Naltrexone Implants Reduced Opioid Use in People with Co-occurring Heroin and Amphetamine Dependence

Long-acting naltrexone has been shown to reduce opioid use in opioid-dependent patients who have achieved abstinence, but its effect on patients with co-occurring opioid and stimulant dependence is not known. Researchers conducted a double-blind placebo-controlled randomized clinical trial of a 1000-mg naltrexone surgical implant among 100 subjects with co-occurring heroin and amphetamine dependence recruited in St. Petersburg. Psychosocial support and advice was provided to both groups. Prior to receiving the naltrexone or placebo implant, subjects were required to provide an opioid-negative urine test or tolerate a naloxone challenge test. At 10-week follow-up,

• the retention rate was 52% in the naltrexone group and 28% in the placebo group.
• 52% of subjects in the naltrexone group had opioid-negative urine tests versus 20% in the placebo group (missing urine samples were counted as positive).
• 40% of subjects in the naltrexone group had amphetamine-negative urine tests versus 24% in the placebo group (not significant).
• subjects in the naltrexone group were more likely to have improved scores on the Clinical Global Impression Scale.
• among subjects who provided subjective ratings of amphetamine effects, 14% (3/22) in the naltrexone group reported full amphetamine effects versus 83% (15/18) in the placebo group.
• no severe adverse events were reported.

Comments:

This trial had substantial losses to follow-up that were unbalanced between study groups, which limits the assessment of treatment effects. Despite this limitation, the study confirms that, in Russia, opioid abstinence can be maintained in subjects with both heroin and amphetamine dependence who receive long-acting naltrexone. Furthermore, the finding that long-acting naltrexone may also decrease co-occurring amphetamine use warrants further study in trials with more complete follow-up.

Alexander Y. Walley, MD, MSc

Reference:

Tiihonen J, Krupitsky E, Verbitskaya E, et al. Naltrexone implant for the treatment of polydrug dependence: a randomized controlled trial. Am J Psychiatry. 2012;169(5):531–536.