OFFICE-BASED TREATMENT RETENTION AMONG PATIENTS WITH OPIOID USE DISORDER AND RECENT FENTANYL USE: EXTENDED-RELEASE INJECTABLE BUPRENORPHINE VS SUBLINGUAL BUPRENORPHINE

High-potency synthetic opioids, including fentanyl, continue to be the leading cause of drug overdose deaths in the United States. Buprenorphine is an effective, FDAapproved medication for opioid use disorder (OUD), with multiple formulations available. Sublingual buprenorphine (SL-BUP) is widely used but presents challenges for patients, including daily dosing burden, diversion and misuse risk, and stigma, that can contribute to treatment discontinuation, a key driver of opioid-related mortality. Extended-release injectable buprenorphine (XR-BUP) may address these challenges and optimize retention on buprenorphine. Real-world evidence comparing treatment retention between buprenorphine formulations among patients with OUD who use fentanyl is limited.

Methods

A retrospective analysis of electronic medical record data from Ideal Option, a national outpatient network of addiction clinics, included adults with moderate-to-severe OUD, a recent fentanyl-positive urine drug screen (UDS), and no prior XR-BUP use known. Patients were assigned to the Brixadi® (CAM2038) cohort if they received their first dose of CAM2038 during the qualifying period (January 1, 2025–June 30, 2025) and were assigned to the SL-BUP cohort if they received SL-BUP and no XR-BUP medications during the qualifying period. Propensity scores were estimated using all eligible patients based on age, gender, race, tenure with Ideal Option, Medicaid status, UDS availability, polysubstance use, fentanyl UDS positivity, and norbuprenorphine UDS positivity. Eligible patients with a fentanyl-positive UDS at their last visit were then matched 1:3 (CAM2038:SL-BUP). Treatment episodes began at first CAM2038 injection or first appointment with an active SLBUP prescription and ended at the last day of observation or when a treatment gap within an episode exceeded the day supply of the last prescription received; only the first treatment episode was analyzed. The analysis evaluated the proportion of patients active in treatment with any buprenorphine medication at Day 30, Day 90, and Day 180 from the start of the treatment episode.

Results

Following propensity score matching, 162 patients were included in the CAM2038 cohort (from eligible population of 694) and 486 patients were included in the SL-BUP cohort (from eligible population of 14,852). Treatment retention on buprenorphine was significantly higher in the CAM2038 cohort than in the SL-BUP cohort during the observation period (log-rank test, P < 0.001). Treatment retention (95% CI) for CAM2038 vs SL-BUP was: Day 30: 51.85% (43.90%–59.22%) vs 25.51% (21.73%–29.46%); Day 90: 31.48% (24.49%–38.69%) vs 11.73% (9.06%–14.77%); Day 180: 20.37% (14.56%–26.87%) vs 7.20% (5.13%–9.73%).

Conclusions

In this real-world, retrospective analysis of patients with OUD and recent fentanyl use, office-based treatment with CAM2038 was associated with greater retention on buprenorphine compared to SL-BUP over a 6-month period. CAM2038 may offer advantages in sustaining engagement in treatment compared to SL-BUP in patients with OUD who use fentanyl.