The investigators propose a rigorous, Phase II, three-group, placebo-controlled double-blind
randomized controlled trial (RCT) to evaluate the efficacy of buspirone for both withdrawal
and craving among individuals with opioid use disorder (OUD) undergoing a standardized
stepwise taper. During this 10 to 12-day residential study, participants with OUD will be
enrolled, stabilized on a short-acting opioid, undergo an opioid stepwise taper, and complete
a post-taper observation period where participants will have the opportunity to initiate
long-term buprenorphine or extended-release naltrexone.