Review: mucolytic drugs reduce exacerbations, illness days, and antibiotic use in chronic bronchitis and COPD.

S t u d y s e l e c t i o n Studies were selected if they were randomized, double-blind, placebo-controlled trials of oral mucolytic drugs taken regularly for ≥ 2 months by adults who were > 20 years of age and had chronic bronchitis or COPD. Studies on inhaled mucolytic drugs, combinations of mucolytic drugs with antibiotics or bronchodilators, deoxyribonucleases, and such proteases as trypsin were excluded, as were studies on patients with asthma or cystic fibrosis.