Jaypirca

Drug overview for JAYPIRCA (pirtobrutinib):

Generic name: PIRTOBRUTINIB
Drug class: Antineoplastic - Protein-Tyrosine Kinase Inhibitors
Therapeutic class: Antineoplastics

Pirtobrutinib, a small-molecule noncovalent (reversible) inhibitor of Bruton's tyrosine kinase (BTK), is an antineoplastic agent.

No enhanced Uses information available for this drug.

DRUG IMAGES

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The following indications for JAYPIRCA (pirtobrutinib) have been approved by the FDA:

Indications:
Chronic lymphocytic leukemia
Mantle cell lymphoma
Small lymphocytic lymphoma

Professional Synonyms:
B-cell chronic lymphocytic leukemia
B-Cell CLL
Chronic B-cell leukemia
Chronic B-lymphocytic leukemia
Chronic lymphatic leukemia
Chronic lymphocytic leukemia of B-cell type
Chronic lymphocytic leukemia, B-cell
Mantle cell B-cell lymphoma

The following dosing information is available for JAYPIRCA (pirtobrutinib):

Dosing
Administration
JAYPIRCA
Generic

Withhold pirtobrutinib therapy if grade 3 or greater nonhematologic toxicity, absolute neutrophil count (ANC) <1000 to 500 cells/mm3 with fever and/or infection, ANC <500 cells/mm3 lasting >=7 days, platelet count <50,000 to 25,000 cells/mm3 with bleeding, or platelet count <25,000 cells/mm3 occurs. Upon resolution or improvement of the toxicity (i.e., return to baseline or resolution to grade 1), pirtobrutinib therapy may be resumed as described in Table 1.

Table 1: Recommended Dosage Modifications for Pirtobrutinib Toxicity

Toxicity Occurrence Recommended Dosage after Recovery from Toxicity (Starting Dosage = 200 mg once daily) First Restart at 200 mg once daily Second Restart at 100 mg once daily Third Restart at 50 mg once daily Fourth Discontinue pirtobrutinib

Evaluate the potential risks and benefits before resuming treatment at the same dose following resolution of grade 4 nonhematologic toxicity.

Dosage adjustment is not recommended for asymptomatic lymphocytosis. Dosage adjustment may not be necessary in case of asymptomatic increases in lipase concentrations.

Avoid concomitant use of strong CYP3A inhibitors with pirtobrutinib. If concomitant use of a strong CYP3A inhibitor cannot be avoided, reduce the pirtobrutinib dosage by 50 mg daily. If the current dosage is 50 mg once daily, interrupt pirtobrutinib therapy for the duration of strong CYP3A inhibitor use.

After discontinuance of the strong CYP3A inhibitor for 5 half-lives, resume pirtobrutinib at the dosage used prior to initiation of the strong CYP3A inhibitor.

Avoid concomitant use of strong or moderate CYP3A inducers with pirtobrutinib. If concomitant use with a moderate CYP3A inducer cannot be avoided and the current dosage of pirtobrutinib is 200 mg once daily, increase the pirtobrutinib dosage to 300 mg once daily. If the current pirtobrutinib dosage is 50 or 100 mg once daily, increase the pirtobrutinib dosage by 50 mg daily.

Administer orally once daily at approximately the same time each day without regard to food. Swallow tablets whole with water; do notcut, crush, or chew tablets. If a dose of pirtobrutinib is missed by >12 hours, skip the dose and administer the next dose at the regularly scheduled time.

Do not take extra tablets of the drug to make up for the missed dose. Store pirtobrutinib tablets at 20-25oC; excursions are permitted to 15-30oC.

Dosing information for JAYPIRCA
DRUG LABEL	DOSING TYPE	DOSING INSTRUCTIONS
JAYPIRCA 50 MG TABLET	Maintenance	Adults take 1 tablet (50 mg) by oral route once daily
JAYPIRCA 100 MG TABLET	Maintenance	Adults take 2 tablets (200 mg) by oral route once daily

No generic dosing information available.

The following drug interaction information is available for JAYPIRCA (pirtobrutinib):

Contraindicated
Severe
Moderate

There are 6 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
Efalizumab; Natalizumab/Immunosuppressives; Immunomodulators 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: Natalizumab,(1-3) efalizumab,(4) immunosuppressives, and immunomodulators all suppress the immune system. CLINICAL EFFECTS: Concurrent use of natalizumab(1-3) or efalizumab(4) with immunosuppressives or immunomodulators may result in an increased risk of infections, including progressive multifocal leukoencephalopathy (PML), an opportunistic infection caused by the JC virus (JCV). PREDISPOSING FACTORS: Previous JCV infection, longer duration of natalizumab treatment - especially if greater than 2 years, and prior or concomitant treatment with immunosuppressant medication are all independent risk factors which increase the risk for PML.(1,5) The FDA has estimated PML incidence stratified by risk factors: If anti-JCV antibody positive, no prior immunosuppressant use and natalizumab treatment less than 25 months, incidence <1/1,000. If anti-JCV antibody positive, history of prior immunosuppressant use and natalizumab treatment less than 25 months, incidence 2/1,000 If anti-JCV antibody positive, no prior immunosuppressant use and natalizumab treatment 25-48 months, incidence 4/1,000 If anti-JCV antibody positive, history of prior immunosuppressant use and natalizumab treatment 25-48 months, incidence 11/1,000. PATIENT MANAGEMENT: The US manufacturer of natalizumab states patients with Crohn's disease should not receive concurrent immunosuppressants, with the exception of limited overlap of corticosteroids, due to the increased risk for PML. For new natalizumab patients currently receiving chronic oral corticosteroids for Crohn's Disease, begin corticosteroid taper when therapeutic response to natalizumab has occurred. If corticosteroids cannot be discontinued within six months of starting natalizumab, discontinue natalizumab.(3) The US manufacturer of natalizumab states that natalizumab should not ordinarily be used in multiple sclerosis patients receiving immunosuppressants or immunomodulators due to the increased risk for PML. Immunosuppressives include, but are not limited to azathioprine, cyclophosphamide, cyclosporine, mercaptopurine, methotrexate, mitoxantrone, mycophenolate, and corticosteroids.(3,6) The UK manufacturer of natalizumab states that concurrent use with immunosuppressives or antineoplastic agents is contraindicated.(1) The Canadian manufacturer of natalizumab states that natalizumab should not be used with immunosuppressive or immunomodulatory agents.(2) The US manufacturer of certolizumab states that concurrent therapy with natalizumab is not recommended.(7) DISCUSSION: Progressive multifocal leukoencephalopathy has been reported in patients receiving concurrent natalizumab were recently or concomitantly taking immunomodulators or immunosuppressants.(1-5,8,9) In a retrospective cohort study of multiple sclerosis patients newly initiated on a disease-modifying therapy, use of high-efficacy agents (alemtuzumab, natalizumab, or ocrelizumab) resulted in the same risk of overall infections as moderate-efficacy agents, but there was an elevated risk of serious infections (adjusted hazard ratio [aHR] = 1.24, 95% confidence interval (CI) = 1.06-1.44) and UTIs (aHR = 1.21, 95% CI = 1.14-1.30).(10)	TYRUKO, TYSABRI
Live Vaccines; Live BCG/Selected Immunosuppressive Agents SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: A variety of disease modifying agents suppress the immune system. Immunocompromised patients may be at increased risk for uninhibited replication after administration of live, attenuated vaccines or intravesicular BCG. Immune response to vaccines may be decreased during periods of immunocompromise.(1) CLINICAL EFFECTS: The expected serum antibody response may not be obtained and/or the vaccine may result in illness.(1) After instillation of intravesicular BCG, immunosuppression may interfere with local immune response, or increase the severity of mycobacterial infection following inadvertent systemic exposure.(2) PREDISPOSING FACTORS: Immunosuppressive diseases (e.g. hematologic malignancies, HIV disease), treatments (e.g. radiation) and drugs may all increase the magnitude of immunodeficiency. PATIENT MANAGEMENT: The Centers for Disease Control(CDC) Advisory Committee on Immunization Practices (ACIP) states that live-virus and live, attenuated vaccines should not be administered to patients who are immunocompromised. The magnitude of immunocompromise and associated risks should be determined by a physician.(1) For patients scheduled to receive chemotherapy, vaccination should ideally precede the initiation of chemotherapy by 14 days. Patients vaccinated while on immunosuppressive therapy or in the 2 weeks prior to starting therapy should be considered unimmunized and should be revaccinated at least 3 months after discontinuation of therapy.(1) Patients who receive anti-B cell therapies should not receive live vaccines for at least 6 months after such therapies due to a prolonged duration of immunosuppression. An exception is the Zoster vaccine, which can be given at least 1 month after receipt of anti-B cell therapies.(1) The US manufacturer of abatacept states live vaccines should not be given during or for up to 3 months after discontinuation of abatacept.(2) The US manufacturer of live BCG for intravesicular treatment of bladder cancer states use is contraindicated in immunosuppressed patients.(3) The US manufacturer of daclizumab states live vaccines are not recommended during and for up to 4 months after discontinuation of treatment.(4) The US manufacturer of guselkumab states that live vaccines should be avoided during treatment with guselkumab.(5) The US manufacturer of inebilizumab-cdon states that live vaccines are not recommended during treatment and after discontinuation until B-cell repletion. Administer all live vaccinations at least 4 weeks prior to initiation of inebilizumab-cdon.(6) The US manufacturer of ocrelizumab states that live vaccines are not recommended during treatment and until B-cell repletion occurs after discontinuation of therapy. Administer all live vaccines at least 4 weeks prior to initiation of ocrelizumab.(7) The US manufacturer of ozanimod states that live vaccines should be avoided during and for up to 3 months after discontinuation of ozanimod.(8) The US manufacturer of siponimod states that live vaccines are not recommended during treatment and for up to 4 weeks after discontinuation of treatment.(9) The US manufacturer of ustekinumab states BCG vaccines should not be given in the year prior to, during, or the year after ustekinumab therapy.(10) The US manufacturer of satralizumab-mwge states that live vaccines are not recommended during treatment and should be administered at least four weeks prior to initiation of satralizumab-mwge.(11) The US manufacturer of ublituximab-xiiy states that live vaccines are not recommended during treatment and until B-cell recovery. Live vaccines should be administered at least 4 weeks prior to initiation of ublituximab-xiiy.(12) The US manufacturer of etrasimod states that live vaccines should be avoided during and for 5 weeks after treatment. Live vaccines should be administered at least 4 weeks prior to initiation of etrasimod.(13) The US manufacturer of emapalumab-lzsg states that live vaccines should not be administered to patients receiving emapalumab-lzsg and for at least 4 weeks after the last dose of emapalumab-lzsg. The safety of immunization with live vaccines during or following emapalumab-lzsg therapy has not been studied.(14) The US manufacturer of sibeprenlimab-szsi states live vaccines should not be given within 30 days prior to initiation or during treatment with sibeprenlimab-szsi.(15) DISCUSSION: Killed or inactivated vaccines do not pose a danger to immunocompromised patients.(1) Patients with a history of leukemia who are in remission and have not received chemotherapy for at least 3 months are not considered to be immunocompromised.(1)	ACAM2000 (NATIONAL STOCKPILE), ADENOVIRUS TYPE 4, ADENOVIRUS TYPE 4 AND TYPE 7, ADENOVIRUS TYPE 7, BCG (TICE STRAIN), BCG VACCINE (TICE STRAIN), DENGVAXIA, ERVEBO (NATIONAL STOCKPILE), FLUMIST 2025-2026, FLUMIST HOME 2025-2026, M-M-R II VACCINE, PRIORIX, PROQUAD, ROTARIX, ROTATEQ, STAMARIL, VARIVAX VACCINE, VAXCHORA ACTIVE COMPONENT, VAXCHORA VACCINE, VIVOTIF, YF-VAX
Talimogene laherparepvec/Selected Immunosuppressants 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: Talimogene laherparepvec is a live, attenuated herpes simplex virus.(1) CLINICAL EFFECTS: Concurrent use of talimogene laherparepvec in patients receiving immunosuppressive therapy may cause a life-threatening disseminated herpetic infection.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Talimogene laherparepvec is contraindicated in immunosuppressed patients.(1) The magnitude of immunocompromise and associated risks due to immunosuppressant drugs should be determined by a physician. DISCUSSION: Concurrent use of talimogene laherparepvec in patients receiving immunosuppressive therapy may cause a life-threatening disseminated herpetic infection.(1)	IMLYGIC
Lemborexant (Greater Than 5 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Inhibitors of CYP3A4 may inhibit the metabolism of lemborexant.(1) CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP3A4 may result in increased levels of and effects from lemborexant, including somnolence, fatigue, CNS depressant effects, daytime impairment, headache, and nightmare or abnormal dreams.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The maximum recommended dose of lemborexant with concurrent use of a weak CYP3A4 inhibitors should not exceed 5 mg per dose.(1) DISCUSSION: Lemborexant is a CYP3A4 substrate. In a PKPB model, concurrent use of lemborexant with itraconazole increased area-under-curve (AUC) and concentration maximum (Cmax) by 3.75-fold and 1.5-fold, respectively. Concurrent use of lemborexant with fluconazole increased AUC and Cmax by 4.25-fold and 1.75-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, anamorelin, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, vonoprazan, and ziftomenib.(1,2)	DAYVIGO
Colchicine (for Cardioprotection)/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may affect the transport of colchicine, a P-gp substrate.(1,2) CLINICAL EFFECTS: Concurrent use of a P-gp inhibitor may result in elevated levels of and toxicity from colchicine. Symptoms of colchicine toxicity include abdominal pain; nausea or vomiting; severe diarrhea; muscle weakness or pain; numbness or tingling in the fingers or toes; myelosuppression; feeling weak or tired; increased infections; and pale or gray color of the lips, tongue, or palms of hands.(1,2) PREDISPOSING FACTORS: This interaction is expected to be more severe in patients with renal or hepatic impairment.(1,2) PATIENT MANAGEMENT: The manufacturer of colchicine used for cardiovascular risk reduction states that concurrent use of colchicine with P-gp inhibitors is contraindicated.(1) DISCUSSION: There are several reports of colchicine toxicity(3-5) and death(6,7) following the addition of clarithromycin to therapy. In a retrospective review of 116 patients who received clarithromycin and colchicine during the same hospitalization, 10.2% (9/88) of patients who received simultaneous therapy died, compared to 3.6% (1/28) of patients who received sequential therapy.(8) An FDA review of 117 colchicine-related deaths that were not attributable to overdose found that 60 deaths (51%) involved concurrent use of clarithromycin.(2) There is one case report of colchicine toxicity with concurrent erythromycin.(9) In a study in 20 subjects, pretreatment with diltiazem (240 mg daily for 7 days) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of colchicine (0.6 mg) by 44.2% (range -46.6% to 318.3%) and by 93.4% (range -30.2% to 338.6%), respectively.(1) In a study in 24 subjects, pretreatment with verapamil (240 mg twice daily for 7 days) increased the Cmax and AUC of a single dose of colchicine (0.6 mg) by 40.1% (range -47.1% to 149.5%) and by 103.3% (range -9.8% to 217.2%), respectively.(1) Colchicine toxicity has been reported with concurrent use of CYP3A4 and P-gp inhibitors such as clarithromycin, cyclosporine, diltiazem, erythromycin, and verapamil.(1,2) P-gp inhibitors include abrocitinib, amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daridorexant, deutivacaftor, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, imlunestrant, ivacaftor, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, schisandra, selpercatinib, sotorasib, tepotinib, valbenazine, velpatasvir, vemurafenib, venetoclax, verapamil, vimseltinib, and voclosporin.(1,10,11)	LODOCO
Ubrogepant (Greater Than 50 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of ubrogepant.(1) CLINICAL EFFECTS: Concurrent use of ubrogepant with weak CYP3A4 inhibitors may result in an increase in exposure of ubrogepant.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when used concomitantly with weak CYP3A4 inhibitors. Initial dose of ubrogepant should not exceed 50 mg when used concomitantly with weak inhibitors of CYP3A4. A second dose may be given within 24 hours but should not exceed 50 mg when used concurrently with weak CYP3A4 inhibitors.(1) DISCUSSION: Coadministration of ubrogepant with verapamil, a moderate CYP3A4 inhibitor, resulted in a 3.5-fold and 2.8-fold increase in area-under-curve (AUC) and concentration maximum (Cmax), respectively. No dedicated drug interaction study was conducted to assess concomitant use with weak CYP3A4 inhibitors. The conservative prediction of the maximal potential increase in ubrogepant exposure with weak CYP3A4 inhibitors is not expected to be more than 2-fold.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, anamorelin, asciminib, azithromycin, Baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, delavirdine, deutivacaftor, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, maribavir, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, pirtobrutinib, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, vonoprazan, and ziftomenib.(2,3)	UBRELVY

