Abstract
In the present study, we compared the plasma levels of the active moiety (i.e. risperidone plus 9-hydroxyrisperidone) in a steady state in 54 Japanese schizophrenic patients with or without emerging extrapyramidal symptoms (EPS and non-EPS groups, respectively) who were treated with 4 mg/day risperidone. No differences were observed in the plasma levels of the active moiety at 4 and 8 weeks after risperiodne administration in both groups. However, the EPS group patients showed a greater number of fluctuations/larger fluctuations in the plasma active moiety levels than those in the non-EPS group. These results suggest that a stable plasma active moiety level maybe important for preventing EPSs during treatment with risperidone.
Acknowledgements
The authors gratefully thank Janssen Research Foundation (Beerse, Belgium) for donating risperidone and 9-hydroxyrisperidone for analyzing the plasma levels of these drugs.