Evaluating Buspirone to Treat Opioid Withdrawal

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.

Inclusion Criteria: * Aged 18-75 * Opioid positive urine sample * Current moderate-severe opioid use disorder with evidence of physical dependence * Interested in undergoing opioid detoxification Exclusion Criteria: * Being pregnant or breastfeeding * Enrolled in methadone or buprenorphine maintenance treatment * Allergic to study medication or taking medications that are contraindicated with study medication (e.g., CYP3A4 inhibitors or inducers and/or monoamine oxidase (MAO) inhibitors) * Significant mental health or physical disorder, or life circumstance, that is expected to interfere with study participation (detailed further in protection of human subjects form). * Hypotension and/or prolonged QTc interval