Objective: To quantify the transfer of risperidone and its active metabolite 9-hydroxyrisperidone into breast milk, estimate the amount the infant receives, measure infant plasma concentrations, and clinically assess the safety of breast feeding during maternal risperidone administration. case summaries: The transfer of risperidone and 9-hydroxyrisperidone into milk was studied in 2 breast-feeding women and one woman with risperidone-induced galactorrhea. Plasma samples were available from 2 of the women and from both breast-fed infants. The milk/plasma concentration ratio determined in 2 women was <0.5 for both compounds. The calculated relative infant "doses" were 2.3%, 2.8%, and 4.7% (as risperidone equivalents) of the maternal weight-adjusted doses. Risperidone and 9-hydroxyrisperidone were not detected in the plasma of the 2 breast-fed infants studied, and no adverse effects were noted.
Discussion: Risperidone therapy is sometimes necessary in breast-feeding women, raising the issue of safety in the exposed infants. Our study shows that the relative infant dose is lower than the arbitrary 10% level of concern. The data provide clear guidance on infant exposure for the cases presented.
Conclusions: Maternal risperidone therapy is unlikely to be a significant hazard for the breast-fed infant in the short term. Nevertheless, decisions on whether a woman may breast-feed should be made as an individual risk-benefit analysis.