Tagrisso

Drug overview for TAGRISSO (osimertinib mesylate):

Generic name: OSIMERTINIB MESYLATE (OH-sim-ER-ti-nib)
Drug class: Antineoplastic - Protein-Tyrosine Kinase Inhibitors
Therapeutic class: Antineoplastics

Osimertinib mesylate, a third-generation inhibitor of receptor tyrosine kinases, is an antineoplastic agent.

No enhanced Uses information available for this drug.

DRUG IMAGES

TAGRISSO 40 MG TABLET
TAGRISSO 80 MG TABLET

The following indications for TAGRISSO (osimertinib mesylate) have been approved by the FDA:

Indications:
EGFR T790M mutation-positive non-small cell lung cancer
Non-small cell lung cancer with EGFR exon 19 deletion
Non-small cell lung cancer with EGFR exon 21 L858R substitution mutation

Professional Synonyms:
EGFR exon 19 deletion mutation-positive NSCLC
EGFR L858R substitution mutation-positive non-small cell lung cancer (NSCLC)
Epidermal growth factor receptor (EGFR) T790M mutation-positive non-small cell lung cancer (NSCLC)
Non-small cell lung cancer with EGFR T790M mutation
NSCLC with EGFR Ex19Del
NSCLC with EGFR exon 21 Leu858Arg substitution
NSCLC with EGFR T790M mutation

The following dosing information is available for TAGRISSO (osimertinib mesylate):

Dosing
Administration
TAGRISSO
Generic

Dosage of osimertinib mesylate is expressed in terms of osimertinib.

Osimertinib is administered orally once daily without regard to meals. The tablets should be swallowed whole and should not be crushed. For patients unable to swallow solids, osimertinib tablets may be dispersed in a container with 60 mL (2 ounces) of noncarbonated water and immediately swallowed; no other liquids should be used.

When preparing the drug dispersion, the water should be stirred (without crushing, heating, or ultrasonicating) until the tablet is dispersed (the tablet will not completely dissolve). Following administration, the container should be rinsed with an additional 120-240 mL (4-8 ounces) of water and the contents swallowed immediately to ensure that the full dose is given. Alternatively, if administration through a nasogastric tube is required, the tablet should be dispersed in a container with 15 mL of noncarbonated water and drawn into a syringe; the container should then be rinsed with an additional 15 mL of water to transfer any residue to the syringe.

The resulting 30-mL drug dispersion should be administered through the nasogastric tube, and the tube should be flushed with appropriate volumes of water (approximately 30 mL). This step should be repeated until no tablet pieces remain in the syringe. The dispersion and residues should be administered within 30 minutes of the addition of the tablet to water. If a dose of osimertinib is missed, the next dose should be taken at the regularly scheduled time; the missed dose should not be taken.

Dosing information for TAGRISSO
DRUG LABEL	DOSING TYPE	DOSING INSTRUCTIONS
TAGRISSO 40 MG TABLET	Maintenance	Adults take 2 tablets (80 mg) by oral route once daily
TAGRISSO 80 MG TABLET	Maintenance	Adults take 1 tablet (80 mg) by oral route once daily

No generic dosing information available.

The following drug interaction information is available for TAGRISSO (osimertinib mesylate):

Contraindicated
Severe
Moderate

There are 1 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
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

