What is "beta blocker"

alt. (context pharmaceutical drug English) A blocking agent, one of a class of drugs used to treat hypertension and control the rate at which the heart beats. n. (context pharmaceutical drug English) A blocking agent, one of a class of drugs used to treat hypertension and control the rate at which the heart beats.

n. any of various drugs used in treating hypertension or arrhythmia; decreases force and rate of heart contractions by blocking beta-adrenergic receptors of the autonomic nervous system [syn: beta-adrenergic blocker, beta-adrenergic blocking agent]

Beta blockers (also β-blockers, beta-adrenergic blocking agents, beta antagonists, beta-adrenergic antagonists, beta-adrenoreceptor antagonists, or beta adrenergic receptor antagonists) are a class of drugs that are particularly used to manage cardiac arrhythmias, and to protect the heart from a second heart attack ( myocardial infarction) after a first heart attack (secondary prevention). They are also widely used to treat hypertension, although they are no longer the first choice for initial treatment of most patients according to current guidelines (as of 2016).

Beta blockers are competitive antagonists that block the receptor sites for the endogenous catecholamines epinephrine (adrenaline) and norepinephrine (noradrenaline) on adrenergic beta receptors, of the sympathetic nervous system, which mediates the fight-or-flight response. Some block activation of all types of β-adrenergic receptors and others are selective for one of the three known types of beta receptors, designated β, β and β receptors. β-adrenergic receptors are located mainly in the heart and in the kidneys. β-adrenergic receptors are located mainly in the lungs, gastrointestinal tract, liver, uterus, vascular smooth muscle, and skeletal muscle. β-adrenergic receptors are located in fat cells.

Beta receptors are found on cells of the heart muscles, smooth muscles, airways, arteries, kidneys, and other tissues that are part of the sympathetic nervous system and lead to stress responses, especially when they are stimulated by epinephrine (adrenaline). Beta blockers interfere with the binding to the receptor of epinephrine and other stress hormones, and weaken the effects of stress hormones.

In 1964, Sir James W. Black synthesized the first clinically significant beta blockers— propranolol and pronethalol; it revolutionized the medical management of angina pectoris and is considered by many to be one of the most important contributions to clinical medicine and pharmacology of the 20th century.

For the treatment of primary hypertension, meta-analyses of studies which mostly used atenolol as the beta-blocker tested have shown although beta-blockers are more effective than placebo in preventing stroke and total cardiovascular events, they are not as effective as diuretics, drugs inhibiting the renin-angiotensin system or calcium channel blockers.