Beta2-adrenergic agonist

Source: Wikipedia, the free encyclopedia.

Salbutamol (albuterol) — an example of β2 agonist

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.[1][2]

Mechanism of action

Activation of

β adrenergic receptors leads to relaxation of smooth muscle in the lung, and dilation and opening of the airways.[3]

β adrenergic receptors are coupled to a stimulatory G protein of adenylyl cyclase. This enzyme produces the second messenger cyclic adenosine monophosphate (cAMP). In the lung, cAMP decreases calcium concentrations within cells and activates protein kinase A. Both of these changes inactivate myosin light-chain kinase and activate myosin light-chain phosphatase. In addition, β2 agonists open large conductance calcium-activated potassium channels and thereby tend to hyperpolarize airway smooth muscle cells. The combination of decreased intracellular calcium, increased membrane potassium conductance, and decreased myosin light chain kinase activity leads to smooth muscle relaxation and bronchodilation.[3]

Adverse effects

Findings indicate that β2 stimulants, especially in parenteral administration such as inhalation or injection, can induce adverse effects:

Overuse of β2 agonists and asthma treatment without proper inhaled corticosteroid use has been associated with an increased risk of asthma exacerbations and asthma-related hospitalizations.[8] The excipients, in particular sulfite, could contribute to the adverse effects.

Delivery

All β2 agonists are available in

dry powder inhalers which dispense a powder to be inhaled, or soft mist inhalers which dispense a mist without use of propellants.[9]

INN) or albuterol (USAN) and some other β2 agonists, such as formoterol, also are sold in a solution form for nebulization, which is more commonly used than inhalers in emergency rooms.[9] Nebulizers continuously deliver aerosolized drug and salbutamol delivered through nebulizer was found to be more effective than IV administration.[10]

Salbutamol and

contractions.[12]

Risks

On 18 November 2005, the U.S.

product labeling.[medical citation needed
]

A 2006 meta-analysis found that "regularly inhaled β agonists (orciprenaline/metaproterenol [Alupent], formoterol [Foradil], fluticasone+salmeterol [Serevent, Advair], and salbutamol/albuterol [Proventil, Ventolin, Volmax, and others]) increased the risk of respiratory death more than two-fold, compared with a placebo," while[vague] used to treat chronic obstructive pulmonary disease.[13] On 11 December 2008, a panel of experts convened by the FDA voted to ban[

Foradil from use in the treatment of asthma. When these two drugs are used without steroids, they increase the risks of more severe attacks. They said that two other, much more popular, asthma drugs containing long-acting β agonists—Advair and Symbicort—should continue to be used.[14]

Types

They can be divided into short-acting, long-acting, and ultra-long-acting beta adrenoreceptor agonists:

Generic name—Trade name

Short-acting β2 agonists (SABAs)

Long-acting β2 agonists (LABAs)

Ultra-long-acting β2 agonists

[17][18]

Unknown duration of action

Research

New drugs in this class with more selective activity or that act simultaneously as

muscarinic receptor antagonists are under development as of 2023.[19]

Society and culture

β2 agonists are used by athletes and bodybuilders as

performance-enhancing drugs and their use has been banned by the World Anti-Doping Agency except for certain drugs that people with asthma may use; they are also used illegally to try to promote the growth of livestock.[20] A 2011 meta-analysis found no evidence that inhaled β₂-agonists improve performance in healthy athletes and found that the evidence was too weak to assess whether systemic administration of β₂-agonists improved performance in healthy people.[21]

See also

References

  1. ^
    NCBI
    .
  2. PMID 38054551
    .
  3. ^
    S2CID 22198277
    .
  4. ^
    PMID 30085570
    . Retrieved 16 March 2020.
  5. PMID 27878470
    .
  6. S2CID 58394547
    .
  7. ISBN 978-1-55938-639-5
    .
  8. PMID 34667060
    .
  9. ^
    S2CID 211727980
    .
  10. ISBN 978-0-12-386455-0
    . Retrieved 24 April 2023.
  11. ISBN 978-0-7020-3064-2
    .
  12. PMID 20697169
    .
  13. PMID 16970553
    .
  14. ^ Harris G (11 December 2008). "F.D.A. Panel Votes to Ban Asthma Drugs". The New York Times. Retrieved 19 January 2009.
  15. S2CID 46976912
    .
  16. PMID 25256258
    .
  17. S2CID 11930383
    .
  18. PMID 21232045
    .
  19. S2CID 265148154
    .
  20. ^ "Clenbuterol" (PDF). Drug Enforcement Administration. November 2013. Archived from the original (PDF) on 17 October 2019.
  21. S2CID 189906919
    .

External links
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