Mucokinetic agents and surfactant

In healthy individuals, airway secretions constitute a bi-layer with a periciliary fluid interposed between the epithelium and the mucous gel. In the airways, mucus is usually cleared by the airflow and ciliary interaction. Effective cough clearance requires high flow velocity to detach the sputum from the epithelium and to mobilize secretions so that they can be expectorated. For the mucus to slide on top of the epithelium. there is a need for a complex of phospholipidprotein compound-similar to the alveolar surfactant to be present (1). Mucokinetic agents improve the cough clearance of mucus by increasing airflow or by altering the sputum/epithelium interface by reducing mucus adhesiveness. In this chapter we discuss the role of surfactant in sputum clearance, its antiinflammatory activity, and the role of surfactant supplementation in improving mucus clearance in some conditions, i.e., chronic bronchitis and cystic fibrosis. We will also review the effect of bronchodilators, pz agonists, and methylxanthines in mucus clearance.