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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 that 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),. They have been used in hypertension, but are no longer a treatment of first choice. Beta blockers block the action of 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 all activation of β-adrenergic receptors and others are selective. 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. 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 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. For the treatment of primary hypertension, in comparison with other first-line anti-hypertensive drugs, first-line beta-blockers are not as effective in preventing stroke and total cardiovascular events as first-line diuretics, drugs inhibiting the renin-angiotensin system and calcium channel blockers.〔Wiysonge CS, Bradley HA, Volmink J, Mayosi BM, Mbewu A, Opie LH. Beta-blockers for hypertension. Cochrane Database of Systematic Reviews 2012, Issue 11. Art. No.: CD002003. DOI: 10.1002/14651858.CD002003.pub4〕〔Xue H, Lu Z, Tang WL, Pang LW, Wang GM, Wong GWK, Wright JM. First-line drugs inhibiting the renin angiotensin system versus other first-line antihypertensive drug classes for hypertension. Cochrane Database of Systematic Reviews 2015, Issue 1. Art. No.: CD008170. DOI: 10.1002/14651858.CD008170.pub2〕〔Chen N, Zhou M, Yang M, Guo J, Zhu C, Yang J, Wang Y, Yang X, He L. Calcium channel blockers versus other classes of drugs for hypertension. Cochrane Database of Systematic Reviews 2010, Issue 8. Art. No.: CD003654. DOI: 10.1002/14651858.CD003654.pub4.〕 == Medical uses == Large differences exist in the pharmacology of agents within the class, thus not all beta blockers are used for all indications listed below. Indications for beta blockers include: * Angina pectoris * Atrial fibrillation * Cardiac arrhythmia * Congestive heart failure * Essential tremor * Glaucoma * Hypertension * Migraine prophylaxis * Mitral valve prolapse * Myocardial infarction * Phaeochromocytoma, in conjunction with α-blocker * Postural orthostatic tachycardia syndrome * Symptomatic control (tachycardia, tremor) in anxiety and hyperthyroidism * Theophylline overdose Beta blockers have also been used for: * Acute aortic dissection * Hypertrophic obstructive cardiomyopathy * Marfan syndrome (treatment with propranolol slows progression of aortic dilation and its complications) * Prevention of variceal bleeding in portal hypertension * Possible mitigation of hyperhidrosis * Social and other anxiety disorders * Controversially, for reduction of perioperative mortality 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「beta blocker」の詳細全文を読む スポンサード リンク
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