Beta Blocker

Beta Blocker

"Beta-Adrenergic antagonist" redirects here

Beta blockers (β-blockers, beta-adrenergic blocking agents, beta antagonists, beta-adrenergic antagonists, beta-adrenoreceptor antagonists, or beta adrenergic receptor antagonists) are a class of drugs.

Beta blockers target the beta receptor. 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.

They are particularly used for the management of cardiac arrhythmias, protecting the heart from a second heart attack (myocardial infarction) after a first heart attack (secondary prevention), and hypertension.

In 1962, Sir James W. Black found 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.

Beta blockers block the action of endogenous catecholamines epinephrine (adrenaline) and norepinephrine (noradrenaline) in particular, on β-adrenergic receptors, part of the sympathetic nervous system which mediates the fight-or-flight response. Three types of beta receptors are known, designated β₁, β₂ and β₃ receptors. β₁-adrenergic receptors are located mainly in the heart and in the kidneys. β₂-adrenergic receptors are located mainly in the lungs, gastrointestinal tract, liver, uterus, vascular smooth muscle, and skeletal muscle. β₃-adrenergic receptors are located in fat cells.

A study published in October 2012 in JAMA found that beta blockers did not prolong the lives of patients. The study followed approximately 45,000 patients for more than three years and found that beta blockers do not reduce risk of heart attacks, deaths from heart attacks or stroke. This study was further supported by another study published several days earlier in the Journal of the American Geriatrics Society which was looking at how drug compliance was affecting death rates in patients with a history of heart attacks.