Background: Breastfeeding among lactating people with opioid use disorder taking buprenorphine monotherapy is generally accepted, as low concentrations of buprenorphine and metabolites in human milk have been well-established. The use of buprenorphine-naloxone for pregnant and lactating people with opioid use disorder is expanding and there is no information available regarding the concentrations of naloxone and their metabolites in human milk to recommend the use of this combination medication during lactation.
Research aims: To determine the concentrations of buprenorphine and naloxone and their primary metabolites in human milk, maternal plasma, and infant plasma, among lactating buprenorphine-naloxone maintained people and their infants.
Methods: Four lactating buprenorphine-naloxone maintained people provided plasma and human milk samples on Days 2, 3, 4, 14, and 30 postpartum. Infant plasma was obtained on Day 14.
Results: Concentrations of buprenorphine, norbuprenorphine and their glucuronide metabolites were present in maternal plasma and human milk at low concentrations, consistent with previous research in lactating buprenorphine monotherapy participants. Naloxone was not detected, or was detected at concentrations below the limit of quantification, in maternal plasma and in all except one human milk sample at Day 30. Naloxone was not detected or detected at concentrations below the limit of quantification in all infant plasma samples.
Conclusion: Results support the use of buprenorphine-naloxone by lactating people who meet appropriate criteria for breastfeeding.
Keywords: breastfeeding; buprenorphine; buprenorphine-naloxone; lactation; maternal opioid use disorder treatment; naloxone; opioid antagonist treatment; opioid exposed infants.