Physiologically based pharmacokinetic modeling to predict exposures in healthy Japanese subjects with different CYP2C19 phenotypes: Esomeprazole case study .

Purpose: The objective of this study was to improve the predictive performance of cytochrome P450 (CYP) 2C19 substrates in Japanese subjects using physiologically based pharmacokinetic (PBPK) modeling.

Materials And Methods: Esomeprazole, a CYP2C19 substrate, was selected as a test compound, and the Simcyp simulator was used for pharmacokinetic prediction. The compound file of esomeprazole model developed in healthy Caucasian subjects was applied directly. The population file "Sim-Japanese" in Simcyp was adopted to predict esomeprazole pharmacokinetics in Japanese, while CYP2C19 enzyme abundances in the liver and the gastrointestinal tract for homozygous extensive metabolizers (homo EMs), heterozygous extensive metabolizers (hetero EMs), and poor metabolizers (PMs) were adjusted to be the same as in Caucasians.

Results: The PBPK model predicted esomeprazole exposure after 10-, 20-, and 40-mg doses in Japanese subjects within 1.5-fold of observed values in all three -CYP2C19 phenotypes. The reported concentration-time profiles were mostly well-captured within the 95% prediction intervals.

Conclusion: By adjusting CYP2C19 enzyme abundances levels in the Japanese population, the systemic exposure of esomeprazole in Japanese subjects can be reasonably extrapolated using a PBPK model developed in Caucasian subjects. This analysis serves as a case application for assessing the predictive performance of CYP2C19 substrate in Japanese subjects by using PBPK modeling approach.