There are 36 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
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, imlunestrant, indinavir, itraconazole, ivacaftor, josamycin, lapatinib, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pibrentasvir, propafenone, quinidine, ranolazine, ritonavir, selpercatinib, sotorasib, telaprevir, telithromycin, tepotinib, tezacaftor, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, voclosporin, and voxilaprevir.(1-9)	DABIGATRAN ETEXILATE, PRADAXA
Aliskiren/Selected P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Aliskiren is a substrate for the P-glycoprotein (P-gp) system. Inhibitors of P-gp may increase the absorption of aliskiren.(1-3) CLINICAL EFFECTS: The concurrent use of aliskiren and P-gp inhibitors may result in elevated levels of aliskiren. This may result in increased effect and toxicity of aliskiren including hypotension.(1-3) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of aliskiren states that concurrent use of itraconazole should be avoided.(1) The UK manufacturer of aliskiren states that the concurrent use of P-gp inhibitors such as itraconazole is contraindicated.(2) The US manufacturer of itraconazole states that concurrent administration of aliskiren is not recommended during and two weeks after itraconazole treatment.(4) DISCUSSION: In a study in healthy subjects, concurrent itraconazole (100 mg) increased the maximum concentration (Cmax) and area-under-curve (AUC) of aliskiren (150 mg) by 5.8-fold and 6.5-fold, respectively.(2,3) Selected P-gp inhibitors linked to this monograph include: azithromycin, belumosudil, clarithromycin, danicopan, daridorexant, fostamatinib, indinavir, itraconazole, lopinavir/ritonavir, mavorixafor, nirmatrelvir/ritonavir, pirtobrutinib, rifampin and vimseltinib.(4,5)	ALISKIREN, TEKTURNA
Citalopram (Greater Than 20 mg)/Select CYP2C19 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Citalopram is primarily metabolized by the CYP2C19 isoenzyme.(1) CLINICAL EFFECTS: Concurrent use of an agent that inhibits CYP2C19 may result in elevated levels of and toxicity from citalopram, including including risks for serotonin syndrome or prolongation of the QTc interval.(1-5) Prolongation of the QT interval may result in life-threatening arrhythmias, including torsades de pointes.(2) Symptoms of serotonin syndrome may include tremor, agitation, diaphoresis, hyperreflexia, clonus, tachycardia, hyperthermia, and muscle rigidity.(5) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, advanced age, poor metabolizer status at CYP2C19, or higher blood concentrations of citalopram.(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) Predisposing factors for serotonin-related adverse effects include use in the elderly, in patients with hepatic impairment, and in patients receiving multiple agents which increase central serotonin levels.(1,5) 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. PATIENT MANAGEMENT: The dose of citalopram should be limited to 20 mg in patients receiving concurrent therapy with an inhibitor of CYP2C19.(1,4) Evaluate the patient for other drugs, diseases and conditions which increase risk for QT prolongation and correct risk factors (e.g. correct hypokalemia, discontinue other QT prolonging drugs) when possible.(1,2) Weigh the specific benefits versus risks for each patient. The US manufacturer recommends ECG monitoring for citalopram patients with congestive heart failure, bradyarrhythmias, taking concomitant QT prolonging medications or receiving concurrent therapy.(4) Citalopram should be discontinued in patients with persistent QTc measurements greater than 500 ms.(2) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If concurrent therapy is warranted, patients should be monitored for signs and symptoms of serotonin syndrome. Instruct patients to report muscle twitching, tremors, shivering and stiffness, fever, heavy sweating, heart palpitations, restlessness, confusion, agitation, trouble with coordination, or severe diarrhea. DISCUSSION: Concurrent use of citalopram (40 mg daily) and cimetidine (400 mg twice daily) for 8 days increased the maximum concentration (Cmax) and area-under-curve (AUC) of citalopram by 39% and 43%, respectively.(1) Inhibitors of CYP2C19 include: abrocitinib, allicin (garlic derivative), berotralstat, cannabidiol (CBD), cenobamate, cimetidine strengths > or = 200 mg, enasidenib, eslicarbazepine, esomeprazole, etravirine, fedratinib, felbamate, fluoxetine, fluvoxamine, givosiran, isoniazid, moclobemide, modafinil, obeticholic acid, omeprazole, piperine, rolapitant, stiripentol, and tecovirimat.(7,8)	CELEXA, CITALOPRAM HBR
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)
Tofacitinib/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of tofacitinib and azathioprine, other biologic disease-modifying antirheumatic drugs (DMARDs), or potent immunosuppressants may result in additive or synergistic effects on the immune system.(1) CLINICAL EFFECTS: Concurrent use of tofacitinib and azathioprine, other biologic DMARDs, or potent immunosuppressants use may increase the risk of serious infections.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Tofacitinib should not be used concurrently with azathioprine, other biologic DMARDs, or cyclosporine.(1) Patient should be monitored for decreases in lymphocytes and neutrophils. Therapy should be adjusted based on the indication. - For all indications: If absolute neutrophil count (ANC) or lymphocyte count is less than 500 cells/mm3, discontinue tofacitinib. - For rheumatoid arthritis or psoriatic arthritis and absolute neutrophil count (ANC) 500 to 1000 cells/mm3: interrupt dosing. When ANC is greater than 1000 cells/mm3, resume Xeljanz 5 mg twice daily or Xeljanz XR 11 mg once daily. - For ulcerative colitis and ANC 500 to 1000 cells/mm3: -If taking Xeljanz 10 mg twice daily, decrease to 5 mg twice daily. When ANC is greater than 1000 cells/mm3, increase to 10 mg twice daily based on clinical response. -If taking Xeljanz 5 mg twice daily, interrupt dosing. When ANC is greater than 1000 cells/mm3, resume 5 mg twice daily. -If taking Xeljanz XR 22 mg once daily, decrease to 11 mg once daily. When ANC is greater than 1000 cells/mm3, increase to 22 mg once daily based on clinical response. -If taking Xeljanz XR 11 mg once daily, interrupt dosing. When ANC is greater than 1000 cells/mm3, resume 11 mg once daily. - For polyarticular course juvenile idiopathic arthritis (pcJIA) and ANC 500 to 1000 cells/mm3: interrupt dosing until ANC is greater than 1000 cells/mm3.(1) DISCUSSION: Concurrent use of tofacitinib and azathioprine, other biologic DMARDs, or potent immunosuppressants may increase the risk of infection.(1) Serious infections due to bacterial, mycobacterial, invasive fungal, viral, or other opportunistic pathogens have been reported in patients receiving tofacitinib. Some patients presented with disseminated disease and were often taking concomitant immunomodulating agents. In the ulcerative colitis population, a greater risk of serious infections was seen with a higher tofacitinib dose. In 7 placebo-controlled rheumatoid arthritis trials (0-3 months exposure), the overall frequency of infections was 20% in the tofacitinib 5 mg twice daily group and 22% in the tofacitinib 10 mg twice daily group compared to 18% in the placebo group. Serious infections were reported in 11 patients (1.7 events per 100 patient-years) with a rate difference between treatment groups of 1.1 (-0.4, 2.5) events per 100 patient-years for both tofacitinib 5 mg twice daily and 10 mg twice daily. During 0-12 months exposure, serious infections were reported in 34 patients (2.7 events per 100 patient years) in the tofacitinib 5 mg twice daily group and 33 patients (2.7 events per 100 patient years) in the tofacitinib 10 mg twice daily group.(1)	TOFACITINIB CITRATE, XELJANZ, XELJANZ XR
Clopidogrel/Selected CYP2C19 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Clopidogrel is a prodrug and is converted to its active metabolite via a 2 step process. The first conversion step is mediated by CYP2C19, CYP1A2 and CYP2B6, while the second step is mediated by CYP3A4, CYP2B6 and CYP2C19.(1,2) CYP2C19 contributes to both steps and is thought to be the more important enzyme involved in formation of the pharmacologically active metabolite.(1) Inhibitors of CYP2C19 may decrease the conversion of clopidogrel to its active metabolite.(1) CLINICAL EFFECTS: Concurrent use of CYP2C19 inhibitors may result in decreased clopidogrel effectiveness, resulting in increased risk of adverse cardiac events. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Evaluate medication list or interaction alerts to determine if patient is receiving additional drugs which may also inhibit clopidogrel active metabolite formation. The US manufacturer of clopidogrel states that alternatives to clopidogrel should be considered in patients who are poor metabolizers of CYP2C19.(1) It would be prudent to assume that patients taking strong inhibitors of CYP2C19 are poor metabolizers of this isoenzyme. Moderate or weak inhibitors of CYP2C19 may have less of an effect on this interaction. Consider alternatives to CYP2C19 inhibitors in patients stabilized on clopidogrel and alternatives to clopidogrel in patients stabilized on CYP2C19 inhibitors. If concurrent therapy is warranted, consider appropriate testing to assure adequate inhibition of platelet reactivity. DISCUSSION: Clopidogrel is a prodrug and requires conversion to the active metabolite by CYP2C19. Clopidogrel is not a sensitive substrate for CYP2C19 as CYP3A4, CYP2B6 and CYP1A2 also participate in active metabolite formation. Studies have not evaluated this specific drug combination; the actual magnitude of this interaction is not known. Given the possible consequences of clopidogrel treatment failure, it would be prudent to avoid concomitant use of clopidogrel and CYP2C19 inhibitors when possible. Selected CYP2C19 inhibitors include: armodafinil, asciminib, berotralstat, cenobamate, elagolix, enasidenib, eslicarbazepine, fedratinib, fexinidazole, givosiran, lonafarnib, moclobemide, modafinil, obeticholic acid, osilodrostat, piperine, pirtobrutinib, rolapitant, rucaparib, tecovirimat, treosulfan, and triclabendazole.(4,5)	CLOPIDOGREL, CLOPIDOGREL BISULFATE, PLAVIX
Lomitapide (Less Than or Equal To 30 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of lomitapide.(1) Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Thus even weak CYP3A4 inhibitors may affect lomitapide exposure (AUC, area-under-curve). CLINICAL EFFECTS: Concurrent use of a weak inhibitor of CYP3A4 may result in 2-fold increases in lomitapide levels and toxicity from lomitapide.(1) PREDISPOSING FACTORS: This interaction may be more severe in patients with hepatic impairment or with end-stage renal disease.(1) PATIENT MANAGEMENT: The maximum lomitapide dose should be 30 mg daily for patients taking concomitant weak CYP3A4 inhibitors. Due to lomitapide's long half-life, it may take 1 to 2 weeks to see the full effect of this interaction. When initiating a weak CYP3A4 inhibitor in patients taking lomitapide 10 mg daily or more, decrease the dose of lomitapide by 50%. In patients taking lomitapide 5 mg daily, continue current dose. DISCUSSION: Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Based upon interactions with stronger inhibitors, weak inhibitors of CYP3A4 are predicted to increase lomitapide area-under-curve(AUC) 2-fold.(1) Weak CYP3A4 inhibitors linked to this interaction include alprazolam, amiodarone, amlodipine, anamorelin, asciminib, atorvastatin, azithromycin, Baikal skullcap, belumosudil, bicalutamide, blueberry juice, brodalumab, cannabidiol, capivasertib, cilostazol, cimetidine, ciprofloxacin, chlorzoxazone, clotrimazole, cranberry juice, cyclosporine, daridorexant, delavirdine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, larotrectinib, lacidipine, lapatinib, lazertinib, leflunomide, levamlodipine, linagliptin, lurasidone, maribavir, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, vonoprazan, ziftomenib, and zileuton.(1-3)	JUXTAPID
Clozapine/Selected Myelosuppressive Agents SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Clozapine and other myelosuppressive agents may be associated with neutropenia or agranulocytosis.(2) CLINICAL EFFECTS: 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 the myelosuppressive agent 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: Low white blood counts prior to initiation of the myelosuppressive agent may increase risk for clinically significant neutropenia. PATIENT MANAGEMENT: If a patient stabilized on clozapine therapy requires treatment with a myelosuppressive agent, the clozapine prescriber should consult with prescriber of the myelosuppressive agent (e.g. oncologist) to discuss treatment and monitoring options.(2) More frequent absolute neutrophil count (ANC) monitoring or treatment alternatives secondary to neutropenic episodes may need to be considered. The U.S. Food and Drug Administration (FDA) recommends that prescribers monitor patients' ANC according to the monitoring frequencies described in the prescribing information. Severe neutropenia remains a serious, potentially fatal risk that is greatest in the first several months of clozapine treatment. ANC monitoring can help identify neutropenia early to allow for timely intervention.(1-2) Australia, Canada, and U.K.: Clozapine is only available through a restricted distribution system which requires documentation of the 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.(2) DISCUSSION: Concurrent use of clozapine and selected myelosuppressive agents may require more frequent ANC monitoring or consideration of treatment alternatives secondary to neutropenic episodes. Agents linked to this interaction generally have > 5% risk for neutropenia and/or warnings describing risk for myelosuppression in manufacturer prescribing information.(3-26)	CLOZAPINE, CLOZAPINE ODT, CLOZARIL, VERSACLOZ
Selected Multiple Sclerosis Agents/Immunosuppressants; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Ocrelizumab or ofatumumab in combination with immunosuppressives and immune-modulators all suppress the immune system.(1,2) CLINICAL EFFECTS: Concurrent use of ocrelizumab or ofatumumab with immunosuppressive or immune-modulating agents may result in an increased risk of serious infections, such as disseminated herpetic infection or progressive multifocal leukoencephalopathy (PML), an opportunistic infection caused by the JC virus (JCV).(1,2) PREDISPOSING FACTORS: Incomplete washout of previously prescribed immunosuppressive or immune-modulating medications. PATIENT MANAGEMENT: The ocrelizumab US prescribing information states: - Ocrelizumab and other immune-modulating or immunosuppressive therapies, (including immunosuppressant doses of corticosteroids) are expected to increase the risk of immunosuppression, and the risk of additive immune system effects must be considered if these therapies are coadministered with ocrelizumab. When switching from drugs with prolonged immune effects, such as daclizumab, fingolimod, natalizumab, teriflunomide, or mitoxantrone, the duration and mode of action of these drugs must be considered to avoid unintended additive immunosuppressive effects when initiating ocrelizumab.(1) The ofatumumab US prescribing information states: - Ofatumumab and other immunosuppressive therapies (including systemic corticosteroids) may have the potential for increased immunosuppressive effects and increase the risk of infection. When switching between therapies, the duration and mechanism of action of each therapy should be considered due to the potential for additive immunosuppressive effects. Ofatumumab for MS therapy has not been studied in combination with other MS agents that suppress the immune system.(2) DISCUSSION: Fatal disseminated herpes zoster and herpes simplex infections and cases of progressive multifocal leukoencephalopathy (PML) have been reported in patients who previously received immunomodulators or immunosuppressants.(1,2) In a retrospective cohort study of multiple sclerosis patients newly initiated on a disease-modifying therapy, use of high-efficacy agents (alemtuzumab, natalizumab, or ocrelizumab) resulted in the same risk of overall infections as moderate-efficacy agents, but there was an elevated risk of serious infections (adjusted hazard ratio [aHR] = 1.24, 95% confidence interval (CI) = 1.06-1.44) and UTIs (aHR = 1.21, 95% CI = 1.14-1.30).(3)	KESIMPTA PEN, OCREVUS, OCREVUS ZUNOVO
