OPERANT ANALYSIS OF HUMAN HEROIN SELF-ADMINISTRATION AND THE EFFECTS OF NALTREXONE

  • 1 January 1981
    • journal article
    • research article
    • Vol. 216  (1) , 45-54
Abstract
The effects of maintenance on a narcotic antagonist, naltrexone (50 mg/day p.o. [per 05]), or placebo on patterns of operant acquisition and use of heroin were studied under double-blind conditions. Male heroin addict volunteers [12] lived on a clinical research ward for 34 days. After a 9 day drug-free period, naltrexone or placebo were given and heroin (40 mg/day) was available for 10 days. Subjects could earn money or heroin (10 mg i.v.) by responding on a 2nd-order schedule of reinforcement [FR [fixed ratio] 300 (FI [fixed interval] 1 s: S)] for .apprx. 90 min. The 3 naltrexone-maintained subjects took only 2-7.5% of the total heroin available. Two maltrexone subjects stopped heroin self-administration after the 1st or 2nd heroin injection; the 3rd subject took a 3rd heroin injection on the 8th day of heroin availability. Naltvexone maintenance for 25 consecutive days did not produce adverse side effects. The 9 placebo naltrexone subjects used 57.5-100% of the total heroin available. Five placebo subjects used all or all but 1 of the 40 injections available; 4 placebo subjects often used less heroin than was available each day. Heroin intoxication did not impair operant performance. Heroin users worked longer hours and earned more purchase points (P < .05) during heroin self-administration and subsequent methadone detoxification than during the drug-free period. Subjects precisely titrated operant work to acquire the desired amount of heroin, then resumed working for money. The feasibility of using direct measures of drug self-administration behavior to evaluate new pharmacotherapies for heroin abuse is demonstrated and the effectiveness of naltrexone in suppressing heroin self-administration indicated.