repeat the first dose monitoring strategy for the second dose of siponimod. If a titration dose is missed or if 4 or more consecutive daily doses are missed during maintenance treatment, reinitiate Day 1 of the dose titration and follow titration monitoring recommendations. Patient will need to be observed in the doctor's office or other facility for at least 6 hours after the first dose and after reinitiation if treatment is interrupted or discontinued for certain periods. Consult the prescribing information for full monitoring recommendations. United Kingdom recommendations:(3) In certain patients, it is recommended that an electrocardiogram (ECG) is obtained prior to dosing and at the end of the observation period. If post-dose bradyarrhythmia or conduction-related symptoms occur or if ECG 6 hours post-dose shows new onset second-degree or higher AV block or QTc > 500 msec, appropriate management should be initiated and observation continued until the symptoms/findings have resolved. If pharmacological treatment is required, monitoring should be continued overnight and 6-hour monitoring should be repeated after the second dose. During the first 6 days of treatment, if a titration dose is missed on one day, treatment needs to be re-initiated with a new titration pack. If there is a missed dose after day 6 the prescribed dose should be taken at the next scheduled time; the next dose should not be doubled. If maintenance treatment is interrupted for 4 or more consecutive daily doses, siponimod needs to be re-initiated with a new titration pack.(1,2) DISCUSSION: 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)	MAYZENT
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
Sirolimus Protein-Bound/Slt Moderate and Weak CYP3A4 Inhibit SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate and weak CYP3A4 inhibitors may inhibit the metabolism of sirolimus by CYP3A4.(1) CLINICAL EFFECTS: Concurrent use of moderate or weak CYP3A4 inhibitors may result in elevated levels of and side effects from sirolimus.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: 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.(1) DISCUSSION: In an open, randomized, cross-over trial in 18 healthy subjects, concurrent single doses of diltiazem (120 mg) and sirolimus (10 mg) increased sirolimus area-under-curve (AUC) and maximum concentration (Cmax) by 60% and by 43%, respectively. Sirolimus apparent oral clearance and volume of distribution decreased by 38% and 45%, respectively. There were no effects on diltiazem pharmacokinetics or pharmacodynamics.(2) In a study in 26 healthy subjects, concurrent sirolimus (2 mg daily) with verapamil (180 mg twice daily) increased sirolimus AUC and Cmax by 2.2-fold and 2.3-fold, respectively. The AUC and Cmax of the active S-enantiomer of verapamil each increased by 1.5-fold. Verapamil time to Cmax (Tmax) was increased by 1.2 hours.(2) Moderate and weak CYP3A4 inhibitors linked to this monograph include: alprazolam, amlodipine, aprepitant, avacopan, azithromycin, berberine, berotralstat, bicalutamide, blueberry, brodalumab, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clofazimine, conivaptan, daclatasvir, daridorexant, delavirdine, diosmin, entrectinib, erythromycin, estrogen, flibanserin, fluvoxamine, fosaprepitant, fosnetupitant, fostamatinib, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lazertinib, lenacapavir, levamlodipine, linagliptin, lomitapide, lumateperone, lurasidone, mavorixafor, netupitant, omeprazole, osilodrostat, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, rimegepant, roxithromycin, scutellarin, simeprevir, sitaxsentan, suvorexant, ticagrelor, tofisopam, tolvaptan, trofinetide and vonoprazan.(3,4)	FYARRO
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
Etrasimod/QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Etrasimod is a sphingosine-1-phosphate (S1P) receptor modulator. Initiation of etrasimod has a negative chronotropic effect, which may increase the risk of developing QT prolongation. CLINICAL EFFECTS: Initiation of etrasimod may result in a transient decrease in heart rate. A mean decrease in heart rate of 7.2 (8.98) beats per minute was seen 2 to 3 hours after the first dose. The first dose has also been associated with heart block. 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: 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 etrasimod 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 etrasimod. 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 etrasimod, obtain an ECG to determine if preexisting conduction abnormalities are present.(1) Advice from a cardiologist is recommended in patients with preexisting heart and cerebrovascular conditions, prolonged QTc interval, risk factors for QT prolongation, concurrent therapy with QT prolonging drugs or drugs that slow the heart rate or AV conduction.(1) Monitor blood pressure during treatment.(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: Initiation of etrasimod may result in a transient decrease in heart rate or transient AV conduction delays.(1) A transient decrease in heart rate was observed during the initial dosing phase of etrasimod and bradyarrhythmic events (AV blocks) were detected at a higher incidence under etrasimod treatment than placebo.(1)	VELSIPITY
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
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 ZITHROMAX (azithromycin):

Overview
Contraindicated
Severe
Moderate

Drug contraindication overview.

