PLYMOUTH MEETING, PA — Adverse-event reports for Braeburn’s Brixadi remained low and relatively stable during its first 18 months on the U.S. market, according to a company-funded study examining federal postmarketing safety reports for the long-acting injectable opioid-use-disorder treatment and a competing formulation.
Published in the Journal of Substance Use and Addiction Treatment, the retrospective analysis compared reports submitted to the Food and Drug Administration Adverse Event Reporting System, or FAERS, during the first 18 months after the U.S. commercial launches of Brixadi and Sublocade. Both are extended-release injectable forms of buprenorphine approved for moderate-to-severe opioid use disorder.
Researchers examined Sublocade reports from March 2018 through August 2019 and Brixadi reports from September 2023 through February 2025. Reporting rates were calculated per 1,000 estimated patients treated and per 1,000 units sold.
An estimated 45,161 patients received Brixadi during the period, compared with 13,120 for Sublocade. FAERS received 1,038 case reports containing 2,080 adverse-event terms for Brixadi, versus 1,844 reports containing 3,848 terms for Sublocade. A single case report can contain multiple adverse-event terms.
Withdrawal syndrome and injection-site pain were the two most frequently reported events across both products at 18 months. For Brixadi, the reporting rates per 1,000 estimated patients were 5.7 for withdrawal syndrome and 1.6 for injection-site pain, compared with 40.6 and 33.6, respectively, for Sublocade.
The researchers found adverse-event reporting rates were generally lower for Brixadi than Sublocade across the postlaunch intervals examined. Brixadi reporting remained relatively stable across successive six-month periods, while total adverse events, withdrawal syndrome and injection-site reactions reported for Sublocade were highest during its first six months and declined thereafter.
The study cautioned against interpreting those differences as comparative incidence rates or proof that one drug caused fewer adverse events. FAERS relies on spontaneous reports, not all adverse events are reported, and reports can contain incomplete information or coding errors. The database also cannot establish that a reported event was caused by a drug.
Researchers further noted that differences in product administration, market timing and familiarity with long-acting injectable buprenorphine may influence reporting. Brixadi entered the U.S. market several years after Sublocade, when clinicians and patients had more experience with the drug class.
“Postmarketing reporting to the FAERS helps give us a fuller picture by providing safety insights across the broader U.S. patient population,” Brian Dawson, chief medical officer at Ideal Option and the study’s lead author, stated in Braeburn’s release.
The analysis concluded that adverse-event reporting rates were low for both products and that the most commonly reported events were similar to those observed during clinical development.
Braeburn funded the study. Four authors were Braeburn employees, another was a consultant to the company, and Dawson’s Ideal Option received compensation from Braeburn for research-based data sharing and analysis. Another author reported receiving consulting or speaking compensation from Braeburn and other pharmaceutical companies.
The full study is available at https://www.jsatjournal.com/article/S2949-8759(26)00215-8/fulltext.
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