Mucolytic agents versus placebo for chronic bronchitis or chronic obstructive pulmonary disease.

Background: Individuals with chronic bronchitis or chronic obstructive pulmonary disease (COPD) may suffer recurrent exacerbations with an increase in volume or purulence of sputum, or both. Personal and healthcare costs associated with exacerbations indicate that therapies that reduce the occurrence of exacerbations are likely to be useful. Mucolytics are oral medicines that are believed to increase expectoration of sputum by reducing its viscosity, thus making it easier to cough it up.