Prolactin levels in risperidone treatment of first-episode schizophrenia

To evaluate the risperidone effect on prolactin (PRL) levels and to analyse the relation between PRL change and treatment response in first-episode schizophrenia patients.

Patients with a first-episode of schizophrenia who were consecutively admitted for hospitalisation participated in a longitudinal follow-up study that included clinical evaluation (PANSS) and PRL assessment. All patients were treated under open conditions with risperidone.

Risperidone in an average dose lower than 4 mg significantly improved both positive and negative symptoms. Co-operating responders undergoing maintenance therapy showed a mild trend towards further long-term improvement. At the end of acute treatment the average elevation of PRL levels almost doubled the baseline value. There was a trend among responders to return to their initial values during long-term therapy. Three-quarters of the subjects had hyperprolactinaemia at the end of acute treatment (44 days), and after 1 year about one-quarter had hyperprolactinaemia. No significant correlation between PRL change and PANSS score change was found.

There is a considerable variation of PRL elevation among subjects. In some patients the development of tolerance of the PRL-elevating effect was observed. Risperidone-induced changes of PRL levels may not be associated with treatment response.