Efficacy and safety of mucolytics in patients with stable chronic obstructive pulmonary disease: A systematic review and meta-analysis

Background: The efficacy and safety of mucolytics in patients with chronic obstructive pulmonary disease (COPD) and chronic bronchitis or exacerbations of COPD have been reported. We conducted a systematic review and meta-analysis of mucolytics in patients with stable COPD. Methods: Reports from randomized controlled trials to evaluate the efficacy and safety of mucolytics, including ambroxol, bromhexine, carbocisteine, erdosteine, fudosteine, L-methylcysteine, and N-acetylcysteine used in patients with stable COPD were searched for in PubMed, Scopus, Embase, Web of Science, the Cochrane Library, and the Igaku Cyuo Zasshi database. Results: Twenty-three reports with ambroxol, carbocisteine, erdosteine, L-methylcysteine, or N-acetylcysteine were included in the review. Mucolytics significantly reduced the rates of exacerbation and hospitalization, shortened the duration of antibiotic use and exacerbations, prolonged the time to first exacerbation, and had a tendency to reduce the occurrence of two or more exacerbations in patients with stable COPD compared to placebo. Mucolytics did not improve mortality, number of lost workdays, scores on St. George's respiratory questionnaire, forced expiratory volume in 1 s, or forced vital capacity. The safety profile of mucolytics was comparable to that of placebo. Conclusions: Mucolytics reduce exacerbations and hospitalizations in patients with stable COPD and have a safety profile comparable to that of placebo.