Adjunctive treatment with aripiprazole for risperidone-induced hyperprolactinemia.

BACKGROUND: Antipsychotics have been used for more than 50 years in the treatment of schizophrenia and many other psychiatric disorders. Prolactin levels usually increase in patients treated with risperidone. Aripiprazole, which has a unique effect as an antipsychotic, is a D2 receptor partial agonist. It is an atypical antipsychotic with limited extrapyramidal symptoms. Since it acts as an antagonist in hyperdopaminergic conditions and as an agonist in hypodopaminergic conditions, it does not have adverse effects on serum prolactin levels. The present study aimed to investigate the effect of aripiprazole on risperidone-induced hyperprolactinemia.

METHODS: This before-and-after clinical trial was performed in 30 patients. Baseline prolactin levels were measured in all patients who were candidates for treatment with risperidone. In subjects with elevated serum prolactin, aripiprazole was added to their treatment. Serum prolactin levels were measured during the first week, second week, and monthly thereafter for at least 3 months or until prolactin levels became normal. The data were analyzed using Stata version 11 software. Survival analysis and McNemar's test were also performed.

RESULTS: The mean age of the participants was 30.8 years. Prolactin levels normalized in 23 (77%) participants during the study, and menstrual disturbances normalized in 25 (83.3%). Prolactin levels normalized in most patients between days 50 and 110. The median time to recovery based on normalization of prolactin was 84 days. Psychotic symptoms were present in 26 subjects at baseline, but in only two by the end of the study.

CONCLUSION: The results of this study confirm the effects of aripiprazole in reducing risperidone-induced hyperprolactinemia and its sequelae. Aripiprazole also led to significant improvements in psychotic symptoms when compared with those present prior to treatment with aripiprazole.