Mucoactive medications and airway disease.

Airway mucociliary clearance depends on the properties and volume of secreted mucus, ciliary function and mucociliary interactions. In chronic airway diseases, mucus viscoelasticity is higher than the optimal values for mucociliary clearance. The mucous glycoproteins (MGs) are produced by goblet and submucosal gland cells and are the most important determinant of the viscoelasticity of normal respiratory mucus, although with chronic infection and inflammation neutrophil-derived DNA and F-actin assume an important role. The quantities and structures of MGs mainly determine the rheological properties of mucus. Mucolytic agents, such as the thiols with free sulphydryl groups (classic mucolytics) and proteolytic enzymes (peptide mucolytics) change the conformation of mucus and lead to the reduction of viscoelasticity. Mucoregulatory medications such as glucocorticoids and macrolide antibiotics may decrease the hypersecretion of MGs.