Extended-Release vs Sublingual Buprenorphine in Pregnancy Through 12 Months Post Partum: A Randomized Clinical Trial

Treating opioid use disorder (OUD) in pregnancy with sublingual buprenorphine is an evidence-based practice, but it has disadvantages that could be addressed with an extended-release formulation.

To evaluate the effectiveness and safety of extended-release buprenorphine vs sublingual buprenorphine for OUD in pregnancy through 12 months post partum.

This 2-group, open-label, noninferiority, randomized clinical trial was conducted between July 2, 2020, and October 30, 2024, among adults with OUD and a singleton pregnancy of 6 to 30 weeks' gestational age at 13 outpatient cross-disciplinary peripartum OUD treatment sites.

Randomization to sublingual or extended-release buprenorphine (weekly formulation during pregnancy, monthly formulation optional post partum if not breastfeeding).

The primary and key secondary outcomes were illicit opioid abstinence during pregnancy and the postpartum period, respectively, defined as the proportion of weekly collected urine samples negative for illicit opioids. If noninferiority was demonstrated at a margin of 0.15, testing for superiority was planned. Key secondary infant outcomes from medical records were opioid treatment for neonatal opioid withdrawal syndrome (NOWS; yes or no) and number of opioid treatment days for NOWS.

Among 140 randomized participants, the mean (SD) age was 31.2 (4.6) years. There were 10 Black participants (7.1%), 10 Hispanic participants (7.1%), 116 (82.9%) White participants, and 14 participants (10.0%) who belonged to additional groups. All but 2 were already prescribed sublingual buprenorphine. Study completion was 98% through pregnancy (137 participants) and 81% through 12 months post partum (114 participants). Illicit opioid abstinence was higher during pregnancy for participants receiving extended-release vs sublingual buprenorphine (82.5% vs 72.6%; mean difference, 9.84 [95% CI, 1.72 to 17.95] percentage points; P = .009). Postpartum abstinence rates declined and were similar in both groups (60.2% vs 59.5%; mean difference, 0.65 [98% CI, -12.72 to 14.02] percentage points; P = .45). Those receiving extended-release buprenorphine experienced fewer serious adverse events during pregnancy (8.7% vs 26.8%; P = .007) and post partum (6.0% vs 18.6%; P = .04). Nonserious adverse events rates did not differ between groups, but more were deemed medication-related for extended-release participants during pregnancy (26.1% vs 7.0%; P = .003). Infants exposed to extended-release vs sublingual buprenorphine did not differ in need for opioid treatment (30.2% vs 26.5%; relative risk, 1.14 [98% CI, 0.54 to 1.99]; P = .64) or mean (SE) treatment days (10.9 [2.2] vs 14.8 [3.0] days; relative risk, 0.73 [98% CI, 0.36 to 1.51]; P = .28). At birth, extended-release-exposed neonates had larger mean (SE) head circumferences than those exposed to sublingual buprenorphine (34.0 [0.2] vs 33.4 [0.2] cm; mean difference, 0.63 [95% CI, -0.00 to 1.26] cm; P = .049).

The findings of this randomized clinical trial support weekly extended-release buprenorphine for OUD treatment during pregnancy.

ClinicalTrials.gov Identifier: NCT03918850.