Beta blockers (beta-blockers, β-blockers, etc.) are a class of medications that are predominantly used to manage abnormal heart rhythms, and to protect the heart from a second heart attack (

myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sy ...

) after a first heart attack (

secondary prevention Preventive healthcare, or prophylaxis, consists of measures taken for disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental health and efficiency ...

). They are also widely used to treat high blood pressure (

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank ...

), although they are no longer the first choice for initial treatment of most patients. Beta blockers are

competitive antagonist A receptor antagonist is a type of receptor ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves ...

s that block the receptor sites for the

endogenous Endogenous substances and processes are those that originate from within a system such as an organism, Tissue (biology), tissue, or Cell (biology), cell. Endogenous substances and processes contrast with exogenous ones, such as Drug, drugs, which ...

catecholamine (noradrenaline) Image:Adrenalin - Adrenaline.svg">140px, epinephrine (adrenaline) A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol">organic_compound.html" ;"title="monoamine neurotra ...

epinephrine Adrenaline, also known as epinephrine, is a hormone A hormone (from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in ...

(adrenaline) and

norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical , CH4; is among the simplest organic compounds. In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and ...

(noradrenaline) on adrenergic beta receptors, of the

sympathetic nervous system The sympathetic nervous system (SNS) is one of two divisions of the autonomic nervous system, along with the parasympathetic nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes co ...

, which mediates the

fight-or-flight response The fight-or-flight-or-freeze or the fight-flight response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack Attack may refer to: Warfare and comba ...

. Some block activation of all types of

β-adrenergic receptor (yellow) on its extracellular This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more speci ...

s and others are selective for one of the three known types of beta receptors, designated β₁, β₂ and β₃ receptors. β₁-adrenergic receptors are located mainly in the heart and in the kidneys.

β₂-adrenergic receptors
β<sub>2</sub>-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 The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste ...

heart

muscles,

smooth muscles Smooth muscle is an involuntary non-striated muscle Striated muscle tissue is a muscle tissue that features repeating functional units called sarcomeres. The presence of sarcomeres manifests as a series of bands visible along the muscle fibers, w ...

airway The respiratory tract is the subdivision of the respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network which connects several biologically re ...

arteries An artery (plural arteries) () is a blood vessel that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pulmonary arteries, pulmonary ...

kidney The kidneys are two reddish-brown bean-shaped organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized ...

kidney

s, and other tissues that are part of the

and lead to stress responses, especially when they are stimulated by

(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,

James Black

synthesized the first clinically significant beta blockers—

propranolol Propranolol, sold under the brand name Inderal among others, is a medication of the class. It is used to treat , a number of types of , , s, , and s, as well to prevent , and to prevent further heart problems in those with or previous . It c ...

and

pronethalol Pronethalol (Alderlin, Nethalide) was an early non-selective beta blocker Beta blockers (beta-blockers, β-blockers, etc.) are a class of medications that are predominantly used to manage abnormal heart rhythms, and to protect the heart from a ...

; it revolutionized the medical management of

angina pectoris Angina, also known as angina pectoris, is chest pain Chest pain is pain or discomfort in the chest, typically the front of the chest. It may be described as sharp, dull, pressure, heaviness or squeezing. Associated symptoms may include pain in ...

and is considered by many to be one of the most important contributions to clinical medicine and

pharmacology Pharmacology is a branch of , and concerned with or action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemical or physiological effect on the cell, tissue, organ ...

of the 20th century. For the treatment of primary hypertension,

meta-analyses A meta-analysis is a statistical analysis that combines the results of multiple . Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting measurements that ar ...

of studies which mostly used

atenolol Atenolol is a beta blocker medication primarily used to treat high blood pressure Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term Disease, medical condition in which the blood pressure in the artery, arter ...

have shown that although beta blockers are more effective than

placebo A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. In general, placebos can af ...

placebo

in preventing

stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Dis ...

stroke

and total cardiovascular events, they are not as effective as

diuretics A diuretic () is any substance that promotes diuresis, the increased production of urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. U ...

