Achieving cannabis cessation -- evaluating N-acetylcysteine treatment (ACCENT): design and implementation of a multi-site, randomized controlled study in the National Institute on Drug Abuse Clinical Trials Network

Contemp Clin Trials. 2014 Nov;39(2):211-23. doi: 10.1016/j.cct.2014.08.011. Epub 2014 Aug 30.


Despite recent advances in behavioral interventions for cannabis use disorders, effect sizes remain modest, and few individuals achieve long-term abstinence. One strategy to enhance outcomes is the addition of pharmacotherapy to complement behavioral treatment, but to date no efficacious medications targeting cannabis use disorders in adults through large, randomized controlled trials have been identified. The National Institute on Drug Abuse Clinical Trials Network (NIDA CTN) is currently conducting a study to test the efficacy of N-acetylcysteine (NAC) versus placebo (PBO), added to contingency management, for cannabis cessation in adults (ages 18-50). This study was designed to replicate positive findings from a study in cannabis-dependent adolescents that found greater odds of abstinence with NAC compared to PBO. This paper describes the design and implementation of an ongoing 12-week, intent-to-treat, double-blind, randomized, placebo-controlled study with one follow-up visit four weeks post-treatment. Approximately 300 treatment-seeking cannabis-dependent adults will be randomized to NAC or PBO across six study sites in the United States. The primary objective of this 12-week study is to evaluate the efficacy of twice-daily orally-administered NAC (1200 mg) versus matched PBO, added to contingency management, on cannabis abstinence. NAC is among the first medications to demonstrate increased odds of abstinence in a randomized controlled study among cannabis users in any age group. The current study will assess the cannabis cessation efficacy of NAC combined with a behavioral intervention in adults, providing a novel and timely contribution to the evidence base for the treatment of cannabis use disorders.

Keywords: Cannabis; Clinical study design; Marijuana; N-acetylcysteine; Pharmacotherapy; Randomized trials.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Acetylcysteine / administration & dosage
  • Acetylcysteine / adverse effects
  • Acetylcysteine / therapeutic use*
  • Adolescent
  • Adult
  • Double-Blind Method
  • Female
  • Genetic Testing
  • Humans
  • Male
  • Marijuana Abuse / drug therapy*
  • Marijuana Abuse / epidemiology
  • Marijuana Abuse / genetics
  • Middle Aged
  • National Institute on Drug Abuse (U.S.)
  • Research Design*
  • Smoking / epidemiology
  • United States
  • Young Adult


  • Acetylcysteine