Pazopanib/Selected Inhibitors of P-gp or BCRP SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of P-glycoprotein (P-gp) or BCRP may increase the absorption of pazopanib.(1) CLINICAL EFFECTS: The concurrent administration of pazopanib with an inhibitor of P-glycoprotein or BCRP may result in elevated levels of pazopanib and signs of toxicity.(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 P-gp inhibitors or BCRP inhibitors should be avoided.(1) Monitor patients for increased side effects from pazopanib. 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: Pazopanib is a substrate of P-gp and BCRP. Inhibitors of these transporters are expected to increase pazopanib levels.(1) BCRP inhibitors linked to this monograph include: asciminib, belumosudil, clopidogrel, cyclosporine, curcumin, darolutamide, eltrombopag, enasidenib, febuxostat, fostemsavir, grazoprevir, lazertinib, leflunomide, leniolisib, momelotinib, oteseconazole, pirtobrutinib, regorafenib, resmetirom, ritonavir, rolapitant, roxadustat, tafamidis, teriflunomide, tolvaptan, turmeric, vadadustat, and zongertinib.(1,3-5) P-glycoprotein inhibitors linked to this monograph include: asunaprevir, belumosudil, capmatinib, carvedilol, cyclosporine, danicopan, daridorexant, diltiazem, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, imlunestrant, isavuconazonium, ivacaftor, ledipasvir, neratinib, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, tezacaftor, ticagrelor, valbenazine, verapamil, vimseltinib, and voclosporin.(3,4)	PAZOPANIB HCL, VOTRIENT
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, deutivacaftor, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, imlunestrant, ivacaftor, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, schisandra, selpercatinib, sotorasib, tepotinib, valbenazine, velpatasvir, vemurafenib, venetoclax, 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, imlunestrant, ivacaftor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tezacaftor, tepotinib, valbenazine, vemurafenib, vimseltinib, and voclosporin.(2)	VENCLEXTA, VENCLEXTA STARTING PACK
Eliglustat/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of eliglustat. If the patient is also taking an inhibitor of CYP2D6, eliglustat metabolism can be further inhibited.(1) CLINICAL EFFECTS: Concurrent use of an agent that is a weak inhibitor of CYP3A4 may result in elevated levels of and clinical effects of eliglustat, including prolongation of the PR, QTc, and/or QRS intervals, which may result in life-threatening cardiac arrhythmias.(1) PREDISPOSING FACTORS: If the patient is also taking an inhibitor of CYP2D6, is a poor metabolizer of CYP2D6, and/or has hepatic impairment, eliglustat metabolism can be further inhibited.(1) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The concurrent use of eliglustat with weak inhibitors of CYP3A4 in poor metabolizers of CYP2D6 should be avoided.(1) The dosage of eliglustat with weak inhibitors of CYP3A4 in extensive metabolizers of CYP2D6 with mild (Child-Pugh Class A) hepatic impairment should be limited to 84 mg daily.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Ketoconazole (400 mg daily), a strong inhibitor of CYP3A4, increased eliglustat (84 mg BID) maximum concentration (Cmax) and area-under-curve (AUC) by 4-fold and 4.4-fold, respectively, in extensive metabolizers. Physiologically-based pharmacokinetic (PKPB) models suggested ketoconazole would increase eliglustat Cmax and AUC by 4.4-fold and 5.4-fold, respectively, in intermediate metabolizers. PKPB models suggested ketoconazole may increase the Cmax and AUC of eliglustat (84 mg daily) by 4.3-fold and 6.2-fold, respectively, in poor metabolizers.(1) PKPB models suggested fluconazole, a moderate inhibitor of CYP3A4, would increase eliglustat Cmax and AUC by 2.8-fold and 3.2-fold, respectively, in extensive metabolizers and by 2.5-fold and 2.9-fold, respectively in intermediate metabolizers. PKPB models suggest that concurrent eliglustat (84 mg BID), paroxetine (a strong inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 16.7-fold and 24.2-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 7.5-fold and 9.8-fold, respectively.(1) PKPB models suggest that concurrent eliglustat (84 mg BID), terbinafine (a moderate inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 10.2-fold and 13.6-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 4.2-fold and 5-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amlodipine, anamorelin, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, vonoprazan, and ziftomenib.(3,4)	CERDELGA
Upadacitinib/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Upadacitinib, immunosuppressives, and immunomodulators all suppress the immune system. CLINICAL EFFECTS: Concurrent use of upadacitinib with immunosuppressives or immunomodulators may result in an increased risk of serious infections. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of upadacitinib states that concurrent use of upadacitinib with immunosuppressives or immunomodulators is not recommended. DISCUSSION: Serious infections have been reported in patients receiving upadacitinib. Reported infections included pneumonia, cellulitis, tuberculosis, multidermatomal herpes zoster, oral/esophageal candidiasis, cryptococcosis. Reports of viral reactivation, including herpes virus reactivation and hepatitis B reactivation, were reported in clinical studies with upadacitinib.(1)	RINVOQ, RINVOQ LQ
Oral Lefamulin/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 (P-gp) may increase the absorption of lefamulin.(1) Oral lefamulin tablets may inhibit the metabolism of P-gp inhibitors that are also sensitive CYP3A4 substrates (i.e., asunaprevir, felodipine, ivacaftor, and neratinib).(1-3) CLINICAL EFFECTS: The concurrent administration of lefamulin with an inhibitor of P-gp may result in elevated levels of lefamulin and signs of toxicity, such as QT prolongation. Coadministration of oral lefamulin with agents that are also sensitive CYP3A4 substrates (i.e., asunaprevir, felodipine, ivacaftor, and neratinib) may result in elevated levels and toxicities of the sensitive CYP3A4 substrate. PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The US manufacturer of lefamulin states that oral lefamulin tablet coadministration with P-gp inhibitors should be avoided.(1) If concomitant therapy with a P-gp inhibitor is necessary, monitor patients closely for prolongation of the QT interval. Obtain serum calcium, magnesium, and potassium levels and monitor ECG at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. Concomitant use of asunaprevir, felodipine, ivacaftor, or neratinib requires close monitoring for adverse effects of these drugs.(1) The manufacturer of venetoclax states that if concurrent use with a P-gp substrate cannot be avoided, take lefamulin at least 6 hours before venetoclax.(5) DISCUSSION: Coadministration of ketoconazole (a strong CYP3A4 and P-gp inhibitor) with lefamulin tablets increased lefamulin area-under-the-curve (AUC) and maximum concentration (Cmax) 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) P-gp inhibitors include: asunaprevir, belumosudil, capmatinib, carvedilol, cimetidine, danicopan, daridorexant, diosmin, flibanserin, fluvoxamine, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, ivacaftor, ledipasvir, neratinib, pirtobrutinib, propafenone, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, valbenazine, venetoclax, vimseltinib, and voclosporin.(1-3)	XENLETA
Inebilizumab/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inebilizumab, immunosuppressives, and immunomodulators all suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of inebilizumab with immunosuppressive or immunomodulating agents may result in myelosuppression including neutropenia resulting in an increased risk for serious infections.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of inebilizumab states that the concurrent use of inebilizumab with immunosuppressive agents, including systemic corticosteroids, may increase the risk of infection. If concurrent therapy is warranted, consider the risk of additive immune suppression and monitor based on prescribing information for both agents.(1) DISCUSSION: Inebilizumab has not been studied in combination with other immunosuppressants. If concurrent therapy is warranted, consider the potential for increased immunosuppressive risks from both agents. The most common infections reported by inebilizumab treated patients in the randomized and open-label clinical trial periods included urinary tract infections (20%), nasopharyngitis (13%), upper respiratory tract infections (8%), and influenza (7%). Although there been no cases of Hepatitis B virus reactivation or progressive multifocal leukoencephalopathy reported in patients taking inebilizumab, these infections have been observed in patients taking other B-cell-depleting antibodies.(1)	UPLIZNA
Baricitinib/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of baricitinib with other biologic disease-modifying antirheumatic drugs (DMARDs) or potent immunosuppressants such as azathioprine or cyclosporine may result in additive or synergistic effects on the immune system. CLINICAL EFFECTS: Concurrent use of baricitinib with other biologic DMARDs or potent immunosuppressants such as azathioprine or cyclosporine may increase the risk of serious infections.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of baricitinib states that concurrent use of baricitinib with biologic DMARDs or potent immunosuppressants is not recommended.(1) DISCUSSION: Most patients who developed serious infections while being treated with baricitinib were on concomitant immunosuppressants like methotrexate and corticosteroids. The combination of baricitinib with other biologic DMARDs has not been studied.(1)	OLUMIANT
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, deutivacaftor, 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, tucatinib, valbenazine, velpatasvir, vemurafenib, venetoclax, verapamil, vimseltinib, and voclosporin.(2,3)	MYFEMBREE, ORGOVYX
Leflunomide; Teriflunomide/Selected Immunosuppressants SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concurrent use of leflunomide or teriflunomide and potent immunosuppressants may result in additive or synergistic effects on the immune system.(1,2) Leflunomide is a prodrug and is converted to its active metabolite teriflunomide.(1) CLINICAL EFFECTS: Concurrent use of leflunomide or teriflunomide with immunosuppressants may result in an increased risk of serious infections, including opportunistic infections, especially Pneumocystis jiroveci pneumonia, tuberculosis (including extra-pulmonary tuberculosis), and aspergillosis. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If leflunomide or teriflunomide is used concurrently with immunosuppressive agents, chronic CBC monitoring should be performed more frequently, every month instead of every 6 to 8 weeks. If bone marrow suppression or a serious infection occurs, leflunomide or teriflunomide should be stopped and rapid drug elimination procedure should be performed.(1,2) DISCUSSION: Pancytopenia, agranulocytosis and thrombocytopenia have been reported in patients receiving leflunomide or teriflunomide alone, but most frequently in patients taking concurrent immunosuppressants.(1,2) Severe and potentially fatal infections, including sepsis, have been reported in patients receiving leflunomide or teriflunomide, especially Pneumocystis jiroveci pneumonia and aspergillosis. Tuberculosis has also been reported.(1,2)	ARAVA, AUBAGIO, LEFLUNICLO, LEFLUNOMIDE, TERIFLUNOMIDE
Ponesimod/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Ponesimod in combination with immunosuppressives and immune-modulators all suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of ponesimod with immunosuppressive or immune-modulating agents may result in an increased risk of serious infections, such as disseminated herpetic infection, cryptococcal infection, or progressive multifocal leukoencephalopathy (PML), an opportunistic infection caused by the JC virus (JCV).(1) PREDISPOSING FACTORS: Incomplete washout of previously prescribed immunosuppressive or immune-modulating medications. PATIENT MANAGEMENT: The ponesimod US prescribing information states ponesimod has not been studied in combination with anti-neoplastic, immune-modulating, or immunosuppressive therapies. Caution should be used during concomitant administration because of the risk of additive immune effects during therapy and in the weeks following administration. When switching from drugs with prolonged immune effects, the half-life and mode of action of these drugs must be considered in order to avoid unintended additive immunosuppressive effects. Initiating treatment with ponesimod after alemtuzumab is not recommended. However, ponesimod can generally be started immediately after discontinuation of beta interferon or glatiramer acetate.(1) DISCUSSION: Fatal disseminated herpes zoster and herpes simplex infections, cryptococcal meningitis, disseminated cryptococcal infections, and cases of progressive multifocal leukoencephalopathy (PML) have been reported in patients who previously received immunomodulators or immunosuppressants.(1)	PONVORY
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
Fingolimod/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Fingolimod in combination with immunosuppressives and immune-modulators all suppress the immune system.(1-3) CLINICAL EFFECTS: Concurrent use of fingolimod with immunosuppressive or immune-modulating agents may result in an increased risk of serious infections, such as disseminated herpetic infection or progressive multifocal leukoencephalopathy (PML), an opportunistic infection caused by the JC virus (JCV).(1-3) PREDISPOSING FACTORS: Incomplete washout of previously prescribed immunosuppressive or immune-modulating medications. PATIENT MANAGEMENT: Recommendations for fingolimod regarding this interaction differ between regulatory approving agencies. The fingolimod US prescribing information states: - Antineoplastic, immune-modulating, or immunosuppressive therapies, (including corticosteroids) are expected to increase the risk of immunosuppression, and the risk of additive immune system effects must be considered if these therapies are coadministered with fingolimod. When switching from drugs with prolonged immune effects, such as natalizumab, teriflunomide or mitoxantrone, the duration and mode of action of these drugs must be considered to avoid unintended additive immunosuppressive effects when initiating fingolimod.(1) The fingolimod Canadian prescribing information states: - Concurrent use with immunosuppressive or immunomodulatory agents is contraindicated due to the risk of additive immune system effects. However, co-administration of a short course of corticosteroids (up to 5 days) did not increase the overall rate of infection in patients participating Phase III clinical trials.(2) The fingolimod UK specific product characteristics states: - Fingolimod is contraindicated in patients currently receiving immunosuppressive therapies or those immunocompromised by prior therapies. When switching patients from another disease modifying therapy to Gilenya, the half-life and mode of action of the other therapy must be considered in order to avoid an additive immune effect whilst at the same time minimizing the risk of disease activation.(3) DISCUSSION: Fatal disseminated herpes zoster and herpes simplex infections and cases of progressive multifocal leukoencephalopathy (PML) have been reported in patients who previously received immunomodulators or immunosuppressants.(1-3)	FINGOLIMOD, GILENYA, TASCENSO ODT
Ozanimod/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Ozanimod in combination with immunosuppressives and immune-modulators all suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of ozanimod with immunosuppressive or immune-modulating agents may result in an increased risk of serious infections, such as disseminated herpetic infection or progressive multifocal leukoencephalopathy (PML), an opportunistic infection caused by the JC virus (JCV).(1) PREDISPOSING FACTORS: Incomplete washout of previously prescribed immunosuppressive or immune-modulating medications. PATIENT MANAGEMENT: The ozanimod US prescribing information state this information regarding this interaction: -Ozanimod has not been studied in combination with anti-neoplastic, immune-modulating, or immunosuppressive therapies. Caution should be used during concomitant administration because of the risk of additive immune effects during therapy and in the week following administration. When switching from drugs with prolonged immune effects, the half-life and mode of action of these drugs must be considered in order to avoid unintended additive immunosuppressive effects. Initiating treatment with ozanimod after alemtuzumab is not recommended. However, ozanimod can generally be started immediately after discontinuation of beta interferon or glatiramer acetate.(1) DISCUSSION: Fatal disseminated herpes zoster and herpes simplex infections and cases of progressive multifocal leukoencephalopathy (PML) have been reported in patients who previously received immunomodulators or immunosuppressants.(1)	ZEPOSIA
