Zepatier

Drug overview for ZEPATIER (elbasvir/grazoprevir):

Generic name: ELBASVIR/GRAZOPREVIR (ELB-as-vir/graz-OH-pre-vir)
Drug class: Hepatitis C Virus NS3/4A Serine Protease Inhibitors
Therapeutic class: Anti-Infective Agents

Elbasvir and grazoprevir (elbasvir/grazoprevir) is a fixed combination containing 2 hepatitis C virus (HCV) antivirals; elbasvir is an HCV nonstructural 5A (NS5A) replication complex inhibitor (NS5A inhibitor) and grazoprevir is an HCV nonstructural 3/4A (NS3/4A) protease inhibitor.

No enhanced Uses information available for this drug.

DRUG IMAGES

ZEPATIER 50-100 MG TABLET

The following indications for ZEPATIER (elbasvir/grazoprevir) have been approved by the FDA:

Indications:
Chronic hepatitis C - genotype 1
Chronic hepatitis C - genotype 4

Professional Synonyms:
Chronic genotype 1 hepatitis C virus infection
Chronic genotype 4 hepatitis C virus infection
Chronic HCV genotype 1 infection
Chronic HCV genotype 4 infection
Chronic hepatitis C genotype 1 infection
Chronic hepatitis C genotype 4 infection

Dosing information for ZEPATIER
DRUG LABEL	DOSING TYPE	DOSING INSTRUCTIONS
ZEPATIER 50-100 MG TABLET	Maintenance	Adults take 1 tablet by oral route once daily

The following drug interaction information is available for ZEPATIER (elbasvir/grazoprevir):

