PROLACTIN RESPONSE TO ZOTEPINE IN SCHIZOPHRENIC-PATIENTS

The prolactin response to an antipsychotic drug zotepine, which has bo th antidopaminergic and antiserotonergic effects, was studied in 24 in patients suffering from schizophrenia. The daily dose was 100 mg in th e first week, and 200 mg for the next three weeks. The mean serum conc entrations of prolactin at the daily dose of 200 mg, but not 100 mg, w ere significantly higher than that before treatment. The DELTA prolact in (the change from the pretreatment concentration) was significantly correlated with zotepine concentrations at each week. At low zotepine concentrations, patients with high pre-treatment prolactin concentrati ons showed negative DELTA prolactin. The present study thus suggests t hat at high concentrations zotepine shows predominantly antidopaminerg ic effects, while at low concentrations its antiserotonergic effects a re predominant and/or it acts as a dopamine agonist.