, medications inhibiting the

renin–angiotensin system The renin–angiotensin system (RAS), or renin–angiotensin–aldosterone system (RAAS), is a hormone system that regulates blood pressure Blood pressure (BP) is the pressure Pressure (symbol: ''p'' or ''P'') is the force In physic ...

(e.g.,

ACE inhibitor Angiotensin-converting-enzyme inhibitors (ACE inhibitors) are a class of medication A medication (also referred to as medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to medical diagnosis, diagnose, cure, therapy ...

s), or

calcium channel blockers Calcium is a chemical element with the Symbol (chemistry), symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties a ...

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 Angina, also known as angina pectoris, is chest pain Chest pain is pain or discomfort in the chest, typically the front of the chest. It may be described as sharp, dull, pressure, heaviness or squeezing. Associated symptoms may include pain in ...

(contraindicated for

Prinzmetal's angina Variant angina, and less commonly Prinzmetal angina, vasospastic angina, angina inversa, coronary vessel spasm, or coronary artery vasospasm, is a syndrome typically consisting of angina Angina, also known as angina pectoris, is chest pain Che ...

) *

Atrial fibrillation Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm (arrhythmia) characterized by the rapid and irregular beating of the atrial chambers of the heart. It often begins as short periods of abnormal beating, which become longer or cont ...

Cardiac arrhythmia Arrhythmia, also known as cardiac arrhythmia or heart arrhythmia, is a group of conditions in which the heartbeat is irregular, too fast, or too slow. The heart rate that is too fast – above 100 beats per minute in adults – is called tach ...

Congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF), (congestive) cardiac failure (CCF), and decompensatio cordis, is when the heart is unable to pump sufficiently to maintain blood flow to meet the body tissues' needs for metabo ...

Essential tremor Essential tremor (ET), also called benign tremor, familial tremor, and idiopathic tremor, is a medical condition characterized by involuntary rhythmic contractions and relaxations (neural oscillations, oscillations or twitching movements) of certai ...

Glaucoma Glaucoma is a group of eye diseases which result in damage to the optic nerve The optic nerve, also known as cranial nerve II, or simply as CN II, is a paired cranial nerve Cranial nerves are the nerve A nerve is an enclosed, cable-li ...

(as eye drops, they decrease

intraocular pressure 250px, A patient in front of a tonometer Intraocular pressure (IOP) is the fluid pressure inside the human eye, eye. Ocular tonometry, Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluatio ...

by lowering

aqueous humor The aqueous humour is a Transparency and translucency, transparent water-like fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens. It fills both the anterior cha ...

secretion.) *

Hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank ...

, although they are generally not preferred as an initial treatment. *

Hyperthyroidism Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. ...

Migraine A migraine (, ) is a characterized by recurrent s that are moderate to severe. Typically, episodes affect one side of the head, are pulsating in nature, and last from a few hours to three days. Associated symptoms may include , , and , , or . ...

prophylaxis Preventive healthcare, or prophylaxis, consists of measures taken for disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental health and efficiency ...

Mitral valve prolapse Mitral valve prolapse (MVP) is a valvular heart disease Valvular heart disease is any cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart The heart is a muscle, muscular Organ (anatomy), ...

Myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sy ...

* Phaeochromocytoma, in conjunction with α-blocker *

Postural orthostatic tachycardia syndrome Postural orthostatic tachycardia syndrome (POTS) is a condition in which a change from lying A lie is an assertion that is believed to be false, typically used with the purpose of deceiving someone. The practice of communicating lies is c ...

* Symptomatic control (

tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (s ...

tremor A tremor is an involuntary, somewhat rhythmic, muscle contraction Muscle contraction is the activation of tension Tension may refer to: Science * Psychological stress * Tension (physics), a force related to the stretching of an object (the opp ...

) in

anxiety Anxiety is an emotion Emotions are mental state, psychological states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavioural responses, and a degree of pleasure or suffering, disp ...

anxiety

and

hyperthyroidism Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. ...

