This workshop will focus on clinical challenges associated with initiating medication for opioid use disorder (MOUD) in medically complicated patients, such as those with injection-related infections. The utility of extended-release buprenorphine (XR-BUP) and issues with its management in this population will be explored. Several challenges will be discussed, including the impact of fentanyl and other high-potency synthetic opioids, as well as patient concerns regarding XR-BUP effectiveness. Additionally, it will examine the pharmacokinetic and pharmacodynamic properties of XR-BUP and their relationship to high-potency synthetic opioid use and MOUD initiation. Preliminary findings from an ongoing trial [NCT04180020] will be presented, and the workshop will facilitate discussions on lessons learned and the clinical implications for optimizing MOUD delivery.