Population pharmacokinetic modeling of quetiapine after administration of seroquel and seroquel XR formulations to Western and Chinese patients with schizophrenia, schizoaffective disorder, or bipolar disorder.

A population model describing quetiapine pharmacokinetics (PK) in Western and Chinese patients following oral administration of immediate-release (IR) and extended-release (XR) formulations was developed using plasma concentrations in 127 patients from 5 studies with quetiapine IR and/or XR in Western patients and 1 study with quetiapine XR in Chinese patients. A 1-compartmental model with first-order absorption and first-order elimination adequately described the quetiapine PK. The typical apparent volume of distribution and elimination rate constant of quetiapine were 574 L and 0.12 h(-) (1) , respectively. The estimated population absorption rate constants were 1.46 and 0.10 h(-1) for quetiapine IR and XR, respectively. Covariate analysis revealed that race was not a significant covariate influencing the PK of quetiapine. Simulation conducted with the final quetiapine population PK model predicted that the administration of a 200-mg twice-daily dose of quetiapine IR in Chinese patients would achieve a steady-state AUC (AUCss ) ± standard deviation of 3087 ± 1480 ng · h/mL, which is in close agreement with the reported value (3538 ± 1728 ng · h/mL). The model also predicted that once-daily administration of 300 mg quetiapine IR or XR would achieve similar exposure in terms of AUCss in Chinese patients.