Differential effects of typical and atypical antipsychotic medication on plasma prolactin levels

Previous studies have found that prolactin levels are elevated following treatment with typical antipsychotic medication (Meltzer et al 1978), but are not significantly elevated with clozapine (Lieberman et al 1986). Animal studies suggest that the putative atypical agent risperidone produces a more marked increase in prolactin level than an equivalent dosage of a typical agent (Bowden et al 1992). The purpose of this study was to examine the differences in prolactin response following treatment with fluphenazine, risperidone and clozapine in a group of treatment naive patients in their first episode of psychosis. Forty-nine patients who met DSM-III-R criteria for schizophrenia (n=30) or schizoaffective disorder (n= 19) were entered into the study. Twenty-four patients (15M, 9F) were treated with fluphenazine (5-20 mg/day), 14 patients (6M, 8F) with clozapine (titrated to 150 mg/day by day 9) and 11 (SM, 6F) with risperidone (6 mg/day by day 3). Blood was drawn for plasma prolactin assay at baseline, weeks 1, 2, 3, 4, 5, 6, and 8 of treatment. Results will be presented and the relevance of risperidoneʹs 5-HT2/dopamine D2 antagonist profile will be discussed.