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
Elbasvir-Grazoprevir/Strong CYP3A4 Inducers 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: Inducers of CYP3A4 may induce the metabolism of elbasvir and grazoprevir.(1,2) CLINICAL EFFECTS: Concurrent use of a strong inducer of CYP3A4 may result in decreased levels and effectiveness of elbasvir and grazoprevir.(1,2) PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. PATIENT MANAGEMENT: Concurrent use of elbasvir-grazoprevir and strong CYP3A4 inducers is contraindicated.(1,2) If concurrent use is deemed medically necessary, monitor the patient for potential treatment failure and decreased elbasvir and grazoprevir levels. DISCUSSION: In single dose studies, rifampin increased levels of both elbasvir and grazoprevir. In a study in 14 subjects, rifampin (600 mg single IV dose) increased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of a single dose of elbasvir (50 mg) by 41%, 22%, and 31%, respectively. In a study in 14 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of elbasvir (50 mg) by 29%, 17%, and 21%, respectively. In a study in 12 subjects, rifampin (600 mg single IV dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 10.94-fold, 10.21-fold, and 1.77-fold, respectively. In a study in 12 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 6.52-fold, 8.35-fold, and 1.61-fold, respectively.(1) However, multiple dose studies with rifampin showed decreased grazoprevir levels. In a study in 12 subjects, rifampin (600 mg orally) decreased the AUC and Cmin of grazoprevir (200 mg daily) by 7% and 90%, respectively. Cmax increased 16%.(1) In a study in 12 subjects, efavirenz (600 mg daily) decreased the Cmax, AUC, and Cmin of elbasvir (50 mg daily) by 45%, 34%, and 59%, respectively.(1) In a study in 12 subjects, efavirenz (600 mg daily) decreased the Cmax, AUC, and Cmin of grazoprevir (200 mg daily) by 87%, 82%, and 69%, respectively.(1) Strong inducers of CYP3A4 include apalutamide, barbiturates, carbamazepine, efavirenz, encorafenib, enzalutamide, fosphenytoin, lumacaftor, mitotane, phenobarbital, primidone, phenytoin, and St. John's wort.(1-4)	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, EFAVIRENZ, EFAVIRENZ-EMTRIC-TENOFOV DISOP, EFAVIRENZ-LAMIVU-TENOFOV DISOP, EPITOL, EQUETRO, ERLEADA, FIORICET, FIORICET WITH CODEINE, FOSPHENYTOIN SODIUM, LYSODREN, MITOTANE, MYSOLINE, ORKAMBI, PENTOBARBITAL SODIUM, PHENOBARBITAL, PHENOBARBITAL SODIUM, PHENOBARBITAL-BELLADONNA, PHENOBARBITAL-HYOSC-ATROP-SCOP, PHENOHYTRO, PHENYTEK, PHENYTOIN, PHENYTOIN SODIUM, PHENYTOIN SODIUM EXTENDED, PRIMIDONE, SEZABY, SYMFI, TEGRETOL, TEGRETOL XR, TENCON, XTANDI
Elbasvir-Grazoprevir/OATP1B1-3 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 OATP1B1/3 may decrease the hepatocyte uptake and increase the plasma concentrations of elbasvir and grazoprevir.(1-3) CLINICAL EFFECTS: Concurrent use of an inhibitor of OATP1B1/3 may result in elevated levels of grazoprevir and an increased risk of ALT elevations.(1-3) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Concurrent use of elbasvir-grazoprevir and OATP1B1/3 inhibitors is contraindicated.(1-2,4) If concurrent use is deemed medically necessary, monitor the patient for toxicity and elevated AST levels. DISCUSSION: In a study in 10 subjects, atazanavir/ritonavir (300/100 mg daily) increased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of elbasvir (50 mg daily) by 4.15-fold, 4.76-fold, and 6.45-fold, respectively. There were no clinically significant effects on atazanavir levels.(1,2) In a study in 12 subjects, atazanavir/ritonavir (300/100 mg daily) increased the Cmax, AUC, and Cmin of grazoprevir (200 mg daily) by 6.24-fold, 10.58-fold, and 11.64-fold, respectively. There were no clinically significant effects on atazanavir levels.(1,2) In a study in 14 subjects, cyclosporine (400 mg single dose) increased the Cmax, AUC, and Cmin of elbasvir (50 mg daily) by 1.95-fold, 1.98-fold, and 2.21-fold, respectively. The Cmax, AUC, and Cmin of grazoprevir (200 mg daily) increased by 17-fold, 15.21-fold, and 3.39-fold, respectively. There were no clinically significant effects on cyclosporine levels.(1,2) In a study in 10 subjects, darunavir/ritonavir (600/100 mg twice daily) increased the Cmax, AUC, and Cmin of elbasvir (50 mg daily) by 1.67-fold, 1.66-fold, and 1.82-fold, respectively. There were no clinically significant effects on darunavir levels.