Drug Interaction

Drug Names

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 19 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
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
Dabigatran/Selected P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Dabigatran etexilate is a substrate for the P-glycoprotein (P-gp) system. Inhibition of intestinal P-gp leads to increased absorption of dabigatran.(1-3) CLINICAL EFFECTS: The concurrent use dabigatran with P-gp inhibitors may lead to elevated plasma levels of dabigatran, increasing the risk for bleeding. PREDISPOSING FACTORS: Factors associated with an increased risk for bleeding include renal impairment, concomitant use of P-gp inhibitors, patient age >74 years, coexisting conditions (e.g. recent trauma) or use of drugs (e.g. NSAIDs) associated with bleeding risk, and patient weight < 50 kg.(1-4) PATIENT MANAGEMENT: Assess renal function and evaluate patient for other pre-existing risk factors for bleeding prior to initiating concurrent therapy. The US manufacturer of dabigatran states that the concurrent use of dabigatran and P-gp inhibitors should be avoided in atrial fibrillation patients with severe renal impairment (CrCl less than 30 ml/min) and in patients with moderate renal impairment (CrCl less than 50 ml/min) being treated for or undergoing prophylaxis for deep vein thrombosis (DVT) or pulmonary embolism (PE). The interaction with P-gp inhibitors can be minimized by taking dabigatran several hours apart from the P-gp inhibitor dose.(1) The concomitant use of dabigatran with P-gp inhibitors has not been studied in pediatric patients but may increase exposure to dabigatran.(1) While the US manufacturer of dabigatran states that no dosage adjustment is necessary in other patients,(1) the Canadian manufacturer of dabigatran states that concomitant use of strong P-gp inhibitors (e.g., glecaprevir-pibrentasvir) is contraindicated. When dabigatran is used for the prevention of venous thromboembolism (VTE) after total hip or knee replacement concurrently with amiodarone, quinidine, or verapamil, the dose of dabigatran should be reduced from 110 mg twice daily to 150 mg once daily. For patients with CrCl less than 50 ml/min on verapamil, a further dabigatran dose reduction to 75 mg once daily should be considered. Verapamil should be given at least 2 hours after dabigatran to minimize the interaction.(2) The UK manufacturer of dabigatran also states the use of dabigatran with strong P-gp inhibitors (e.g., cyclosporine, glecaprevir-pibrentasvir or itraconazole) is contraindicated. Concurrent use of ritonavir is not recommended. When dabigatran is used in atrial fibrillation patients and for treatment of DVT and PE concurrently with verapamil, the UK manufacturer recommends reducing the dose of dabigatran from 150 mg twice daily to 110 mg twice daily, taken simultaneously with verapamil. When used for VTE prophylaxis after orthopedic surgery concurrently with amiodarone, quinidine, or verapamil, the dabigatran loading dose should be reduced from 110 mg to 75 mg, and the maintenance dose should be reduced from 220 mg daily to 150 mg daily, taken simultaneously with the P-gp inhibitor. For patients with CLcr 30-50 mL/min on concurrent verapamil, consider further lowering the dabigatran dose to 75 mg daily.(3) If concurrent therapy is warranted, monitor patients for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Consider regular monitoring of hemoglobin, platelet levels, and/or activated partial thromboplastin time (aPTT) or ecarin clotting time (ECT). When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. DISCUSSION: When dabigatran was co-administered with amiodarone, the extent and rate of absorption of amiodarone and its active metabolite DEA were essentially unchanged. The dabigatran area-under-curve (AUC) and maximum concentration (Cmax) were increased by about 60% and 50%, respectively;(1,2) however, dabigatran clearance was increased by 65%.(1) Pretreatment with quinidine (200 mg every 2 hours to a total dose of 1000 mg) increased the AUC and Cmax of dabigatran by 53% and 56%, respectively.(1,2) Chronic administration of immediate release verapamil one hour prior to dabigatran dose increased dabigatran AUC by 154%.(4) Administration of dabigatran two hours before verapamil results in a negligible increase in dabigatran AUC.(1) Administration of sofosbuvir-velpatasvir-voxilaprevir (400/100/200 mg daily) increased the Cmax and AUC of a single dose of dabigatran (75 mg) by 2.87-fold and 2.61-fold, respectively.(5) Simultaneous administration of glecaprevir-pibrentasvir (300/120 mg daily) with a single dose of dabigatran (150 mg) increased the Cmax and AUC by 2.05-fold and 2.38-fold, respectively.(6) A retrospective comparative effectiveness cohort study including data from 9,886 individuals evaluated adverse bleeding rates with standard doses of oral anticoagulants with concurrent verapamil or diltiazem in patients with nonvalvular atrial fibrillation and normal kidney function. The study compared rates of bleeding following co-administration of either dabigatran, rivaroxaban, or apixaban with verapamil or diltiazem, compared to co-administration with amlodipine or metoprolol. Results of the study found that concomitant dabigatran use with verapamil or diltiazem was associated with increased overall bleeding (hazard ratio (HR) 1.52; 95% confidence interval (CI), 1.05-2.20, p<0.05) and increased overall GI bleeding (HR 2.16; 95% CI, 1.30-3.60, p<0.05) when compared to amlodipine. When compared to metoprolol, concomitant dabigatran use with verapamil or diltiazem was also associated with increased overall bleeding (HR, 1.43; 95% CI, 1.02-2.00, p<0.05) and increased overall GI bleeding (HR, 2.32; 95% CI, 1.42-3.79, p<0.05). No association was found between increased bleeding of any kind and concurrent use of rivaroxaban or apixaban with verapamil or diltiazem.(7) A summary of pharmacokinetic interactions with dabigatran and amiodarone or verapamil concluded that concurrent use is considered safe if CrCl is greater than 50 ml/min but should be avoided if CrCl is less than 50 ml/min in VTE and less than 30 ml/min for NVAF. Concurrent use with diltiazem was considered safe.(9) P-gp inhibitors include amiodarone, asunaprevir, belumosudil, capmatinib, carvedilol, cimetidine, conivaptan, cyclosporine, daclatasvir, danicopan, daridorexant, diosmin, erythromycin, flibanserin, fostamatinib, ginseng, glecaprevir, indinavir, itraconazole, ivacaftor, josamycin, lapatinib, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pibrentasvir, propafenone, quinidine, ranolazine, ritonavir, sotorasib, telaprevir, telithromycin, tepotinib, tezacaftor, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, voclosporin, and voxilaprevir.(1-9)	DABIGATRAN ETEXILATE, PRADAXA
