Drugs that bind to but do not activate muscarinic cholinergic receptors (RECEPTORS, MUSCARINIC), thereby blocking the actions of endogenous acetylcholine or exogenous agonists. Muscarinic antagonists have widespread effects including actions on the iris and ciliary muscle of the eye, the heart and blood vessels, secretions of the respiratory tract, GI system, and salivary glands, GI motility, urinary bladder tone, and the central nervous system. Antagonists that discriminate among the various muscarinic receptor subtypes and might allow better control of peripheral and central actions are under development.
