Efficacy and Safety of N-Acetylcysteine for Chronic Obstructive Pulmonary Disease and Chronic Bronchitis

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) and chronic bronchitis are associated with poor clinical outcomes. N-acetylcysteine (NAC) is a widely used therapeutic option for such patients; however, the clinical efficacy of NAC has not been conclusively determined. We hypothesized that high-dose oral NAC can improve the clinical outcomes for patients with concurrent chronic bronchitis and COPD. Objective and Methods. This was a randomized, double-blind, placebo-controlled trial evaluating the efficacy of high-dose NAC for COPD patients with concurrent chronic bronchitis. Study participants were randomized into two groups and administered with NAC (900 mg) twice daily or matching placebo for 3 months. Then, respiratory health status was evaluated using the St. George's Respiratory Questionnaire (SGQR), which was set as the primary end point. RESULTS: A total of 143 COPD patients with chronic bronchitis were screened, and as a result, only 100 patients were enrolled in this study (50 participants were randomized to receive placebo, and others were randomized to receive NAC). After treatment, differences in SGQR scores between the placebo and NAC groups were not significant. Moreover, differences in secondary end points between the two groups after treatment were insignificant. Discussion. High-dose NAC has no marked clinical benefits for COPD patients with concurrent chronic bronchitis.