Naltrexone use in pregnancy ‘reasonable’ for opioid use disorder option

Key takeaways:

• Gestational age at delivery was similar for naltrexone, buprenorphine and methadone.
• Naltrexone was associated with lower neonatal abstinence syndrome compared with buprenorphine or methadone.

Current data support naltrexone use as medication for opioid use disorder in pregnancy, with encouraging perinatal outcomes, according to a systematic review published in Obstetrics & Gynecology.

Naltrexone is a mu-opioid receptor antagonist available in oral, implant and injectable forms and is currently FDA approved as a therapy for opioid use disorder (MOUD).

“Based on the data that are currently published, naltrexone is a reasonable choice for medication of opioid use disorder with reassuring maternal and neonatal outcomes, when compared to methadone or buprenorphine,” Marcela C. Smid, MD, MA, MS, of the department of obstetrics and gynecology at the University of Utah Health, told Healio. “We hope that these data will support pregnant people and their clinicians in having a more informed discussion about medication for opioid use disorder in pregnancy.”

Smid and colleagues conducted a systematic review and electronically searched PubMed, CINAHL, Embase, PsycINFO, conference proceedings and ClinicalTrials.gov through May 2023. Researchers identified four retrospective cohort studies and one prospective cohort study that evaluated oral, implant or extended-release naltrexone compared with methadone or sublingual or extended-release buprenorphine use by pregnant women with opioid use disorder.

The primary outcome was gestational age at delivery and neonatal abstinence syndrome.

In total, four studies had data on gestational age at delivery in weeks for 748 pregnant women with no difference observed between the naltrexone group and the buprenorphine or methadone groups. Three studies had data on neonatal abstinence syndrome for 641 newborns, and all studies observed a lower risk in the naltrexone group compared with the buprenorphine or methadone groups with RRs ranging from 0.08 to 0.15.

In addition, researchers noted no differences in the proportion of vaginal or preterm births between those who received naltrexone and those who received buprenorphine or methadone. In the largest included study of 391 pregnant women, those who received naltrexone had significantly higher birth weight compared with those who received methadone or buprenorphine. However, the other three studies with 362 pregnant women found no mean difference in birth weight between groups.

“As the opioid epidemic continues to affect all types of people in the U.S., including pregnant people, we needed larger studies that follow pregnant people and their infants and their outcomes long term,” Smid said. “The University of Utah is a clinical site and one question we are hoping to answer is what are the maternal, infant and child outcomes of pregnant people who took naltrexone.”

For more information:

Marcela C. Smid, MD, MA, MS, can be reached at u6008308@umail.utah.edu.