Chest. 2013 Jan 24. doi: 10.1378/chest.12-2357. [Epub ahead of print]
High-Dose N-Acetylcysteine in Stable Chronic Obstructive Pulmonary Disease: the 1-Year, Double-Blind, Randomized, Placebo-Controlled HIACE Study.

ABSTRACT BACKGROUND: N-acetylcysteine's (NAC) mucolytic and antioxidant effects may have great value in COPD treatment. However, beneficial effects have not been confirmed in clinical studies, possibly due to insufficient NAC doses and/or inadequate outcome parameters used.

OBJECTIVE: to investigate high-dose NAC plus usual therapy in stable Chinese COPD patients.

METHODS: The 1-year HIACE double-blind trial conducted in Kwong Wah Hospital, Hong Kong, randomized eligible stable COPD patients aged 50-80 yrs to NAC 600mg twice daily (Fluimucil, Zambon SpA, Italy) or placebo after 4 weeks' run-in. Lung function parameters, symptoms, modified Medical Research Council (mMRC) dyspnea and St. George Respiratory Questionnaire (SGRQ) scores, 6-minute walking distance (6-MWD), and exacerbation and admission rates, were measured at baseline and every 16 weeks for 1 year.

RESULTS: Of 133 patients screened, 120 were eligible (93.2% male; mean age 70.8 0.74 years; %FEV1 53.9 2.0%). Baseline characteristics were similar in the two groups. At 1-year, there was a significant improvement in Forced Expiratory Flow 25% to 75% (FEF25-75%; P = .037) and forced oscillation technique (FOT), a significant reduction in exacerbation frequency (0.96 vs 1.71 times/year, P = .019) and a tendency towards reduction in admission rate (0.5 vs 0.8 times/year, P = .196) with NAC versus placebo. There were no significant between-group differences in mMRC, SGRQ and 6MWD. No major adverse effects were reported.

CONCLUSION: 1-year treatment with high-dose NAC resulted in significantly improved small airways function and decreased exacerbation frequency in patients with stable COPD.