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Research Summary

Extended-Release Naltrexone Works Particularly Well for Abstinent Patients With Dependence

Many patients with alcohol dependence do not receive the full benefits of treatment because they do not adhere to it. In part to address issues with adherence, extended-release naltrexone, which is released over a month after one injection, was developed.

In the pivotal randomized, placebo-controlled trial that showed the efficacy of naltrexone combined with psychosocial therapy, subjects with ≥7 days of abstinence benefited the most from the drug. However, achieving 7 days of abstinence before treatment is difficult. Therefore, researchers assessed naltrexone’s efficacy, in that same clinical trial, among the subgroup of 82 subjects with ≥4 days of abstinence. 

In that subgroup, 380 mg of naltrexone in 28 subjects versus placebo in 28 subjects

  • increased the time to first drink (median days, 41 versus 12);
  • increased continuous abstinence over 6 months (32% versus 11%);
  • increased time to first heavy drinking (>180 versus 20 days);
  • decreased days with any drinking (median days per month, 0.7 versus 7.2);
  • decreased days with heavy drinking (median days per month, 0.2 versus 2.9).

Smaller benefits, which were not always statistically significant, were found among the 28 subjects treated with 190 mg of naltrexone.


Requiring abstinence before starting treatment for alcohol dependence can be a barrier to care. But at least in this industry-sponsored secondary analysis of a small subgroup of subjects, those who achieved 4 days of abstinence before entering treatment responded well to extended-release naltrexone. Unfortunately, this and other medications with proven efficacy (e.g., acamprosate, oral naltrexone, and disulfiram) remain underutilized in the treatment of alcohol dependence.

Richard Saitz, MD, MPH


O’Malley SS, Garbutt JC, Gastfriend DR, et al. Efficacy of extended-release naltrexone in alcohol-dependent patients who are abstinent before treatment. J Clin Psychopharm. 2007;27(5):507–512.