(1,2) In a study in 13 subjects, darunavir/ritonavir (600/100 mg twice daily) increased the Cmax, AUC, and Cmin of grazoprevir (200 mg daily) by 5.27-fold, 7.50-fold, and 8.05-fold, respectively. There were no clinically significant effects on darunavir levels.(1,2) In a study in 10 subjects, lopinavir/ritonavir (400/100 mg twice daily) increased the Cmax, AUC, and Cmin of elbasvir (50 mg daily) by 2.87-fold, 3.71-fold, and 4.58-fold, respectively. There were no clinically significant effects on lopinavir levels.(1,2) In a study in 13 subjects, lopinavir/ritonavir (400/100 mg twice daily) increased the Cmax, AUC, and Cmin of grazoprevir (200 mg daily) by 7.31-fold, 12.86-fold, and 21.70-fold, respectively. There were no clinically significant effects on lopinavir levels.(1,2) In single dose studies, rifampin increased levels of both elbasvir and grazoprevir. In a study in 14 subjects, rifampin (600 mg single IV dose) increased the Cmax, AUC, and Cmin of a single dose of elbasvir (50 mg) by 41%, 22%, and 31%, respectively. In a study in 14 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of elbasvir (50 mg) by 29%, 17%, and 21%, respectively. In a study in 12 subjects, rifampin (600 mg single IV dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 10.94-fold, 10.21-fold, and 1.77-fold, respectively. In a study in 12 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 6.52-fold, 8.35-fold, and 1.61-fold, respectively.(1) OATP1B1/3 inhibitors include asciminib, atazanavir, belumosudil, cyclosporine, darunavir, fostemsavir, leniolisib, letermovir, lopinavir, nirmatrelvir/ritonavir, paritaprevir, resmetirom, roxadustat, saquinavir, tipranavir, vadadustat, and voclosporin.(1-3)	APTIVUS, ATAZANAVIR SULFATE, CYCLOSPORINE, CYCLOSPORINE MODIFIED, DARUNAVIR, EVOTAZ, GENGRAF, JOENJA, KALETRA, LOPINAVIR-RITONAVIR, LUPKYNIS, NEORAL, PAXLOVID, PREVYMIS, PREZCOBIX, PREZISTA, REYATAZ, REZDIFFRA, REZUROCK, RUKOBIA, SANDIMMUNE, SCEMBLIX, SYMTUZA, VAFSEO
Elbasvir-Grazoprevir/Rifampin 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: Rifampin inhibits OATP1B3 transporters(1) and induces CYP3A4.(2) CLINICAL EFFECTS: The addition of rifampin to a regimen containing elbasvir-grazoprevir may initially result in elevated levels of grazoprevir and toxicity, including elevated ALT levels.(1) Continued use will result in induction of elbasvir-grazoprevir metabolism, decreased levels of elbasvir-grazoprevir, and loss of efficacy.(2) The addition of elbasvir-grazoprevir to a patient already receiving rifampin or who has recently discontinued rifampin result in induction of elbasvir-grazoprevir metabolism, decreased levels of elbasvir-grazoprevir, and loss of efficacy.(2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Concurrent use of elbasvir-grazoprevir and rifampin is contraindicated.(1,2) If concurrent use is deemed medically necessary and rifampin is being added to elbasvir-grazoprevir therapy, initially monitor the patient for toxicity and elevated ALT levels. After several days, monitor for loss of efficacy. If concurrent use is deemed medically necessary and elbasvir-grazoprevir is being added to rifampin therapy (or if rifampin therapy recently ended), monitor the patient for potential treatment failure and decreased elbasvir and grazoprevir levels.(2) DISCUSSION: In single dose studies, rifampin increased levels of both elbasvir and grazoprevir. In a study in 14 subjects, rifampin (600 mg single IV dose) increased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of a single dose of elbasvir (50 mg) by 41%, 22%, and 31%, respectively. In a study in 14 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of elbasvir (50 mg) by 29%, 17%, and 21%, respectively. In a study in 12 subjects, rifampin (600 mg single IV dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 10.94-fold, 10.21-fold, and 1.77-fold, respectively. In a study in 12 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 6.52-fold, 8.35-fold, and 1.61-fold, respectively.(1) However, multiple dose studies with rifampin showed decreased grazoprevir levels. In a study in 12 subjects, rifampin (600 mg orally) decreased the AUC and Cmin of grazoprevir (200 mg daily) by 7% and 90%, respectively. Cmax increased 16%.(1)	RIFADIN, RIFAMPIN
