RecruitingDrug trialEfficacy of Buprenorphine and XR-Naltrexone Combination for Relapse Prevention in Opioid Use DisorderThis study will evaluate the effectiveness of a new pharmacological approach to increase efficacy of treatment with extended release naltrexone (XR-naltrexone) for individuals with opioid use disorder by combining it with buprenorphine-naloxone. This is a two arm, double-blind, placebo-controlled study to examine whether addition of buprenorphine-naloxone will improve treatment retention, reduce opioid craving, and improve mood over 24 weeks of treatment with extended release naltrexone (XR-naltrexone) administered every four weeks for a total of 6 injections.