Is Naltrexone safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Naltrexone. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
A 1.5-month-old breastfed infant of a mother who was taking 50 mg of oral naltrexone daily during pregnancy and lactation was reportedly healthy with no naltrexone-related adverse effects.[ 1 ]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Naltrexone is used as maintenance treatment of opiate dependence in opiate-detoxified patients. Peak plasma levels of 40 to 50 mcg/L at 1 hour after the dose and average plasma levels of 3 to 5 mcg/L have been reported in adults taking daily maintenance doses. Oral bioavailability is 5 to 40% in adults. Naltrexone is metabolized to active beta-naltrexol and to other inactive metabolites. Maternal Levels. One lactating woman who was 1.5 months postpartum and taking 50 mg of oral naltrexone daily during pregnancy and lactation had her milk sampled several times between 3.7 and 23 hours after her dose. Naltrexone milk levels were undetectable ( 2 mcg/L) by 8 hours after the dose while beta-naltrexol milk levels remained detectable throughout the study period and averaged 46 mcg/L. The half-life of elimination from milk was 2.5 and 7.7 hours for naltrexone and beta-naltrexol, respectively. The authors estimated that an exclusively breastfed infant would receive about 7 mcg/kg daily of naltrexone including the active metabolite, equivalent to 0.86% of the maternal weight-adjusted dosage.[ 1 ] In a study of the pharmacokinetics of naltrexone in pregnant women, one mother had a milk sample analyzed for naltrexone and 6-beta-naltrexol 25 days after her last injection of long-acting naltrexone XR and 31 days postpartum. The naltrexone concentration was 9.58 mcg/L and the 6-beta-naltrexol concentration was 14.7 mcg/L. The molar sum of the two values indicated that the relative infant dose was 0.83% of the maternal dose.[ 2 ] Infant Levels. A 1.5 month-old breastfed male infant of a mother who was taking 50 mg of oral naltrexone daily during pregnancy and lactation had undetectable ( 2 mcg/L) plasma levels of both naltrexone and beta-naltrexol 9.5 hours after the maternal dose, 30 minutes after starting a feeding.[ 1 ] In a study of the pharmacokinetics of naltrexone in pregnant women, a 31-day-old breastfed infant had a plasma sample analyzed for naltrexone and 6-beta-naltrex
Alternatives LactMed lists
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.