Pharmacokinetic interactions between the hepatitis C virus protease inhibitor boceprevir and ritonavir-boosted HIV-1 protease inhibitors atazanavir, darunavir, and lopinavir.

BACKGROUND: Boceprevir represents a new treatment option for hepatitis C (HCV)-infected patients, including those with HCV/human immunodeficiency virus coinfection; however, little is known about pharmacokinetic interactions between boceprevir and antiretroviral drugs. METHODS: A randomized, open-label study to assess the pharmacokinetic interactions between boceprevir and ritonavir-boosted protease inhibitors (PI/r) was conducted in 39 healthy adults. Subjects received boceprevir (800 mg, 3 times daily) for 6 days and then received PI/r as follows: atazanavir (ATV) 300 mg once daily, lopinavir (LPV) 400 mg twice daily, or darunavir (DRV) 600 mg twice daily, each with ritonavir (RTV) 100 mg on days 10-31, plus concomitant boceprevir on days 25-31. RESULTS: Boceprevir decreased the exposure of all PI/r, with area under the concentration-time curve [AUC] from time 0 to the time of the last measurable sample geometric mean ratios of 0.65 (90% confidence interval [CI], .55-.78) for ATV/r; 0.66 (90% CI, .60-.72) for LPV/r, and 0.56 (90% CI, .51-.61) for DRV/r. Coadministration with boceprevir decreased RTV AUC during a dosing interval τ (AUC(τ)) by 22%-36%. ATV/r did not significantly affect boceprevir exposure, but boceprevir AUC(τ) was reduced by 45% and 32% when coadministered with LPV/r and DRV/r, respectively. Overall, treatments were well tolerated with no unexpected adverse events. CONCLUSIONS: Concomitant administration of boceprevir with PI/r resulted in reduced exposures of PI and boceprevir. These drug-drug interactions may reduce the effectiveness of PI/r and/or boceprevir when coadministered.

Antiviral activity of narlaprevir combined with ritonavir and pegylated interferon in chronic hepatitis C patients.

UNLABELLED: Narlaprevir (SCH 900518) is a potent inhibitor of the hepatitis C virus (HCV) nonstructural protein 3 serine protease that is primarily metabolized by the cytochrome P450-3A4 system. In order to explore the use of ritonavir-based pharmacokinetic enhancement of an HCV protease inhibitor, this study investigated the safety, tolerability, pharmacokinetics, and antiviral activity of narlaprevir (with or without ritonavir) administered as monotherapy and as combination therapy with pegylated interferon-α-2b (PEG-IFN-α-2b) to HCV genotype 1-infected patients. This was a randomized, placebo-controlled, two-period, blinded study in 40 HCV genotype 1-infected patients (naïve and treatment-experienced). In period 1, narlaprevir was administered for 7 days as 800 mg three times daily without ritonavir or 400 mg twice daily with 200 mg ritonavir twice daily. In period 2, after a 4-week washout, the same dose and regimen of narlaprevir was administered in combination with PEG-IFN-α-2b for 14 days. Upon completion of period 2, all patients initiated PEG-IFN-α-2b and ribavirin treatment. A rapid and persistent decline in plasma HCV-RNA was observed in both treatment-experienced and treatment-naïve patients during period 1, with a mean viral load decline of at least 4 log10 in all treatment groups. A high percentage of both treatment-experienced (50%) and treatment-naïve (≥ 60%) patients had undetectable HCV-RNA (< 25 IU/mL) after period 2. Standard of care resulted in sustained virological response (SVR) rates of 38% and 81% in treatment-experienced and treatment-naïve patients, respectively. Narlaprevir (with or without ritonavir) alone or in combination with PEG-IFN-α-2b was safe and well tolerated. CONCLUSION: Narlaprevir administration resulted in a robust HCV-RNA decline and high SVR rates when followed by standard of care in both treatment-experienced and treatment-naïve HCV genotype 1-infected patients.