Background: The clinical development program of the direct-acting antiviral (DAA) combination therapy of paritaprevir (coadministered with ritonavir) and ombitasvir, with and without dasabuvir (3-DAA [3D] and 2-DAA [2D] regimens, respectively) used in the treatment of chronic hepatitis C infection has generated a robust dataset across various dosing regimens and patient populations.
Objective: The current analysis aimed to characterize the population pharmacokinetics in patients without cirrhosis ('non-cirrhotic') and with compensated cirrhosis ('cirrhotic'), while accounting for differences across hepatitis C virus (HCV) genotypes (GT) 1, 2, and 4, multiple regimens (3D regimen ± ribavirin for GT1 in global studies, 2D regimen for subgenotype 1b in Japan, 2D regimen + ribavirin for GT2 in Japan, and 2D regimen + ribavirin for GT4), and ethnicities.
Methods: Pharmacokinetic data from nine clinical studies (~ 1850 patients) were used to model the population pharmacokinetics of each component of the DAA regimens. Model development was performed in stages, starting with an initial base model. Covariate-parameter relationships were then assessed using forward inclusion/backward elimination procedures. Model development was guided by goodness-of-fit plots, likelihood ratio tests, plausibility of parameter estimates, and knowledge of DAA, ritonavir, and ribavirin pharmacokinetics. Paritaprevir, ombitasvir, and ritonavir pharmacokinetics were described by a one-compartment model, while dasabuvir and ribavirin pharmacokinetics were characterized by a two-compartment model.
Results: The analysis showed generally overlapping exposures between compensated cirrhotic and non-cirrhotic patients or between subgroups of the identified significant covariates. The largest differences were the approximately 30-60% higher dasabuvir and paritaprevir exposures in compensated cirrhotic patients.
Conclusion: These differences did not warrant dose adjustments for the DAAs when used in HCV-infected patients with compensated cirrhosis.