Topotecan/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of P-glycoprotein may increase the absorption of topotecan.(1) CLINICAL EFFECTS: The concurrent administration of topotecan with an inhibitor of P-glycoprotein may result in elevated levels of topotecan and signs of toxicity. These signs may include but are not limited to anemia, diarrhea, and thrombocytopenia.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of topotecan states that the use of topotecan and P-glycoprotein inhibitors should be avoided. If concurrent use is warranted, carefully monitor patients for adverse effects.(1) DISCUSSION: In clinical studies, the combined use of elacridar (100 mg to 1000 mg) increased the area-under-curve (AUC) of topotecan approximately 2.5-fold.(1) Oral cyclosporine (15 mg/kg) increased the AUC of topotecan lactone and total topotecan to 2-fold to 3-fold of the control group, respectively.(1) P-gp inhibitors linked to this monograph include: adagrasib, amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, bosutinib, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, cyclosporine, danicopan, daridorexant, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fostamatinib, ginseng, hydroquinidine, isavuconazonium, itraconazole, ivacaftor, josamycin, ketoconazole, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pibrentasvir/glecaprevir, pirtobrutinib, propafenone, quinidine, ranolazine, ritonavir, selpercatinib, sotorasib, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(2,3)	HYCAMTIN
Deferiprone/Selected Myelosuppressive Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of deferiprone with other drugs known to be associated with neutropenia or agranulocytosis may increase the frequency or risk for severe toxicity.(1) CLINICAL EFFECTS: Concurrent use of deferiprone and myelosuppressive agents may result in severe neutropenia or agranulocytosis, which may be fatal. PREDISPOSING FACTORS: Agranulocytosis may be less common in patients receiving deferiprone for thalassemia, and more common in patients treated for other systemic iron overload conditions (e.g. myelodysplastic syndromes, sickle cell disease).(2,3) Inadequate monitoring appears to increase the risk for severe outcomes. Manufacturer post market surveillance found that in all fatal cases of agranulocytosis reported between 1999 and 2005, data on weekly white blood count (WBC) monitoring was missing. In three fatal cases, deferiprone was continued for two to seven days after the detection of neutropenia or agranulocytosis.(2) PATIENT MANAGEMENT: If possible, discontinue one of the drugs associated with risk for neutropenia or agranulocytosis. If alternative therapy is not available, documentation and adherence to the deferiprone monitoring protocol is essential. Baseline absolute neutrophil count (ANC) must be at least 1,500/uL prior to starting deferiprone. Monitor ANC weekly during therapy. If infection develops, interrupt deferiprone therapy and monitor ANC more frequently. If ANC is less than 1,500/uL but greater than 500/uL, discontinue deferiprone and any other drugs possibly associated with neutropenia. Initiate ANC and platelet counts daily until recovery (i.e. ANC at least 1,500/uL). If ANC is less than 500/uL, discontinue deferiprone, evaluate patient and hospitalize if appropriate. Do not resume deferiprone unless potential benefits outweigh potential risks.(1) DISCUSSION: Drugs linked to this monograph have an FDA Boxed Warning for risk of neutropenia, agranulocytosis, or pancytopenia, or have > 5% risk for neutropenia and/or warnings describing risk for myelosuppression in manufacturer prescribing information.(1-25) In pooled clinical studies submitted to the FDA, 6.1% of deferiprone patients met criteria for neutropenia and 1.7% of patients developed agranulocytosis.(1) The time to onset of agranulocytosis was highly variable with a range of 65 days to 9.2 years (median, 161 days).(3)	DEFERIPRONE, DEFERIPRONE (3 TIMES A DAY), FERRIPROX, FERRIPROX (2 TIMES A DAY), FERRIPROX (3 TIMES A DAY)
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)	ADLARITY, AGRYLIN, AMIODARONE HCL, AMIODARONE HCL-D5W, ANAGRELIDE HCL, ARICEPT, ARSENIC TRIOXIDE, AVELOX IV, AZITHROMYCIN, BETAPACE, BETAPACE AF, CAPRELSA, CELEXA, CESIUM CHLORIDE, CHLOROQUINE PHOSPHATE, CHLORPROMAZINE HCL, CILOSTAZOL, CIPRO, CIPROFLOXACIN, CIPROFLOXACIN HCL, CIPROFLOXACIN-D5W, CITALOPRAM HBR, CLARITHROMYCIN, CLARITHROMYCIN ER, CORVERT, DIFLUCAN, DIPRIVAN, DISKETS, DISOPYRAMIDE PHOSPHATE, DOFETILIDE, DONEPEZIL HCL, DONEPEZIL HCL ODT, DROPERIDOL, E.E.S. 200, E.E.S. 400, ERY-TAB, ERYPED 200, ERYPED 400, ERYTHROCIN LACTOBIONATE, ERYTHROCIN STEARATE, ERYTHROMYCIN, ERYTHROMYCIN ESTOLATE, ERYTHROMYCIN ETHYLSUCCINATE, ERYTHROMYCIN LACTOBIONATE, FLECAINIDE ACETATE, FLUCONAZOLE, FLUCONAZOLE-NACL, GATIFLOXACIN SESQUIHYDRATE, HALDOL DECANOATE 100, HALDOL DECANOATE 50, HALOPERIDOL, HALOPERIDOL DECANOATE, HALOPERIDOL DECANOATE 100, HALOPERIDOL LACTATE, HYDROXYCHLOROQUINE SULFATE, IBUTILIDE FUMARATE, KRAZATI, LANSOPRAZOL-AMOXICIL-CLARITHRO, MEMANTINE HCL-DONEPEZIL HCL ER, METHADONE HCL, METHADONE HCL-0.9% NACL, METHADONE HCL-NACL, METHADONE INTENSOL, METHADOSE, MOXIFLOXACIN, MOXIFLOXACIN HCL, MULTAQ, NAMZARIC, NEXTERONE, NORPACE, NORPACE CR, NUEDEXTA, OMECLAMOX-PAK, PACERONE, PENTAM 300, PENTAMIDINE ISETHIONATE, PIMOZIDE, PLAQUENIL, PROCAINAMIDE HCL, PROPOFOL, QUINIDINE GLUCONATE, QUINIDINE SULFATE, REVUFORJ, SEVOFLURANE, SOTALOL, SOTALOL AF, SOTALOL HCL, SOTYLIZE, SOVUNA, THIORIDAZINE HCL, THIORIDAZINE HYDROCHLORIDE, TIKOSYN, TRISENOX, ULTANE, VANFLYTA, VOQUEZNA TRIPLE PAK, ZITHROMAX, ZITHROMAX TRI-PAK, ZOKINVY