No enhanced Contraindications information available for this drug.

There are 2 contraindications. Absolute contraindication.

Contraindication List
Congenital long QT syndrome
Torsades de pointes

There are 8 severe contraindications. Adequate patient monitoring is recommended for safer drug use.

Severe List
Bradycardia
Cholestatic hepatitis
Clostridioides difficile infection
Disease of liver
Jaundice
Myasthenia gravis
Prolonged QT interval
Pyloroduodenal obstruction

There are 6 moderate contraindications. Clinically significant contraindication, where the condition can be managed or treated before the drug may be given safely.

Moderate List
Chronic heart failure
Chronic kidney disease stage 5 (failure) GFr<15 ml/min
Hearing loss
Hypokalemia
Hypomagnesemia
Kidney disease with likely reduction in glomerular filtration rate (GFr)

The following adverse reaction information is available for ZITHROMAX (azithromycin):

Overview
Severe
Less Severe

Adverse reaction overview.

No enhanced Common Adverse Effects information available for this drug.

There are 30 severe adverse reactions.

More Frequent	Less Frequent
None.	Increased alanine transaminase Increased aspartate transaminase Skin rash

Rare/Very Rare
Acute generalized exanthematous pustulosis Acute renal failure Anaphylaxis Angioedema Bronchospastic pulmonary disease Clostridioides difficile infection DRESS syndrome Dyspnea Eosinophilia Erythema multiforme Hearing loss Hepatic failure Hepatic necrosis Hepatitis Hypotension Interstitial nephritis Neuromuscular blockade Obstructive hyperbilirubinemia Pancreatitis Prolonged QT interval Seizure disorder Stevens-johnson syndrome Thrombocytopenic disorder Torsades de pointes Toxic epidermal necrolysis Urticaria Ventricular tachycardia

Rare/Very Rare

Acute generalized exanthematous pustulosis
Acute renal failure
Anaphylaxis
Angioedema
Bronchospastic pulmonary disease
Clostridioides difficile infection
DRESS syndrome
Dyspnea
Eosinophilia
Erythema multiforme
Hearing loss
Hepatic failure
Hepatic necrosis
Hepatitis
Hypotension
Interstitial nephritis
Neuromuscular blockade
Obstructive hyperbilirubinemia
Pancreatitis
Prolonged QT interval
Seizure disorder
Stevens-johnson syndrome
Thrombocytopenic disorder
Torsades de pointes
Toxic epidermal necrolysis
Urticaria
Ventricular tachycardia

There are 39 less severe adverse reactions.

More Frequent	Less Frequent
Acute abdominal pain Diarrhea Nausea	Abnormal hepatic function tests Anorexia Headache disorder Pruritus of skin Vaginitis Vomiting

Rare/Very Rare
Aggressive behavior Agitation Arthralgia Chest pain Constipation Dizziness Drowsy Dysgeusia Dyspepsia Fatigue Flatulence Gastritis General weakness Hyperkinesis Insomnia Irritability Loose stools Malaise Nervousness Oral candidiasis Palpitations Paresthesia Parosmia Skin inflammation Skin photosensitivity Symptoms of anxiety Syncope Tinnitus Tongue discoloration Vertigo

The following precautions are available for ZITHROMAX (azithromycin):

Pediatric
Pregnant
Lactation
Geriatric

No enhanced Pediatric Use information available for this drug.

Contraindicated

None

Severe Precaution

None

Management or Monitoring Precaution

None

Reproduction studies in rats and mice using azithromycin dosages up to 200 mg/kg daily (approximately equivalent on a mg/m2 basis to 4 and 2 times, respectively, the human daily oral azithromycin dosage of 500 mg; to 2 or 1 times, respectively, the 1.2-g weekly dosage used for prevention of M. avium complex infection; or 3.3 or 1.7 times, respectively, the 600-mg daily oral dosage used for the treatment of M. avium complex) have not revealed evidence of harm to the fetus. However, there are no adequate and controlled studies to date using azithromycin in pregnant women, and the drug should be used during pregnancy only when clearly needed. Preliminary data indicate that azithromycin may be safe and effective in the treatment of chlamydial infections in pregnant women; however, there are insufficient data to recommend routine use of the drug during pregnancy.

