The purpose of this study is to evaluate the effects of treatment medications (methadone, buprenorphine, LAAM, naltrexone, naltrexone microcapsules, and methoclocinnamox) on I.V. and smoked heroin self-administration."

Abuse of prescription opioid medications has increased dramatically in the U.S. during the past decade, as indicated by a variety of epidemiological sources. However, few studies have systematically examined the relative reinforcing effects of commonly abused opioid medications. The current inpatient study was designed to compare the effects of intravenously delivered fentanyl , oxycodone, morphine, buprenorphine and heroin in morphine-maintained heroin abusers. All of the participants received all of the drugs tested; drugs and doses were administered in non-systematic order.

Inclusion Criterion

1. DSM IV criteria for opioid dependence
2. No major mood, psychotic, or anxiety disorder
3. Physically healthy
4. Able to perform study procedures
5. 21-45 years of age
6. Current use of i.v. heroin in amounts/frequencies
7. Not seeking treatment for opioid dependence

Exclusion Criterion

1. DSM IV criteria for dependence on drugs other
2. Participants requesting treatment
3. Participants on parole or probation
4. Pregnancy or lactation
5. Birth, miscarriage or abortion with 6 months
6. Recent history of or current significant violent behavior
7. Current major Axis I psychopathology, other than heroin dependence ( e.g., mood disorder with functional impairment or suicide risk, schizophrenia), which might interfere with ability to participate in the study
8. Hepatitis with SGOT or SGPT > 3 times normal
9. Significant suicide risk
10. Current or history of chronic pain
11. Sensitivity, allergy, or contraindication to opioids