Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms (arrhythmia), and to protect the heart from a second heart attack after a first heart attack. They are also widely used to treat high blood pressure, although they are no longer the first choice for initial treatment of most patients.
The adrenergic receptors or adrenoceptors are a class of G protein-coupled receptors that are targets of many catecholamines like norepinephrine (noradrenaline) and epinephrine (adrenaline) produced by the body, but also many medications like beta blockers, beta-2 (β2) agonists and alpha-2 (α2) agonists, which are used to treat high blood pressure and asthma, for example.
Bronchospasm or a bronchial spasm is a sudden constriction of the muscles in the walls of the bronchioles. It is caused by the release (degranulation) of substances from mast cells or basophils under the influence of anaphylatoxins. It causes difficulty in breathing which ranges from mild to severe.
An adrenergic agonist is a drug that stimulates a response from the adrenergic receptors. The five main categories of adrenergic receptors are: α1, α2, β1, β2, and β3, although there are more subtypes, and agonists vary in specificity between these receptors, and may be classified respectively. However, there are also other mechanisms of adrenergic agonism. Epinephrine and norepinephrine are endogenous and broad-spectrum. More selective agonists are more useful in pharmacology.
Beta2-adrenergic agonists, also known as adrenergic β2 receptor agonists, are a class of drugs that act on the β2 adrenergic receptor. Like other β adrenergic agonists, they cause smooth muscle relaxation. β2 adrenergic agonists' effects on smooth muscle cause dilation of bronchial passages, vasodilation in muscle and liver, relaxation of uterine muscle, and release of insulin. They are primarily used to treat asthma and other pulmonary disorders. Bronchodilators are considered an important treatment regime for chronic obstructive pulmonary disease (COPD) and are usually used in combination with short acting medications and long acting medications in a combined inhaler.
Isoprenaline, or isoproterenol, is a medication used for the treatment of bradycardia, heart block, and rarely for asthma. It is a non-selective β adrenoceptor agonist that is the isopropylamine analog of epinephrine (adrenaline).
Dobutamine is a medication used in the treatment of cardiogenic shock and severe heart failure. It may also be used in certain types of cardiac stress tests. It is given by IV only, as an injection into a vein or intraosseous as a continuous infusion. The amount of medication needs to be adjusted to the desired effect. Onset of effects is generally seen within 2 minutes. It has a half-life of two minutes. This drug is generally only administered short term, although it may be used for longer periods to relieve symptoms of heart failure in patients awaiting heart transplantation.
Levosalbutamol, also known as levalbuterol, is a short-acting β2 adrenergic receptor agonist used in the treatment of asthma and chronic obstructive pulmonary disease (COPD). Evidence is inconclusive regarding the efficacy of levosalbutamol versus salbutamol or salbutamol-levosalbutamol combinations, though levosalbutamol is believed to have a better safety profile due to its more selective binding to β2 receptors versus β1.
Ritodrine is a tocolytic drug used to stop premature labor. This drug has been removed from the US market, according to FDA Orange Book. It was available in oral tablets or as an injection and was typically used as the hydrochloride salt, ritodrine hydrochloride.
The beta-1 adrenergic receptor, also known as ADRB1, can refer to either the protein-encoding gene or one of the four adrenergic receptors. It is a G-protein coupled receptor associated with the Gs heterotrimeric G-protein that is expressed predominantly in cardiac tissue. In addition to cardiac tissue, beta-1 adrenergic receptors are also expressed in the cerebral cortex.
The beta-2 adrenergic receptor, also known as ADRB2, is a cell membrane-spanning beta-adrenergic receptor that binds epinephrine (adrenaline), a hormone and neurotransmitter whose signaling, via adenylate cyclase stimulation through trimeric Gs proteins, increases cAMP, and, via downstream L-type calcium channel interaction, mediates physiologic responses such as smooth muscle relaxation and bronchodilation.
Isoetharine is a selective short-acting β2 adrenoreceptor agonist. It can be called the "granddaughter of adrenalin" in the line of β2 agonists that gave quick relief for bronchospasm and asthma. Epinephrine (adrenalin) was the first of these, and next came isoprenaline (isoproterenol). Isoetharine was the third drug in this line, thus the third generation or granddaughter of the original.
The beta-3 adrenergic receptor (β3-adrenoceptor), also known as ADRB3, is a beta-adrenergic receptor, and also denotes the human gene encoding it.
Beta1-adrenergic agonists, also known as Beta1-adrenergic receptor agonists, are a class of drugs that bind selectively to the beta-1 adrenergic receptor. As a result, they act more selectively upon the heart. Beta-adrenoceptors typically bind to norepinephrine release by sympathetic adrenergic nerves and to circulating epinephrine. The effect of B-adrenoceptors is cardiac stimulation, such as increased heart rate, heart contractility, heart conduction velocity and heart relaxation.
Olodaterol is an ultra-long-acting β adrenoreceptor agonist (ultra-LABA) used as an inhalation for treating people with chronic obstructive pulmonary disease (COPD). It is manufactured by Boehringer Ingelheim.
β2-adrenoceptor agonists are a group of drugs that act selectively on β2-receptors in the lungs causing bronchodilation. β2-agonists are used to treat asthma and COPD, diseases that cause obstruction in the airways. Prior to their discovery, the non-selective beta-agonist isoprenaline was used. The aim of the drug development through the years has been to minimise side effects, achieve selectivity and longer duration of action. The mechanism of action is well understood and has facilitated the development. The structure of the binding site and the nature of the binding is also well known, as is the structure activity relationship.
The β3 adrenergic receptor agonist or β3-adrenoceptor agonist, also known as β3-AR agonist, are a class of medicine that bind selectively to β3-adrenergic receptors.
Autonomic drugs can either inhibit or enhance the functions of the parasympathetic and sympathetic nervous systems. This type of drug can be used to treat a wide range of diseases, such as glaucoma, asthma, urinary, gastrointestinal and cardiopulmonary disorders.
Adrenergic blocking agents are a class of drugs that exhibit its pharmacological action through inhibiting the action of the sympathetic nervous system in the body. The sympathetic nervous system(SNS) is an autonomic nervous system that we cannot control by will. It triggers a series of responses after the body releases chemicals named noradrenaline and epinephrine. These chemicals will act on adrenergic receptors, with subtypes Alpha-1, Alpha-2, Beta-1, Beta-2, Beta-3, which ultimately allow the body to trigger a "fight-or-flight" response to handle external stress. These responses include vessel constriction in general vessels whereas there is vasodilation in vessels that supply skeletal muscles or in coronary vessels. Additionally, the heart rate and contractile force increase when SNS is activated, which may be harmful to cardiac function as it increases metabolic demand.
Adrenergic neurone blockers, commonly known as adrenergic antagonists, are a group of drugs that inhibit the sympathetic nervous system by blocking the activity of adrenergic neurones. They prevent the action or release of catecholamines such as norepinephrine and epinephrine. They are located throughout the body, causing various physiological reactions including bronchodilation, accelerated heartbeat, and vasoconstriction. They work by inhibiting the synthesis, release, or reuptake of the neurotransmitters or by antagonising the receptors on postsynaptic neurones. Their medical uses, mechanisms of action, adverse effects, and contraindications depend on the specific types of adrenergic blockers used, including alpha 1, alpha 2, beta 1, and beta 2.