Siponimod/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Siponimod in combination with immunosuppressives and immune-modulators all suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of siponimod with immunosuppressive or immune-modulating agents may result in an increased risk of serious infections, such as disseminated herpetic infection or progressive multifocal leukoencephalopathy (PML), an opportunistic infection caused by the JC virus (JCV).(1) PREDISPOSING FACTORS: Incomplete washout of previously prescribed immunosuppressive or immune-modulating medications. PATIENT MANAGEMENT: The siponimod US prescribing information state this information regarding this interaction: -Siponimod has not been studied in combination with anti-neoplastic, immune-modulating, or immunosuppressive therapies. Caution should be used during concomitant administration because of the risk of additive immune effects during therapy and in the week following administration. When switching from drugs with prolonged immune effects, the half-life and mode of action of these drugs must be considered in order to avoid unintended additive immunosuppressive effects. Initiating treatment with siponimod after alemtuzumab is not recommended. However, siponimod can generally be started immediately after discontinuation of beta interferon or glatiramer acetate.(1) DISCUSSION: Fatal disseminated herpes zoster and herpes simplex infections and cases of progressive multifocal leukoencephalopathy (PML) have been reported in patients who previously received immunomodulators or immunosuppressants.(1)	MAYZENT
Cladribine/Selected Inhibitors of BCRP with Myelosuppression SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of BCRP may increase the absorption of cladribine.(1-2) Also, cladribine in combination with immunosuppressives and immune-modulators all suppress the immune system.(1-2) CLINICAL EFFECTS: The concurrent administration of cladribine with an inhibitor of BCRP may result in elevated levels of cladribine and signs of toxicity.(1-2) Concurrent use of cladribine with immunosuppressive or immune-modulating agents may result in an increased risk of serious infections, such as disseminated herpetic infection or progressive multifocal leukoencephalopathy (PML), an opportunistic infection caused by the JC virus (JCV).(1-2) PREDISPOSING FACTORS: Incomplete washout of previously prescribed immunosuppressive or immune-modulating medications. PATIENT MANAGEMENT: The manufacturer of cladribine states concurrent use of BCRP inhibitors should be avoided during the 4- to 5-day cladribine treatment.(1-2) Selection of an alternative concurrent medication with no or minimal transporter inhibiting proprieties should be considered. If this is not possible, dose reduction to the minimum mandatory dose of the BCRP inhibitor, separation in timing of administration, and careful patient monitoring is recommended.(1-2) Myelosuppression risk recommendations for cladribine regarding this interaction differ between regulatory approving agencies. The cladribine US prescribing information states: -Concomitant use with myelosuppressive or other immunosuppressive drugs is not recommended. Acute short-term therapy with corticosteroids can be administered. In patients who have previously been treated with immunomodulatory or immunosuppressive drugs, consider potential additive effect, the mode of action, and duration of effect of the other drugs prior to initiation of cladribine.(1) The cladribine Canadian prescribing information states: -Use of cladribine in immunocompromised patients is contraindicated because of a risk of additive effects on the immune system. Acute short-term therapy with corticosteroids can be administered during cladribine treatment.(2) Monitor for signs of hematologic toxicity. Lymphocyte counts should be monitored. DISCUSSION: Cladribine is a substrate of BCRP. Inhibitors of this transporter are expected to increase cladribine levels.(1-2) BCRP inhibitors linked to this monograph include: asciminib, belumosudil, cyclosporine, encorafenib, leflunomide, leniolisib, momelotinib, pirtobrutinib, and teriflunomide.(1,2) Fatal disseminated herpes zoster and herpes simplex infections and cases of progressive multifocal leukoencephalopathy (PML) have been reported in patients who previously received immunomodulators or immunosuppressants.(1-2)	CLADRIBINE, MAVENCLAD
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, deutivacaftor, diltiazem, diosmin, dronedarone, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo, ginseng, glecaprevir/pibrentasvir, hydroquinidine, imlunestrant, istradefylline, ivacaftor, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, paroxetine, pirtobrutinib, propafenone, quercetin, quinidine, quinine, ranolazine, sarecycline, schisandra, selpercatinib, simeprevir, sofosbuvir/velpatasvir/voxilaprevir, sotorasib, tepotinib, valbenazine, vemurafenib, verapamil, vimseltinib, and voclosporin.(4,5)	ADRIAMYCIN, CAELYX, DOXIL, DOXORUBICIN HCL, DOXORUBICIN HCL LIPOSOME
Pirtobrutinib/Strong CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Strong inhibitors of CYP3A4 may inhibit the metabolism of pirtobrutinib.(1) CLINICAL EFFECTS: Concurrent use of a strong inhibitor of CYP3A4 may result in increased levels of and effects from pirtobrutinib including hemorrhage and cytopenias such as neutropenia, anemia, and thrombocytopenia.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The concurrent use of strong CYP3A4 inhibitors with pirtobrutinib should be avoided. If concurrent use cannot be avoided, reduce the dose of pirtobrutinib by 50 mg. If the current pirtobrutinib dosage is 50 mg once daily, interrupt pirtobrutinib treatment for the duration of strong CYP3A4 inhibitor use.(1) After discontinuation of a strong CYP3A4 inhibitor for 5 half-lives, resume the previous pirtobrutinib dose.(1) DISCUSSION: Co-administration of a single 200 mg dose of pirtobrutinib with itraconazole (a strong CYP3A4 inhibitor) increased area-under-curve (AUC) of pirtobrutinib by 49%.(1) Strong inhibitors of CYP3A4 include: adagrasib, boceprevir, ceritinib, clarithromycin, cobicistat, idelalisib, indinavir, itraconazole, josamycin, ketoconazole, levoketoconazole, lonafarnib, lopinavir, mibefradil, mifepristone, nefazodone, nelfinavir, nirmatrelvir, paritaprevir, posaconazole, ribociclib, saquinavir, telaprevir, telithromycin, tipranavir, troleandomycin, tucatinib, and voriconazole.(2)	APTIVUS, CLARITHROMYCIN, CLARITHROMYCIN ER, EVOTAZ, GENVOYA, ITRACONAZOLE, ITRACONAZOLE MICRONIZED, KALETRA, KETOCONAZOLE, KISQALI, KORLYM, KRAZATI, LANSOPRAZOL-AMOXICIL-CLARITHRO, LOPINAVIR-RITONAVIR, MIFEPREX, MIFEPRISTONE, NEFAZODONE HCL, NOXAFIL, OMECLAMOX-PAK, PAXLOVID, POSACONAZOLE, PREZCOBIX, RECORLEV, SPORANOX, STRIBILD, SYMTUZA, TOLSURA, TUKYSA, TYBOST, VFEND, VFEND IV, VIRACEPT, VOQUEZNA TRIPLE PAK, VORICONAZOLE, VORICONAZOLE (HPBCD), ZOKINVY, ZYDELIG, ZYKADIA
Pirtobrutinib/Strong CYP3A4 Inducers SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Pirtobrutinib is metabolized by CYP3A4. Strong inducers of CYP3A4 may increase the metabolism of pirtobrutinib.(1) CLINICAL EFFECTS: Concurrent use of a strong inducer of CYP3A4 may result in decreased levels and effectiveness of pirtobrutinib.(1) PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. PATIENT MANAGEMENT: Avoid concomitant use of pirtobrutinib with strong CYP3A4 inducers.(1) DISCUSSION: Coadministration of a single 200 mg dose of pirtobrutinib with rifampin (a strong CYP3A inducer) decreased the area-under-curve (AUC) of pirtobrutinib by 71%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3)	ASA-BUTALB-CAFFEINE-CODEINE, ASCOMP WITH CODEINE, BRAFTOVI, BUTALB-ACETAMINOPH-CAFF-CODEIN, BUTALBITAL, BUTALBITAL-ACETAMINOPHEN, BUTALBITAL-ACETAMINOPHEN-CAFFE, BUTALBITAL-ASPIRIN-CAFFEINE, CARBAMAZEPINE, CARBAMAZEPINE ER, CARBATROL, CEREBYX, DILANTIN, DILANTIN-125, DONNATAL, EQUETRO, ERLEADA, FIORICET, 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, TIBSOVO, XTANDI
Pirtobrutinib/Moderate CYP3A4 Inducers SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Pirtobrutinib is metabolized by CYP3A4. Moderate inducers of CYP3A4 may increase the metabolism of pirtobrutinib.(1) CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of pirtobrutinib.(1) PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. PATIENT MANAGEMENT: Avoid concomitant use of pirtobrutinib with moderate CYP3A4 inducers.(1) If concomitant use of moderate CYP3A4 inducers is unavoidable, and the current dose of pirtobrutinib is 200 mg daily, increase the dose to 300 mg daily. If the current pirtobrutinib dosage is 50 mg or 100 mg once daily, increase the dose by 50 mg.(1) DISCUSSION: Efavirenz and bosentan (moderate CYP3A inducers) are predicted to decrease the area-under-curve (AUC) of pirtobrutinib by 49% and 27%, respectively.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, and thioridazine.(2,3)	AUGTYRO, BOSENTAN, CAMZYOS, EFAVIRENZ, EFAVIRENZ-EMTRIC-TENOFOV DISOP, EFAVIRENZ-LAMIVU-TENOFOV DISOP, ETRAVIRINE, INTELENCE, LORBRENA, LUMAKRAS, MODAFINIL, NAFCILLIN, NAFCILLIN SODIUM, ORIAHNN, ORILISSA, PROVIGIL, PYRUKYND, RIFABUTIN, SYMFI, TAFINLAR, TALICIA, THIORIDAZINE HCL, THIORIDAZINE HYDROCHLORIDE, TRACLEER, TURALIO, VONJO, WELIREG, XCOPRI, XERMELO
Ritlecitinib/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Ritlecitinib, immunosuppressives, and immunomodulators all suppress the immune system. CLINICAL EFFECTS: Concurrent use of ritlecitinib with immunosuppressives or immunomodulators may result in an increased risk of serious infections. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of ritlecitinib states that concurrent use of ritlecitinib with other JAK inhibitors, biologic immunomodulators, cyclosporine or other potent immunosuppressants is not recommended.(1) DISCUSSION: Serious infections have been reported in patients receiving ritlecitinib. Reported infections included appendicitis, COVID-19 infection (including pneumonia), and sepsis. Reports of viral reactivation, including herpes virus reactivation was reported in clinical studies with ritlecitinib.(1)	LITFULO
Etrasimod/Immunosuppressive CYP2C8 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Strong and moderate inhibitors of CYP2C8 may impair the CYP2C8-mediated metabolism of etrasimod. Etrasimod is metabolized by CYP2C8, CYP2C9, and CYP3A4.(1) Etrasimod causes reversible sequestration of lymphocytes in lymphoid tissues, resulting in a mean 55% decrease in peripheral blood lymphocyte count at 52 weeks.(1) Other immunosuppressives and immune-modulators also suppress the immune system. CLINICAL EFFECTS: In patients who are poor metabolizers of CYP2C9, concurrent use of a strong or moderate inhibitor of CYP2C8 may result in elevated levels of and clinical effects from etrasimod including immunosuppression, decreased lung function, bradycardia, and AV conduction delays. Concurrent use of etrasimod with immunosuppressive or immune-modulating agents may result in an increased risk of serious and fatal infections, such as disseminated herpetic infection, cryptococcal infection, or progressive multifocal leukoencephalopathy (PML).(1) PREDISPOSING FACTORS: CYP2C9 poor metabolizers (e.g., 2/3, 3/3) may have decreased clearance of etrasimod when etrasimod is used concomitantly with strong or moderate inhibitors of CYP2C8.(1) Incomplete washout of previously prescribed immunosuppressive or immune-modulating medications increases the risk of adverse effects. PATIENT MANAGEMENT: The etrasimod US prescribing information states etrasimod has not been studied in combination with anti-neoplastic, immune-modulating, or immunosuppressive therapies. Concomitant administration of these therapies with etrasimod should be avoided because of the risk of additive immune effects during therapy and in the weeks following administration. Etrasimod's effect on peripheral lymphocytes may persist for up to 5 weeks after discontinuation.(1) When switching from drugs with prolonged immune effects, the half-life and mode of action of these drugs must be considered in order to avoid unintended additive immunosuppressive effects.(1) In addition, concomitant use with strong to moderate CYP2C8 inhibitors in patients who are CYP2C9 poor metabolizers is not recommended.(1) DISCUSSION: Fatal disseminated herpes zoster and herpes simplex infections, cryptococcal meningitis, disseminated cryptococcal infections, and cases of progressive multifocal leukoencephalopathy (PML) have been reported in patients treated with other sphingosine-1 phosphate receptor modulators.(1) CYP2C9 activity is decreased in individuals with genetic variants such as CYP2C92 and CYP2C93 alleles. The impact of CYP2C9 genetic variants on the pharmacokinetics of etrasimod has not been directly evaluated. Increased exposure of etrasimod in patients who are CYP2C9 poor metabolizers is expected with concomitant use of moderate to strong inhibitors of CYP2C8 or CYP3A4.(1) Concomitant use of etrasimod with steady-state fluconazole (a moderate CYP2C9 and CYP3A4 inhibitor) increased etrasimod area-under-curve (AUC) by 84%.(1) Moderate inhibitors of CYP2C8 include: leflunomide, pirtobrutinib, and teriflunomide.(2,3)	VELSIPITY
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) Inhibitors of P-gp linked to this monograph include: abrocitinib, amiodarone, Asian ginseng (Panax ginseng), asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daridorexant, deutivacaftor, diltiazem, diosmin, dronedarone, elagolix, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo biloba, glecaprevir and pibrentasvir, imlunestrant, isavuconazonium, ivacaftor, lapatinib, mavorixafor, milk thistle (Silybum marianum), neratinib, osimertinib, pirtobrutinib, propafenone, quercetin, quinidine, ranolazine, rolapitant, Schisandra chinensis, selpercatinib, sofosbuvir, sotorasib, tepotinib, valbenazine, velpatasvir, vemurafenib, venetoclax, verapamil, vilazodone, vimseltinib, and voclosporin.(8,9)	VINCASAR PFS, VINCRISTINE SULFATE
Ropeginterferon alfa-2b/Slt Immunosuppress; Immunomodulator SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Ropeginterferon alfa-2b and immunosuppressives both suppress the immune system. CLINICAL EFFECTS: Concurrent use of ropeginterferon alfa-2b with immunosuppressives may result in an increased risk of serious infections. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid concurrent use of myelosuppressive agents.(1-2) If concurrent use cannot be avoided, monitor for effects of excessive immunosuppression. DISCUSSION: In clinical trials, 20% of patients experienced leukopenia. Interferon alfa products may cause fatal or life-threatening infections.(1-2)	BESREMI
Deuruxolitinib/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Deuruxolitinib, immunosuppressives, and immunomodulators all suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of deuruxolitinib and potent immunosuppressants may increase the risk of serious infections.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of deuruxolitinib states that concurrent use of deuruxolitinib with other JAK inhibitors, biologic immunomodulators, cyclosporine or other potent immunosuppressants is not recommended.(1) If concurrent use cannot be avoided, patients should be monitored for signs and symptoms of infection. If a patient develops a serious or opportunistic infection, interrupt deuruxolitinib treatment until the infection is controlled. DISCUSSION: Serious infections have been reported in patients receiving treatment with deuruxolitinib.(1)	LEQSELVI
Tovorafenib/Pirtobrutinib SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Moderate inhibitors of CYP2C8 may inhibit the metabolism of tovorafenib.(1) Pirtobrutinib is a moderate CYP2C8 inhibitor.(3) Moderate inducers of CYP3A4 may increase the metabolism of pirtobrutinib.(2) Tovorafenib is a moderate CYP3A4 inducer.(3) CLINICAL EFFECTS: Concomitant use of a moderate CYP2C8 inhibitor may increase tovorafenib plasma concentrations, which may increase the risk of tovorafenib toxicity, including hepatotoxicity, bleeding, and photosensitivity.(1) Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of pirtobrutinib.(2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of tovorafenib recommends avoiding concomitant use of tovorafenib with moderate CYP2C8 inhibitors.(1) The manufacturer of pirtobrutinib recommends avoiding concomitant use of pirtobrutinib with moderate CYP3A4 inducers.(2) If concomitant use of moderate CYP3A4 inducers is unavoidable, and the current dose of pirtobrutinib is 200 mg daily, increase the dose to 300 mg daily. If the current pirtobrutinib dosage is 50 mg or 100 mg once daily, increase the dose by 50 mg.(2) DISCUSSION: No formal interaction studies have been done with tovorafenib and pirtobrutinib. Moderate CYP2C8 inhibitors are predicted to increase tovorafenib exposure.(1) Efavirenz and bosentan (moderate CYP3A inducers) are predicted to decrease the area-under-curve (AUC) of pirtobrutinib by 49% and 27%, respectively.(2)	OJEMDA
Topotecan/BCRP Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of the BCRP transporter may increase the intestinal absorption and hepatic uptake of topotecan.(1) CLINICAL EFFECTS: The concurrent administration of topotecan with an inhibitor of BCRP 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 BCRP 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), a BCRP and P-gp inhibitor, increased the area-under-curve (AUC) of topotecan approximately 2.5-fold.(1) BCRP inhibitors linked to this monograph include: capmatinib, clopidogrel, curcumin, danicopan, dasabuvir, elbasvir, enasidenib, febuxostat, fostamatinib, fostemsavir, glecaprevir, grazoprevir, lazertinib, oteseconazole, pacritinib, pantoprazole, paritaprevir, pibrentasvir, pirtobrutinib, regorafenib, resmetirom, ritonavir, roxadustat, tafamidis, ticagrelor, tolvaptan, turmeric, vadadustat, velpatasvir, voxilaprevir, and zongertinib.(2,3)	HYCAMTIN, TOPOTECAN HCL

