Balancing Mental Health and Breastfeeding: Evaluating the Transfer of Lurasidone Into Human Milk

Objective: Lurasidone, a second-generation atypical antipsychotic, lacks significant published data on its transfer into human milk during lactation. The objective of this study was to (1) quantify the transfer of lurasidone into human milk, allowing for an estimation of maternal drug exposure to the breastfed infant and (2) report observations of infants exposed to lurasidone via breast milk.

Methods: Milk samples and health histories were collected from 9 lactating mothers who donated milk samples to the InfantRisk Human Milk Biorepository while taking lurasidone (20-80 mg/day) from 2022 to 2024. The drug concentration-time profile of lurasidone in milk was determined using liquid chromatography-mass spectrometry, and maternal lurasidone doses were standardized to 40 mg/day.

Results: Lurasidone had an average milk concentration of 39.5 ng/mL at the 40 mg/day standardized dose. The relative infant dose (RID) was 1.16%, which is below the standard 10% threshold for infant safety. Even using the highest observed individual concentration of 174 ng/mL, the calculated RID was 3.03%. There were no maternal reports of adverse effects in the infants exposed to varying degrees of lurasidone in milk.

Conclusion: The levels of lurasidone observed in all participants' milk samples were exceedingly low. The subsequently low RID is below the 10% threshold for infant safety, suggesting that the transfer of maternal lurasidone into human milk is clinically insignificant and poses minimal risk to a breastfed infant.