Effects of N-acetylcysteine on outcomes in chronic obstructive pulmonary disease (Bronchitis Randomized on NAC Cost-Utility Study, BRONCUS): a randomised placebo-controlled trial

Lancet. 2005;365(9470):1552-60. doi: 10.1016/S0140-6736(05)66456-2.


Background: Increased oxidative stress is important in the pathogenesis of chronic obstructive pulmonary disease (COPD). We postulated that treatment with the antioxidant N-acetylcysteine would reduce the rate of lung-function decline, reduce yearly exacerbation rate, and improve outcomes.

Methods: In a randomised placebo-controlled study in 50 centres, 523 patients with COPD were randomly assigned to 600 mg daily N-acetylcysteine or placebo. Patients were followed for 3 years. Primary outcomes were yearly reduction in forced expiratory volume in 1 s (FEV1) and the number of exacerbations per year. Analysis was by intention to treat.

Findings: The yearly rate of decline in FEV1 did not differ between patients assigned N-acetylcysteine and those assigned placebo (54 mL [SE 6] vs 47 mL [6]; difference in slope between groups 8 mL [9]; 95% CI -25 to 10). The number of exacerbations per year did not differ between groups (1.25 [SD 1.35] vs 1.29 [SD 1.46]; hazard ratio 0.99 [95% CI 0.89-1.10, p=0.85]). Subgroup analysis suggested that the exacerbation rate might be reduced with N acetylcysteine in patients not treated with inhaled corticosteroids and secondary analysis was suggestive of an effect on hyperinflation.

Interpretation: N-acetylcysteine is ineffective at prevention of deterioration in lung function and prevention of exacerbations in patients with COPD.

Publication types

  • Clinical Trial
  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcysteine / adverse effects
  • Acetylcysteine / therapeutic use*
  • Administration, Inhalation
  • Antioxidants / therapeutic use*
  • Disease Progression
  • Double-Blind Method
  • Female
  • Forced Expiratory Volume
  • Glucocorticoids / administration & dosage
  • Humans
  • Male
  • Middle Aged
  • Oxidative Stress
  • Pulmonary Disease, Chronic Obstructive / drug therapy*
  • Pulmonary Disease, Chronic Obstructive / physiopathology
  • Vital Capacity


  • Antioxidants
  • Glucocorticoids
  • Acetylcysteine