Osimertinib/Strong CYP3A4 Inducers SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Strong inducers of CYP3A4 may induce the metabolism of osimertinib via this pathway.(1) CLINICAL EFFECTS: Concurrent or recent use of strong CYP3A4 inducers may reduce the clinical effectiveness of osimertinib.(1) PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. PATIENT MANAGEMENT: Whenever possible, it would be prudent to use an alternative agent in place of the strong CYP3A4 inducer. After discontinuation of a strong CYP3A4 inducer, osimertinib systemic concentrations will gradually increase due to the relatively long half-life of osimertinib.(1) The US manufacturer of osimertinib states that concurrent use of CYP3A4 inducers should be avoided.(1) If concurrent therapy cannot be avoided increase the osimertinib dose to 160 mg daily. Resume osimertinib at 80 mg three weeks after the discontinuation of the strong CYP3A4 inducer. DISCUSSION: Osimertinib is itself an inducer of CYP3A4. The magnitude of induction and whether osimertinib auto-induces its own metabolism has not yet been described.(1) In a clinical pharmacokinetic study, the AUC of osimertinib was reduced by 78% in patients when coadministered with rifampin (600 mg daily for 21 days).(1) Strong CYP3A4 inducers linked to this monograph are: apalutamide, barbiturates, carbamazepine, enzalutamide, fosphenytoin, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine and St. John's Wort.(4,5)	ASA-BUTALB-CAFFEINE-CODEINE, ASCOMP WITH CODEINE, BUTALB-ACETAMINOPH-CAFF-CODEIN, BUTALBITAL, BUTALBITAL-ACETAMINOPHEN, BUTALBITAL-ACETAMINOPHEN-CAFFE, BUTALBITAL-ASPIRIN-CAFFEINE, CARBAMAZEPINE, CARBAMAZEPINE ER, CARBATROL, CEREBYX, DILANTIN, DILANTIN-125, DONNATAL, EPITOL, EQUETRO, ERLEADA, FIORICET, FIORICET WITH CODEINE, FOSPHENYTOIN SODIUM, LYSODREN, MITOTANE, MYSOLINE, ORKAMBI, PENTOBARBITAL SODIUM, PHENOBARBITAL, PHENOBARBITAL SODIUM, PHENOBARBITAL-BELLADONNA, PHENOBARBITAL-HYOSC-ATROP-SCOP, PHENOHYTRO, PHENYTEK, PHENYTOIN, PHENYTOIN SODIUM, PHENYTOIN SODIUM EXTENDED, PRIFTIN, PRIMIDONE, RIFADIN, RIFAMPIN, SEZABY, TEGRETOL, TEGRETOL XR, TENCON, XTANDI
Colchicine (for Gout & FMF)/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may affect the transport of colchicine, a P-gp substrate.(1,2) CLINICAL EFFECTS: Concurrent use of a P-gp inhibitor may result in elevated levels of and toxicity from colchicine. Symptoms of colchicine toxicity include abdominal pain; nausea or vomiting; severe diarrhea; muscle weakness or pain; numbness or tingling in the fingers or toes; myelosuppression; feeling weak or tired; increased infections; and pale or gray color of the lips, tongue, or palms of hands.(1,2) PREDISPOSING FACTORS: This interaction is expected to be more severe in patients with renal and/or hepatic impairment(1,2) and in patients who receive concurrent therapy. PATIENT MANAGEMENT: The concurrent use of colchicine with P-gp inhibitors is contraindicated in patients with renal or hepatic impairment.(1-3) Avoid concurrent use in other patients, if possible.(3) In patients without renal or hepatic impairment who are currently taking or have taken a P-gp inhibitor in the previous 14 days, the dosage of colchicine should be reduced. For gout flares, the recommended dosage is 0.6 mg (1 tablet) for one dose. This dose should be repeated no earlier than in 3 days.(1,2) For gout prophylaxis, if the original dosage was 0.6 mg twice daily, use 0.3 mg daily. If the original dosage was 0.6 mg daily, use 0.3 mg every other day.(3-12) For Familial Mediterranean fever (FMF), the recommended maximum daily dose is 0.6 mg (may be given as 0.3 mg twice a day).(1,2) Patients should be instructed to immediately report any signs of colchicine toxicity, such as abdominal pain, nausea/significant diarrhea, vomiting; muscle weakness/pain; numbness/tingling in fingers/toes; unusual bleeding or bruising, infections, weakness/tiredness, or pale/gray color of the lips/tongue/palms of hands. DISCUSSION: There are several reports of colchicine toxicity(4-6) and death(7,8) following the addition of clarithromycin to therapy. In a retrospective review of 116 patients who received clarithromycin and colchicine during the same hospitalization, 10.2% (9/88) of patients who received simultaneous therapy died, compared to 3.6% (1/28) of patients who received sequential therapy.(9) An FDA review of 117 colchicine-related deaths that were not attributable to overdose found that 60 deaths (51%) involved concurrent use of clarithromycin.(2) There is one case report of colchicine toxicity with concurrent erythromycin.(10) In a study in 20 subjects, pretreatment with diltiazem (240 mg daily for 7 days) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of colchicine (0.6 mg) by 44.2% (range -46.6% to 318.3%) and by 93.4% (range -30.2% to 338.6%), respectively.(1) In a study in 24 subjects, pretreatment with verapamil (240 mg twice daily for 7 days) increased the Cmax and AUC of a single dose of colchicine (0.6 mg) by 40.1% (range -47.1% to 149.5%) and by 103.3% (range -9.8% to 217.2%), respectively.(1) Colchicine toxicity has been reported with concurrent use of CYP3A4 and P-gp inhibitors such as clarithromycin, cyclosporine, diltiazem, erythromycin, and verapamil.(1,2) P-gp inhibitors include abrocitinib, amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, danicopan, daridorexant, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, schisandra, selpercatinib, sotorasib, tepotinib, tezacaftor, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(1,11,12)	COLCHICINE, COLCRYS, GLOPERBA, MITIGARE, PROBENECID-COLCHICINE
Venetoclax/Selected P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Venetoclax is a substrate for the P-glycoprotein (P-gp) system. P-gp inhibitors may lead to increased levels of venetoclax.(1) CLINICAL EFFECTS: Concurrent use of P-gp inhibitors may result in elevated levels of venetoclax, increasing the risk for tumor lysis syndrome and other toxicities.(1) PREDISPOSING FACTORS: Risk factors for tumor lysis syndrome include (1): - the ramp-up phase of venetoclax therapy when tumor burden is highest - initial magnitude of tumor burden - renal impairment The risk of venetoclax toxicities may be increased in patients with severe hepatic impairment.(1) PATIENT MANAGEMENT: Avoid P-gp inhibitors and consider alternative treatments when possible. If a P-gp inhibitor must be used, reduce venetoclax dose by at least 50%. Monitor more closely for signs of toxicity such as tumor lysis syndrome, hematologic and non-hematologic toxicities.(1) If the P-gp inhibitor is discontinued, the manufacturer of venetoclax recommends resuming the prior (i.e. pre-inhibitor) dose of venetoclax 2 to 3 days after discontinuation of the P-gp inhibitor.(1) DISCUSSION: In 11 healthy subjects, a single dose of rifampin (a P-gp inhibitor) increased venetoclax maximum concentration (Cmax) and area-under-curve (AUC) by 106% and 78%, respectively.(1) In 11 previously treated NHL subjects, ketoconazole (a strong CYP3A4 inhibitor which also inhibits P-gp and BCRP) 400 mg daily for 7 days increased the Cmax and AUC of venetoclax 2.3-fold and 6.4-fold respectively.(1) In 12 healthy subjects, coadministration of azithromycin (500 mg Day 1, 250 mg for Days 2-5) decreased venetoclax Cmax and AUC by 25% and 35%. No dosage adjustment is needed when venetoclax is coadministered with azithromycin.(1) P-gp inhibitors include: amiodarone, asunaprevir, belumosudil, capmatinib, carvedilol, cyclosporine, danicopan, daridorexant, diosmin, flibanserin, fostamatinib, ginseng, ivacaftor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tezacaftor, tepotinib, valbenazine, vemurafenib, vimseltinib, and voclosporin.(2)	VENCLEXTA, VENCLEXTA STARTING PACK
