Infant Exposure to Methylphenidate and Duloxetine During Lactation

Duloxetine and methylphenidate are commonly prescribed for the management of depression and attention-deficit/hyperactivity disorder (ADHD), respectively. However, little information is available concerning their safety during lactation. The purpose of this case series was to provide additional information to the medical literature concerning infant exposure to methylphenidate and duloxetine through breast milk.

Bioanalytical method (liquid chromatography coupled to mass spectrometry) was developed and validated before its use to determine the concentrations of both medications in breast milk samples.

Case 1: A 30-year-old woman with depression and ADHD took duloxetine 90 mg daily and methylphenidate 36 mg daily during pregnancy and breastfeeding. The newborn was found to have a congenital pulmonary airway malformation. The breastfeeding status was nonexclusive. At week 4 postpartum, the concentration found in the milk was 32.8 ng/mL of duloxetine and 7.9 ng/mL of methylphenidate (estimated relative infant dose [RID] of 0.3% and 0.2%, respectively). Case 2: A 41-year-old women with depression took duloxetine 60 mg daily during pregnancy and lactation. She gave birth to a healthy child. The breastfeeding status was nonexclusive. Cord to maternal plasma concentration ratio was 0.4. At day 6 postpartum, the concentration of duloxetine was 23.6 ng/mL in the foremilk and 14.3 ng/mL in the hindmilk (RID of 0.4% and 0.2%, respectively). At week 6 postpartum, the concentration was 25.2 ng/mL in the foremilk and 29.3 ng/mL in the hindmilk (RID of 0.4% and 0.4%, respectively).

In accordance with previously published data, this case series suggests a minimal exposure to duloxetine and methylphenidate through breast milk. Thus, these drugs are likely compatible with lactation. However, large cohort studies are necessary to evaluate their long-term impact on the exposed infants.