(See Chlamydial Infections: Urogenital Chlamydial Infections, in Uses.) Azithromycin is considered the drug of choice for Mycobacterium avium complex (MAC) prophylaxis in HIV-infected pregnant women. (See Mycobacterium Avium Complex (MAC) infections: Prevention of Disseminated MAC Infection, in Uses.)

Azithromycin has been detected in human milk. The drug should be used with caution in nursing women.

No enhanced Geriatric Use information available for this drug.

The following icd codes are available for ZITHROMAX (azithromycin)'s list of indications:

Acute bacterial otitis media
H66	Suppurative and unspecified otitis media
H66.0	Acute suppurative otitis media
H66.00	Acute suppurative otitis media without spontaneous rupture of ear drum
H66.001	Acute suppurative otitis media without spontaneous rupture of ear drum, right ear
H66.002	Acute suppurative otitis media without spontaneous rupture of ear drum, left ear
H66.003	Acute suppurative otitis media without spontaneous rupture of ear drum, bilateral
H66.004	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, right ear
H66.005	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, left ear
H66.006	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, bilateral
H66.007	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, unspecified ear
H66.009	Acute suppurative otitis media without spontaneous rupture of ear drum, unspecified ear
H66.01	Acute suppurative otitis media with spontaneous rupture of ear drum
H66.011	Acute suppurative otitis media with spontaneous rupture of ear drum, right ear
H66.012	Acute suppurative otitis media with spontaneous rupture of ear drum, left ear
H66.013	Acute suppurative otitis media with spontaneous rupture of ear drum, bilateral
H66.014	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, right ear
H66.015	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, left ear
H66.016	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, bilateral
H66.017	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, unspecified ear
H66.019	Acute suppurative otitis media with spontaneous rupture of ear drum, unspecified ear
H66.4	Suppurative otitis media, unspecified
H66.40	Suppurative otitis media, unspecified, unspecified ear
H66.41	Suppurative otitis media, unspecified, right ear
H66.42	Suppurative otitis media, unspecified, left ear
H66.43	Suppurative otitis media, unspecified, bilateral
H66.9	Otitis media, unspecified
H66.90	Otitis media, unspecified, unspecified ear
H66.91	Otitis media, unspecified, right ear
H66.92	Otitis media, unspecified, left ear
H66.93	Otitis media, unspecified, bilateral
Acute exacerbation obst chr bronchitis by m. catarrhalis
B96.89	Other specified bacterial agents as the cause of diseases classified elsewhere
J44.0	Chronic obstructive pulmonary disease with (acute) lower respiratory infection
Acute exacerbation obstr chr bronchitis s. pneumoniae
B95.3	Streptococcus pneumoniae as the cause of diseases classified elsewhere
J44.0	Chronic obstructive pulmonary disease with (acute) lower respiratory infection
Acute gonococcal cervicitis
A54.03	Gonococcal cervicitis, unspecified
Acute gonococcal urethritis
A54.00	Gonococcal infection of lower genitourinary tract, unspecified
A54.01	Gonococcal cystitis and urethritis, unspecified
Acute h. flu exacerbation of obstructive chr. bronchitis
B96.3	Hemophilus influenzae [h. influenzae] as the cause of diseases classified elsewhere
J44.0	Chronic obstructive pulmonary disease with (acute) lower respiratory infection
Acute haemophilus influenzae bacterial sinusitis
B96.3	Hemophilus influenzae [h. influenzae] as the cause of diseases classified elsewhere
J01	Acute sinusitis
J01.0	Acute maxillary sinusitis
J01.00	Acute maxillary sinusitis, unspecified
J01.01	Acute recurrent maxillary sinusitis
J01.1	Acute frontal sinusitis
J01.10	Acute frontal sinusitis, unspecified
J01.11	Acute recurrent frontal sinusitis
J01.2	Acute ethmoidal sinusitis
J01.20	Acute ethmoidal sinusitis, unspecified
J01.21	Acute recurrent ethmoidal sinusitis
J01.3	Acute sphenoidal sinusitis
