Expectorants, Antitussives, and Related Agents

Abstract

Expectorants enhance the projection of respiratory tract fluid and thus facilitate the mobilization and discharge of bronchial secretions. Stimulant expectorants increase respiratory tract secretion by a direct effect on the bronchial secretory cells, and sedative expectorants act by gastric reflex stimulation. Classes of expectorants discussed include quaiacols, volatile oils, iodides and other inorganic compounds, and miscellaneous natural products. Mucolytics reduce the viscosity of tenacious and purulent mucus, thus facilitating removal. Some agents discussed that chemically depolymerize certain components of mucus include trypsin, other proteolytic enzymes, and cis ‐4‐hydroxymethyl‐2‐iodomethyl‐1,3‐dioxolane. Antitussives control excessive coughing. A brief description of the cough reflex is presented. Centrally active antitussives, both narcotic and nonnarcotic, as well as peripherally active antitussives are presented and discussed.