RecruitingPhase 2Drug trialExtended-release Buprenorphine as a Novel Low-dose Induction StrategyThis is a clinical trial to characterize the safety and pharmacokinetics of using extended-release buprenorphine (XR-BUP) as a novel low-dose buprenorphine induction strategy. Individuals with a diagnosis of Opioid Use Disorder (OUD) (n=30) will be admitted to an inpatient unit to complete study procedures over the course of 3 days. Participants will receive fentanyl to prevent the emergence of withdrawal. Each participant will then receive a single injection of XR-BUP after which study staff will monitor for any precipitated withdrawal.