An NIH‑supported randomized trial of 140 pregnant adults with opioid use disorder found that weekly injectable extended‑release buprenorphine produced higher illicit opioid abstinence during pregnancy than daily sublingual buprenorphine, with fewer serious maternal adverse events and no increase in neonatal withdrawal rates.
What the trial actually tested and the primary signal
The study randomized 140 pregnant people with OUD to either weekly subcutaneous extended‑release buprenorphine or the standard daily sublingual buprenorphine (with or without naloxone). It was the first randomized trial comparing these formulations in pregnancy and was supported by the NIH; lead investigator Dr. John Winhusen of the University of Cincinnati reported the higher abstinence signal, and NIDA director Nora Volkow framed the finding as an important advance amid the overdose crisis.
The main, measurable signal: participants receiving the weekly injectable formulation had significantly higher rates of illicit opioid abstinence during pregnancy. At the same time, serious maternal adverse events occurred less often in the extended‑release group, while more mild or non‑serious events were attributed to the medication in that same group.
How the formulation changes exposure, adherence, and trade‑offs
Weekly extended‑release buprenorphine provides steadier plasma levels than daily sublingual dosing, reducing the peak‑and‑trough swings that can trigger cravings or precipitate withdrawal. That pharmacokinetic consistency explains why people who struggle with daily adherence, unstable housing, or high misuse risk are plausibly more likely to remain abstinent when given an injectable weekly option.
However, steadier exposure brings trade‑offs: the trial found more medication‑related non‑serious events among those receiving the injections. Clinicians should weigh the improved adherence and fewer serious events against these milder side effects and discuss expectations with patients before switching formulations.
Side‑by‑side outcomes and practical implications
| Feature | Weekly extended‑release | Daily sublingual |
|---|---|---|
| Trial population | 140 pregnant adults randomized (NIH‑supported) | Same randomized comparator arm |
| Illicit opioid abstinence (during pregnancy) | Significantly higher | Lower than extended‑release in trial |
| Serious maternal adverse events | Less common in trial | More common relative to extended‑release |
| Medication‑related non‑serious events | More often reported | Fewer medication‑related non‑serious events |
| Neonatal opioid withdrawal syndrome (NOWS) | Rates similar to sublingual | Rates similar to extended‑release |
| Postpartum switching | Not breastfeeding participants could switch to monthly ER and maintain non‑inferior abstinence | Standard outpatient sublingual options available |
The table highlights where the trial gives clear directional information and where it does not supply exact numeric thresholds. The result supports offering weekly injectable ER buprenorphine to pregnant patients who have documented adherence problems or frequent cravings on daily dosing; conversely, if a patient experiences intolerable medication‑related side effects, that would be a reason to pause and reassess.
Monitoring checkpoints, breastfeeding, and the next data milestones
Decisions about initiating or switching to weekly ER buprenorphine should incorporate breastfeeding plans: the trial specifically reports a postpartum pathway for participants who were not breastfeeding to switch to a monthly ER formulation and retain abstinence gains. That does not mean extended‑release formulations are contraindicated in breastfeeding, but breastfeeding status was treated as a practical constraint in the study and should shape shared decision‑making in clinics.
Key stop signals clinicians should track: any new serious maternal adverse event, escalating non‑serious medication reactions that interfere with function, and unexpected neonatal concerns at birth. The investigators flagged the need for longer postpartum follow‑up; the next checkpoint will be studies and registry data that report maternal and infant outcomes beyond the immediate perinatal period to confirm sustained safety and effectiveness.
Short Q&A
Q: Does weekly extended‑release prevent neonatal withdrawal?
A: No—NOWS rates were similar between groups in the trial. Extended‑release improved maternal abstinence but did not eliminate neonatal withdrawal risk.
Q: Who should be offered the weekly injections first?
A: Patients with documented difficulty adhering to daily sublingual dosing, frequent cravings or intermittent use, or clinical situations where steady exposure would reduce relapse risk are the clearest candidates.
Q: When should the treatment be paused or changed?
A: Pause or change if the patient develops a serious adverse event, intolerable medication‑related side effects, or if breastfeeding plans make a different formulation preferable; all changes should include close maternal and neonatal monitoring.