Population Pharmacokinetics of Paliperidone Palmitate (Once-Monthly Formulation) in Japanese, Korean, and Taiwanese Patients With Schizophrenia.

The paliperidone pharmacokinetics after intramuscular administration of once-monthly paliperidone palmitate in Japanese patients were studied in 3 phase 1 studies and in 2 phase 3 studies performed in Japan, Korea, and Taiwan. These data (Japanese, n = 509; Korean, n = 31; Taiwanese, n = 47) were used to describe the paliperidone palmitate pharmacokinetics in Japanese, to compare with non-Japanese, and to validate the historical population pharmacokinetic (Pop-PK) model for paliperidone palmitate, developed using data from studies in patients with schizophrenia outside Japan. The final historical Pop-PK model, including all significant patient covariates of Japanese studies, was used to simulate paliperidone plasma concentration-time data using nonlinear mixed effects, followed by comparison with actual data. Visual predictive checks displayed considerable overlap between predicted and actual plasma concentrations; the majority of observations were within the 90% prediction interval. Japanese, Korean, and Taiwanese patients had comparable plasma concentrations. Covariate distributions demonstrated comparatively lower median body mass index in Japanese, Korean, and Taiwanese patients versus rest-of-world population. Prediction errors for the data set used for external validation were within cutoff values, confirming accuracy/precision of the model. Paliperidone pharmacokinetics were adequately predicted for Japanese studies using the historical Pop-PK model, confirming its robustness. Pharmacokinetics in Japanese, Korean, and Taiwanese patients with schizophrenia were comparable with rest-of-world population.