Characterizing the Pharmacokinetic Interaction Between Simeprevir and Odalasvir in Healthy Volunteers Using a Population Modeling Approach

The aim of this study was to characterize the pharmacokinetic drug–drug interaction (DDI) between simeprevir (NS3/4A protease inhibitor) and odalasvir (NS5A inhibitor) after oral administration to support the design and dose selection of clinical studies with this combination for the treatment of chronic hepatitis C infection (HCV). Simeprevir and odalasvir plasma concentrations from 30 healthy subjects receiving these drugs in monotherapy as well as in combination were pooled and analyzed using a population pharmacokinetic modeling approach. Previous pharmacokinetic models developed to characterize the pharmacokinetics for each drug were used as starting point. The dual effect of simeprevir and odalasvir on their pharmacokinetic parameters was explored. Simulations were performed to assess the impact of the DDI on exposure parameters. In presence of odalasvir, the relative bioavailability of simeprevir increased by 26% and the apparent clearance was reduced following competitive inhibition depending on odalasvir plasma concentrations, with an inhibitory constant (Ki) estimated to be 1610 ng/mL. The apparent odalasvir clearance was reduced by simeprevir plasma concentrations following an Imax model, characterized by a maximum inhibitory effect of 46.7% and an IC50 of 257 ng/mL. Model-based simulations indicated that both Cmax and AUC24h increased for both drugs, when co-administered. The pharmacokinetic model adequately describes the time course of plasma concentrations and their variability when simeprevir and/or odalasvir were orally administered. This model can be used as a first step to predict the exposures of concomitant administration of simeprevir and odalasvir in HCV-infected subjects. Data from study AL355-602 (NCT02512562) were used for this analysis.