Methadone levels in human milk

Pregnant women on methadone maintenance therapy frequently want to nurse yet are often discouraged from doing so because of concern about the amount of methadone that may be in the breast milk. This study analyzed the levels of methadone in the milk of nursing mothers and compared these levels to those in other published reports. Fourteen breast milk samples were obtained from 8 women maintained on methadone doses of 25 to 180 mg/day. Methadone levels in milk ranged from 27 to 260 ng/ml, with a mean level for the group of 95 ng/ml. The mean daily methadone ingestion, based on a newborn intake of 475 ml/day of breast milk, was 0.05 mg/day. This level is small and consistent with those in other published reports. Breastfeeding duration ranged from 2.5 to 21 months. There were no adverse events associated with breastfeeding or weaning. This study supports the compatibility of breastfeeding and methadone maintenance therapy.