Atorvastatin (Greater Than 20 mg); Rosuvastatin (Greater Than 10 mg)/Elbasvir-Grazoprevir 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: Elbasvir-grazoprevir may inhibit intestinal BCRP, resulting in increased absorption of atorvastatin and rosuvastatin.(1,2) CLINICAL EFFECTS: Concurrent use of elbasvir-grazoprevir may result in elevated levels of and toxicity from atorvastatin and 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: In patients requiring elbasvir-grazoprevir, do not use more than 20 mg daily of atorvastatin or 10 mg daily of rosuvastatin.(1,2) If concurrent use is deemed medically necessary, instruct patients to report symptoms of muscle pain, tenderness, or weakness. DISCUSSION: In a study in 16 healthy subjects, elbasvir-grazoprevir (50-200 mg daily) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of atorvastatin (10 mg) by 4.34-fold and 1.94-fold, respectively. The minimum concentration (Cmin) of atorvastatin decreased by 81%. There were no clinically significant effects on elbasvir-grazoprevir.(1,2) In a study in 12 healthy subjects, elbasvir-grazoprevir (50-200 mg daily) increased the Cmax and AUC of a single dose of rosuvastatin (10 mg) by 5.49-fold and 2.26-fold, respectively. There were no clinically significant effects on rosuvastatin Cmin or on elbasvir-grazoprevir.(1,2)	AMLODIPINE-ATORVASTATIN, ATORVALIQ, ATORVASTATIN CALCIUM, CADUET, CRESTOR, EZALLOR SPRINKLE, LIPITOR, ROSUVASTATIN CALCIUM, ROSUVASTATIN-EZETIMIBE, ROSZET
Fluvastatin (Greater Than 20 mg); Lovastatin (Greater Than 20 mg); Simvastatin (Greater Than 20 mg)/Elbasvir-Grazoprevir 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: Elbasvir-grazoprevir may inhibit intestinal BCRP, resulting in increased absorption of simvastatin. The mechanism of interaction with fluvastatin and lovastatin is not known, but may be related to competitive inhibition of OATP1B1 by elbasvir-grazoprevir.(1-3) CLINICAL EFFECTS: Concurrent use of elbasvir-grazoprevir may result in elevated levels of and toxicity from fluvastatin, lovastatin, and simvastatin, including rhabdomyolysis.(1-3) 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 fluvastatin who are CYP2C9 intermediate or poor metabolizers may have increased fluvastatin concentrations and risk of myopathy. PATIENT MANAGEMENT: The Canadian and UK manufacturers of elbasvir-grazoprevir and of simvastatin recommend that, in patients requiring elbasvir-grazoprevir, doses greater than 20 mg daily of fluvastatin, lovastatin, or simvastatin should not be used.(1,2) The US manufacturer of elbasvir-grazoprevir states that the lowest possible dose of fluvastatin, lovastatin, or simvastatin should be used.(3) If concurrent use is deemed medically necessary, instruct patients to report symptoms of muscle pain, tenderness, or weakness. DISCUSSION: Elbasvir-grazoprevir is a substrate of OATP1B1 and has been shown to inhibit intestinal BCRP.(1,3) Fluvastatin and lovastatin are substrates of OATP1B1 and simvastatin is a substrate of BCRP and OATP1B1.(4) Studies with other statins (i.e., atorvastatin, rosuvastatin) have shown that elbasvir-grazoprevir can increase the concentrations of these statins. While interaction studies of elbasvir-grazoprevir with fluvastatin, lovastatin, and simvastatin have not been done, fluvastatin and lovastatin concentrations have been shown to increase with other OATP1B1 inhibitors, and simvastatin levels have been shown to increase with other BCRP inhibitors.(4)	ALTOPREV, EZETIMIBE-SIMVASTATIN, FLOLIPID, FLUVASTATIN ER, FLUVASTATIN SODIUM, LESCOL XL, LOVASTATIN, SIMVASTATIN, VYTORIN, ZOCOR
Lemborexant (Greater Than 5 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Inhibitors of CYP3A4 may inhibit the metabolism of lemborexant.(1) CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP3A4 may result in increased levels of and effects from lemborexant, including somnolence, fatigue, CNS depressant effects, daytime impairment, headache, and nightmare or abnormal dreams.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The maximum recommended dose of lemborexant with concurrent use of a weak CYP3A4 inhibitors should not exceed 5 mg per dose.(1) DISCUSSION: Lemborexant is a CYP3A4 substrate. In a PKPB model, concurrent use of lemborexant with itraconazole increased area-under-curve (AUC) and concentration maximum (Cmax) by 3.75-fold and 1.5-fold, respectively. Concurrent use of lemborexant with fluconazole increased AUC and Cmax by 4.25-fold and 1.75-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(1,2)	DAYVIGO