There are 23 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, capmatinib, cimetidine, clarithromycin, cyclosporine, daridorexant, danicopan, deutivacaftor, diosmin, flibanserin, fostamatinib, glecaprevir/pibrentasvir, imlunestrant, itraconazole, ivacaftor, josamycin, ketoconazole, lonafarnib, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, sotorasib, tepotinib, tucatinib, valbenazine, vemurafenib, verapamil, vimseltinib, and voclosporin.	ETOPOPHOS, ETOPOSIDE
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
Rivaroxaban/Selected P-gp and Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Amiodarone, azithromycin, brodalumab, chloramphenicol, cimetidine, cyclosporine, felodipine, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, hydroquinidine, ivacaftor, nilotinib, piperine, pirtobrutinib, quinidine, ranolazine, simeprevir, ticagrelor and tolvaptan may inhibit the metabolism of rivaroxaban by CYP3A4 and by P-glycoprotein.(1,2) CLINICAL EFFECTS: Concurrent use of an agent that is both an inhibitor of P-gp and a weak inhibitor of CYP3A4 may result in elevated levels of and clinical effects of rivaroxaban, including an increased risk of bleeding, in patients with decreased renal function.(1,2) PREDISPOSING FACTORS: Patients with decreased renal function (CrCL of 15 ml/min to 80 ml/min) may be predisposed to this interaction.(1) The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). PATIENT MANAGEMENT: The US manufacturer states no precautions are necessary with the concurrent use of these agents and rivaroxaban in patients with normal renal function.(1) It would be prudent to closely monitor concurrent use in patients with reduced renal function (CrCL of 15 ml/min to 80 ml/min). If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. DISCUSSION: Clarithromycin (500 mg twice daily) increased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of rivaroxaban by 50% and 40%, respectively.(1,2) Erythromycin (500 mg three times daily) increased the AUC and Cmax of a single dose of rivaroxaban by 30% and 30%, respectively.(1-3) In patients with mild renal impairment (CrCl of 50 ml/min to 79 ml/min) who were receiving erythromycin, rivaroxaban levels were increased 76% when compared to administration of rivaroxaban in patients with normal renal function receiving rivaroxaban alone. In patients with moderate renal impairment (CrCl of 30 ml/min to 49 ml/min) who were receiving erythromycin, rivaroxaban levels were increased 99% when compared to administration of rivaroxaban in patients with normal renal function receiving rivaroxaban alone.(1) Fluconazole increased the AUC and Cmax of a single dose of rivaroxaban by 40%% and 30%, respectively.(1) These changes are not expected to be clinically significant in patients with normal renal function.(1,2) In a case report, an 88-year-old woman with renal impairment on rivaroxaban presented with an elevated INR of 2.5 and a rivaroxaban peak plasma concentration above the upper limit of detection at >800 mcg/L (therapeutic range 58-211 mcg/L). Nothing in her medical history suggested a reason for supratherapeutic rivaroxaban levels except for a 7-week amiodarone regimen that was discontinued 3 weeks prior. This suggests the potential for amiodarone to persist in the body weeks after its use and precipitate drug-drug interactions.(4) A retrospective cohort study examined 24,943 patients aged 66 years and older with concurrent therapy of an anticoagulant, either rivaroxaban (40.0%), apixaban (31.9%), or dabigatran (28.1%), with either azithromycin or clarithromycin. The primary outcome of hospital admission with major hemorrhage within 30 days on concurrent therapy was higher in patients on clarithromycin (0.77%) compared to azithromycin (0.43%) with an adjusted hazard ratio of 1.71 (95% CI, 1.20-2.45). In a self-controlled case series, 744 major hemorrhage events were identified among 647 unique individuals taking anticoagulants who were exposed to clarithromycin. The rate of events that occurred during clarithromycin use had a significant rate ratio of 1.44 (95% CI, 1.08-1.92).(5) A propensity matched cohort evaluated the concurrent use of combined P-gp and moderate CYP3A4 inhibitors with apixaban or rivaroxaban. Combined inhibitors included amiodarone, diltiazem, erythromycin, dronedarone, and verapamil. Bleeding occurred in 26.4% of patients in the inhibitor group compared to 18.4% in the control group (hazard ratio 1.8; 95% CI 1.19-2.73; p=0.006). Although not statistically significant, patients in the inhibitor group also had a higher rate of major bleeding (15% vs 10.3%) and minor bleeding (8.9% vs 5.2%), respectively.(6) A summary of pharmacokinetic interactions with rivaroxaban and amiodarone concluded that concurrent use should be avoided if CrCl < 80 ml/min.(7) A prospective cohort study of 174 patients evaluated the concurrent use of rivaroxaban and amiodarone. The combination of rivaroxaban and amiodarone was associated with a higher incidence of bleeding events (p=0.041; HR=2.83, 95% CI 1.05-7.66) and clinically relevant non-major bleeding (p=0.021; HR=3.65, 95% CI 1.21-10.94). Concurrent use of amiodarone and rivaroxaban in non-valvular atrial fibrillation patients was an independent risk factor for increased risk of bleeding (p=0.044; OR 2.871, 95% CI 1.028-8.023).(8) P-gp and weak CYP3A4 inhibitors linked to this monograph are: amiodarone, azithromycin, belumosudil, brodalumab, chloramphenicol, cimetidine, cyclosporine, daridorexant, diosmin, flibanserin, fostamatinib, glecaprevir/pibrentasvir, hydroquinidine, istradefylline, ivacaftor, mavorixafor, nilotinib, piperine, pirtobrutinib, quinidine, ranolazine, selpercatinib, simeprevir and tolvaptan.(9,10)	RIVAROXABAN, XARELTO
Citalopram (Less than or Equal To 20 mg)/Selected CYP2C19 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Citalopram is primarily metabolized by the CYP2C19 isoenzyme.(1) CLINICAL EFFECTS: Concurrent use of an agent that inhibits CYP2C19 may result in elevated levels of and toxicity from citalopram, including including risks for serotonin syndrome or prolongation of the QTc interval.(1-5) Prolongation of the QT interval may result in life-threatening arrhythmias, including torsades de pointes.(2) Symptoms of serotonin syndrome may include tremor, agitation, diaphoresis, hyperreflexia, clonus, tachycardia, hyperthermia, and muscle rigidity.(5) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, advanced age, poor metabolizer status at CYP2C19, or higher blood concentrations of citalopram.(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) Predisposing factors for serotonin-related adverse effects include use in the elderly, in patients with hepatic impairment, and in patients receiving multiple agents which increase central serotonin levels.(1,5) 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. PATIENT MANAGEMENT: The dose of citalopram should be limited to 20 mg in patients receiving concurrent therapy with an inhibitor of CYP2C19.(1,4) Evaluate the patient for other drugs, diseases and conditions which increase risk for QT prolongation and correct risk factors (e.g. correct hypokalemia, hypocalcemia, hypomagnesemia, discontinue other QT prolonging drugs) when possible.(1,2) Weigh the specific benefits versus risks for each patient. The US manufacturer recommends ECG monitoring for citalopram patients with congestive heart failure, bradyarrhythmias, taking concomitant QT prolonging medications or receiving concurrent therapy.(4) Citalopram should be discontinued in patients with persistent QTc measurements greater than 500 ms.(2) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If concurrent therapy is warranted, patients should be monitored for signs and symptoms of serotonin syndrome. Instruct patients to report muscle twitching, tremors, shivering and stiffness, fever, heavy sweating, heart palpitations, restlessness, confusion, agitation, trouble with coordination, or severe diarrhea. DISCUSSION: Concurrent use of citalopram (40 mg daily) and cimetidine (400 mg twice daily) for 8 days increased the maximum concentration (Cmax) and area-under-curve (AUC) of citalopram by 39% and 43%, respectively.(1) Inhibitors of CYP2C19 include: abrocitinib, allicin (garlic derivative), berotralstat, cannabidiol (CBD), cenobamate, cimetidine strengths > or = 200 mg, enasidenib, eslicarbazepine, esomeprazole, etravirine, fedratinib, felbamate, fluoxetine, fluvoxamine, givosiran, isoniazid, moclobemide, modafinil, obeticholic acid, omeprazole, piperine, rolapitant, stiripentol, and tecovirimat.(7,8)	CELEXA, CITALOPRAM HBR
Escitalopram (Greater Than 15 mg)/Selected CYP2C19 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: At lower systemic concentrations, escitalopram is primarily metabolized by CYP2C19; at higher concentrations is also metabolized by CYP3A4.(1) CLINICAL EFFECTS: Concurrent use of an agent which significantly inhibits CYP2C19, or which inhibits both CYP2C19 and CYP3A4 may result in elevated concentrations and toxicity from escitalopram, including risks for serotonin syndrome or prolongation of the QTc interval.(1,5) Prolongation of the QT interval may result in life-threatening arrhythmias, including torsades de pointes.(2) Symptoms of serotonin syndrome may include tremor, agitation, diaphoresis, hyperreflexia, clonus, tachycardia, hyperthermia, and muscle rigidity.(3) PREDISPOSING FACTORS: The risk of QT prolongation may be increased in patients with congenital long QT syndrome, cardiovascular disease (e.g. heart failure, myocardial infarction), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female sex, advanced age, poor metabolizer status at CYP2C19, concurrent use of more than one agent known to cause QT prolongation, or with higher blood concentrations of escitalopram.(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) Predisposing factors for serotonin-related adverse effects include use in the elderly, in patients with hepatic impairment, and in patients receiving multiple agents which increase central serotonin levels.(1,3) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. PATIENT MANAGEMENT: Evaluate patient for other drugs, diseases and conditions which may further increase risk for QT prolongation and correct risk factors (e.g. correct hypokalemia, discontinue other QT prolonging drugs) when possible.(2,3) It would be prudent to limit the escitalopram dose to 10 mg daily in patients with QT prolonging risk factors who also receive concurrent therapy with selected CYP2C19 inhibitors.(5) Weigh the specific benefits versus risks for each patient. If concurrent therapy is warranted, patients should be monitored for signs and symptoms of serotonin syndrome. Instruct patients to report muscle twitching, tremors, shivering and stiffness, fever, heavy sweating, heart palpitations, restlessness, confusion, agitation, trouble with coordination, or severe diarrhea. DISCUSSION: A thorough QT study evaluating escitalopram 10 mg or 30 mg once daily was conducted; a change of 10 msec for upper bound of the 95% confidence level is the threshold for regulatory concern. In this study, changes to the upper bound of the 95% confidence interval were 6.4 msec and 12.6 msec for the 10 mg and supratherapeutic 30 mg dose respectively. The Cmax for 30 mg was 1.7-fold higher than the Cmax for the maximum recommended escitalopram dose of 20 mg. Systemic exposure at the 30 mg dose was similar to expected steady state concentrations in 2C19 poor metabolizers following a 20 mg escitalopram dose.(1) In an interaction study, 30 mg of omeprazole, an irreversible inhibitor of CYP2C19 was administered daily for 6 days. On day 5 a single dose of escitalopram 20 mg was also administered; the area-under-curve (AUC) of escitalopram was increased by 50%. Manufacturer prescribing information recommends a maximum citalopram dose of 20mg daily in patients receiving CYP2C19 inhibitors.(1) Inhibitors of CYP2C19 include: abrocitinib, allicin (garlic derivative), berotralstat, cannabidiol (CBD), cenobamate, cimetidine strengths > or = 200 mg, enasidenib, eslicarbazepine, esomeprazole, etravirine, fedratinib, felbamate, fluoxetine, fluvoxamine, givosiran, isoniazid, moclobemide, modafinil, obeticholic acid, omeprazole, piperine, rolapitant, stiripentol, tecovirimat, and tipranavir.(4)	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, imlunestrant, indinavir, oral itraconazole, ivacaftor, josamycin, ledipasvir, lonafarnib, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, selpercatinib, sotorasib, telaprevir, telithromycin, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(8)	SAVAYSA
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, imlunestrant, indinavir, oral itraconazole, ivacaftor, josamycin, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, selpercatinib, sotorasib, telaprevir, telithromycin, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(8)	SAVAYSA
Escitalopram (Less Than or Equal To 15 mg)/Selected CYP2C19 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: At lower systemic concentrations, escitalopram is primarily metabolized by CYP2C19; at higher concentrations is also metabolized by CYP3A4.(1) CLINICAL EFFECTS: Concurrent use of an agent which significantly inhibits CYP2C19, or which inhibits both CYP2C19 and CYP3A4 may result in elevated concentrations and toxicity from escitalopram, including risks for serotonin syndrome or prolongation of the QTc interval.(1,5) Prolongation of the QT interval may result in life-threatening arrhythmias, including torsades de pointes.(2) Symptoms of serotonin syndrome may include tremor, agitation, diaphoresis, hyperreflexia, clonus, tachycardia, hyperthermia, and muscle rigidity.(3) PREDISPOSING FACTORS: The risk of QT prolongation may be increased in patients with congenital long QT syndrome, cardiovascular disease (e.g. heart failure, myocardial infarction), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female sex, advanced age, poor metabolizer status at CYP2C19, concurrent use of more than one agent known to cause QT prolongation, or with higher blood concentrations of escitalopram.(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) Predisposing factors for serotonin-related adverse effects include use in the elderly, in patients with hepatic impairment, and in patients receiving multiple agents which increase central serotonin levels.(1,3) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. PATIENT MANAGEMENT: Evaluate patient for other drugs, diseases and conditions which may further increase risk for QT prolongation and correct risk factors (e.g. correct hypokalemia, discontinue other QT prolonging drugs) when possible.(2,3) It would be prudent to limit the escitalopram dose to 10 mg daily in patients with QT prolonging risk factors who also receive concurrent therapy with selected CYP2C19 inhibitors.(5) Weigh the specific benefits versus risks for each patient. If concurrent therapy is warranted, patients should be monitored for signs and symptoms of serotonin syndrome. Instruct patients to report muscle twitching, tremors, shivering and stiffness, fever, heavy sweating, heart palpitations, restlessness, confusion, agitation, trouble with coordination, or severe diarrhea. DISCUSSION: A thorough QT study evaluating escitalopram 10 mg or 30 mg once daily was conducted; a change of 10 msec for upper bound of the 95% confidence level is the threshold for regulatory concern. In this study, changes to the upper bound of the 95% confidence interval were 6.4 msec and 12.6 msec for the 10 mg and supratherapeutic 30 mg dose respectively. The Cmax for 30 mg was 1.7-fold higher than the Cmax for the maximum recommended escitalopram dose of 20 mg. Systemic exposure at the 30 mg dose was similar to expected steady state concentrations in 2C19 poor metabolizers following a 20 mg escitalopram dose.(1) In an interaction study, 30 mg of omeprazole, an irreversible inhibitor of CYP2C19 was administered daily for 6 days. On day 5 a single dose of escitalopram 20 mg was also administered; the area-under-curve (AUC) of escitalopram was increased by 50%. Manufacturer prescribing information recommends a maximum citalopram dose of 20mg daily in patients receiving CYP2C19 inhibitors.(1) Inhibitors of CYP2C19 include: abrocitinib, allicin (garlic derivative), berotralstat, cannabidiol (CBD), cenobamate, cimetidine strengths > or = 200 mg, enasidenib, eslicarbazepine, esomeprazole, etravirine, fedratinib, felbamate, fluoxetine, fluvoxamine, givosiran, isoniazid, moclobemide, modafinil, obeticholic acid, omeprazole, piperine, rolapitant, stiripentol, tecovirimat, and tipranavir.(4)	ESCITALOPRAM OXALATE, LEXAPRO
