Abstract
Direct-acting antiviral agents (DAAs) are established as the standard of care for chronic hepatitis C virus (HCV) infection. One of the newest additions to the HCV arsenal is an oral three-DAA combination therapy (i.e., the 3D regimen) that does not require concomitant use of pegylated interferon. The clinical development program for the 3D regimen has yielded a robust dataset that is inclusive of various dosing schemes and a diverse patient population. Using data from nine phase 1b/2a/2b studies that enrolled patients with HCV genotype 1 infection, population pharmacokinetic models were developed for each component of the 3D regimen (ombitasvir, paritaprevir, ritonavir, and dasabuvir) and for ribavirin, an adjunctive therapy used to enhance therapeutic efficacy in some populations. Formulation effects, accumulation, relative bioavailability, and interactions between DAAs were assessed during model development, and demographic and clinical covariates were identified and evaluated for their effects on drug exposures. Proposed models were assessed via goodness-of-fit plots, visual predictive checks, and bootstrap evaluations. Population pharmacokinetic models adequately described their respective plasma concentration-time data with precise and reliable model parameter estimates and with good predictive performance. Covariates, including age, sex, body weight, cytochrome P450 2C8 inhibitor use, non-Hispanic ethnicity, and creatinine clearance, were associated with apparent clearance and/or apparent volume parameters; however, the magnitude of effect on drug exposure was modest and not considered to be clinically significant. No patient-related or clinical parameters were identified that would necessitate dose adjustment of the 3D regimen in patients with HCV genotype 1 infection.