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BEHAVIORAL PHARMACOLOGY
Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, New York (S.D.C., M.A.S.); and Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, Pennsylvania (E.A.W.)
Although buprenorphine is used worldwide as a safe and effective maintenance medication for opioid dependence, some countries have reported a growing incidence of abuse of this medication. Buprenorphine is considered to have lower abuse potential because of its partial agonist profile, but no studies have directly compared the reinforcing effects of buprenorphine with those of full µ opioid agonists in humans. The present double-blind, placebo-controlled inpatient study compared the reinforcing and subjective effects of intravenously administered buprenorphine (0.5, 2, and 8 mg) and methadone (5, 10, and 20 mg). Participants (n = 6) were detoxified from heroin during the first 1 to 2 weeks after admission. During subsequent weeks, participants received a sample drug dose and $20 on Monday, and they could self-administer either the sampled dose or $20 during one choice session per day on Thursday and Friday. Participants responded under a modified progressive ratio schedule during each choice session. All active doses maintained higher progressive ratio break points (largest completed ratio) than placebo. There were no significant differences in break point values between buprenorphine and methadone or among the different doses of drug. However, several subjective ratings, including "good drug effect", "high", and "liking" dose-dependently increased after administration of buprenorphine and methadone. The peak ratings for these effects did not significantly differ for the two drugs. These results demonstrate that under these experimental conditions, buprenorphine and methadone were equally effective in producing reinforcing and subjective effects.
Address correspondence to: Dr. Sandra D. Comer, The New York State Psychiatric Institute and College of Physicians and Surgeons of Columbia University, 1051 Riverside Dr., Unit 120, New York, NY 10032. E-mail: sdc10{at}columbia.edu