Buprenorphine, a treatment for opioid dependence, can be mixed with naloxone, to limit abuse potential. The purpose of this study is to examine the effectiveness of buprenorphine/naloxone that is given at less than daily intervals, in order to prevent withdrawal symptoms associated with stopping opioid abuse.

Buprenorphine and naloxone are often combined to decrease withdrawal symptoms in opioid dependent individuals. Buprenorphine/naloxone is usually given daily to individuals who are attempting to stop opioid abuse; however, research suggests that individuals may be more inclined to take medication if it is given in less than daily intervals. The purpose of this study is to examine the opioid blockade effects of buprenorphine/naloxone that is administered in less than daily doses to opioid dependent individuals.

This study will last 11 weeks. Participants will stay in a residential research unit for the duration of the study. Participants will be randomly assigned to receive different doses of daily, sublingual buprenorphine/naloxone. After a minimum of 2 weeks on each dose, participants will undergo challenge sessions on each weekday for 1 week (Monday through Friday). Challenge sessions will consist of increasing doses of intramuscular hydromorphone. During the challenge session week, buprenorphine/naloxone will be given only on Monday; a placebo will be given the rest of the week. Challenge sessions will examine the blockade effects of buprenorphine/naloxone at 2, 26, 50, 74, and 98 hours after the last active dose of buprenorphine/naloxone.

Inclusion Criteria:

• Meets diagnostic criteria for opioid dependence
• Qualifies for opioid substitution treatment (e.g., methadone)

Exclusion Criteria:

• Significant psychiatric or physical disorder