Studies of Opioid Seeking Behavior: Yohimbine and Hydrocortisone Effects

Phase 1: Participants will first be an outpatient and must come to the Tolan Park Medical Building daily to receive buprenorphine doses. This phase will last at least 10 days or longer. Three times per week during the first two weeks (i.e., on 6 different days), participants will be asked to provide urine samples and to complete questionnaires that ask about opiate withdrawal symptoms. Phase 2: Participants will then live on an inpatient research unit (located in Detroit Michigan) for at least 16 consecutive nights and possibly up to 18 consecutive nights. Participants will continue on the same dose of buprenorphine as in phase 1. During this stay they will participate in a total of 11 experimental sessions. Participants will take part in multiple trials in which they have the opportunity to choose drug, hydromorphone, or money. Hydromorphone is a heroin-like opioid. During the first two test sessions, participants will receive a sample of the drug doses that can be chosen. Before each of the final 9 test sessions begin, participants will be given a capsule containing either different doses of the drug yohimbine or a placebo (blank). Yohimbine is a drug that has been shown to produce a "stress"-like response in humans. Then participants will be given a capsule that contains either different doses of the drug hydrocortisone or a placebo (blank). Hydrocortisone is also a drug that can produce a "stress"-like response in humans. Then participants will have the opportunity to choose either drug or money by using a computer to earn choices. Respiration rate, oxygen saturation, heart rate, and blood pressure will be monitored throughout choice trials. Self-report questionnaires will be completed at different times during the study. Phase 3: After participants have completed the experimental procedures, they will again come to the Tolan Park Medical Building daily to receive buprenorphine doses. The dose of buprenorphine will be gradually decreased so that they will eventually be free from medication. This will take three weeks. We will administer questionnaires and collect urine samples three times each week.