Highlights
- In a randomized clinical trial of 435 participants, maintenance with 300 mg of extended-release (XR) buprenorphine was significantly more effective than 100 mg for individuals with high-frequency fentanyl use.
- The 300-mg maintenance dose achieved an 11.1% to 15.4% higher response rate compared to the 100-mg dose among those using fentanyl daily or multiple times per week.
- Both dosing regimens were highly effective in reducing overall opioid use, with instances dropping from over 43 per week to fewer than three by the end of the study.
- The safety profiles were comparable, though injection-site reactions were more frequent in the 300-mg cohort.
Background: The Fentanyl Era and the Need for Potent Solutions
The landscape of opioid use disorder (OUD) in North America has undergone a seismic shift. The transition from heroin to highly potent synthetic opioids, primarily illicitly manufactured fentanyl, has rendered traditional treatment strategies less effective for some patients. Fentanyl’s high potency, rapid onset, and high affinity for the mu-opioid receptor present unique pharmacological challenges. Clinicians have long suspected that the standard 100-mg maintenance dose of extended-release buprenorphine might provide insufficient receptor blockade or craving suppression for those exposed to high-potency synthetics. This study, published in JAMA Network Open, addresses a critical unmet medical need: determining whether higher maintenance doses can improve clinical outcomes in high-risk populations.
Study Design and Methodology
This multicenter, randomized, double-blind clinical trial was conducted across 28 outpatient treatment centers in the United States and Canada between October 2021 and June 2024. The study enrolled 436 treatment-seeking participants with moderate-to-severe OUD who met high-risk criteria, including injection drug use, high-dose opioid use, or fentanyl use.
Intervention and Randomization
Following a standard buprenorphine induction and an initial 300-mg XR-buprenorphine dose (the standard initiation protocol), participants were randomized at week 6 in a 1:1 ratio. The experimental group received eight additional monthly 300-mg maintenance injections, while the control group received the standard 100-mg maintenance injections.
Endpoints
The primary endpoint was the proportion of “responders,” defined as participants who achieved opioid abstinence in 80% or more of their weekly visits during the maintenance phase (weeks 20 to 38). Secondary measures included overall reductions in opioid use frequency and safety assessments.
Key Findings: Overall Efficacy vs. Subgroup Success
The intent-to-treat analysis included 435 participants with a mean age of 41.6 years. The results revealed a nuanced picture of OUD management.
Primary Results
In the overall study population, the difference between the two doses did not reach statistical significance. In the 100-mg arm, 20.2% of participants were responders, compared to 23.2% in the 300-mg arm (difference, 2.6%; 95% CI, -4.7% to 9.9%). This suggests that for a general high-risk population, the standard 100-mg dose remains a viable and effective maintenance option.
The Fentanyl Subgroup Advantage
The most striking data emerged from the post hoc analyses focused on fentanyl users. For participants who reported daily fentanyl use at baseline, the 300-mg maintenance dose was significantly more effective, with a response rate difference of 11.1% (95% CI, 0.4%-21.6%) over the 100-mg dose. Among those using fentanyl 14 or more times per week, the difference was 12.2%. For those meeting both criteria (daily and frequent use), the 300-mg dose outperformed the 100-mg dose by 15.4% (95% CI, 4.6%-26.1%).
Dramatic Reductions in Use
Regardless of the maintenance dose, both groups saw a profound reduction in the frequency of opioid use. At screening, participants averaged more than 43 instances of opioid use per week. By week 3, this dropped to fewer than three instances per week and remained low throughout the 38-week study period. This highlights the overall efficacy of extended-release buprenorphine as a cornerstone of modern OUD treatment.
Safety and Tolerability
Both doses were well tolerated, and no new safety signals were identified. The most notable difference was in injection-site reactions, which occurred in 14.7% of the 300-mg group compared to 5.5% of the 100-mg group. These reactions were generally mild to moderate and did not lead to high rates of treatment discontinuation. Other adverse events were similar between the groups, reinforcing the safety of higher-dose buprenorphine regimens.
Expert Commentary: Personalized Dosing in Clinical Practice
The findings by Shiwach et al. provide essential evidence for the clinical transition toward personalized addiction medicine. The lack of a significant difference in the overall population confirms that 100 mg is an appropriate maintenance dose for many. However, the superior performance of the 300-mg dose in heavy fentanyl users aligns with the biological plausibility that higher serum levels of buprenorphine are required to compete with fentanyl’s high receptor affinity.
Mechanistic Insights
Buprenorphine is a partial mu-opioid receptor agonist. In the presence of high-potency full agonists like fentanyl, a higher concentration of buprenorphine may be necessary to maintain sufficient receptor occupancy to prevent withdrawal and blunt the euphoric effects of illicit use. This study provides the first randomized clinical trial evidence to support the “dose-intensification” strategy that many clinicians have already begun to adopt empirically in areas hard-hit by fentanyl.
Limitations
The primary limitation is that the findings regarding fentanyl were derived from post hoc analyses. While statistically significant and clinically logical, post hoc results generally require confirmation in prospective trials specifically powered for those subgroups. Additionally, the study’s 80% abstinence threshold is a rigorous metric; lower thresholds might show different patterns of benefit.
Conclusion: Implications for Healthcare Policy
This trial demonstrates that while the standard 100-mg maintenance dose of XR-buprenorphine is effective for a broad range of high-risk patients, the 300-mg dose offers a critical advantage for those with heavy fentanyl exposure. As fentanyl continues to drive overdose mortality across the globe, the ability to tailor buprenorphine dosing to a patient’s specific risk profile is a vital tool for clinicians. These results support the use of 300-mg maintenance doses as a safe and potentially more effective strategy for the most vulnerable patients in the synthetic opioid era.
Funding and ClinicalTrials.gov
This study was funded by Indivior Inc. The trial is registered at ClinicalTrials.gov with the identifier NCT04995029.
References
Shiwach R, Le Foll B, Alho H, Dunn KE, Strafford S, Zhao Y, Dobbins RL. Comparison of Extended-Release Buprenorphine Doses for Treating High-Risk Opioid Use: A Randomized Clinical Trial. JAMA Netw Open. 2025 Dec 1;8(12):e2548043. doi: 10.1001/jamanetworkopen.2025.48043. PMID: 41405885.
