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Research Summary

Acamprosate May Work Only When Abstinence Is the Goal

The Food and Drug Administration’s approval of acamprosate to maintain abstinence in patients with alcohol dependence is based on data from international randomized, placebo-controlled clinical trials. To evaluate acamprosate’s efficacy in U.S. patients, researchers conducted a randomized controlled trial of the drug (the first in this country) in 21 alcohol treatment clinics. Subjects, recruited primarily by newspaper advertisement, were assigned to receive either the standard 2 g of acamprosate per day (n=258), 3 g per day (n=83), or placebo (n=260). All subjects also received self-help materials and 8 sessions of brief counseling.

  • In unadjusted analyses, the percentage of days abstinent at 6 months did not significantly differ across groups.
  • However, in analyses adjusted for potential confounders (e.g., readiness to change, treatment goal of abstinence), the percentage was significantly higher in subjects who received acamprosate (52% for the placebo group, 58% for subjects on 2 g of acamprosate, and 63% for subjects on 3 g).
  • Patients who stated at baseline that abstinence was their goal achieved the best results (58% days abstinent for the placebo group, 70% for subjects on 2 g of acamprosate, and 73% for subjects on 3 g).


Acamprosate’s lack of efficacy in this large, well-designed trial is surprising, though also noted in another recent study. One explanation may be that the U.S. subjects had less established abstinence (i.e., abstinent for a shorter time) than did the international subjects. Lastly, the link between having abstinence as a goal and benefit from acamprosate may guide clinicians’ prescribing practices and merits confirmation.

Jeffrey H. Samet, MD, MA, MPH


Mason BJ, Goodman AM, Chabac S, et al. Effect of oral acamprosate on abstinence in patients with alcohol dependence in a double-blind, placebo-controlled trial: the role of patient motivation. J Psychiatr Res. 2006;40(5):382–392.