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
Clozapine/Myelosuppressive Agents that Prolong QT SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of clozapine with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-3) Clozapine and concurrent use with other myelosuppressive agents may be associated with additive risk of neutropenia or agranulocytosis.(4) CLINICAL EFFECTS: The use of clozapine in patients maintained on other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1-3) Moderate neutropenia, even if due to combination therapy, may require abrupt discontinuation of clozapine resulting in decompensation of the patient's psychiatric disorder (e.g. schizophrenia). The disease treated by other agents may be compromised if myelosuppression requires dose reduction, delay, or discontinuation of the myelosuppressive agent. Undetected severe neutropenia or agranulocytosis may be fatal. 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) Low white blood counts prior to initiation of the myelosuppressive agent may increase risk for clinically significant neutropenia.(2) PATIENT MANAGEMENT: Approach the concurrent use of clozapine and other agents that 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. If a patient stabilized on clozapine therapy requires treatment with other myelosuppressive agents the clozapine prescriber should consult with the prescriber of the myelosuppressive agent to discuss treatment and monitoring options. More frequent ANC monitoring or treatment alternatives secondary to neutropenic episodes may need to be considered. Clozapine is only available through a restricted distribution system which requires documentation of the absolute neutrophil count (ANC) prior to dispensing. For most clozapine patients, clozapine treatment must be interrupted for a suspected clozapine-induced ANC < 1000 cells/microliter. For patients with benign ethnic neutropenia (BEN), treatment must be interrupted for suspected clozapine-induced neutropenia < 500 cells/microliter.(1) DISCUSSION: Treatment with clozapine has been associated with QT prolongation as well as ventricular arrhythmia, torsades de pointes, cardiac arrest, and sudden death.(1) Clozapine is only available through a restricted distribution system which requires documentation of the ANC prior to dispensing.(1) Myelosuppressive agents that prolong QT linked to this monograph include: arsenic, crizotinib, dasatinib, encorafenib, entrectinib, epirubicin, eribulin, fexinidazole, glasdegib, inotuzumab, lenvatinib, midostaurin, nilotinib, osimertinib, oxaliplatin, pacritinib, panobinostat, pazopanib, pentamidine, quinine, quizartinib, revumenib, ribociclib, romidepsin, rucaparib, sorafenib, tacrolimus, and vinflunine.	CLOZAPINE, CLOZAPINE ODT, CLOZARIL, VERSACLOZ
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
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
Sodium Iodide I 131/Myelosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Sodium iodide I 131 can cause depression of the hematopoetic system. Myelosuppressives and immunomodulators also suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of sodium iodide I 131 with agents that cause bone marrow depression, including myelosuppressives or immunomodulators, may result in an enhanced risk of hematologic disorders, including anemia, blood dyscrasias, bone marrow depression, leukopenia, and thrombocytopenia. Bone marrow depression may increase the risk of serious infections and bleeding.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of sodium iodide I 131 states that concurrent use with bone marrow depressants may enhance the depression of the hematopoetic system caused by large doses of sodium iodide I 131.(1) Sodium iodide I 131 causes a dose-dependent bone marrow suppression, including neutropenia or thrombocytopenia, in the 3 to 5 weeks following administration. Patients may be at increased risk of infections or bleeding during this time. Monitor complete blood counts within one month of therapy. If results indicate leukopenia or thrombocytopenia, dosimetry should be used to determine a safe sodium iodide I 131 activity.(1) DISCUSSION: Hematologic disorders including death have been reported with sodium iodide I 131. The most common hematologic disorders reported include anemia, blood dyscrasias, bone marrow depression, leukopenia, and thrombocytopenia.(1)	HICON, SODIUM IODIDE I-131
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
Levoketoconazole/Possible QT Prolonging Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. 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
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
Osimertinib/Strong CYP3A4 Inducers that Prolong QT SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Strong CYP3A4 inducers may induce the metabolism of osimertinib by CYP3A4. Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inducers may result in decreased levels and effectiveness of osimertinib and increase the risk of potentially life-threatening 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) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. PATIENT MANAGEMENT: The US manufacturer of osimertinib states that concurrent use of CYP3A4 inducers that prolong QT should be avoided. If concurrent therapy cannot be avoided increase the osimertinib dose to 160 mg daily. Resume osimertinib at 80 mg three weeks after the discontinuation of the strong CYP3A4 inducer. 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. Dose adjustments for prolonged QTc interval(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.(1) DISCUSSION: In a clinical pharmacokinetic study, the AUC of osimertinib was reduced by 78% in patients when coadministered with rifampin (600 mg daily for 21 days).(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 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.(3) 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 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.(4) Strong CYP3A4 inducers that prolong QT linked to this monograph include: encorafenib and ivosidenib.(5)	BRAFTOVI, TIBSOVO
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