Theophylline Theophylline, also known as 1,3-dimethylxanthine, is a phosphodiesterase inhibiting drug used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma under a variety of brand names. As a member of the xa ...

overdose Beta-blockers have also been used for: * Acute

aortic dissection Aortic dissection (AD) occurs when an injury to the innermost layer of the aorta allows blood to flow between the layers of the aortic wall, forcing the layers apart. In most cases, this is associated with a sudden onset of severe chest or ...

* Hypertrophic obstructive

cardiomyopathy Cardiomyopathy is a group of diseases that affect the heart muscle Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate Vertebrates () comprise all species of animal Animals (also called Metaz ...

Long QT syndrome Long QT syndrome (LQTS) is a condition in which repolarization of the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood car ...

Marfan syndrome Marfan syndrome (MFS) is a rare multi-systemic genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome In the fields of molecular biology and genetics Genetics is a branch of b ...

(treatment with

slows progression of aortic dilation and its complications) * Prevention of variceal bleeding in

portal hypertension Portal hypertension is abnormally increased portal venous pressure – blood pressure in the portal vein and its branches, that drain from most of the intestine to the liver. Portal hypertension is defined as a hepatic venous pressure gradient grea ...

* Possible mitigation of

hyperhidrosis Hyperhidrosis is a condition characterized by abnormally increased sweating, in excess of that required for regulation of body temperature. Although primarily a physical burden, hyperhidrosis can deteriorate quality of life from a psychological, e ...

Social Social organisms, including humans, live collectively in interacting populations. This interaction is considered social whether they are aware of it or not, and whether the exchange is voluntary/involuntary. Etymology The word "Social" derives fr ...

and other

anxiety disorders Anxiety disorders are a cluster of mental disorder A mental disorder, also called a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such featu ...

* Controversially, for reduction of perioperative mortality in non-cardiac surgery, but the best evidence suggests that they increase mortality when used this way

Congestive heart failure

Although beta blockers were once contraindicated in

congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mos ...

, as they have the potential to worsen the condition due to their effect of decreasing cardiac contractility, studies in the late 1990s showed their efficacy at reducing morbidity and mortality.

Bisoprolol

carvedilol

, and sustained-release

metoprolol

are specifically indicated as adjuncts to standard

and

diuretic A diuretic () is any substance that promotes diuresis Diuresis () is increased urination Urination is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretio ...

therapy in congestive heart failure, although at doses typically much lower than those indicated for other conditions. Beta-blockers are only indicated in cases of compensated, stable congestive heart failure; in cases of acute decompensated heart failure, beta-blockers will cause a further decrease in ejection fraction, worsening the patient's current symptoms. Beta-blockers are known primarily for their reductive effect on heart rate, although this is not the only mechanism of action of importance in congestive heart failure. Beta-blockers, in addition to their sympatholytic β1 activity in the heart, influence the

at the kidneys. Beta-blockers cause a decrease in

renin Renin (#Discovery and naming, etymology and pronunciation), also known as an angiotensinogenase, is an aspartic protease protein and enzyme secreted by the kidneys that participates in the body's renin–angiotensin system, renin–angiotensin� ...

renin

secretion, which in turn reduces the heart oxygen demand by lowering the extracellular volume and increasing the oxygen-carrying capacity of the blood. Heart failure characteristically involves increased catecholamine activity on the heart, which is responsible for several deleterious effects, including increased oxygen demand, propagation of inflammatory mediators, and abnormal cardiac tissue remodeling, all of which decrease the efficiency of cardiac contraction and contribute to the low ejection fraction. Beta-blockers counter this inappropriately high sympathetic activity, eventually leading to an improved ejection fraction, despite an initial reduction in ejection fraction. Trials have shown beta blockers reduce the absolute risk of death by 4.5% over a 13-month period. In addition to reducing the risk of mortality, the numbers of hospital visits and hospitalizations were also reduced in the trials. Therapeutic administration of beta-blockers for congestive heart failure ought to begin at very low doses (1/8 of target) with a gradual escalation of the dose. The heart of the patient must adjust to decreasing stimulation by catecholamines and find a new equilibrium at a lower adrenergic drive.