J01.30	Acute sphenoidal sinusitis, unspecified
J01.31	Acute recurrent sphenoidal sinusitis
J01.4	Acute pansinusitis
J01.40	Acute pansinusitis, unspecified
J01.41	Acute recurrent pansinusitis
J01.8	Other acute sinusitis
J01.80	Other acute sinusitis
J01.81	Other acute recurrent sinusitis
J01.9	Acute sinusitis, unspecified
J01.90	Acute sinusitis, unspecified
J01.91	Acute recurrent sinusitis, unspecified
Acute moraxella catarrhalis bacterial sinusitis
J01	Acute sinusitis
J01.0	Acute maxillary sinusitis
J01.00	Acute maxillary sinusitis, unspecified
J01.01	Acute recurrent maxillary sinusitis
J01.1	Acute frontal sinusitis
J01.10	Acute frontal sinusitis, unspecified
J01.11	Acute recurrent frontal sinusitis
J01.2	Acute ethmoidal sinusitis
J01.20	Acute ethmoidal sinusitis, unspecified
J01.21	Acute recurrent ethmoidal sinusitis
J01.3	Acute sphenoidal sinusitis
J01.30	Acute sphenoidal sinusitis, unspecified
J01.31	Acute recurrent sphenoidal sinusitis
J01.4	Acute pansinusitis
J01.40	Acute pansinusitis, unspecified
J01.41	Acute recurrent pansinusitis
J01.8	Other acute sinusitis
J01.80	Other acute sinusitis
J01.81	Other acute recurrent sinusitis
J01.9	Acute sinusitis, unspecified
J01.90	Acute sinusitis, unspecified
J01.91	Acute recurrent sinusitis, unspecified
Acute streptococcus pneumoniae bacterial sinusitis
B95.3	Streptococcus pneumoniae as the cause of diseases classified elsewhere
J01	Acute sinusitis
J01.0	Acute maxillary sinusitis
J01.00	Acute maxillary sinusitis, unspecified
J01.01	Acute recurrent maxillary sinusitis
J01.1	Acute frontal sinusitis
J01.10	Acute frontal sinusitis, unspecified
J01.11	Acute recurrent frontal sinusitis
J01.2	Acute ethmoidal sinusitis
J01.20	Acute ethmoidal sinusitis, unspecified
J01.21	Acute recurrent ethmoidal sinusitis
J01.3	Acute sphenoidal sinusitis
J01.30	Acute sphenoidal sinusitis, unspecified
J01.31	Acute recurrent sphenoidal sinusitis
J01.4	Acute pansinusitis
J01.40	Acute pansinusitis, unspecified
J01.41	Acute recurrent pansinusitis
J01.8	Other acute sinusitis
J01.80	Other acute sinusitis
J01.81	Other acute recurrent sinusitis
J01.9	Acute sinusitis, unspecified
J01.90	Acute sinusitis, unspecified
J01.91	Acute recurrent sinusitis, unspecified
Bacterial pneumonia
J15.9	Unspecified bacterial pneumonia
Chancroid
A57	Chancroid
Chlamydia cervicitis
A56.09	Other chlamydial infection of lower genitourinary tract
Chlamydia trachomatis pelvic inflammatory disease
A56.11	Chlamydial female pelvic inflammatory disease
Chlamydia trachomatis urethritis
A56.00	Chlamydial infection of lower genitourinary tract, unspecified
A56.01	Chlamydial cystitis and urethritis
Chlamydial pneumonia
J16.0	Chlamydial pneumonia
Chronic bronchitis with bacterial exacerbation
J44.0	Chronic obstructive pulmonary disease with (acute) lower respiratory infection
Haemophilus influenzae acute otitis media
B96.3	Hemophilus influenzae [h. influenzae] as the cause of diseases classified elsewhere
H66.0	Acute suppurative otitis media
H66.00	Acute suppurative otitis media without spontaneous rupture of ear drum
H66.001	Acute suppurative otitis media without spontaneous rupture of ear drum, right ear
H66.002	Acute suppurative otitis media without spontaneous rupture of ear drum, left ear
H66.003	Acute suppurative otitis media without spontaneous rupture of ear drum, bilateral
H66.004	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, right ear
H66.005	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, left ear
H66.006	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, bilateral
H66.007	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, unspecified ear
H66.009	Acute suppurative otitis media without spontaneous rupture of ear drum, unspecified ear
H66.01	Acute suppurative otitis media with spontaneous rupture of ear drum
H66.011	Acute suppurative otitis media with spontaneous rupture of ear drum, right ear
H66.012	Acute suppurative otitis media with spontaneous rupture of ear drum, left ear
H66.013	Acute suppurative otitis media with spontaneous rupture of ear drum, bilateral
H66.014	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, right ear