There are 30 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
Levofloxacin/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 levofloxacin 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 know 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 U.S. manufacturer of levofloxacin states that levofloxacin 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) 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.	LEVOFLOXACIN, LEVOFLOXACIN HEMIHYDRATE, LEVOFLOXACIN-D5W
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
Quetiapine/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 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
Ondansetron/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 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)	ONDANSETRON HCL, ONDANSETRON HCL-0.9% NACL
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
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
Escitalopram/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 multiple agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) CLINICAL EFFECTS: The concurrent use of multiple 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) 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).(1) PATIENT MANAGEMENT: While the US FDA and manufacturer recommend no special precautions when escitalopram is used with QT prolonging agents,(2,3) Health Canada and the Canadian manufacturer of escitalopram discourage the concurrent use of agents known to prolong the QT interval(4,5) and the UK manufacturer states that concurrent use is contraindicated.(6) 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.(7) 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.	ESCITALOPRAM OXALATE, LEXAPRO
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
Osimertinib/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. 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)	ALFUZOSIN HCL ER, APOKYN, APOMORPHINE HCL, ASPRUZYO SPRINKLE, ASTAGRAF XL, ATOMOXETINE HCL, DANZITEN, DASATINIB, ELLENCE, ENVARSUS XR, EPIRUBICIN HCL, ERIBULIN MESYLATE, ERZOFRI, FANAPT, FARESTON, FARYDAK, GRANISETRON HCL, HALAVEN, INVEGA, INVEGA HAFYERA, INVEGA SUSTENNA, INVEGA TRINZA, ISRADIPINE, LAPATINIB, NEXAVAR, NILOTINIB HCL, OFLOXACIN, ONAPGO, PALIPERIDONE ER, PROGRAF, RANOLAZINE ER, RUBRACA, RYDAPT, SANCUSO, SIGNIFOR, SIGNIFOR LAR, SIRTURO, SORAFENIB, SPRYCEL, STRATTERA, SUNITINIB MALATE, SUSTOL, SUTENT, TACROLIMUS, TACROLIMUS XL, TASIGNA, TOLTERODINE TARTRATE, TOLTERODINE TARTRATE ER, TOREMIFENE CITRATE, TYKERB, UROXATRAL, VIBATIV, XALKORI, ZELBORAF, ZYKADIA
Ribociclib/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 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) In MONALEESA-7, an increase of greater than 60 ms from baseline in the QTcF interval was observed in 14/87 (16%) of patients in the ribociclib and tamoxifen combination group.(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
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
Ubrogepant/P-gp or BCRP 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) or BCRP may increase the absorption of ubrogepant.(1) CLINICAL EFFECTS: The concurrent administration of ubrogepant with an inhibitor of P-glycoprotein or BCRP may result in elevated levels of ubrogepant.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when coadministered with P-gp or BCRP inhibitors. The dose of ubrogepant should not exceed 50 mg for initial dose. If a second dose of ubrogepant is needed, the dose should not exceed 50 mg.(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 ubrogepant.(3) DISCUSSION: Ubrogepant is a substrate of P-gp and BCRP transporters. Use of P-gp or BCRP inhibitors may increase the exposure of ubrogepant. Clinical drug interaction studies with inhibitors of these transporters were not conducted. The US manufacturer of ubrogepant recommends dose adjustment if ubrogepant is coadministered with P-gp or BCRP inhibitors.(1) BCRP inhibitors linked to this monograph include: belumosudil, clopidogrel, curcumin, eltrombopag, gefitinib, grazoprevir, momelotinib, oteseconazole, rolapitant, roxadustat, safinamide, tafamidis, oral tedizolid, and vadadustat.(2-5) P-glycoprotein inhibitors linked to this monograph include: asunaprevir, belumosudil, carvedilol, danicopan, daridorexant, neratinib, osimertinib, propafenone, quinidine, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, tezacaftor, valbenazine, vimseltinib, and voclosporin.(2-5)	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
Oxaliplatin/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 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/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. 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
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
Intravenous Lefamulin/Selected 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 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
Pacritinib/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. 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
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
Dexmedetomidine Sublingual/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. 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
Digoxin/Osimertinib SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Osimertinib may increase the absorption of digoxin by inhibiting P-glycoprotein (P-gp).(1) CLINICAL EFFECTS: Concurrent use of osimertinib may result in elevated levels of and toxicity from digoxin.(1) Symptoms of digoxin toxicity can include anorexia, nausea, vomiting, headache, fatigue, malaise, drowsiness, generalized muscle weakness, disorientation, hallucinations, visual disturbances, and arrhythmias. PREDISPOSING FACTORS: Low body weight, advanced age, impaired renal function, hypokalemia, hypercalcemia, and/or hypomagnesemia may increase the risk of digoxin toxicity. PATIENT MANAGEMENT: Monitor digoxin concentrations before and during the administration of osimertinib. The manufacturer of digoxin recommends decreasing the dose of digoxin by approximately 15-30% or by modifying the dosing frequency to reduce digoxin concentrations.(2) DISCUSSION: Osimertinib increased the area-under-curve (AUC) and maximum concentration (Cmax) of fexofenadine (a P-gp substrate) by 56% and 76% after a single dose of osimertinib, respectively, and by 27% and 25% at steady-state of osimertinib, respectively.(1)	DIGITEK, DIGOXIN, DIGOXIN MICRONIZED, LANOXIN
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
Givinostat/Possible QT Prolonging Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. 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