Tacrolimus/Moderate and Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate and weak inhibitors of CYP3A4 may inhibit the metabolism of tacrolimus.(1) CLINICAL EFFECTS: Concurrent use of a CYP3A4 inhibitor may result in elevated levels of and toxicity from tacrolimus, including nephrotoxicity, neurotoxicity, and prolongation of the QTc interval and life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of tacrolimus recommends monitoring tacrolimus whole blood trough concentrations and reducing tacrolimus dose if needed.(1) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a study of 26 renal transplant recipients, conjugated estrogens 3.75 mg daily increased the tacrolimus dose-corrected concentration of tacrolimus by 85.6%. Discontinuation of the conjugated estrogens led to a decrease in tacrolimus concentration of 46.6%.(3) A case report describes a 65-year-old kidney transplant recipient who was stable on tacrolimus 9 mg per day with trough levels of 5 to 7.5 ng/mL. Ten days after starting on estradiol gel 0.5 mg per day, her tacrolimus level rose to 18.3 ng/mL and serum creatinine (Scr) rose from 1.1 mg/dL at baseline to 2 mg/dL. Tacrolimus dose was reduced by 60%, and trough levels and Scr normalized after two weeks.(4) A study of 16 healthy volunteers found that elbasvir 50 mg/grazoprevir 200 mg daily increased the area-under-curve (AUC) of tacrolimus by 43%, while the maximum concentration (Cmax) of tacrolimus was decreased by 40%.(5) An analysis of FAERS data from 2004-2017, found a significant association between transplant rejection and concurrent use of tacrolimus and clotrimazole (reporting odds ratio 1.92, 95% CI). A retrospective study of 7 heart transplant patients on concurrent tacrolimus and clotrimazole troche showed a significant correlation between tacrolimus trough concentration and AUC after clotrimazole discontinuation. Tacrolimus clearance and bioavailability after clotrimazole discontinuation was 2.2-fold greater (0.27 vs. 0.59 L/h/kg) and the trough concentration decreased from 6.5 ng/mL at 1 day to 5.3 ng/mL at 2 days after clotrimazole discontinuation.(7) A retrospective study of 26 heart transplant patients found that discontinuation of concurrent clotrimazole with tacrolimus in the CYP3A5 expresser group had a 3.3-fold increase in apparent oral clearance and AUC of tacrolimus (0.27 vs. 0.89 L/h/kg) compared to the CYP3A5 non expresser group with a 2.2-fold mean increase (0.18 vs. 0.39 L/h/kg).(8) A study of 6 adult kidney transplant recipients found that clotrimazole (5-day course) increased the tacrolimus AUC 250% and the blood trough concentrations doubled (27.7 ng/ml versus 27.4 ng/ml). Tacrolimus clearance decreased 60% with coadministration of clotrimazole.(9) A case report describes a 23-year-old kidney transplant recipient who was stable on tacrolimus 5 mg twice daily, mycophenolate mofetil 30 mg daily, prednisone (30 mg daily tapered over time to 5 mg), and clotrimazole troche 10 mg four times daily. Discontinuation of clotrimazole resulted in a decrease in tacrolimus trough levels from 13.7 ng/ml to 5.4 ng/ml over a period of 6 days. Clotrimazole was restarted with tacrolimus 6 mg resulting in an increased tacrolimus level of 19.2 ng/ml.(10) A retrospective study in 95 heart transplant recipients on concurrent clotrimazole and tacrolimus found a median tacrolimus dose increase of 66.7% was required after clotrimazole discontinuation. Tacrolimus trough concentration was found to have decreased 42.5% after clotrimazole discontinuation.(11) A retrospective study in 65 pancreas transplant patients on concurrent tacrolimus, clotrimazole, cyclosporine, and prednisone found that clotrimazole discontinuation at 3 months after transplantation may cause significant tacrolimus trough level reductions.(12) A case report describes a 6-year-old kidney transplant recipient who was on a regimen of tacrolimus and mycophenolate mofetil. The patient was started letermovir 240 mg via G-tube 2 months post kidney transplant. One week after starting letermovir, the routine tacrolimus level showed a supratherapeutic concentration of 22.9 ng/L. A 36% dose reduction of tacrolimus was required. Upon discontinuation of letermovir, the tacrolimus level decreased by 42%.(13) Moderate CYP3A4 inhibitors linked to this monograph include: aprepitant, berotralstat, conivaptan, fluvoxamine, lenacapavir, letermovir, netupitant, nirogacestat, sevabertinib, stiripentol, and tofisopam.(6) Weak CYP3A4 inhibitors linked to this monograph include: alprazolam, avacopan, baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, chlorzoxazone, cimetidine, cranberry juice, daclatasvir, daridorexant, delavirdine, diosmin, elinzanetant, estrogens, flibanserin, fosaprepitant, fostamatinib, ginkgo biloba, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lazertinib, linagliptin, lomitapide, lumateperone, lurasidone, peppermint oil, piperine, propiverine, ranitidine, remdesivir, resveratrol, rimegepant, simeprevir, sitaxsentan, skullcap, suvorexant, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan-amoxicillin.(6)	ASTAGRAF XL, ENVARSUS XR, PROGRAF, TACROLIMUS, TACROLIMUS XL
Lemborexant (Less Than or Equal To 5 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of CYP3A4 may inhibit the metabolism of lemborexant.(1) CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP3A4 may result in increased levels of and effects from lemborexant, including somnolence, fatigue, CNS depressant effects, daytime impairment, headache, and nightmare or abnormal dreams.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The maximum recommended dose of lemborexant with concurrent use of a weak CYP3A4 inhibitors should not exceed 5 mg per dose.(1) DISCUSSION: Lemborexant is a CYP3A4 substrate. In a PKPB model, concurrent use of lemborexant with itraconazole increased area-under-curve (AUC) and concentration maximum (Cmax) by 3.75-fold and 1.5-fold, respectively. Concurrent use of lemborexant with fluconazole increased AUC and Cmax by 4.25-fold and 1.75-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, anamorelin, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, vonoprazan, and ziftomenib.(1,2)	DAYVIGO
Ubrogepant (Less Than or Equal To 50 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of ubrogepant.(1) CLINICAL EFFECTS: Concurrent use of ubrogepant with weak CYP3A4 inhibitors may result in an increase in exposure of ubrogepant.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when used concomitantly with weak CYP3A4 inhibitors. Initial dose of ubrogepant should not exceed 50 mg when used concomitantly with weak inhibitors of CYP3A4. A second dose may be given within 24 hours but should not exceed 50 mg when used concurrently with weak CYP3A4 inhibitors.(1) DISCUSSION: Coadministration of ubrogepant with verapamil, a moderate CYP3A4 inhibitor, resulted in a 3.5-fold and 2.8-fold increase in area-under-curve (AUC) and concentration maximum (Cmax), respectively. No dedicated drug interaction study was conducted to assess concomitant use with weak CYP3A4 inhibitors. The conservative prediction of the maximal potential increase in ubrogepant exposure with weak CYP3A4 inhibitors is not expected to be more than 2-fold.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, anamorelin, asciminib, azithromycin, Baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, delavirdine, deutivacaftor, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, maribavir, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, pirtobrutinib, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, vonoprazan, and ziftomenib.(2,3)	UBRELVY
Ustekinumab/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Ustekinumab, immunosuppressives, and immunomodulators all suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of ustekinumab with immunosuppressive or immunomodulating agents may result in an increased risk for serious infections.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of ustekinumab recommends caution because the concurrent use of ustekinumab with immunosuppressive agents may increase the risk of infection. If concurrent therapy is warranted, consider the risk of additive immune suppression and monitor based on prescribing information for both agents.(1) DISCUSSION: Ustekinumab has not been studied in combination with other immunosuppressants in psoriasis studies. In psoriatic arthritis studies, concomitant methotrexate use did not appear to influence the safety or efficacy of ustekinumab. In Crohn's disease and ulcerative colitis studies, concomitant use of immunosuppressants or corticosteroids did not appear to influence the safety or efficacy of ustekinumab. If concurrent therapy is warranted, consider the potential for increased immunosuppressive risks from both agents.(1) The most common infections reported by ustekinumab treated patients in the clinical trial periods included nasopharyngitis(8%) and upper respiratory tract infection(5%). Serious bacterial, mycobacterial, fungal, and viral infections were observed in patients receiving ustekinumab. Cases of interstitial pneumonia, eosinophilic pneumonia, and cryptogenic organizing pneumonia resulting in respiratory failure or prolonged hospitalization have been reported in patients receiving ustekinumab.(1)	IMULDOSA, OTULFI, PYZCHIVA, PYZCHIVA AUTOINJECTOR, SELARSDI, STARJEMZA, STELARA, STEQEYMA, USTEKINUMAB, USTEKINUMAB-AAUZ, USTEKINUMAB-AEKN, USTEKINUMAB-TTWE, WEZLANA, YESINTEK
COVID-19 Vaccines/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Immunosuppressants and immunomodulators may prevent the immune system from properly responding to the COVID-19 vaccine.(1,2) CLINICAL EFFECTS: Administration of a COVID-19 vaccine with immunosuppressants or immunomodulators may interfere with vaccine-induced immune response and impair the efficacy of the vaccine. However, patients should be offered and given a COVID-19 vaccine even if the use and timing of immunosuppressive agents cannot be adjusted.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: In an effort to optimize COVID-19 vaccine response, the American College of Rheumatology (ACR) published conditional recommendations for administration of COVID-19 vaccines with immunosuppressants and immunomodulators.(1) The CDC also provides clinical considerations for COVID-19 vaccination in patients on immunosuppressants.(2) The CDC states that all immunocompromised patients over 6 months of age should receive at least 1 dose of COVID-19 vaccine if eligible. See the CDC's Interim Clinical Considerations for Use of COVID-19 Vaccines for specific recommendations based on age, vaccination history, and vaccine manufacturer.(2) The ACR states that in general, immunosuppressants and immunomodulators should be held for 1-2 weeks after each vaccine dose. See below for specific recommendations for certain agents.(1) The CDC advises planning for vaccination at least 2 weeks before starting or resuming immunosuppressive therapy.(2) Patients should be offered and given a COVID-19 vaccine even if the use and timing of immunosuppressive agents cannot be adjusted.(1,2) B-cell depleting agents, including rituximab: The ACR recommends consulting with the rheumatologist to determine optimal timing of COVID-19 vaccination. Measuring CD19 B cells may be considered to determine need for a booster vaccine dose. If B cell levels are not measured, a supplemental vaccine dose 2-4 weeks before the next scheduled dose of rituximab is recommended.(1) The CDC states that the utility of B-cell quantification to guide clinical care is not known and is not recommended. Patients who receive B-cell depleting therapy should receive COVID-19 vaccines about 4 weeks before the next scheduled dose. For patients who received 1 or more doses of COVID-19 vaccine during treatment with B-cell-depleting therapies that were administered over a limited period (e.g., as part of a treatment regimen for certain malignancies), revaccination may be considered. The suggested interval to start revaccination is about 6 months after completion of the B-cell-depleting therapy.(2) Abatacept: - Subcutaneous abatacept should be withheld for 1-2 weeks after each vaccine dose, as disease activity allows. - For intravenous abatacept, time administration so that vaccination will occur 1 week before the next abatacept infusion.(1) Cyclophosphamide: When feasible, administer cyclophosphamide one week after each COVID-19 vaccine dose.(1) Recipients of hematopoietic cell transplant or CAR-T-cell therapy who received one or more doses of COVID-19 vaccine prior to or during treatment should undergo revaccination following the current CDC recommendations for unvaccinated patients. Revaccination should start at least 3 months (12 weeks) after transplant or CAR-T-cell therapy.(2) TNF-alpha inhibitors and cytokine inhibitors: The ACR was not able to reach consensus on whether to modify dosing or timing of these agents with COVID-19 vaccination.(1) The CDC includes these agents in their general recommendation to hold therapy for at least 2 weeks following vaccination.(2) DISCUSSION: The ACR convened a COVID-19 Vaccine Guidance Task Force to provide guidance on optimal use of COVID-19 vaccines in rheumatology patients. These recommendations are based on limited clinical evidence of COVID-19 vaccines in patients without rheumatic and musculoskeletal disorders and evidence of other vaccines in this patient population.(1) The ACR recommendation for rituximab is based on studies of humoral immunity following receipt of other vaccines. These studies have uncertain generalizability to vaccination against COVID-19, as it is unknown if efficacy is attributable to induction of host T cells versus B cell (antibody-based) immunity.(1) The ACR recommendation for mycophenolate is based on preexisting data of mycophenolate on non-COVID-19 vaccine immunogenicity. Emerging data suggests that mycophenolate may impair SARS-CoV-2 vaccine response in rheumatic and musculoskeletal disease and transplant patients.(1) The ACR recommendation for methotrexate is based on data from influenza vaccines and pneumococcal vaccines with methotrexate.(1) The ACR recommendation for JAK inhibitors is based on concerns related to the effects of JAK inhibitors on interferon signaling that may result in a diminished vaccine response.(1) The ACR recommendation for subcutaneous abatacept is based on several studies suggesting a negative effect of abatacept on vaccine immunogenicity. The first vaccine dose primes naive T cells, naive T cell priming is inhibited by CTLA-4, and abatacept is a CTLA-4Ig construct. CTLA-4 should not inhibit boosts of already primed T cells at the time of the second vaccine dose.(1)	COMIRNATY 2025-2026 (12Y UP), COMIRNATY 2025-2026(5-11Y), MNEXSPIKE 2025-2026 (12Y UP), NUVAXOVID 2025-2026, SPIKEVAX 2025-2026 (12Y UP), SPIKEVAX 2025-2026 (6M-11Y)
