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Brexanolone use while Breastfeeding

Drugs containing Brexanolone: Zulresso

Medically reviewed by Last updated on Jan 29, 2021.

Brexanolone Levels and Effects while Breastfeeding

Summary of Use during Lactation

Because of the low amounts of brexanolone in milk and low oral bioavailability, brexanolone would not be expected to cause any adverse effects in breastfed infants. If brexanolone is required by the mother, it is not a reason to discontinue breastfeeding.

Drug Levels

Maternal Levels. Brexanolone is the pharmaceutical name for the naturally occurring hormone allopregnanolone. Brexanolone has an oral bioavailability of less than 5% in adults.

Twelve healthy women who were less than 6 months postpartum received an intravenous infusion of brexanolone titrated to a maximum of 90 mg/kg per hour for 60 hours. Breastmilk was collected at random times, but at least every 12 hours, daily for 7 days. Allopregnanolone was measured in maternal serum and breastmilk. Breastmilk levels were not reported, but closely paralleled serum levels which averaged 71 mcg/L and had an average serum half-life of 11.3 hours. Milk levels fell below the limit of detection (5 mcg/L) in most women by about 3 days after the end of the infusion.[1] These data were incorporated into a population pharmacokinetic model that predicted that 95% of patients have milk allopregnanolone levels <10 mcg/L at 36 hours after the end of the infusion. The predicted weight-adjusted percent of maternal dosage was 1.3%.[2] The product information reports that in this study, the amount in milk was 1% to 2% of the weight-adjusted maternal dosage.

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

Relevant published information was not found as of the revision date.

Effects on Lactation and Breastmilk

In a study of 12 healthy women given a 60-hour infusion of brexanolone, there were no reports of effects on milk production according to the manufacturer.


Hoffmann E, Wald J, Colquhoun H. Evaluation of breast milk concentrations following brexanolone iv administration to healthy lactating women. Am J Obstet Gynecol 2019;220:S554. Abstract. doi:10.1016/j.ajog.2018.11.873. [CrossRef]
Hoffmann E, Wald J, Dray D, et al. Brexanolone injection administration to lactating women: Breast milk allopregnanolone levels. Obstet Gynecol. 2019;133 Suppl 1:115S–Abstract 30J. [CrossRef]

Substance Identification

Substance Name


CAS Registry Number


Drug Class




Progesterone Congeners


Antidepressive Agents

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Further information

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