Atomoxetine as a Viable ADHD Treatment in Breastfeeding Mothers: Evidence From Human Milk Pharmacokinetic Analysis

Atomoxetine is a selective norepinephrine reuptake inhibitor prescribed for the management of attention-deficit hyperactivity disorder (ADHD). Untreated ADHD can significantly damage a woman's well-being and often worsens during postpartum. As a result, physicians often recommend continued medication therapy during pregnancy and postpartum; however, there is limited data evaluating the safety of atomoxetine's transfer into human milk.

The InfantRisk Center's Human Milk Biorepository collected milk samples from 10 lactating participants who were treated with atomoxetine 40 to 100 mg daily. The concentrations of atomoxetine in milk were quantified using liquid chromatography-tandem mass spectrometry.

The mean atomoxetine concentration in milk was 12 ng/mL at an adjusted daily dose of 80 mg, resulting in a relative infant dose (RID) of 0.19%. To estimate a worst-case scenario, the maximum concentration of 39 ng/mL was used to simulate a worst-case scenario RID of 0.65%. There were no reported adverse effects in the breastfed infants.

The transfer of atomoxetine into human milk is minimal, with a 0.19% RID, well below the 5% safety threshold for psychoactive medications. The minimal transfer suggests that maternal atomoxetine use poses a very low risk to breastfed infants, making it a suitable choice for medication management of ADHD in lactating women.