Rimegepant/P-gp Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. 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, imlunestrant, lapatinib, mavorixafor, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, vemurafenib, vimseltinib, and verapamil.(1-3)	NURTEC ODT
Sirolimus Protein-Bound/Slt Moderate and Weak CYP3A4 Inhibit SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate and weak CYP3A4 inhibitors may inhibit the metabolism of sirolimus by CYP3A4.(1) CLINICAL EFFECTS: Concurrent use of moderate or weak CYP3A4 inhibitors may result in elevated levels of and side effects from sirolimus.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of sirolimus protein-bound injection (Fyarro) states a dose reduction to 56 mg/m2 is recommended when used concurrently with moderate or weak CYP3A4 inhibitors. Concurrent use with strong CYP3A4 inhibitors should be avoided.(1) DISCUSSION: In an open, randomized, cross-over trial in 18 healthy subjects, concurrent single doses of diltiazem (120 mg) and sirolimus (10 mg) increased sirolimus area-under-curve (AUC) and maximum concentration (Cmax) by 60% and by 43%, respectively. Sirolimus apparent oral clearance and volume of distribution decreased by 38% and 45%, respectively. There were no effects on diltiazem pharmacokinetics or pharmacodynamics.(2) In a study in 26 healthy subjects, concurrent sirolimus (2 mg daily) with verapamil (180 mg twice daily) increased sirolimus AUC and Cmax by 2.2-fold and 2.3-fold, respectively. The AUC and Cmax of the active S-enantiomer of verapamil each increased by 1.5-fold. Verapamil time to Cmax (Tmax) was increased by 1.2 hours.(2) Moderate and weak CYP3A4 inhibitors linked to this monograph include: alprazolam, amlodipine, anamorelin, aprepitant, avacopan, azithromycin, berberine, berotralstat, bicalutamide, blueberry, brodalumab, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clofazimine, conivaptan, daclatasvir, daridorexant, delavirdine, diosmin, elinzanetant, entrectinib, erythromycin, estrogen, flibanserin, fluvoxamine, fosaprepitant, fosnetupitant, fostamatinib, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lazertinib, lenacapavir, levamlodipine, linagliptin, lomitapide, lumateperone, lurasidone, mavorixafor, netupitant, omeprazole, osilodrostat, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, rimegepant, roxithromycin, scutellarin, sevabertinib, simeprevir, sitaxsentan, stiripentol, suvorexant, ticagrelor, tofisopam, tolvaptan, trofinetide, and vonoprazan.(3,4)	FYARRO
Sarilumab/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Sarilumab, immunosuppressives, and immunomodulators all suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of sarilumab with immunosuppressive or immunomodulating agents may result in an increased risk for serious infections.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of sarilumab recommends caution because the concurrent use of sarilumab with immunosuppressive agents may increase the risk of infection. If concurrent therapy is warranted, consider the risk of additive immune suppression and monitor based on prescribing information for both agents.(1) DISCUSSION: Sarilumab was studied as monotherapy and in combination with methotrexate or conventional disease modifying antirheumatic drugs (DMARDs) in rheumatoid arthritis studies. Sarilumab has not been studied with biological DMARDs and concurrent use should be avoided. If concurrent therapy is warranted, consider the potential for increased immunosuppressive risks from both agents.(1) The most common infections reported by sarilumab treated patients in the clinical trial periods included pneumonia and cellulitis. Serious bacterial, mycobacterial, fungal, and viral infections were observed in patients receiving sarilumab. Cases of tuberculosis, candidiasis, and pneumocystis with sarilumab have been reported.(1)	KEVZARA
Ublituximab/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Ublituximab, immunosuppressives, and immunomodulators all suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of ublituximab with immunosuppressive or immunomodulating agents may result in an increased risk for serious infections.(1) PREDISPOSING FACTORS: Incomplete washout of previously prescribed immunosuppressive or immune-modulating medications. PATIENT MANAGEMENT: The US manufacturer of ublituximab recommends caution because the concurrent use of ublituximab with immunomodulating or immunosuppressive agents, including immunosuppressant doses of corticosteroids, may increase the risk of infection.(1) If concurrent therapy is warranted, consider the risk of additive immune suppression and monitor based on prescribing information for both agents. When switching from agents with immune effects, the half-life and mechanism of action of these drugs must be taken into consideration in order to prevent additive immunosuppressive effects.(1) DISCUSSION: The most common infections reported by ublituximab-treated patients in the clinical trial periods included upper respiratory tract infections and urinary tract infections. Serious, including life-threatening or fatal, bacterial and viral infections were observed in patients receiving ublituximab.(1) Serious and/or fatal bacterial, fungal, and new or reactivated viral infections have been associated with other anti-CD20 B-cell depleting therapies. There were no cases of progressive multifocal leukoencephalopathy (PML) reported during the clinical trials; however, there have been reports of PML during or following completion of other anti-CD20 B-cell depleting therapies.(1)	BRIUMVI
Digoxin/Pirtobrutinib SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Pirtobrutinib may increase the absorption of digoxin by inhibiting P-glycoprotein (P-gp).(1) CLINICAL EFFECTS: Concurrent use of pirtobrutinib 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 pirtobrutinib. 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: A single 200 mg dose of pirtobrutinib increased the area-under-curve (AUC) and maximum concentration (Cmax) of digoxin (sensitive P-gp substrate) by 17% and 51%, respectively. Multiple doses of pirtobrutinib (200 mg daily) further increased the AUC and Cmax of digoxin (sensitive P-gp substrate) up to 35% and 55%, respectively.(1)	DIGITEK, DIGOXIN, DIGOXIN MICRONIZED, LANOXIN
Rosuvastatin/Pirtobrutinib SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Rosuvastatin is a substrate of the BCRP transporter.(1,2) Pirtobrutinib has been shown to inhibit this transporter and may increase intestinal absorption and hepatic uptake of rosuvastatin.(1-3) CLINICAL EFFECTS: Simultaneous use of pirtobrutinib may result in increased levels and side effects from rosuvastatin, including rhabdomyolysis.(1,2) PREDISPOSING FACTORS: The risk for myopathy or rhabdomyolysis may be greater in patients 65 years and older, inadequately treated hypothyroidism, renal impairment, carnitine deficiency, malignant hyperthermia, or in patients with a history of myopathy or rhabdomyolysis. Patients with a SLCO1B1 polymorphism that leads to decreased function of the hepatic uptake transporter OATP1B1 may have increased statin concentrations and be predisposed to myopathy or rhabdomyolysis. Patients on rosuvastatin with ABCG2 polymorphisms leading to decreased or poor BCRP transporter function may have increased rosuvastatin concentrations and risk of myopathy. PATIENT MANAGEMENT: Concurrent use may result in increased risk of side effects associated with rosuvastatin. If concurrent therapy is warranted, close monitoring would be prudent for statin related side effects including rhabdomyolysis. Educate the patient on signs and symptoms of rhabdomyolysis. DISCUSSION: In a clinical study of healthy subjects, pirtobrutinib (multiple doses of 200 mg daily) increased the area-under-curve (AUC) and concentration maximum (Cmax) of rosuvastatin by 140% and 146%, respectively.(3)	CRESTOR, EZALLOR SPRINKLE, ROSUVASTATIN CALCIUM, ROSUVASTATIN-EZETIMIBE, ROSZET
Tocilizumab/Immunosuppressives; Immunomodulators SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Tocilizumab, immunosuppressives, and immunomodulators all suppress the immune system.(1) CLINICAL EFFECTS: Concurrent use of tocilizumab with immunosuppressive or immunomodulating agents may result in an increased risk for serious infections.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of tocilizumab recommends caution because the concurrent use of tocilizumab with immunosuppressive agents may increase the risk of infection. If concurrent therapy is warranted, consider the risk of additive immune suppression and monitor based on prescribing information for both agents.(1) DISCUSSION: Tocilizumab was studied as monotherapy and in combination with methotrexate, non-biologic DMARDs or corticosteroids, depending on the indication. Tocilizumab has not been studied with biological DMARDs and concurrent use should be avoided. If concurrent therapy is warranted, consider the potential for increased immunosuppressive risks from both agents.(1) The most common infections reported by tocilizumab treated patients in the clinical trial periods included pneumonia, urinary tract infection, cellulitis, herpes zoster, gastroenteritis, diverticulitis, sepsis and bacterial arthritis. Serious bacterial, mycobacterial, fungal, and viral infections were observed in patients receiving tocilizumab. Cases of tuberculosis, cryptococcus, aspergillosis, candidiasis, and pneumocystosis have been reported.(1)	ACTEMRA, ACTEMRA ACTPEN, AVTOZMA, TOFIDENCE, TYENNE, TYENNE AUTOINJECTOR
Resmetirom/Moderate CYP2C8 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate inhibitors of CYP2C8 may inhibit the metabolism of resmetirom.(1) CLINICAL EFFECTS: Concomitant use of a moderate CYP2C8 inhibitor may increase resmetirom plasma concentrations, which may increase the risk of resmetirom toxicity, including hepatotoxicity.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Concomitant use of resmetirom with moderate CYP2C8 inhibitors is not recommended. If concurrent use is warranted, reduce the dose of resmetirom based on the patient's weight. -If <100 kg, reduce the dose of resmetirom to 60 mg once daily; -If >=100 kg, reduce the dose of resmetirom to 80 mg once daily.(1) DISCUSSION: Multiple doses of resmetirom 100 mg daily were given with clopidogrel, a moderate CYP2C8 inhibitor, and the resmetirom area-under-curve (AUC) and maximum concentration (Cmax) increased 1.7-fold and 1.3-fold, respectively.(1) Moderate CYP2C8 inhibitors linked to this monograph include: clopidogrel, deferasirox, leflunomide, mifepristone (chronic therapy), pirtobrutinib, selpercatinib, and teriflunomide.(2)	REZDIFFRA
Mavorixafor/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Mavorixafor is a substrate of the P-glycoprotein (P-gp) transporter. P-gp inhibitors may significantly increase the absorption of mavorixafor.(1) CLINICAL EFFECTS: Concurrent administration of mavorixafor with an inhibitor of P-glycoprotein may result in elevated levels of and effects from mavorixafor, including potentially life-threatening cardiac arrhythmias, 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 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 mavorixafor.(4) 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. DISCUSSION: 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.(1) P-glycoprotein inhibitors linked to this monograph include: abrocitinib, Asian ginseng, asunaprevir, capmatinib, carvedilol, cyclosporine, danicopan, daridorexant, deutivacaftor, diosmin, elagolix, flibanserin, fostamatinib, ginkgo biloba, glecaprevir/pibrentasvir, ivacaftor, milk thistle, neratinib, pirtobrutinib, quercetin, rolapitant, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, velpatasvir, vilazodone, vimseltinib, and voclosporin.(1,4-6)	XOLREMDI
Atorvastatin/Selected BCRP Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Atorvastatin is a substrate of the BCRP transporter.(1) Inhibitors of this transporter may increase intestinal absorption and hepatic uptake of BCRP substrates atorvastatin.(1) CLINICAL EFFECTS: Administration of atorvastatin with BCRP inhibitors may result in elevated levels of atorvastatin, which could result in rhabdomyolysis.(1) PREDISPOSING FACTORS: The risk for myopathy or rhabdomyolysis may be greater in patients 65 years and older, inadequately treated hypothyroidism, renal impairment, carnitine deficiency, malignant hyperthermia, or in patients with a history of myopathy or rhabdomyolysis. Patients with a SLCO1B1 polymorphism that leads to decreased function of the hepatic uptake transporter OATP1B1 may have increased statin concentrations and be predisposed to myopathy or rhabdomyolysis. PATIENT MANAGEMENT: Concurrent use of atorvastatin with BCRP inhibitors may result in increased risk of side effects associated with atorvastatin. Close monitoring would be prudent for statin related side effects including rhabdomyolysis. If concurrent therapy is deemed medically necessary, monitor patients for signs and symptoms of myopathy/rhabdomyolysis, including muscle pain/tenderness/weakness, fever, unusual tiredness, changes in the amount of urine, and/or discolored urine. DISCUSSION: Atorvastatin is a BCRP substrate.(1) BCRP inhibitors linked to this monograph include: capmatinib, clopidogrel, curcumin, danicopan, encorafenib, fostamatinib, lazertinib, leflunomide, momelotinib, oteseconazole, pacritinib, pantoprazole, pirtobrutinib, regorafenib, ritonavir, rolapitant, roxadustat, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tafamidis, teriflunomide, tolvaptan, turmeric, vadadustat, velpatasvir, and zongertinib.(2,3)	AMLODIPINE-ATORVASTATIN, ATORVALIQ, ATORVASTATIN CALCIUM, CADUET, LIPITOR