H66.015	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, left ear
H66.016	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, bilateral
H66.017	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, unspecified ear
H66.019	Acute suppurative otitis media with spontaneous rupture of ear drum, unspecified ear
H66.9	Otitis media, unspecified
H66.90	Otitis media, unspecified, unspecified ear
H66.91	Otitis media, unspecified, right ear
H66.92	Otitis media, unspecified, left ear
H66.93	Otitis media, unspecified, bilateral
Haemophilus influenzae pneumonia
J14	Pneumonia due to hemophilus influenzae
Legionella pneumophila pneumonia
A48.1	Legionnaires' disease
Moraxella catarrhalis acute otitis media
B96.89	Other specified bacterial agents as the cause of diseases classified elsewhere
H66.0	Acute suppurative otitis media
H66.00	Acute suppurative otitis media without spontaneous rupture of ear drum
H66.001	Acute suppurative otitis media without spontaneous rupture of ear drum, right ear
H66.002	Acute suppurative otitis media without spontaneous rupture of ear drum, left ear
H66.003	Acute suppurative otitis media without spontaneous rupture of ear drum, bilateral
H66.004	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, right ear
H66.005	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, left ear
H66.006	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, bilateral
H66.007	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, unspecified ear
H66.009	Acute suppurative otitis media without spontaneous rupture of ear drum, unspecified ear
H66.01	Acute suppurative otitis media with spontaneous rupture of ear drum
H66.011	Acute suppurative otitis media with spontaneous rupture of ear drum, right ear
H66.012	Acute suppurative otitis media with spontaneous rupture of ear drum, left ear
H66.013	Acute suppurative otitis media with spontaneous rupture of ear drum, bilateral
H66.014	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, right ear
H66.015	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, left ear
H66.016	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, bilateral
H66.017	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, unspecified ear
H66.019	Acute suppurative otitis media with spontaneous rupture of ear drum, unspecified ear
H66.4	Suppurative otitis media, unspecified
H66.40	Suppurative otitis media, unspecified, unspecified ear
H66.41	Suppurative otitis media, unspecified, right ear
H66.42	Suppurative otitis media, unspecified, left ear
H66.43	Suppurative otitis media, unspecified, bilateral
H66.9	Otitis media, unspecified
H66.91	Otitis media, unspecified, right ear
H66.92	Otitis media, unspecified, left ear
H66.93	Otitis media, unspecified, bilateral
Moraxella catarrhalis pneumonia
J15.6	Pneumonia due to other gram-negative bacteria
Mycoplasma hominis pelvic inflammatory disease
B96.89	Other specified bacterial agents as the cause of diseases classified elsewhere
N70	Salpingitis and oophoritis
N70.0	Acute salpingitis and oophoritis
N70.01	Acute salpingitis
N70.02	Acute oophoritis
N70.03	Acute salpingitis and oophoritis
N70.1	Chronic salpingitis and oophoritis
N70.11	Chronic salpingitis
N70.12	Chronic oophoritis
N70.13	Chronic salpingitis and oophoritis
N70.9	Salpingitis and oophoritis, unspecified
N70.91	Salpingitis, unspecified
N70.92	Oophoritis, unspecified
N70.93	Salpingitis and oophoritis, unspecified
N71	Inflammatory disease of uterus, except cervix
N71.0	Acute inflammatory disease of uterus
N71.1	Chronic inflammatory disease of uterus
N71.9	Inflammatory disease of uterus, unspecified
N72	Inflammatory disease of cervix uteri
N73	Other female pelvic inflammatory diseases
N73.0	Acute parametritis and pelvic cellulitis
N73.1	Chronic parametritis and pelvic cellulitis
N73.2	Unspecified parametritis and pelvic cellulitis
N73.3	Female acute pelvic peritonitis
N73.4	Female chronic pelvic peritonitis
N73.5	Female pelvic peritonitis, unspecified
N73.8	Other specified female pelvic inflammatory diseases
N73.9	Female pelvic inflammatory disease, unspecified