Contraindication List
Lactation

Severe List
Congenital long QT syndrome
Hypokalemia
Hypomagnesemia
Pregnancy
Prolonged QT interval

The following adverse reaction information is available for TAGRISSO (osimertinib mesylate):

Overview
Severe
Less Severe

Adverse reaction overview.

Adverse effects reported in more than 20% of patients receiving osimertinib as monotherapy include leukopenia, lymphophenia, anemia, diarrhea, rash, musculoskeletal pain, neutropenia, nail toxicity, dry skin, stomatitis, and fatigue. Adverse effects reported in more than 20% of patients receiving osimertinib following platinum-based chemoradiation therapy include lymphopenia, leukopenia, ILD/pneumonitis, thrombocytopenia, neutropenia, rash, diarrhea, nail toxicity, musculoskeletal pain, cough, and COVID-19. Adverse effects reported in more than 20% of patients receiving osimertinib in combination with pemetrexed and platinum-based chemotherapy include leukopenia, thrombocytopenia, neutropenia, lymphophenia, rash, diarrhea, stomatitis, nail toxicity, dry skin, and increased creatinine.

There are 26 severe adverse reactions.

More Frequent	Less Frequent
Anemia Interstitial lung disease Interstitial pneumonitis Leukopenia Lymphopenia Neutropenic disorder Thrombocytopenic disorder	Cardiomyopathy Cerebrovascular accident Left ventricular failure Pneumonia Pulmonary thromboembolism Venous thrombosis

Rare/Very Rare
Aplastic anemia Bronchiolitis obliterans with organizing pneumonia Cutaneous vasculitis Endophthalmitis Erythema multiforme Hypersensitivity angiitis Keratitis Prolonged QT interval Rhabdomyolysis Stevens-johnson syndrome Toxic epidermal necrolysis Transient blindness Uveitis

There are 41 less severe adverse reactions.

More Frequent	Less Frequent
Anorexia Cough Diarrhea Dry skin Fatigue Musculoskeletal pain Nail disorders Skin rash Stomatitis	Abnormal hepatic function tests Acute abdominal pain Alopecia Back pain Blepharitis Blurred vision Constipation Dizziness Dry eye Epistaxis Eye tearing Fever Gastroenteritis Headache disorder Hyperbilirubinemia Hyperglycemia Hypermagnesemia Hypokalemia Hyponatremia Nausea Ocular pain Pruritus of skin Upper respiratory infection Urinary tract infection Urticaria

Rare/Very Rare
Dyspnea Erythema dyschromicum perstans Increased creatine kinase level Myopathy Palmar-plantar erythrodysesthesia Skin pigmentation enhancement Vomiting

The following precautions are available for TAGRISSO (osimertinib mesylate):

Pediatric
Pregnant
Lactation
Geriatric

Safety and efficacy of osimertinib have not been established in pediatric patients.

Contraindicated

None

Severe Precaution

None

Management or Monitoring Precaution

None

Although there are no available data in pregnant women, animal studies suggest that osimertinib may cause fetal harm. If osimertinib is used during pregnancy or if the patient becomes pregnant while receiving the drug, the patient should be apprised of the potential fetal hazard.

It is not known whether osimertinib is distributed into human milk or if the drug has any effect on milk production or the nursing infant. Adverse effects (e.g., reduced growth rates, neonatal deaths) have been observed in the offspring of rats administered osimertinib during gestation and early lactation. Because of the potential for serious adverse reactions to osimertinib in nursing infants, women should be advised to discontinue nursing while receiving the drug and for 2 weeks after the drug is discontinued.

In clinical trials of osimertinib monotherapy involving 1813 patients, 770 patients were >=65 years of age and 207 patients were >=75 years of age. Although no overall differences in efficacy or safety were observed between patients >=65 years of age and younger patients, exploratory analysis suggested an increased incidence of >=grade 3 adverse reactions (43% versus 33%) and more frequent dosage modifications for adverse reactions (34% versus 23%) in patients >=65 years of age. In a clinical study of osimertinib following definitive platinum-based chemoradiation therapy involving 142 patients, 62 patients were >=65 years of age and 13 patients were >=75 years of age.

