Aim: The role of sex on the association of plasma prolactin levels with risperidone (R) and 9-hydroxyrisperidone (9-OHR) concentrations is investigated. Methods: Plasma R and prolactin concentrations, CYP2D6 and exon 21 and 26 ABCB1 gene variants were studied in 110 patients. Results: In females, a 1 ng/ml increase in R levels was associated with a significant 1.02% increase in prolactin levels. In males, a 1 ng/ml increase in 9-OHR levels was associated with a significant 1.18% increase in prolactin levels. ABCB1 haplotype 12 had significant but opposite effects in males and females. In the combined sample, 9-OHR, but not R levels had significant effects on prolactin levels. Conclusion: Genes had sex-specific effects on risperidone-associated prolactin elevations.