Anxiety

Officially, beta blockers are not approved for

anxiolytic An anxiolytic (; also antipanic or antianxiety agent) is a medication, or other intervention, that reduces anxiety (mood), anxiety. This effect is in contrast to anxiogenic agents, which increase anxiety. Together these categories of Psychoactiv ...

use by the U.S.

Food and Drug Administration The United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, st ...

. However, many controlled trials in the past 25 years indicate beta blockers are effective in

, though the mechanism of action is not known. The physiological symptoms of the

fight-or-flight The fight-or-flight response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first described by Walter Bradford Cann ...

response (pounding heart, cold/clammy hands, increased respiration, sweating, etc.) are significantly reduced, thus enabling anxious individuals to concentrate on the task at hand. Musicians, public speakers, actors, and professional

dancers Dance is a performing art The performing arts are arts such as music, dance, and drama which are performed for an audience. It is different from visual arts The visual arts are art forms such as painting Painting is the pract ...

dancers

have been known to use beta-blockers to avoid performance anxiety,

stage fright Stage fright or performance anxiety is the anxiety Anxiety is an emotion Emotions are biological states associated with all of the nerve systems brought on by neurophysiological changes variously associated with thoughts, feelings, behaviou ...

, and tremor during both

audition An audition is a sample performance by an actor An actor is a person who portrays a character Character(s) may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ...

s and public performances. The application to stage fright was first recognized in ''

The Lancet ''The Lancet'' is a weekly peer-reviewed Peer review is the evaluation of work by one or more people with similar competencies as the producers of the work ( peers). It functions as a form of self-regulation by qualified members of a prof ...

'' in 1976, and by 1987, a survey conducted by the International Conference of Symphony Orchestra Musicians, representing the 51 largest orchestras in the United States, revealed 27% of its musicians had used beta-blockers and 70% obtained them from friends, not physicians. Beta-blockers are inexpensive, said to be relatively safe, and on one hand, seem to improve musicians' performances on a technical level, while some, such as Barry Green, the author of "The Inner Game of Music" and Don Greene, a former Olympic diving coach who teaches Juilliard students to overcome their stage fright naturally, say the performances may be perceived as "soulless and inauthentic".

Cardiac surgery

The use of beta blockers around the time of cardiac surgery decreases the risk of heart dysrhythmias. Starting them around the time of other types of surgery, however, may worsen outcomes.

Performance-enhancing use

Because they promote lower heart rates and reduce tremors, beta blockers have been used in professional sports where high accuracy is required, including

archery Archery is the art, sport, practice, or skill of using a bow Bow often refers to: * Bow and arrow, a weapon * Bowing, bending the upper body as a social gesture * An ornamental knot made of ribbon Bow may also refer to: Boats * Bow (sh ...

shooting Shooting is the act or process of discharging a projectile from a ranged weapon (such as a gun, bow and arrow, bow, crossbow, slingshot, or blowgun, blowpipe). Even the acts of launching flamethrower, flame, artillery, dart (missile), darts, ha ...

golf Golf is a club-and-ball sport Sport pertains to any form of competitive Competition is a rivalry A rivalry is the state of two people or groups engaging in a lasting competitive relationship. Rivalry is the "against each other" ...

golf

and

snooker Snooker (pronounced , ) is a cue sport Cue sports (sometimes written cuesports), also known as billiard sports, are a wide variety of games of skill generally played with a cue stick, which is used to strike billiard balls and thereby c ...

snooker

. Beta blockers are banned by the

International Olympic Committee The International Olympic Committee (IOC; french: Comité international olympique, ''CIO'') is a non-governmental sports organisation based in Lausanne , neighboring_municipalities= Bottens Bottens is a municipalities of Switzerland, m ...

. In the

2008 Summer Olympics The 2008 Summer Olympics (), officially known as the Games of the XXIX Olympiad () and commonly known as Beijing 2008 (), was an international multisport event A multi-sport event is an organized sport, sporting event, often held over multip ...

