Buprenorphine is a treatment for opioid dependence. Naloxone is given in addition to buprenorphine in order to limit the abuse potential that is commonly associated with buprenorphine. The purpose of this study is to examine the effects of buprenorphine/naloxone when given through different routes and at different doses.

Buprenorphine, a mixed agonist-antagonist opioid (or partial agonist), is a safe and effective treatment for opioid dependence. However, there is concern that buprenorphine may be abused due to its high abuse potential. A sublingual buprenorphine/naloxone combination tablet may reduce the risk of abuse associated with buprenorphine alone. The purpose of this study is to characterize the effects of buprenorphine/naloxone in opioid-dependent individuals.

This study will last 10 weeks. Participants will stay in a residential research unit, and will be maintained on oral hydromorphone (10 mg). During twice-weekly experimental sessions, participants will be randomly assigned to receive either sublingual tablets, intramuscular injections, or a placebo. The 15 conditions studied will include: sublingual or intramuscular buprenorphine/naloxone (1/0.25 mg, 2/0.5 mg, 4/1 mg, 8/2 mg, and 16/4 mg), 0.25 mg of intramuscular naloxone (antagonist control), 10 mg of intramuscular hydromorphone (agonist control), sublingual and intramuscular buprenorphine (8 mg), and placebo.

Inclusion Criteria:

• Currently opioid dependent
• In good health, as determined by a pre-participation medical examination
• Seeking and eligible for methadone maintenance or detoxification treatment

Exclusion Criteria:

• Significant medical or psychiatric illness, other than drug dependence