Anatomical Therapeutic Chemical Classification System
Hyoscyamine inhibits specifically the actions of acetylcholine on structures innervated by postganglionic cholinergic nerves and on smooth muscles that respond to acetylcholine but lack cholinergic innervation. Hyoscyamine inhibits gastrointestinal propulsive motility and decreases gastric acid secretion. It also controls excessive pharyngeal, tracheal and bronchial secretions.