Mycoplasmal pneumonia
J15.7	Pneumonia due to mycoplasma pneumoniae
Pelvic inflammatory disease with neisseria gonorrhea
A54.24	Gonococcal female pelvic inflammatory disease
Pharyngitis due to streptococcus pyogenes
J02.0	Streptococcal pharyngitis
Pneumococcal acute otitis media
B95.3	Streptococcus pneumoniae as the cause of diseases classified elsewhere
H66.0	Acute suppurative otitis media
H66.00	Acute suppurative otitis media without spontaneous rupture of ear drum
H66.001	Acute suppurative otitis media without spontaneous rupture of ear drum, right ear
H66.002	Acute suppurative otitis media without spontaneous rupture of ear drum, left ear
H66.003	Acute suppurative otitis media without spontaneous rupture of ear drum, bilateral
H66.004	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, right ear
H66.005	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, left ear
H66.006	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, bilateral
H66.007	Acute suppurative otitis media without spontaneous rupture of ear drum, recurrent, unspecified ear
H66.009	Acute suppurative otitis media without spontaneous rupture of ear drum, unspecified ear
H66.01	Acute suppurative otitis media with spontaneous rupture of ear drum
H66.011	Acute suppurative otitis media with spontaneous rupture of ear drum, right ear
H66.012	Acute suppurative otitis media with spontaneous rupture of ear drum, left ear
H66.013	Acute suppurative otitis media with spontaneous rupture of ear drum, bilateral
H66.014	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, right ear
H66.015	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, left ear
H66.016	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, bilateral
H66.017	Acute suppurative otitis media with spontaneous rupture of ear drum, recurrent, unspecified ear
H66.019	Acute suppurative otitis media with spontaneous rupture of ear drum, unspecified ear
H66.4	Suppurative otitis media, unspecified
H66.40	Suppurative otitis media, unspecified, unspecified ear
H66.41	Suppurative otitis media, unspecified, right ear
H66.42	Suppurative otitis media, unspecified, left ear
H66.43	Suppurative otitis media, unspecified, bilateral
H66.9	Otitis media, unspecified
H66.91	Otitis media, unspecified, right ear
H66.92	Otitis media, unspecified, left ear
H66.93	Otitis media, unspecified, bilateral
Pneumococcal pneumonia
J13	Pneumonia due to streptococcus pneumoniae
Pneumonia due to staphylococcus aureus
J15.21	Pneumonia due to staphylococcus aureus
J15.211	Pneumonia due to methicillin susceptible staphylococcus aureus
J15.212	Pneumonia due to methicillin resistant staphylococcus aureus
Skin and skin structure strep agalactiae infection
B95.1	Streptococcus, group b, as the cause of diseases classified elsewhere
B95.4	Other streptococcus as the cause of diseases classified elsewhere
L08.89	Other specified local infections of the skin and subcutaneous tissue
L08.9	Local infection of the skin and subcutaneous tissue, unspecified
Skin and skin structure strep. pyogenes infection
B95.0	Streptococcus, group a, as the cause of diseases classified elsewhere
B95.4	Other streptococcus as the cause of diseases classified elsewhere
L08.89	Other specified local infections of the skin and subcutaneous tissue
L08.9	Local infection of the skin and subcutaneous tissue, unspecified
Staphylococcus aureus skin and skin structure infection
B95.6	Staphylococcus aureus as the cause of diseases classified elsewhere
H60.1	Cellulitis of external ear
H60.10	Cellulitis of external ear, unspecified ear
H60.11	Cellulitis of right external ear
H60.12	Cellulitis of left external ear
H60.13	Cellulitis of external ear, bilateral
J34.0	Abscess, furuncle and carbuncle of nose
L02	Cutaneous abscess, furuncle and carbuncle
L02.0	Cutaneous abscess, furuncle and carbuncle of face
L02.02	Furuncle of face
L02.03	Carbuncle of face
L02.1	Cutaneous abscess, furuncle and carbuncle of neck
L02.12	Furuncle of neck
L02.13	Carbuncle of neck
L02.2	Cutaneous abscess, furuncle and carbuncle of trunk
L02.22	Furuncle of trunk
