Risperidone-associated hyperprolactinemia.

Objective: To compare the prolactogenic effects of risperidone, clozapine, and typical antipsychotic agents in an outpatient community-based psychiatric population.

Methods: Prolactin and thyroid-stimulating hormone (TSH) concentrations were measured in 68 outpatients with schizophrenia who were receiving antipsychotic medications and were recruited from a community mental health clinic.

Results: The percentage of women with increased prolactin concentrations was significantly greater in the risperidone group (100%, 12 of 12 patients) than in the clozapine group (25%, 1 of 4) (P = 0.0071) but not in comparison with the typical antipsychotic agent group (83%, 5 of 6) (P = 0.333). The percentage of men with increased prolactin concentrations was significantly greater in the risperidone group (94%, 17 of 18) than in the clozapine group (18%, 3 of 17) (P<0.0001) and in comparison with the typical antipsychotic agent group (27%, 3 of 11) (P = 0.0003). The mean prolactin concentration (all ng/mL +/- standard deviation) was also significantly higher in patients taking risperidone (women, 125.0 +/- 56.6; men, 37.3 +/- 23.9) than clozapine (women, 22.0 +/- 25.9; men, 13.3 +/- 22.4) (female patients, P = 0.0004; male patients, P<0.0001) or typical antipsychotic agents (women, 69.0 +/- 59.8; men, 13. 3 +/- 9.1) (female patients, P = 0.036; male patients, P = 0.0003). In the risperidone group, gender affected prolactin level, with women having higher concentrations than men, but the duration of therapy did not. In this group, prolactin was inversely dependent on age. No difference was noted in TSH concentrations between medication groups.

Conclusion: Risperidone is a potent inducer of hyperprolactinemia in outpatients with schizophrenia in a community population. The higher and more frequently increased prolactin concentrations caused by risperidone could adversely affect patient health and compliance.