, 50-metre pistol silver medalist and 10-metre air pistol bronze medalist Kim Jong-su tested positive for

and was stripped of his medals. For similar reasons, beta blockers have also been used by surgeons. Classical musicians have commonly used beta blockers since the 1970's to reduce stage fright.

Adverse effects

Adverse drug reactions associated with the use of beta blockers include:

nausea Nausea is a diffuse sensation of unease and discomfort, often perceived as an urge to vomiting, vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, upper abdomen, or ...

nausea

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery defecation, bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration of ...

bronchospasm Bronchospasm or a bronchial spasm is a sudden constriction Constriction is a method used by various snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, ...

dyspnea Shortness of breath (SOB), also known as dyspnea (BrE British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codificat ...

, cold extremities, exacerbation of

Raynaud's syndrome Raynaud syndrome, also known as Raynaud's phenomenon, eponymously named after the physician, Auguste Gabriel Maurice Raynaud, who first described it in his doctoral thesis in 1862, is a medical condition in which spasm of small arteries cause ...

bradycardia Bradycardia is a condition typically defined wherein an individual has a resting heart rate Heart rate is the speed of the heartbeat Heartbeat or heartbeats may refer to: Physiology *Cardiac cycle, of the heart *Contraction of the cardiac musc ...

hypotension Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the Systole, systolic blood pressure (the top number) and ...

heart failure Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mo ...

heart block Heart block (HB) is a disorder in the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the ...

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo Vertigo is a condition where a person has the sensation of moving or of surrounding objects moving when they are not. Often it feels like a spinnin ...

alopecia Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarrin ...

(hair loss), abnormal vision,

hallucinations A hallucination is a perception Perception (from the Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ' ...

insomnia Insomnia, also known as sleeplessness, is a sleep disorder A sleep disorder, or somnipathy, is a medical disorder of an individual's sleep patterns. Some sleep disorders are severe enough to interfere with normal physical, mental, social and ...

, nightmares, sexual dysfunction, erectile dysfunction and/or alteration of glucose and lipid metabolism. Mixed α₁/β-antagonist therapy is also commonly associated with orthostatic hypotension. Carvedilol therapy is commonly associated with edema. Due to the high penetration across the blood–brain barrier, lipophilic beta blockers, such as

and

metoprolol

, are more likely than other less lipophilic beta blockers to cause sleep disturbances, such as insomnia, vivid dreams and nightmares. Adverse effects associated with β₂-adrenergic receptor antagonist activity (bronchospasm, peripheral vasoconstriction, alteration of glucose and lipid metabolism) are less common with β₁-selective (often termed "cardioselective") agents, but receptor selectivity diminishes at higher doses. Beta blockade, especially of the beta-1 receptor at the macula densa, inhibits renin release, thus decreasing the release of aldosterone. This causes hyponatremia and hyperkalemia. Hypoglycemia can occur with beta blockade because β2-adrenoceptors normally stimulate glycogen breakdown (glycogenolysis) in the liver and pancreatic release of the hormone glucagon, which work together to increase plasma glucose. Therefore, blocking β2-adrenoceptors lowers plasma glucose. β1-blockers have fewer metabolic side effects in diabetic patients; however, the fast heart rate that serves as a warning sign for insulin-induced low blood sugar may be masked, resulting in diabetic hypoglycemia#Unawareness, hypoglycemia unawareness. This is termed diabetic hypoglycemia#Beta blockers, beta blocker-induced hypoglycemia unawareness. Therefore, beta blockers are to be used cautiously in diabetics. A 2007 study revealed diuretics and beta blockers used for hypertension increase a patient's risk of developing diabetes mellitus, while ACE inhibitors and angiotensin II receptor antagonists (angiotensin receptor blockers) actually decrease the risk of diabetes. Clinical guidelines in Great Britain, but not in the United States, call for avoiding diuretics and beta blockers as first-line treatment of hypertension due to the risk of diabetes. Beta blockers must not be used in the treatment of selective alpha-adrenergic agonist overdose. The blockade of only beta receptors increases hypertension, blood pressure, reduces coronary blood flow, left ventricular function, and cardiac output and tissue perfusion by means of leaving the alpha-adrenergic system stimulation unopposed. Beta blockers with lipophilic properties and CNS penetration such as

