beta -blocker

beta -blocker

 in full beta-adrenergic blocking agent

Any of a class of synthetic drugs used to treat a wide range of diseases and conditions of the sympathetic nervous system (see autonomic nervous system). Stimulation by epinephrine of beta-adrenergic receptors, which are predominately found in the heart but are also present in vascular and other smooth muscle, results in excitation of the sympathetic nervous system. By preventing that excitation, beta-blockers are useful in controlling anxiety, hypertension, and a variety of heart conditions (see heart disease). They reduce the risk of a second heart attack.