There are 7 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
Lomitapide (Less Than or Equal To 30 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of lomitapide.(1) Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Thus even weak CYP3A4 inhibitors may affect lomitapide exposure (AUC, area-under-curve). CLINICAL EFFECTS: Concurrent use of a weak inhibitor of CYP3A4 may result in 2-fold increases in lomitapide levels and toxicity from lomitapide.(1) PREDISPOSING FACTORS: This interaction may be more severe in patients with hepatic impairment or with end-stage renal disease.(1) PATIENT MANAGEMENT: The maximum lomitapide dose should be 30 mg daily for patients taking concomitant weak CYP3A4 inhibitors. Due to lomitapide's long half-life, it may take 1 to 2 weeks to see the full effect of this interaction. When initiating a weak CYP3A4 inhibitor in patients taking lomitapide 10 mg daily or more, decrease the dose of lomitapide by 50%. In patients taking lomitapide 5 mg daily, continue current dose. DISCUSSION: Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Based upon interactions with stronger inhibitors, weak inhibitors of CYP3A4 are predicted to increase lomitapide area-under-curve(AUC) 2-fold.(1) Weak CYP3A4 inhibitors linked to this interaction include alprazolam, amiodarone, amlodipine, asciminib, atorvastatin, azithromycin, Baikal skullcap, belumosudil, bicalutamide, blueberry juice, brodalumab, cannabidiol, capivasertib, cilostazol, cimetidine, ciprofloxacin, chlorzoxazone, clotrimazole, cranberry juice, cyclosporine, daridorexant, delavirdine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, larotrectinib, lacidipine, lapatinib, lazertinib, leflunomide, levamlodipine, linagliptin, lurasidone, maribavir, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, vonoprazan, and zileuton.(1-3)	JUXTAPID
Elbasvir-Grazoprevir/Moderate CYP3A4 Inducers SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inducers of CYP3A4 may induce the metabolism of elbasvir and grazoprevir.(1,2) CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of elbasvir and grazoprevir.(1,2) PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. PATIENT MANAGEMENT: Concurrent use of elbasvir-grazoprevir and a moderate CYP3A4 inducers is not recommended.(1,2) If concurrent use is required, monitor the patient for potential treatment failure and decreased elbasvir and grazoprevir levels. DISCUSSION: In single dose studies, rifampin increased levels of both elbasvir and grazoprevir. In a study in 14 subjects, rifampin (600 mg single IV dose) increased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of a single dose of elbasvir (50 mg) by 41%, 22%, and 31%, respectively. In a study in 14 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of elbasvir (50 mg) by 29%, 17%, and 21%, respectively. In a study in 12 subjects, rifampin (600 mg single IV dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 10.94-fold, 10.21-fold, and 1.77-fold, respectively. In a study in 12 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 6.52-fold, 8.35-fold, and 1.61-fold, respectively.(1) However, multiple dose studies with rifampin showed decreased grazoprevir levels. In a study in 12 subjects, rifampin (600 mg orally) decreased the AUC and Cmin of grazoprevir (200 mg daily) by 7% and 90%, respectively. Cmax increased 16%.(1) In a study in 12 subjects, efavirenz (600 mg daily) decreased the Cmax, AUC, and Cmin of elbasvir (50 mg daily) by 45%, 34%, and 59%, respectively.(1) In a study in 12 subjects, efavirenz (600 mg daily) decreased the Cmax, AUC, and Cmin of grazoprevir (200 mg daily) by 87%, 82%, and 69%, respectively.(1) Moderate inducers of CYP3A4 include belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, elagolix, etravirine, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(1-4)	AUGTYRO, BOSENTAN, CAMZYOS, DUZALLO, ETRAVIRINE, INTELENCE, LORBRENA, LUMAKRAS, MODAFINIL, NAFCILLIN, NAFCILLIN SODIUM, OJEMDA, ORIAHNN, ORILISSA, PROVIGIL, PYRUKYND, RIFABUTIN, TAFINLAR, TALICIA, THIORIDAZINE HCL, THIORIDAZINE HYDROCHLORIDE, TRACLEER, TURALIO, VONJO, WELIREG, XCOPRI, XERMELO
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, pantoprazole, pirtobrutinib, regorafenib, resmetirom, ritonavir, rolapitant, roxadustat, tafamidis, teriflunomide, tolvaptan, turmeric, and vadadustat.(1,3-5) P-glycoprotein inhibitors linked to this monograph include: asunaprevir, belumosudil, capmatinib, carvedilol, cyclosporine, danicopan, daridorexant, diltiazem, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, isavuconazonium, ivacaftor, ledipasvir, neratinib, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, tezacaftor, ticagrelor, valbenazine, verapamil, vimseltinib, and voclosporin.(3,4)	PAZOPANIB HCL, VOTRIENT
Cladribine/Selected Inhibitors of BCRP 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) 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) PREDISPOSING FACTORS: None determined. 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) 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: capmatinib, clopidogrel, curcumin, danicopan, darolutamide, dasabuvir, eltrombopag, enasidenib, febuxostat, fostamatinib, fostemsavir, glecaprevir/pibrentasvir, grazoprevir, lazertinib, oteseconazole, pacritinib, pantoprazole, paritaprevir, regorafenib, resmetirom, ritonavir, rolapitant, roxadustat, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tafamidis, ticagrelor, tolvaptan, turmeric, and vadadustat.(1-4)	CLADRIBINE, MAVENCLAD
Eliglustat/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of eliglustat. If the patient is also taking an inhibitor of CYP2D6, eliglustat metabolism can be further inhibited.(1) CLINICAL EFFECTS: Concurrent use of an agent that is a weak inhibitor of CYP3A4 may result in elevated levels of and clinical effects of eliglustat, including prolongation of the PR, QTc, and/or QRS intervals, which may result in life-threatening cardiac arrhythmias.(1) PREDISPOSING FACTORS: If the patient is also taking an inhibitor of CYP2D6, is a poor metabolizer of CYP2D6, and/or has hepatic impairment, eliglustat metabolism can be further inhibited.(1) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The concurrent use of eliglustat with weak inhibitors of CYP3A4 in poor metabolizers of CYP2D6 should be avoided.(1) The dosage of eliglustat with weak inhibitors of CYP3A4 in extensive metabolizers of CYP2D6 with mild (Child-Pugh Class A) hepatic impairment should be limited to 84 mg daily.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Ketoconazole (400 mg daily), a strong inhibitor of CYP3A4, increased eliglustat (84 mg BID) maximum concentration (Cmax) and area-under-curve (AUC) by 4-fold and 4.4-fold, respectively, in extensive metabolizers. Physiologically-based pharmacokinetic (PKPB) models suggested ketoconazole would increase eliglustat Cmax and AUC by 4.4-fold and 5.4-fold, respectively, in intermediate metabolizers. PKPB models suggested ketoconazole may increase the Cmax and AUC of eliglustat (84 mg daily) by 4.3-fold and 6.2-fold, respectively, in poor metabolizers.(1) PKPB models suggested fluconazole, a moderate inhibitor of CYP3A4, would increase eliglustat Cmax and AUC by 2.8-fold and 3.2-fold, respectively, in extensive metabolizers and by 2.5-fold and 2.9-fold, respectively in intermediate metabolizers. PKPB models suggest that concurrent eliglustat (84 mg BID), paroxetine (a strong inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 16.7-fold and 24.2-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 7.5-fold and 9.8-fold, respectively.(1) PKPB models suggest that concurrent eliglustat (84 mg BID), terbinafine (a moderate inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 10.2-fold and 13.6-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 4.2-fold and 5-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amlodipine, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, and vonoprazan.(3,4)	CERDELGA
Elbasvir-Grazoprevir/Selected 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 elbasvir-grazoprevir.(1-3) CLINICAL EFFECTS: Concurrent use of selected strong CYP3A4 inhibitors may result in increased levels of elbasvir and grazoprevir.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Concurrent use of elbasvir-grazoprevir and strong CYP3A4 inhibitors is not recommended. (1) Concurrent use of elbasvir-grazoprevir and itraconazole is not recommended during and 2 weeks after treatment. (2) DISCUSSION: A study in seven healthy patients, concurrent therapy with ketoconazole (400 mg once daily) increased the elbasvir area-under-curve (AUC) and concentration maximum (Cmax) by 1.8-fold and 1.29-fold, respectively, and increased the grazoprevir AUC and Cmax by 3.02-fold and 1.13-fold, respectively.(1) Selected CYP3A4 inhibitors include elvitegravir/cobicistat, itraconazole, ketoconazole, and levoketoconazole.(3)	GENVOYA, ITRACONAZOLE, ITRACONAZOLE MICRONIZED, KETOCONAZOLE, RECORLEV, SPORANOX, STRIBILD, TOLSURA
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, and voxilaprevir.(2,3)	HYCAMTIN, TOPOTECAN HCL

