Differential olanzapine plasma concentrations by sex in a fixed-dose study

This study examined plasma concentrations of olanzapine by sex (20 males an d seven females) in an 8-week fixed-dose study. Dosing was 12.5 mg/day for the first week, then 25 mg/day. Trough plasma concentrations were drawn at weeks 1, 3, 5 and 8. Women volunteers were found to have significantly high er plasma concentrations than men. This difference was first evident at stu dy week 5. Women have higher plasma concentrations of olanzapine, possibly due to differences in metabolism of the CYP450 isoenzyme system. (C) 1999 E lsevier Science B.V. All rights reserved.