No overall differences in efficacy or safety were observed between patients >=65 years of age and younger patients. In a clinical study of osimertinib in combination with pemetrexed and platinum-based chemotherapy involving 276 patients, 104 patients were >=65 years of age and 23 patients were >=75 years of age. Clinical studies of combination therapy did not include sufficient numbers of patients >=65 years of age to determine whether they respond differently from younger patients; however, exploratory analysis suggested an increased incidence of >=grade 3 adverse reactions (68% versus 61%) and more frequent dosage modifications for adverse reactions (55% versus 43%) in patients >=65 years of age.

The following icd codes are available for TAGRISSO (osimertinib mesylate)'s list of indications:

EGFR t790M mutation-positive non-small cell lung cancer
C34	Malignant neoplasm of bronchus and lung
C34.0	Malignant neoplasm of main bronchus
C34.00	Malignant neoplasm of unspecified main bronchus
C34.01	Malignant neoplasm of right main bronchus
C34.02	Malignant neoplasm of left main bronchus
C34.1	Malignant neoplasm of upper lobe, bronchus or lung
C34.10	Malignant neoplasm of upper lobe, unspecified bronchus or lung
C34.11	Malignant neoplasm of upper lobe, right bronchus or lung
C34.12	Malignant neoplasm of upper lobe, left bronchus or lung
C34.2	Malignant neoplasm of middle lobe, bronchus or lung
C34.3	Malignant neoplasm of lower lobe, bronchus or lung
C34.30	Malignant neoplasm of lower lobe, unspecified bronchus or lung
C34.31	Malignant neoplasm of lower lobe, right bronchus or lung
C34.32	Malignant neoplasm of lower lobe, left bronchus or lung
C34.8	Malignant neoplasm of overlapping sites of bronchus and lung
C34.80	Malignant neoplasm of overlapping sites of unspecified bronchus and lung
C34.81	Malignant neoplasm of overlapping sites of right bronchus and lung
C34.82	Malignant neoplasm of overlapping sites of left bronchus and lung
C34.9	Malignant neoplasm of unspecified part of bronchus or lung
C34.90	Malignant neoplasm of unspecified part of unspecified bronchus or lung
C34.91	Malignant neoplasm of unspecified part of right bronchus or lung
C34.92	Malignant neoplasm of unspecified part of left bronchus or lung
C39.9	Malignant neoplasm of lower respiratory tract, part unspecified
Non-small cell lung cancer with EGFR exon 19 deletion
C34	Malignant neoplasm of bronchus and lung
C34.0	Malignant neoplasm of main bronchus
C34.00	Malignant neoplasm of unspecified main bronchus
C34.01	Malignant neoplasm of right main bronchus
C34.02	Malignant neoplasm of left main bronchus
C34.1	Malignant neoplasm of upper lobe, bronchus or lung
C34.10	Malignant neoplasm of upper lobe, unspecified bronchus or lung
C34.11	Malignant neoplasm of upper lobe, right bronchus or lung
C34.12	Malignant neoplasm of upper lobe, left bronchus or lung
C34.2	Malignant neoplasm of middle lobe, bronchus or lung
C34.3	Malignant neoplasm of lower lobe, bronchus or lung
C34.30	Malignant neoplasm of lower lobe, unspecified bronchus or lung
C34.31	Malignant neoplasm of lower lobe, right bronchus or lung
C34.32	Malignant neoplasm of lower lobe, left bronchus or lung
C34.8	Malignant neoplasm of overlapping sites of bronchus and lung
C34.80	Malignant neoplasm of overlapping sites of unspecified bronchus and lung
C34.81	Malignant neoplasm of overlapping sites of right bronchus and lung
C34.82	Malignant neoplasm of overlapping sites of left bronchus and lung
C34.9	Malignant neoplasm of unspecified part of bronchus or lung
C34.90	Malignant neoplasm of unspecified part of unspecified bronchus or lung
C34.91	Malignant neoplasm of unspecified part of right bronchus or lung
C34.92	Malignant neoplasm of unspecified part of left bronchus or lung
C39.9	Malignant neoplasm of lower respiratory tract, part unspecified
NSCLC with EGFR exon 21 l858R substitution mutation
C34	Malignant neoplasm of bronchus and lung
C34.0	Malignant neoplasm of main bronchus
C34.00	Malignant neoplasm of unspecified main bronchus
C34.01	Malignant neoplasm of right main bronchus
C34.02	Malignant neoplasm of left main bronchus
C34.1	Malignant neoplasm of upper lobe, bronchus or lung
C34.10	Malignant neoplasm of upper lobe, unspecified bronchus or lung
C34.11	Malignant neoplasm of upper lobe, right bronchus or lung
C34.12	Malignant neoplasm of upper lobe, left bronchus or lung
C34.2	Malignant neoplasm of middle lobe, bronchus or lung
C34.3	Malignant neoplasm of lower lobe, bronchus or lung
C34.30	Malignant neoplasm of lower lobe, unspecified bronchus or lung
C34.31	Malignant neoplasm of lower lobe, right bronchus or lung
C34.32	Malignant neoplasm of lower lobe, left bronchus or lung
C34.8	Malignant neoplasm of overlapping sites of bronchus and lung
C34.80	Malignant neoplasm of overlapping sites of unspecified bronchus and lung
C34.81	Malignant neoplasm of overlapping sites of right bronchus and lung
C34.82	Malignant neoplasm of overlapping sites of left bronchus and lung
C34.9	Malignant neoplasm of unspecified part of bronchus or lung
C34.90	Malignant neoplasm of unspecified part of unspecified bronchus or lung
C34.91	Malignant neoplasm of unspecified part of right bronchus or lung
C34.92	Malignant neoplasm of unspecified part of left bronchus or lung
C39.9	Malignant neoplasm of lower respiratory tract, part unspecified