There are 7 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
Atorvastatin (Less Than or Equal To 20 mg); Rosuvastatin (Less Than or Equal To 10 mg)/Elbasvir-Grazoprevir SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Elbasvir-grazoprevir may inhibit intestinal BCRP, resulting in increased absorption of atorvastatin and rosuvastatin.(1,2) CLINICAL EFFECTS: Concurrent use of elbasvir-grazoprevir may result in elevated levels of and toxicity from atorvastatin and 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: In patients requiring elbasvir-grazoprevir, do not use more than 20 mg daily of atorvastatin or 10 mg daily of rosuvastatin.(1,2) Instruct patients to report symptoms of muscle pain, tenderness, or weakness. DISCUSSION: In a study in 16 healthy subjects, elbasvir-grazoprevir (50-200 mg daily) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of atorvastatin (10 mg) by 4.34-fold and 1.94-fold, respectively. The minimum concentration (Cmin) of atorvastatin decreased by 81%. There were no clinically significant effects on elbasvir-grazoprevir.(1,2) In a study in 12 healthy subjects, elbasvir-grazoprevir (50-200 mg daily) increased the Cmax and AUC of a single dose of rosuvastatin (10 mg) by 5.49-fold and 2.26-fold, respectively. There were no clinically significant effects on rosuvastatin Cmin or on elbasvir-grazoprevir.(1,2)	AMLODIPINE-ATORVASTATIN, ATORVASTATIN CALCIUM, CADUET, CRESTOR, EZALLOR SPRINKLE, LIPITOR, ROSUVASTATIN CALCIUM, ROSUVASTATIN-EZETIMIBE, ROSZET
Select Anticoagulants (Vitamin K antagonists)/Selected Direct-Acting Antivirals SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The exact mechanism is unknown. Warfarin sensitivity may be decreased during concurrent therapy with direct-acting antivirals. Improved hepatic function as a result of successful treatment of Hepatitis C may also play a role. CLINICAL EFFECTS: Use of direct-acting antivirals in the treatment of Hepatitis C may result in decreased warfarin effects, which may increase the risk of thrombosis. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Monitor INR response closely in patients maintained on warfarin during treatment with direct-acting antivirals. Consider more frequent monitoring of INR during concurrent therapy and after the completion of therapy with direct-acting antivirals until a stable warfarin dose is established. DISCUSSION: In a clinical study of 43 patients treated with elbasvir-grazoprevir, the warfarin sensitivity index (WSI) (steady state INR/mean daily warfarin dose) decreased from 0.53 +/- 0.25 to 0.4 +/- 0.22 at treatment completion with elbasvir-grazoprevir which represents a 25.2% decrease. Twelve weeks after treatment completion the WSI returned to 0.51 +/- 0.28. Mean weekly warfarin dose requirement increased over the course of therapy, from 40.3 +/- 22.0 mg to 44.6 +/- 23.4 mg, and returned to near original warfarin dose requirement after therapy at 46 mg. Time in therapeutic range for INR dropped from 74.1% to 39.8% during treatment and returned to 64.9% after treatment.(1) In a retrospective review of patients treated with either ombitasvir-paritaprevir-ritonavir-dasabuvir or sofosbuvir, the warfarin sensitivity index (steady state INR/mean daily warfarin dose) decreased 23% during therapy. The percentage of subtherapeutic INRs increased from 28% prior to treatment to 58% during treatment.(2) Pharmacokinetic studies found no significant effects on warfarin from either ombitasvir-paritaprevir-ritonavir(3) or ombitasvir-paritaprevir-ritonavir-dasabuvir.(4) There have been case reports of decreased warfarin effects and increased warfarin dosage requirements during the treatment of Hepatitis C with: ombitasvir-paritaprevir-ritonavir-dasabuvir,(5) sofosbuvir,(6) sofosbuvir-ledipasvir,(7) and sofosbuvir-velpatasvir.(8) There is a case report of decreased INR following the addition of ombitasvir-paritaprevir-ritonavir-dasabuvir to acenocoumarol.(9)	JANTOVEN, WARFARIN SODIUM
Fluvastatin (Less Than or Equal To 20 mg); Lovastatin (Less Than or Equal To 20 mg); Simvastatin (Less Than or Equal To 20 mg)/Elbasvir-Grazoprevir SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Elbasvir-grazoprevir may inhibit intestinal BCRP, resulting in increased absorption of simvastatin. The mechanism of interaction with fluvastatin and lovastatin is not known, but may be related to competitive inhibition of OATP1B1 by elbasvir-grazoprevir.(1-3) CLINICAL EFFECTS: Concurrent use of elbasvir-grazoprevir may result in elevated levels of and toxicity from fluvastatin, lovastatin, and simvastatin, including rhabdomyolysis.(1-3) 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 fluvastatin who are CYP2C9 intermediate or poor metabolizers may have increased fluvastatin concentrations and risk of myopathy. PATIENT MANAGEMENT: The Canadian and UK manufacturers of elbasvir-grazoprevir and of simvastatin recommend that, in patients requiring elbasvir-grazoprevir, doses greater than 20 mg daily of fluvastatin, lovastatin, or simvastatin should not be used.