Individuals who have opioid use disorder and are interested in being tapered off of opioids will be admitted to a residential research unit for an 11-day period. All participants will be maintained on morphine for 5 days. During this period participants will complete 2 sessions (on two different days) wherein participants will receive an intramuscular injection of naloxone to precipitate a short withdrawal syndrome. Participants will take a capsule prior to both sessions that will contain either placebo or the opioid withdrawal medication lofexidine. Beginning on day 6 participants will be tapered off of morphine using lofexidine (as clinically indicated). At the end of the study all participants will be able to transition to buprenorphine maintenance or receive oral naltrexone and an injection of Vivitrol (extended release naltrexone), consistent with standard of care practices. Investigators will collect a variety of biological samples and questionnaire ratings during the study and primary outcomes will be measures of withdrawal collected throughout the study. Investigators will use these data to learn more about why individuals express opioid withdrawal symptoms differently, which will help inform how to change current treatment practices to be more effective for persons with OUD.
Evaluate individual differences in the expression of opioid withdrawal symptoms in persons with opioid use disorder (OUD) while completing a clinically-indicated medication taper.