Buprenorphine (BUP) is the preferred treatment for opioid use disorder during pregnancy
but can cause neonatal opioid withdrawal syndrome (NOWS). Norbuprenorphine (NorBUP),
an active metabolite of BUP, is implicated in BUP-associated NOWS. We hypothesized that
BUP, a low-efficacy agonist of mu opioid receptors, will not antagonize NorBUP, a high-
efficacy agonist of mu opioid receptors, in producing NOWS. To test this hypothesis, we
treated pregnant Long-Evans rats with BUP (0, 0.01, 0.1 or 1 mg/kg/day)±NorBUP (1 …

OBJECTIVES/GOALS: Buprenorphine (BUP) is used for opioid use disorder during
pregnancy but causes neonatal opioid withdrawal syndrome (NOWS). The goal of this study
was to determine the contribution of the active metabolite, norbuprenorphine (NorBUP), to
the development of NOWS when the parent drug, BUP, is administered during pregnancy.
METHODS/STUDY POPULATION: Subcutaneously implanted osmotic minipumps delivered
BUP (0, 0.01, 0.1 or 1 mg/kg/day)±NorBUP (1 mg/kg/day) to pregnant Long-Evans rats from …