Differential add-on effects of aripiprazole in resolving hyperprolactinemia induced by risperidone in comparison to benzamide antipsychotics

Hyperprolactinemia is associated with typical antipsychotic agents and atypical antipsychotics such as risperidone and amisulpride. This study investigates the effects of 8-week adjunctive treatment with aripiprazole in patients with hyperprolactinemia induced by risperidone in comparison to benzamide antipsychotics (amisulpride and sulpiride). Aripiprazole was administered to 24 patients with antipsychotic-induced hyperprolactinemia. The doses of pre-existing antipsychotics were fixed, while the aripiprazole dose was 5-20. mg/day during the 8-week study period. Serum prolactin levels were measured at weeks 4 and 8. Symptoms and side effects were assessed using the Positive and Negative Syndrome Scale (PANSS), Arizona Sexual Experience Scale, Abnormal Involuntary Movement Scale, Simpson-Angus Scale, Barnes Akathisia Scale, and metabolic measures at weeks 2, 4 and 8. Mean (standard error) prolactin levels decreased from 77.0 ± 13.3. ng/mL to 18.3 ± 2.1. ng/mL (p< 0.001 vs. baseline), from 144.9 ± 24.4. ng/mL to 127.5 ± 21.7. ng/mL (p= 0.099 vs. baseline) and 71.4 ± 24.6. ng/mL to 43.3 ± 14.7. ng/mL (p= 0.106 vs. baseline) for those taking risperidone, amisulpride, and sulpiride, respectively. For those who took risperidone before the study started, 14 of 15 (93.3%) patients had normalized prolactin levels, while only 1 of 10 (10%) taking benzamide antipsychotics had normalized prolactin levels. The PANSS score improved significantly, and aripiprazole had no significant influence on metabolic measures or scales of movement side effects. Adjunctive aripiprazole treatment reversed effectively hyperprolactinemia induced by risperidone, but was less effective for that induced by benzamide antipsychotics. Trial registration: clinicaltrials.gov Identifier: NCT00541554.