(1,2) The US manufacturer of elbasvir-grazoprevir states that the lowest possible dose of fluvastatin, lovastatin, or simvastatin should be used.(3) If concurrent use is deemed medically necessary, instruct patients to report symptoms of muscle pain, tenderness, or weakness. DISCUSSION: Elbasvir-grazoprevir is a substrate of OATP1B1 and has been shown to inhibit intestinal BCRP.(1,3) Fluvastatin and lovastatin are substrates of OATP1B1 and simvastatin is a substrate of BCRP and OATP1B1.(4) Studies with other statins (i.e., atorvastatin, rosuvastatin) have shown that elbasvir-grazoprevir can increase the concentrations of these statins. While interaction studies of elbasvir-grazoprevir with fluvastatin, lovastatin, and simvastatin have not been done, fluvastatin and lovastatin concentrations have been shown to increase with other OATP1B1 inhibitors, and simvastatin levels have been shown to increase with other BCRP inhibitors.(4)	ALTOPREV, EZETIMIBE-SIMVASTATIN, FLUVASTATIN SODIUM, LOVASTATIN, SIMVASTATIN, VYTORIN, ZOCOR
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 assoc ation between transplant rejection and concurrent use of tacrolimus and clotrimazole (reporting odds ration 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) Moderate CYP3A4 inhibitors linked to this monograph include: aprepitant, berotralstat, clofazimine, conivaptan, fluvoxamine, lenacapavir, letermovir, netupitant, nirogacestat, 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, 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, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(1,2)	DAYVIGO
Ubrogepant/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of ubrogepant.(1) CLINICAL EFFECTS: Concurrent use of ubrogepant with weak CYP3A4 inhibitors may result in an increase in exposure of ubrogepant.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when used concomitantly with weak CYP3A4 inhibitors. Initial dose of ubrogepant should not exceed 50 mg when used concomitantly with weak inhibitors of CYP3A4. A second dose may be given within 24 hours but should not exceed 50 mg when used concurrently with weak CYP3A4 inhibitors.(1) DISCUSSION: Coadministration of ubrogepant with verapamil, a moderate CYP3A4 inhibitor, resulted in a 3.5-fold and 2.8-fold increase in area-under-curve (AUC) and concentration maximum (Cmax), respectively. No dedicated drug interaction study was conducted to assess concomitant use with weak CYP3A4 inhibitors. The conservative prediction of the maximal potential increase in ubrogepant exposure with weak CYP3A4 inhibitors is not expected to be more than 2-fold.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, asciminib, azithromycin, Baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, delavirdine, dihydroberberine, diosmin, elagolix, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, maribavir, mavorixafor, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(2,3)	UBRELVY
Sirolimus Protein-Bound/Slt Moderate and Weak CYP3A4 Inhibit SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate and weak CYP3A4 inhibitors may inhibit the metabolism of sirolimus by CYP3A4.(1) CLINICAL EFFECTS: Concurrent use of moderate or weak CYP3A4 inhibitors may result in elevated levels of and side effects from sirolimus.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of sirolimus protein-bound injection (Fyarro) states a dose reduction to 56 mg/m2 is recommended when used concurrently with moderate or weak CYP3A4 inhibitors. Concurrent use with strong CYP3A4 inhibitors should be avoided.(1) DISCUSSION: In an open, randomized, cross-over trial in 18 healthy subjects, concurrent single doses of diltiazem (120 mg) and sirolimus (10 mg) increased sirolimus area-under-curve (AUC) and maximum concentration (Cmax) by 60% and by 43%, respectively. Sirolimus apparent oral clearance and volume of distribution decreased by 38% and 45%, respectively. There were no effects on diltiazem pharmacokinetics or pharmacodynamics.(2) In a study in 26 healthy subjects, concurrent sirolimus (2 mg daily) with verapamil (180 mg twice daily) increased sirolimus AUC and Cmax by 2.2-fold and 2.3-fold, respectively. The AUC and Cmax of the active S-enantiomer of verapamil each increased by 1.5-fold. Verapamil time to Cmax (Tmax) was increased by 1.2 hours.(2) Moderate and weak CYP3A4 inhibitors linked to this monograph include: alprazolam, amlodipine, aprepitant, avacopan, azithromycin, berberine, berotralstat, bicalutamide, blueberry, brodalumab, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clofazimine, conivaptan, daclatasvir, daridorexant, delavirdine, diosmin, entrectinib, erythromycin, estrogen, flibanserin, fluvoxamine, fosaprepitant, fosnetupitant, fostamatinib, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lazertinib, lenacapavir, levamlodipine, linagliptin, lomitapide, lumateperone, lurasidone, mavorixafor, netupitant, omeprazole, osilodrostat, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, rimegepant, roxithromycin, scutellarin, simeprevir, sitaxsentan, stiripentol, suvorexant, ticagrelor, tofisopam, tolvaptan, trofinetide, and vonoprazan.(3,4)	FYARRO