metoprolol

and labetalol may be useful for treating CNS and cardiovascular toxicity from a methamphetamine overdose. The mixed alpha blocker, alpha- and beta blocker labetalol is especially useful for treatment of concomitant tachycardia and hypertension induced by methamphetamine. The phenomenon of "unopposed alpha stimulation" has not been reported with the use of beta blockers for treatment of methamphetamine toxicity. Other appropriate antihypertensive drugs to administer during hypertensive crisis resulting from stimulant overdose are vasodilators such as nitroglycerin (drug), nitroglycerin,

such as furosemide, and alpha blockers such as phentolamine.

Contraindications

Contraindications for beta-blockers include: * Abrupt discontinuations *Bronchospasm, Acute bronchospasm *Heart failure, Acute heart failure *Asthma *Av block, AV block *Bradycardia *Bronchitis *Cardiogenic shock *Cerebrovascular disease *Chronic obstructive pulmonary disease, Chronic obstructive pulmonary disease (COPD) *Diabetes, Diabetes mellitus *Emphysema *Hypersensitivity to beta blockers *Hypotension *Kidney failure *Liver disease, Hepatic disease *Myopathy *Pheochromocytoma *Psoriasis *Stroke *Vasospastic angina *Wolff–Parkinson–White syndrome

Asthma

The 2007 National Heart, Lung, and Blood Institute (NHLBI) asthma guidelines recommend against the use of non-selective beta blockers in asthmatics, while allowing for the use of cardioselective beta blockers. Cardioselective beta-blocker (β1 blockers), if really required, can be prescribed at the least possible dose to those with mild to moderate respiratory symptoms. β2-agonists can somewhat mitigate β-Blocker-induced

where it exerts greater efficacy on reversing ''selective'' β-blocker-induced bronchospasm than the ''nonselective'' β-blocker-induced worsening asthma and/or COPD.

Diabetes mellitus

Epinephrine signals early warning of the upcoming hypoglycemia. Beta-blockers' inhibition on epinephrine's effect can somewhat exacerbate hypoglycemia by interfering with glycogenesis and mask signs of hypoglycemia such as tachycardia, palpitations, diaphoresis, and tremors. Diligent blood glucose level monitoring is necessary for a patient with diabetes mellitus on beta-blocker.

Hyperthyroidism

Abrupt withdrawal can result in a thyroid storm.

Bradycardia or AV block

Unless a pacemaker is present, beta-blockers can severely depress conduction in the AV node, resulting in a reduction of heart rate and cardiac output. Usage of beta-blockers in tachycardic patients with Wolff-Parkinson-White Syndrome can result in severe bradycardia, necessitating treatment with a pacemaker.

Toxicity

Glucagon, used in the treatment of overdose, increases the strength of heart contractions, increases intracellular Cyclic adenosine monophosphate, cAMP, and decreases renal vascular resistance. It is, therefore, useful in patients with beta blocker cardiotoxicity. Artificial cardiac pacemaker, Cardiac pacing is usually reserved for patients unresponsive to pharmacological therapy. People experiencing bronchospasm due to the β₂ receptor-blocking effects of nonselective beta blockers may be treated with anticholinergic drugs, such as ipratropium, which are safer than Beta-adrenergic agonist, beta agonists in patients with cardiovascular disease. Other antidotes for beta blocker poisoning are salbutamol and isoprenaline.

