Prolactin level during 5 years of risperidone treatment in patients with psychotic disorders.

OBJECTIVE To investigate prolactin levels and related side effects in 128 men and 90 women initially treated with risperidone. METHOD Patients initially treated with risperidone were followed over 5 years, during which 45% were switched to other antipsychotic drugs. RESULTS Initially, prolactin levels were fivefold the norm in women, and threefold in men. Diagnosis did not affect the prolactin level if adjustment for sex, current age, and age at onset of psychosis was applied. Prolactin levels did not correlate significantly neither with any Positive and Negative Symptom Scale item or subscale, nor with side effects. Drugs other than risperidone were not associated with high prolactin levels. For patients on continuous monotherapy risperidone treatment, there was a marked linear reduction of prolactin level over all 5 years. CONCLUSION Risperidone induces a higher prolactin elevation than other atypical antipsychotics, but the effect adapts over time. Prolactin was not associated with expected side effects (e.g. sexual, mental, or weight gain).