Drug Interactions between Caduet and dasabuvir / ombitasvir / paritaprevir / ritonavir

ADJUST DOSE: Protease inhibitors (PIs), particularly ritonavir, may significantly increase the plasma concentrations of atorvastatin. The mechanism is PI inhibition of CYP450 3A4 metabolism. In 14 healthy volunteers, ritonavir (400 mg twice a day) and saquinavir (soft gelatin capsule 400 mg twice a day) given for 14 days increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of atorvastatin plus atorvastatin acid (given as atorvastatin 40 mg once a day for 4 days) by 148% and 73%, respectively. In 16 study subjects, amprenavir (given as fosamprenavir 1400 mg twice a day for 2 weeks) increased Cmax and AUC of atorvastatin (10 mg once a day) by 304% and 130%, respectively. These values were increased 184% and 153%, respectively, with ritonavir-fosamprenavir (700 mg-100 mg twice a day). High levels of HMG-CoA reductase inhibitory activity in plasma is associated with an increased risk of musculoskeletal toxicity. Myopathy manifested as muscle pain and/or weakness associated with grossly elevated creatine kinase exceeding ten times the upper limit of normal has been reported occasionally. Rhabdomyolysis has also occurred rarely, which may be accompanied by acute renal failure secondary to myoglobinuria and may result in death.

MANAGEMENT: The benefits of using atorvastatin in combination with protease inhibitors should be carefully weighed against the potentially increased risk of myopathy including rhabdomyolysis. A lower dosage of atorvastatin should be considered if concomitant use is required. Atorvastatin labeling recommends that the dosage not exceed 20 mg/day when used in combination with fosamprenavir or with dual protease inhibitor therapy consisting of ritonavir plus darunavir, saquinavir, or fosamprenavir. Use of atorvastatin with the fixed combination of atazanavir-cobicistat is not recommended. The dosage should not exceed 40 mg/day when used with nelfinavir. Nirmatrelvir-ritonavir product labeling advises temporary discontinuation of atorvastatin be considered during treatment with nirmatrelvir-ritonavir. Fluvastatin, pitavastatin, and pravastatin may be safer alternatives, since they are not metabolized by CYP450 3A4. All patients receiving statin therapy should be advised to promptly report any unexplained muscle pain, tenderness or weakness, particularly if accompanied by fever, malaise and/or dark colored urine. Therapy should be discontinued if creatine kinase is markedly elevated in the absence of strenuous exercise or if myopathy is otherwise suspected or diagnosed.

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GENERALLY AVOID: Theoretically, coadministration with ombitasvir/paritaprevir/ritonavir with or without dasabuvir may significantly increase the plasma concentrations of certain HMG-CoA reductase inhibitors. The proposed mechanism may involve inhibition of the hepatic uptake transporter OATP1B1 by paritaprevir and/or inhibition of CYP450 3A4 by ritonavir. High levels of HMG-CoA reductase inhibitory activity in plasma are associated with an increased risk of musculoskeletal toxicity. Myopathy manifested as muscle pain and/or weakness associated with grossly elevated creatine kinase exceeding ten times the upper limit of normal has been reported occasionally. Rhabdomyolysis has also occurred rarely, which may be accompanied by acute renal failure secondary to myoglobinuria and may result in death.

MANAGEMENT: Concomitant use of atorvastatin and ombitasvir/paritaprevir/ritonavir with or without dasabuvir should be avoided. All patients receiving statin therapy should be advised to promptly report any unexplained muscle pain, tenderness or weakness, particularly if accompanied by fever, malaise and/or dark colored urine. Therapy should be discontinued if creatine kinase is markedly elevated in the absence of strenuous exercise or if myopathy is otherwise suspected or diagnosed.

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MONITOR: Coadministration with CYP450 3A4 inhibitors may increase the plasma concentrations of amlodipine, which is a substrate of the isoenzyme. In 8 elderly hypertensive patients, administration of a single 5 mg dose of amlodipine in combination with the moderate CYP450 3A4 inhibitor diltiazem (180 mg orally daily for 3 days) resulted in a nearly 60% increase in amlodipine peak plasma concentration (Cmax) and systemic exposure (AUC). Associated systolic, diastolic, and standing blood pressures decreased compared to those obtained with amlodipine alone. Erythromycin, another moderate inhibitor, did not significantly alter amlodipine systemic exposure in healthy volunteers. However, pharmacokinetic changes may be more pronounced in elderly patients.

MANAGEMENT: Close monitoring of clinical response and tolerance is recommended if amlodipine is prescribed with potent or moderate CYP450 3A4 inhibitors. Dosage reduction may be required for amlodipine. Patients should be advised to seek medical attention if they experience edema or swelling of the lower extremities; sudden, unexplained weight gain; difficulty breathing; chest pain or tightness; or hypotension as indicated by dizziness, fainting, or orthostasis.

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MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of HMG-CoA reductase inhibitors (i.e., statins) that are metabolized by the isoenzyme. Lovastatin and simvastatin are particularly susceptible because of their low oral bioavailability, but others such as atorvastatin and cerivastatin may also be affected. High levels of HMG-CoA reductase inhibitory activity in plasma is associated with an increased risk of musculoskeletal toxicity. Myopathy manifested as muscle pain and/or weakness associated with grossly elevated creatine kinase exceeding ten times the upper limit of normal has been reported occasionally. Rhabdomyolysis has also occurred rarely, which may be accompanied by acute renal failure secondary to myoglobinuria and may result in death. Clinically significant interactions have been reported with potent CYP450 3A4 inhibitors such as macrolide antibiotics, azole antifungals, protease inhibitors and nefazodone, and moderate inhibitors such as amiodarone, cyclosporine, danazol, diltiazem and verapamil.

MANAGEMENT: Caution is recommended if atorvastatin, cerivastatin, lovastatin, simvastatin, or red yeast rice (which contains lovastatin) is prescribed with a CYP450 3A4 inhibitor. It is advisable to monitor lipid levels and use the lowest effective statin dose. All patients receiving statin therapy should be advised to promptly report any unexplained muscle pain, tenderness or weakness, particularly if accompanied by fever, malaise and/or dark colored urine. Therapy should be discontinued if creatine kinase is markedly elevated in the absence of strenuous exercise or if myopathy is otherwise suspected or diagnosed. Fluvastatin, pravastatin, and rosuvastatin are not expected to interact with CYP450 3A4 inhibitors.

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