Abuse Potential of Buprenorphine/Naloxone

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 determine the abuse potential of acute doses of buprenorphine/naloxone in
individuals who are maintained on different daily doses of sublingual
buprenorphine/naloxone.

Participants will be maintained on both low and high doses of buprenorphine/naloxone. They
will be challenged with low- and high-dose injected buprenorphine/naloxone, as well as
active and placebo controls at each maintenance dose. During study visits, physiologic,
subjective, and psychomotor responses to challenge sessions will be monitored and compared
to known pharmacologic effects of opioid drugs.

Inclusion Criteria:

- Actively abusing illegal opioids

- Qualifies for opioid substitution treatment (e.g., methadone or buprenorphine), but
not in active treatment at the time of study entry

- Meets DSM-IV criteria for opioid dependence

Exclusion Criteria:

- Significant medical problems (e.g., insulin dependent diabetes mellitus)

- Non-substance use psychiatric disorders (e.g., schizophrenia)

- Seeking substance abuse treatment