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Research Summary

Monthly Injectable Naltrexone Is Efficacious for Treating Alcohol Dependence

Medications have moderate efficacy for treating alcohol dependence. However, adherence is a great challenge in patients with alcoholism. Researchers tested a new polylactideco-glycolide-based, long-acting formulation of naltrexone in a multicenter randomized trial of 624 patients with alcohol dependence and >=2 heavy drinking episodes* per week in the month before screening. Subjects were assigned to receive injections of either naltrexone (380 mg or 190 mg) or placebo every 4 weeks for 6 months. They were also provided with supportive therapy sessions that included feedback on addiction-related consequences.

  • Nausea, fatigue, decreased appetite, dizziness, injection site pain, and discontinuation of injections due to adverse effects were significantly more common in the higher-dose naltrexone group than in the placebo group. Results appeared similar for the lower-dose group.
  • The rate of heavy drinking decreased significantly in the higher-dose group and at a borderline significant level in the lower-dose group (hazard ratios 0.8 for both compared with placebo).
  • Subgroup analyses indicated that
    • heavy drinking decreased only in men;
    • having abstinence as a treatment goal did not affect the results, though naltrexone's efficacy was greatest in the 8% who had abstained for 7 days before study entry.


This trial is particularly important among studies of pharmacotherapy for alcohol dependence. It not only highlights the potential advantages of a medication that poses fewer challenges to good adherence, but also did not require patients to stop drinking to enroll. Injectable naltrexone will likely become an attractive adjunct to supportive therapy for people who seek treatment for alcohol dependence.

Richard Saitz, MD, MPH
*>=5 drinks for men or >=4 drinks for women


Garbutt JC, Kranzler HR, O'Malley SS, et al. Efficacy and tolerability of long-acting injectable naltrexone for alcohol dependence. A randomized controlled trial. JAMA. 2005;293(13):1617-1625.