Effects of aripiprazole on prolactin levels in subjects with schizophrenia during cross-titration with risperidone or olanzapine: Analysis of a randomized, open-label study

Hyperprolactinemia, an adverse effect associated with the use of typical antipsychotics and the atypical antipsychotic risperidone, has both acute and chronic clinical consequences. One option for clinical management is switching to an agent with a lower liability for inducing hyperprolactinemia. This post-hoc sub-analysis of an 8-week, open-label study in outpatients with schizophrenia (CN138-215) examined short-term effects on prolactin levels during a switch from risperidone or olanzapine to aripiprazole 30 mg/day. Three switch strategies were used: (I) immediate aripiprazole initiation with simultaneous immediate discontinuation of olanzapine/risperidone; (II) immediate aripiprazole initiation while tapering off olanzapine/risperidone over 14 days; (III) titrating aripiprazole upwards while tapering off olanzapine/risperidone over 14 days. Changes in prolactin levels from baseline to each last observation carried forward time point were compared with t-tests using Bonferroni correction for multiple comparisons. This sub-analysis included 269 subjects: 105 previously treated with risperidone; 164 previously treated with olanzapine. Mean baseline prolactin levels (ng/mL) were within normal range for the three olanzapine groups (Group-I, 11.7; Group-II, 13.2; Group-III, 11.2), but above normal for the risperidone groups (Group-I, 39.7; Group-II, 48.5; Group-III, 33.5). Following aripiprazole initiation, mean prolactin levels decreased significantly (p < 0.001) at week-1 and were maintained to week-8 in all groups irrespective of prior treatment. Previously elevated prolactin levels in the risperidone groups were reduced to within normal range within 1 week, irrespective of switching strategy. Tolerability was good regardless of prior medication or switching strategy. Overall, rapid decreases of prolactin levels were achieved safely with all three aripiprazole switching strategies. Reversal of hyperprolactinemia during the crossover period indicates the safety and potential utility of aripiprazole addition in patients with elevated prolactin.