The following contraindication information is available for ZEPATIER (elbasvir/grazoprevir):

Overview
Contraindicated
Severe
Moderate

Drug contraindication overview.

The fixed combination of elbasvir and grazoprevir (elbasvir/grazoprevir) is contraindicated in patients with moderate or severe hepatic impairment (Child-Pugh class B or C) and in those with any history of hepatic decompensation. Concomitant use of elbasvir/grazoprevir with certain drugs (e.g., inhibitors of organic anion transporting polypeptides (OATP) 1B1 and 1B3, potent inducers of cytochrome P-450 (CYP) 3A, efavirenz) is contraindicated. When elbasvir/grazoprevir is used in conjunction with ribavirin, the contraindications for ribavirin apply.

There are 3 contraindications. Absolute contraindication.

Contraindication List
Child-pugh class B hepatic impairment
Child-pugh class C hepatic impairment
Hepatic failure

There are 0 severe contraindications.

There are 2 moderate contraindications. Clinically significant contraindication, where the condition can be managed or treated before the drug may be given safely.

Moderate List
Hypoglycemic disorder
Reactivation of hepatitis B

The following adverse reaction information is available for ZEPATIER (elbasvir/grazoprevir):

Overview
Severe
Less Severe

Adverse reaction overview.

Elbasvir/grazoprevir (>=5%): Fatigue, headache, and nausea. Elbasvir/grazoprevir in conjunction with ribavirin (>=5%): Anemia and headache.

There are 7 severe adverse reactions.

More Frequent	Less Frequent
Anemia	Abnormal hepatic function tests Hyperbilirubinemia Increased alanine transaminase

Rare/Very Rare
Dysglycemia Hepatic failure Reactivation of hepatitis B

There are 18 less severe adverse reactions.

More Frequent	Less Frequent
Fatigue Headache disorder Nausea	Acute abdominal pain Anorexia Depression Diarrhea Dyspepsia Dyspnea Flatulence General weakness Insomnia Night sweats Pruritus of skin Vomiting Xerostomia

Rare/Very Rare
Angioedema Irritability

The following precautions are available for ZEPATIER (elbasvir/grazoprevir):

Pediatric
Pregnant
Lactation
Geriatric

Safety and efficacy of elbasvir/grazoprevir have not been established in pediatric patients younger than 12 years of age or who weigh less than 30 kg. Safety and efficacy of elbasvir/grazoprevir for the treatment of HCV genotype 1 or 4 infection in pediatric patients 12 years of age and older or weighing greater than 30 kg are based on safety, efficacy, and pharmacokinetic data from an open-label trial that included 22 treatment-naive or previously treated noncirrhotic pediatric patients. Trial data indicated that safety, efficacy, and pharmacokinetics of elbasvir/grazoprevir in these pediatric patients were consistent with those observed in HCV-infected adults receiving the drug in clinical trials. In a pharmacokinetic study of 22 pediatric patients 12 years of age and older with HCV genotype 1 or 4, administration of elbasvir 50 mg/grazoprevir 100 mg once daily led to similar drug exposures to those observed in adult patients.

Contraindicated

None

Severe Precaution

None

Management or Monitoring Precaution

None

Adequate data are not available regarding use of elbasvir/grazoprevir in pregnant women. Animal reproduction studies using elbasvir or grazoprevir have not revealed evidence of fetal harm at exposures greater than those attained with recommended human dosage. When elbasvir/grazoprevir is used in conjunction with ribavirin, consider the cautions, precautions, and contraindications associated with ribavirin.

(See Cautions in Ribavirin 8:18.32.)

It is not known whether elbasvir/grazoprevir is distributed into human milk, affects human milk production, or affects the breast-fed infant. Both elbasvir and grazoprevir are distributed into milk in rats. Consider the benefits of breast-feeding and the importance of elbasvir/grazoprevir to the woman along with the potential adverse effects on the breast-fed child from the drug or from the underlying maternal condition.

When elbasvir/grazoprevir is used in conjunction with ribavirin, consider the potential for adverse reactions to ribavirin in nursing infants. A decision should be made whether to discontinue nursing or the ribavirin-containing regimen, taking into account the importance of the treatment regimen to the woman.

In clinical trials, a higher rate of late-onset ALT elevations was reported in individuals 65 years of age and older. In population pharmacokinetic analyses, the areas under the plasma concentration-time curves (AUCs) of elbasvir and grazoprevir are estimated to be increased by 16 and 45%, respectively, in individuals 65 years of age and older compared with AUCs in younger adults.

Chronic hepatitis C - genotype 1
B18.2	Chronic viral hepatitis C
Chronic hepatitis C - genotype 4
B18.2	Chronic viral hepatitis C