L02.221	Furuncle of abdominal wall
L02.222	Furuncle of back [any part, except buttock]
L02.223	Furuncle of chest wall
L02.224	Furuncle of groin
L02.225	Furuncle of perineum
L02.226	Furuncle of umbilicus
L02.229	Furuncle of trunk, unspecified
L02.23	Carbuncle of trunk
L02.231	Carbuncle of abdominal wall
L02.232	Carbuncle of back [any part, except buttock]
L02.233	Carbuncle of chest wall
L02.234	Carbuncle of groin
L02.235	Carbuncle of perineum
L02.236	Carbuncle of umbilicus
L02.239	Carbuncle of trunk, unspecified
L02.3	Cutaneous abscess, furuncle and carbuncle of buttock
L02.32	Furuncle of buttock
L02.33	Carbuncle of buttock
L02.4	Cutaneous abscess, furuncle and carbuncle of limb
L02.42	Furuncle of limb
L02.421	Furuncle of right axilla
L02.422	Furuncle of left axilla
L02.423	Furuncle of right upper limb
L02.424	Furuncle of left upper limb
L02.425	Furuncle of right lower limb
L02.426	Furuncle of left lower limb
L02.429	Furuncle of limb, unspecified
L02.43	Carbuncle of limb
L02.431	Carbuncle of right axilla
L02.432	Carbuncle of left axilla
L02.433	Carbuncle of right upper limb
L02.434	Carbuncle of left upper limb
L02.435	Carbuncle of right lower limb
L02.436	Carbuncle of left lower limb
L02.439	Carbuncle of limb, unspecified
L02.5	Cutaneous abscess, furuncle and carbuncle of hand
L02.52	Furuncle hand
L02.521	Furuncle right hand
L02.522	Furuncle left hand
L02.529	Furuncle unspecified hand
L02.53	Carbuncle of hand
L02.531	Carbuncle of right hand
L02.532	Carbuncle of left hand
L02.539	Carbuncle of unspecified hand
L02.6	Cutaneous abscess, furuncle and carbuncle of foot
L02.62	Furuncle of foot
L02.621	Furuncle of right foot
L02.622	Furuncle of left foot
L02.629	Furuncle of unspecified foot
L02.63	Carbuncle of foot
L02.631	Carbuncle of right foot
L02.632	Carbuncle of left foot
L02.639	Carbuncle of unspecified foot
L02.8	Cutaneous abscess, furuncle and carbuncle of other sites
L02.82	Furuncle of other sites
L02.821	Furuncle of head [any part, except face]
L02.828	Furuncle of other sites
L02.83	Carbuncle of other sites
L02.831	Carbuncle of head [any part, except face]
L02.838	Carbuncle of other sites
L02.9	Cutaneous abscess, furuncle and carbuncle, unspecified
L02.92	Furuncle, unspecified
L02.93	Carbuncle, unspecified
L03.01	Cellulitis of finger
L03.011	Cellulitis of right finger
L03.012	Cellulitis of left finger
L03.019	Cellulitis of unspecified finger
L03.03	Cellulitis of toe
L03.031	Cellulitis of right toe
L03.032	Cellulitis of left toe
L03.039	Cellulitis of unspecified toe
L03.1	Cellulitis and acute lymphangitis of other parts of limb
L03.11	Cellulitis of other parts of limb
L03.111	Cellulitis of right axilla
L03.112	Cellulitis of left axilla
L03.113	Cellulitis of right upper limb
L03.114	Cellulitis of left upper limb
L03.115	Cellulitis of right lower limb
L03.116	Cellulitis of left lower limb
L03.119	Cellulitis of unspecified part of limb
L03.2	Cellulitis and acute lymphangitis of face and neck
L03.21	Cellulitis and acute lymphangitis of face
L03.211	Cellulitis of face
L03.22	Cellulitis and acute lymphangitis of neck
L03.221	Cellulitis of neck
L03.3	Cellulitis and acute lymphangitis of trunk
L03.31	Cellulitis of trunk
L03.311	Cellulitis of abdominal wall
L03.312	Cellulitis of back [any part except buttock]
L03.313	Cellulitis of chest wall
L03.314	Cellulitis of groin
L03.315	Cellulitis of perineum
L03.316	Cellulitis of umbilicus
L03.317	Cellulitis of buttock
L03.319	Cellulitis of trunk, unspecified
L03.8	Cellulitis and acute lymphangitis of other sites
L03.81	Cellulitis of other sites
L03.811	Cellulitis of head [any part, except face]
L03.818	Cellulitis of other sites
L03.9	Cellulitis and acute lymphangitis, unspecified
L03.90	Cellulitis, unspecified
L08.89	Other specified local infections of the skin and subcutaneous tissue
L08.9	Local infection of the skin and subcutaneous tissue, unspecified
N48.22	Cellulitis of corpus cavernosum and penis
Tonsillitis due to streptococcus pyogenes
J03.0	Streptococcal tonsillitis
J03.00	Acute streptococcal tonsillitis, unspecified
J03.01	Acute recurrent streptococcal tonsillitis