Samir Gupta

Pharmacokinetic interaction between the hepatitis C virus protease inhibitor boceprevir and cyclosporine and tacrolimus in healthy volunteers

The hepatitis C virus protease inhibitor boceprevir is a strong inhibitor of cytochrome P450 3A4 and 3A5 (CYP3A4/5). Cyclosporine and tacrolimus are calcineurin inhibitor immunosuppressants used to prevent organ rejection after liver transplantation; both are substrates of CYP3A4. This two‐part pharmacokinetic interaction study evaluated boceprevir with cyclosporine (part 1) and tacrolimus (part 2). In part 1, 10 subjects received single‐dose cyclosporine (100 mg) on day 1, single‐dose boceprevir (800 mg) on day 3, and concomitant cyclosporine/boceprevir on day 4. After washout, subjects received boceprevir (800 mg three times a day) for 7 days plus single‐dose cyclosporine (100 mg) on day 6. In part 2A, 12 subjects received single‐dose tacrolimus (0.5 mg). After washout, they received boceprevir (800 mg three times a day) for 11 days plus single‐dose tacrolimus (0.5 mg) on day 6. In part 2B, 10 subjects received single‐dose boceprevir (800 mg) and 24 hours later received boceprevir (800 mg) plus tacrolimus (0.5 mg). Coadministration of boceprevir with cyclosporine/tacrolimus was well tolerated. Concomitant boceprevir increased the area under the concentration‐time curve from time 0 to infinity after single dosing (AUCinf) and maximum observed plasma (or blood) concentration (Cmax) of cyclosporine with geometric mean ratios (GMRs) (90% confidence interval [CI]) of 2.7 (2.4‐3.1) and 2.0 (1.7‐2.4), respectively. Concomitant boceprevir increased the AUCinf and Cmax of tacrolimus with GMRs (90% CI) of 17 (14‐21) and 9.9 (8.0‐12), respectively. Neither cyclosporine nor tacrolimus coadministration had a meaningful effect on boceprevir pharmacokinetics. Conclusion: Dose adjustments of cyclosporine should be anticipated when administered with boceprevir, guided by close monitoring of cyclosporine blood concentrations and frequent assessments of renal function and cyclosporine‐related side effects. Administration of boceprevir plus tacrolimus requires significant dose reduction and prolongation of the dosing interval for tacrolimus, with close monitoring of tacrolimus blood concentrations and frequent assessments of renal function and tacrolimus‐related side effects. (HEPATOLOGY 2012;56:1622–1630)

Antiviral activity of boceprevir monotherapy in treatment-naive subjects with chronic hepatitis C genotype 2/3

BACKGROUND & AIMS To examine the antiviral activity of boceprevir, a hepatitis C virus (HCV) protease inhibitor, in HCV genotype (G) 2/3-infected patients. METHODS We assessed boceprevir and telaprevir activity against an HCV G2 and G3 isolates enzyme panel, in replicon, and in phenotypic cell-based assays. Additionally, a phase I study evaluated the antiviral activity of boceprevir monotherapy (200mg BID, 400mg BID, or 400mg TID) vs. placebo for 14 days in HCV G2/3 treatment-naive patients. RESULTS Boceprevir and telaprevir similarly inhibited G1 and G2 NS3/4A enzymes and replication in G1 and G2 replicon and cell-based assays. However, telaprevir demonstrated lower potency than boceprevir against HCV G3a enzyme (Ki=75 nM vs. 17 nM), in the G3a replicon assay (EC₅₀=953 nM vs. 159 nM), and against HCV G3a NS3 isolates (IC₅₀=3312 nM vs. 803 nM) in the cell-based assay. In HCV G2/3-infected patients, boceprevir (400 mg TID) resulted in a maximum mean decrease in HCV RNA of -1.60 log vs. -0.21 log with placebo. CONCLUSIONS In vitro, boceprevir is more active than telaprevir against the HCV G3 NS3/4A enzyme in cell-based and biochemical assays and against G3 isolates in replicon assays. In HCV G2/3-infected treatment-naive patients, decreases in HCV RNA levels with boceprevir (400 mg TID) were comparable to those observed with the same dose in HCV treatment-experienced G1-infected patients.

