Low-dose risperidone augmentation of antidepressants or anxiolytics is associated with hyperprolactinemia.

Objective: Risperidone in antipsychotic doses induces hyperprolactinemia. The aim of this study was to verify whether the same is true for low doses of risperidone (0.5-2 mg per day) added to antidepressants or anxiolytics.
Methods: Prolactin levels were measured in 4 men (mean age 49.5+/-19.1 years) and 8 women (mean age 31.3+/-8.2 years) inpatients with depressive and anxiety disorders who were treated with risperidone (median doses per day 1.25 mg) for median 15.5 days as an augmentation treatment to antidepressants (n=8), anxiolytics (n=6) and mood stabilizers (n=2).
Results: 11 of 12 patients had hyperprolactinemia. Median plasma prolactin level was 1598 mIU/ml, 95% CI 1 040-2 661 mIU/ml. Significant correlation between risperidone daily dose and plasma prolactin level (Spearman's R=0.655, p=0.02) was detected. Two women suffered from galactorrhea and one from amenorrhea.
Conclusions: Even low doses of risperidone used as an augmentation to antidepressants or benzodiazepines are associated with hyperprolactinemia and can induce endocrinological side effects. The co-medication of antidepressants and benzodiazepines can potentially increase intensity of prolactinemia.