β-receptor antagonism

Stimulation of β₁ receptors by epinephrine and norepinephrine induces a positive chronotropic and inotropic effect on the heart and increases cardiac conduction velocity and automaticity. Stimulation of β₁ receptors on the kidney causes

release. Stimulation of β₂ receptors induces smooth muscle relaxation, induces tremor in skeletal muscle, and increases glycogenolysis in the liver and skeletal muscle. Stimulation of β₃ receptors induces lipolysis. Beta blockers inhibit these normal epinephrine- and norepinephrine-mediated sympathetic nervous system, sympathetic actions, but have minimal effect on resting subjects. That is, they reduce the effect of excitement or physical exertion on heart rate and force of contraction, and also tremor, and breakdown of glycogen. Beta blockers can have a constricting effect on the bronchi of the lungs, possibly worsening or causing asthma symptoms. Since β₂ adrenergic receptors can cause vascular smooth muscle dilation, beta blockers may cause some vasoconstriction. However, this effect tends to be small because the activity of β₂ receptors is overshadowed by the more dominant vasoconstricting α₁ receptors. By far the greatest effect of beta blockers remains in the heart. Newer, third-generation beta blockers can cause vasodilation through blockade of alpha-adrenergic receptors. Accordingly, nonselective beta blockers are expected to have antihypertensive effects. The primary antihypertensive mechanism of beta blockers is unclear, but may involve reduction in cardiac output (due to negative chronotropic and inotropic effects). It may also be due to reduction in renin release from the kidneys, and a central nervous system effect to reduce sympathetic activity (for those beta blockers that do cross the blood–brain barrier, e.g. propranolol). Antianginal effects result from negative chronotropic and inotropic effects, which decrease cardiac workload and oxygen demand. Negative chronotropic properties of beta-blockers allow the lifesaving property of heart rate control. Beta-blockers are readily titrated to optimal rate control in many pathologic states. The antiarrhythmic effects of beta blockers arise from sympathetic nervous system blockade—resulting in depression of sinus node function and atrioventricular node conduction, and prolonged atrium (anatomy), atrial refractory period (cardiac), refractory periods. Sotalol, in particular, has additional antiarrhythmic properties and prolongs action potential duration through potassium channel blockade. Blockade of the sympathetic nervous system on renin release leads to reduced aldosterone via the Renin–angiotensin system, renin–angiotensin–aldosterone system, with a resultant decrease in blood pressure due to decreased sodium and water retention.

Intrinsic sympathomimetic activity

Also referred to as intrinsic sympathomimetic effect, this term is used particularly with beta-blockers that can show both agonism and antagonism at a given beta receptor, depending on the concentration of the agent (beta-blocker) and the concentration of the antagonized agent (usually an endogenous compound, such as norepinephrine). See partial agonist for a more general description. Some beta blockers (e.g. oxprenolol, pindolol, penbutolol, labetalol and acebutolol) exhibit intrinsic sympathomimetic activity (ISA). These agents are capable of exerting low-level receptor agonist, agonist activity at the β-adrenergic receptor while simultaneously acting as a receptor site receptor antagonist, antagonist. These agents, therefore, may be useful in individuals exhibiting excessive

with sustained beta blocker therapy. Agents with ISA are not used after myocardial infarctions, as they have not been demonstrated to be beneficial. They may also be less effective than other beta-blockers in the management of Angina pectoris, angina and tachyarrhythmia.

α₁-receptor antagonism

Some beta blockers (e.g., labetalol and

carvedilol

) exhibit mixed antagonism of both β- and α₁-adrenergic receptors, which provides additional arteriole, arteriolar vasodilating action.

Examples

Nonselective agents

Nonselective beta blockers display both β₁ and β₂ antagonism. *Propranolol *Bucindolol (has additional α₁-blocking activity) *Carteolol *Carvedilol (has additional α₁-blocking activity) *Labetalol (has additional α₁-blocking activity) *Nadolol *Oxprenolol (has intrinsic sympathomimetic activity) *Penbutolol (has intrinsic sympathomimetic activity) *Pindolol (has intrinsic sympathomimetic activity) *Sotalol (not considered a "typical beta blocker") *Timolol

β₁-selective agents

β₁-selective beta blockers are also known as cardioselective beta blockers. *Acebutolol (has intrinsic sympathomimetic activity, ISA) *Atenolol *Betaxolol *