The following contraindication information is available for JAYPIRCA (pirtobrutinib):

Overview
Contraindicated
Severe
Moderate

Drug contraindication overview.

*None.

There are 1 contraindications. Absolute contraindication.

Contraindication List
Lactation

There are 7 severe contraindications. Adequate patient monitoring is recommended for safer drug use.

Severe List
Anemia
Chronic kidney disease stage 4 (severe) GFR 15-29 ml/min
Increased risk of bleeding
Infection
Neutropenic disorder
Pregnancy
Thrombocytopenic disorder

There are 3 moderate contraindications. Clinically significant contraindication, where the condition can be managed or treated before the drug may be given safely.

Moderate List
Cardiac arrhythmia
Disease of liver
Hypertension

The following adverse reaction information is available for JAYPIRCA (pirtobrutinib):

Overview
Severe
Less Severe

Adverse reaction overview.

Adverse effects reported in >=20% of patients include fatigue, musculoskeletal pain, diarrhea, COVID-19, bruising, and cough. Grade 3 or 4 laboratory abnormalities (reported in >=10% of patients): neutropenia, lymphopenia, thrombocytopenia, and anemia.

There are 19 severe adverse reactions.

More Frequent	Less Frequent
Anemia Dyspnea Infection Lymphocytosis Lymphopenia Neutropenic disorder Pneumonia Thrombocytopenic disorder	Atrial fibrillation Atrial flutter Cardiac arrhythmia Hemorrhage Malignancy Malignant neoplasm of skin Pleural effusions Sepsis Tumor lysis syndrome

Rare/Very Rare
Opportunistic fungal infection Opportunistic viral infection

There are 38 less severe adverse reactions.

More Frequent	Less Frequent
Accidental fall Diarrhea Edema Fatigue Hyperbilirubinemia Hyperkalemia Kidney disease with reduction in glomerular filtration rate (GFr) Leukopenia Musculoskeletal pain Petechiae Skin rash Supraventricular tachycardia	Abnormal hepatic function tests Acute abdominal pain Anorexia Arthralgia Arthritis Bruising Constipation Cough Dizziness Drug-induced hepatitis Elevated serum lipase Fever Headache disorder Herpes simplex infection Hypertension Hypocalcemia Hypokalemia Hyponatremia Insomnia Memory impairment Nausea Peripheral neuropathy Stomatitis Upper respiratory infection Urinary tract infection Visual changes

Rare/Very Rare
None.

The following precautions are available for JAYPIRCA (pirtobrutinib):

Pediatric
Pregnant
Lactation
Geriatric

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

Contraindicated

None

Severe Precaution

None

Management or Monitoring Precaution

None

Pirtobrutinib may cause fetal harm if administered to pregnant women based on animal findings.

It is not known whether pirtobrutinib is distributed into human milk or if the drug has any effect on milk production or the nursing infant. Women are advised not to breast-feed during treatment with pirtobrutinib and for 1 week after discontinuing the drug due to the potential for serious adverse reactions in the breast-fed child.

Among the patients with mantle cell lymphoma (MCL) who received pirtobrutinib 200 mg daily in the clinical trial, 78% were >=65 years of age and 33% were >=75 years of age. Clinical studies of pirtobrutinib did not include sufficient numbers of patients with MCL who were <65 years of age to determine whether older patients respond differently from younger adult patients. Among the patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) who received pirtobrutinib 200 mg daily in the clinical trial, 63% were >=65 years of age and 19% were >=75 years of age.

No overall differences in efficacy were observed between geriatric patients and younger adult patients. In the pooled safety population in patients with hematologic malignancies, 68% were >=65 years of age, while 26% were >=75 years of age. Patients >=65 years of age experienced higher rates of grade 3 and higher adverse reactions and serious adverse reactions compared to patients who were <65 years of age.

The following icd codes are available for JAYPIRCA (pirtobrutinib)'s list of indications:

Chronic lymphocytic leukemia
C91.1	Chronic lymphocytic leukemia of b-cell type
C91.10	Chronic lymphocytic leukemia of b-cell type not having achieved remission
C91.12	Chronic lymphocytic leukemia of b-cell type in relapse
Mantle cell lymphoma
C83.1	Mantle cell lymphoma
C83.10	Mantle cell lymphoma, unspecified site
C83.11	Mantle cell lymphoma, lymph nodes of head, face, and neck
C83.12	Mantle cell lymphoma, intrathoracic lymph nodes
C83.13	Mantle cell lymphoma, intra-abdominal lymph nodes
C83.14	Mantle cell lymphoma, lymph nodes of axilla and upper limb
C83.15	Mantle cell lymphoma, lymph nodes of inguinal region and lower limb
C83.16	Mantle cell lymphoma, intrapelvic lymph nodes
C83.17	Mantle cell lymphoma, spleen
C83.18	Mantle cell lymphoma, lymph nodes of multiple sites
C83.19	Mantle cell lymphoma, extranodal and solid organ sites
Small lymphocytic lymphoma
C83.0	Small cell b-cell lymphoma
C83.00	Small cell b-cell lymphoma, unspecified site
C83.01	Small cell b-cell lymphoma, lymph nodes of head, face, and neck
C83.02	Small cell b-cell lymphoma, intrathoracic lymph nodes
C83.03	Small cell b-cell lymphoma, intra-abdominal lymph nodes
C83.04	Small cell b-cell lymphoma, lymph nodes of axilla and upper limb
C83.05	Small cell b-cell lymphoma, lymph nodes of inguinal region and lower limb
C83.06	Small cell b-cell lymphoma, intrapelvic lymph nodes
C83.07	Small cell b-cell lymphoma, spleen
C83.08	Small cell b-cell lymphoma, lymph nodes of multiple sites
C83.09	Small cell b-cell lymphoma, extranodal and solid organ sites