Single-Dose Pharmacokinetics of Boceprevir in Subjects with Impaired Hepatic or Renal Function

Background and ObjectiveBoceprevir is a novel inhibitor of the hepatitis C virus NS3 protease and was recently approved for the treatment of patients with chronic hepatitis C infection. The objective of this study was to evaluate the impact of impaired hepatic or renal function on boceprevir pharmacokinetics and safety/tolerability.MethodsWe conducted two open-label, single-dose, parallel-group studies comparing the safety and pharmacokinetics of boceprevir in patients with varying degrees of hepatic impairment compared with healthy controls in one study and patients with end-stage renal disease (ESRD) on haemodialysis with healthy controls in the other. Patients with hepatic impairment (mild [n = 6], moderate [n = 6], severe [n = 6] and healthy controls [n = 6]) received a single dose of boceprevir (400 mg) on day 1, and whole blood was collected at selected timepoints up to 72 hours postdose to measure plasma drug concentrations. Patients with ESRD and healthy subjects received a single dose of boceprevir 800 mg orally on days 1 and 4, with samples for pharmacokinetic analyses collected at selected timepoints up to 48 hours postdose on both days. In addition, 4 hours after dosing on day 4, patients with ESRD underwent haemodialysis with arterial and venous blood samples collected up to 8 hours postdose.ResultsIn the hepatic impairment study, there was a trend toward increased mean maximum (peak) plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) of boceprevir with increasing severity of liver impairment. Point estimates for the geometric mean ratio for Cmax ranged from 100% in patients with mild hepatic impairment to 161% in patients with severe hepatic impairment, with the geometric mean ratio for AUC ranging from 91% in patients with mild hepatic impairment to 149% for patients with severe hepatic impairment, relative to healthy subjects. The mean elimination half-life (t1/2) and median time to Cmax (tmax) values of boceprevir were similar in healthy subjects and patients with hepatic impairment. In the renal impairment study, mean boceprevir Cmax and AUC values were comparable in patients with ESRD and in healthy subjects, with point estimates for the geometric mean ratio of 81% and 90%, respectively, compared with healthy subjects. Mean t1/2, median tmax and mean apparent oral total clearance (CL/F) values were similar in healthy subjects and patients with ESRD. Boceprevir exposure was also similar in patients with ESRD on day 1 (no dialysis) and day 4 (dialysis beginning 4 hours postdose), with point estimates for the geometric mean ratio of Cmax and AUC to the last measurable sampling time (AUClast) on day 1 compared with day 4 of 88% and 98%, respectively. Treatment-emergent adverse events were reported in one patient with severe hepatic impairment (mild vomiting) and two patients with ESRD (moderate ventricular extrasystoles, flatulence and catheter thrombosis).ConclusionIn the present studies, the pharmacokinetic properties of boceprevir were not altered to a clinically meaningful extent in patients with impaired liver or renal function. These data indicate that boceprevir dose adjustment is not warranted in patients with impaired hepatic function or ESRD, including those receiving dialysis. Boceprevir is not removed by haemodialysis.

Pharmacokinetic Evaluation of the Interaction between Hepatitis C Virus Protease Inhibitor Boceprevir and 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Inhibitors Atorvastatin and Pravastatin

ABSTRACT Boceprevir is a potent orally administered inhibitor of hepatitis C virus and a strong, reversible inhibitor of CYP3A4, the primary metabolic pathway for many 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors. Thus, the aim of the present study was to investigate drug-drug interactions between atorvastatin or pravastatin and boceprevir. We conducted a single-center, open-label, fixed-sequence, one-way-crossover study with 20 healthy adult volunteers. Subjects received single-dose atorvastatin (40 mg) or pravastatin (40 mg) on day 1, followed by boceprevir (800 mg three times daily) for 7 to 10 days. Repeat single doses of atorvastatin or pravastatin were administered in the presence of steady-state boceprevir. Atorvastatin exposure increased in the presence of boceprevir, with atorvastatin area under the concentration-time curve from time zero to infinity after single dosing (AUCinf) increasing 2.3-fold (90% confidence interval [CI], 1.85, 2.90) and maximum observed concentration in plasma (Cmax) 2.7-fold (90% CI, 1.81, 3.90). Pravastatin exposure was slightly increased in the presence of boceprevir, with pravastatin AUCinf increasing 1.63-fold (90% CI, 1.03, 2.58) and Cmax 1.49-fold (90% CI, 1.03, 2.14). Boceprevir exposure was generally unchanged when the drug was coadministered with atorvastatin or pravastatin. All adverse events were mild and consistent with the known safety profile of boceprevir. The observed 130% increase in AUC of atorvastatin supports the use of the lowest possible effective dose of atorvastatin when coadministered with boceprevir, without exceeding a maximum daily dose of 40 mg. The observed 60% increase in pravastatin AUC with boceprevir coadministration supports the initiation of pravastatin treatment at the recommended dose when coadministered with boceprevir, with close clinical monitoring.

Current drug discovery strategies for treatment of hepatitis C virus infection.

Objectives  Hepatitis C virus (HCV) infection represents a major worldwide‐health problem. The current standard of care is combination therapy with pegylated interferon and ribavirin, which achieves a successful response in only approximately 40% of genotype I patients.