Bisoprolol

*Celiprolol (has intrinsic sympathomimetic activity) *Metoprolol *Nebivolol *Esmolol

β₂-selective agents

*Butaxamine *ICI-118,551

β₃-selective agents

*SR 59230A

β₁ selective antagonist and β₃ agonist agents

* Nebivolol

Comparative information

Pharmacological differences

*Agents with intrinsic sympathomimetic action (ISA) **Acebutolol, pindolol, labetalol, mepindolol, oxprenolol, celiprolol, penbutolol *Agents organized by lipid solubility (lipophilicity) **High lipophilicity: propranolol, labetalol **Intermediate lipophilicity: metoprolol, bisoprolol, carvedilol, acebutolol, timolol, pindolol **Low lipophilicity (also known as hydrophilic beta-blockers): atenolol, nadolol, and sotalol *Agents with membrane stabilizing effect **Carvedilol, propranolol > oxprenolol > labetalol, metoprolol, timolol

Indication differences

*Agents specifically labeled for cardiac arrhythmia **Esmolol, sotalol, landiolol (Japan) *Agents specifically labeled for congestive heart failure **

Bisoprolol

carvedilol

, metoprolol, sustained-release metoprolol *Agents specifically labeled for glaucoma **Betaxolol, carteolol, levobunolol, timolol, metipranolol *Agents specifically labeled for myocardial infarction **Atenolol,

metoprolol

(immediate release),

(immediate release), timolol,

carvedilol

(after left ventricular dysfunction), bisoprolol (preventive treatment before and primary treatment after heart attacks) *Agents specifically labeled for migraine prophylaxis **Timolol,

Propranolol is the only agent indicated for the control of tremor, portal hypertension, and esophageal variceal bleeding, and used in conjunction with α-blocker therapy in phaeochromocytoma.

Other effects

Beta blockers, due to their antagonism at beta-1 adrenergic receptors, inhibit both the synthesis of new melatonin and its secretion by the pineal gland. The neuropsychiatric side effects of some beta blockers (e.g. sleep disruption,

) may be due to this effect. Some pre-clinical and clinical research suggests that some beta blockers may be beneficial for cancer treatment. However, other studies do not show a correlation between cancer survival and beta blocker usage. Also, a 2017 meta-analysis failed to show any benefit for the use of beta blockers in breast cancer. Beta blockers have also been used for the treatment of schizoid personality disorder. However, there is limited evidence supporting the efficacy of supplemental beta-blocker use in addition to antipsychotic drugs for treating schizophrenia. Contrast media are not contraindicated in patients receiving beta blockers.

References

External links

Musicians and beta-blockers
by Gerald Klickstein, March 11, 2010 (A blog post that considers "whether beta-blockers are safe, effective, and appropriate for performers to use.")

by Blair Tindall, ''The New York Times'', October 17, 2004. (Discusses the use of beta-blockers among professional musicians)
Musicians using beta blockers
by Blair Tindall. A condensed version of the above article.
In Defense of the Beta Blocker
by Carl Elliott, ''The Atlantic'', August 20, 2008. (Discusses the use of propranolol by a North Korean pistol shooter in the 2008 Olympics) * {{DEFAULTSORT:Beta Blocker Beta blockers, Scottish inventions

Medical uses

Congestive heart failure

Anxiety

Cardiac surgery

Performance-enhancing use

Adverse effects

Contraindications

Asthma

Diabetes mellitus

Hyperthyroidism

Bradycardia or AV block

Toxicity

β-receptor antagonism

Intrinsic sympathomimetic activity

α1-receptor antagonism

Examples

Nonselective agents

β1-selective agents

β2-selective agents

β3-selective agents

β1 selective antagonist and β3 agonist agents

Comparative information

Pharmacological differences

Indication differences

Other effects

See also

References

External links

α₁-receptor antagonism

β₁-selective agents

β₂-selective agents

β₃-selective agents

β₁ selective antagonist and β₃ agonist agents