Naltrexone as treatment for amphetaminism

Abstract

There is no approved medication for the treatment of amphetamine dependence despite the widespread abuse of this type of psychostimulant drugs. Animal studies have shown that naltrexone, a non-selective opioid receptor antagonist, reduces certain behavioural effects of amphetamine. We have recently shown that naltrexone reduces drug seeking in experimental models of amphetamine self-adminstration, and modulates sensitized locomotor behaviour. In our human laboratory models, naltrexone blunts the subjective effects of amphetamine in both healthy subjects and amphetamine dependent patients. The efficacy of naltrexone to increase weeks of abstinence in amphetamine-dependent patients was tested in a placebo controlled trial. Eighty individuals meeting DSM IV criteria for amphetamine dependence were randomized to either naltrexone or placebo treatment. All patients visited the clinic weekly to receive medication (50 mg naltrexone or identical placebo) and relapse prevention therapy. Urine samples were analysed twice weekly for illicit drug use. The primary outcome measure was abstinence from amphetamine use, as measured by the total number of negative amphetamine urine samples during 12 weeks of treatment. Overall, 55 patients (68.7%) completed study. The intention-to-treat analysis showed that the naltrexone group had a significantly higher number of amphetamine negative urine samples, compared to the placebo treated group (p<0.05). There was a reduction in craving levels and self reported weekly consumption of amphetamine, over 12 weeks of treatment, in the naltrexone group compared to placebo. Naltrexone had minimal side effects and was well tolerated. The results suggest that naltrexone is efficacious in reducing relapse to amphetamine use in amphetamine dependent individuals.

 

¹Department of Clinical Neuroscience, Division of Psychiatry, Karolinska Institutet, SE-17176 Stockholm, Sweden

*johan.franck@ki.se