Excretion of methylphenidate in breast milk.

A 31-year-old woman with narcolepsy had used methylphenidate regularly before she became pregnant. During pregnancy and the first months postpartum, the drug was discontinued. When she started work after her maternity leave, the need for methylphenidate reappeared. She had a desire to continue breast-feeding, and the question was thus raised as to whether the use of methylphenidate was compatible with breast feeding. Her daily methylphenidate dose was 5 mg in the morning and 10 mg at noon, using immediate-release tablets (Ritalin, Novartis, Switzerland). After giving written informed consent, maternal serum and breast milk were obtained at the following five points of time: immediately before the morning dose at 8 a.m., just before the dose at noon, and 4, 8, and 21 hours after the dose at noon. The first three samples were from foremilk, whereas the two last samples were from hindmilk. Concentrations of methylphenidate were analyzed by liquid chromatographymass spectrometry with a limit of quantification of 0.3 ng/ ml. The maternal serum concentrations in the five samples were <0.3, 2.3, 3.8, 1.7, and <0.3 ng/ml, respectively. The corresponding milk concentrations were <0.3, 2.4, 5.9, 1.4, and <0.3 ng/ml.