Sex differences in changes in prolactin levels and sexual function after switching from risperidone to paliperidone palmitate in schizophrenia

Background and objectives

Hyperprolactinaemia is a significant side effect of antipsychotic medications and may cause sexual dysfunction. Although risperidone and paliperidone can induce prolactin elevation, previous studies suggest that switching from risperidone long-acting injectable (LAI) to paliperidone palmitate (PP) might reduce prolactin concentrations in early psychosis patients. We aimed to evaluate the effect of switching from risperidone to PP on sexual functionality and prolactin levels in patients with schizophrenia.

Methods

We studied 38 patients with schizophrenia who were treated with risperidone (oral or R-LAI) monotherapy at stable doses for at least two months and had an indication to be switched to PP by their psychiatrists. Three assessments were completed: 1) baseline (preswitch), 2) 3 months post-switch, and 3) 6 months post-switch. Prolactin concentrations in plasma were determined. Sexual functioning was assessed with the Arizona Sexual Experience Scale (ASEX). Statistical analyses were conducted in 27 patients who had at least one follow-up visit. Longitudinal changes in prolactin levels and sexual function after switching from risperidone to PP were analysed with linear mixed models. Significance was set at p < 0.05.

Results

Prolactin concentrations were reduced in women after the switch, with a significant time by sex effect (p = 0.035). Antipsychotic doses influenced prolactin levels (p = 0.006), such that higher antipsychotic doses were associated with higher prolactin concentrations. No significant differences were found in ASEX total scores at 6 months after the switch.

Conclusions

In patients with schizophrenia, switching from risperidone to PP was associated with a reduction in prolactin concentrations in women but not men.