Early serum levels of neuroleptics do not predict therapeutic response in schizophrenia.

Thirty-six acute schizophrenics were included in a 28-day open treatment study with the neuroleptic perazine. Peak serum levels of parent drug and its main inactive metabolite desmethyl-perazine were assessed 2 hours after an oral test dose given at the beginning of the study. Whereas peak levels of perazine were not significantly different in treatment responders and nonresponders, desmethyl-perazine was significantly higher in nonresponders. The ratio between desmethyl-perazine and perazine was not predictive of (non-) response to neuroleptic treatment in schizophrenia.