This 24-week randomized clinical trial compared monthly extended-release injectable buprenorphine (XR-BUP) with daily sublingual buprenorphine-naloxone among adults actively using illicit opioids, including fentanyl.  The trial found significantly higher treatment retention with XR-BUP. Nearly 68% of patients receiving XR-BUP remained in treatment at six months compared to 52% of those on daily medication, while both groups achieved similar reductions in illicit opioid use. The findings underscore that while extended-release formulations may not further reduce opioid use beyond daily therapy, they meaningfully improve treatment continuity, which is a critical factor for long-term recovery, harm reduction, and system-level impact.