How Do Beta2 Agonists Work?

Reviewed on 1/12/2022

How do beta2 agonists work?

Beta2 agonists are bronchodilators that ease breathing difficulties caused by bronchial conditions such as bronchospasm, chronic obstructive pulmonary disease (COPD), and asthma. Beta2 agonists relax bronchial smooth muscles and inhibit hypersensitivity reactions in the bronchial passage.

Beta2 agonists, also known as long-acting beta2 agonists (LABAs), enhance the activity of beta2 adrenergic receptors, which are protein particles on cell membranes. Beta2 receptors activate intracellular activity when stimulated by epinephrine, a natural hormone in the body.

Beta2 receptors are abundant in airway smooth muscles and are also present in many other parts of the body including the heart, uterine and skeletal muscles, mucous glands, and many types of immune cells such as mast cells, eosinophils, and lymphocytes.

When stimulated by beta2 agonists, beta2 receptors stimulate adenyl cyclase, an enzyme involved in the regulation of smooth muscle function. Adenyl cyclase increases the intracellular levels of cyclic adenosine monophosphate (cAMP), a substance important for downstream signaling within the cell.

An increase in cAMP levels relaxes the bronchial smooth muscles and dilates the airway. Adenyl cyclase also inhibits the release of inflammatory substances from mast cells that are part of the first-line immune defense which play a prime role in initiating immediate hypersensitivity reactions common in asthma attacks.

Beta2 agonists may also be combined with other types of medications that include:

  • Corticosteroids: Corticosteroids are potent anti-inflammatory agents that work on many types of immune cells to control inflammation. 
  • Respiratory anticholinergics: Respiratory anticholinergics relax bronchial muscles by blocking the activity of acetylcholine, a neurotransmitter that nerve endings secrete to make muscles contract. Anticholinergics also reduce mucus secretion in the respiratory passage and improve lung function.

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COPD (chronic obstructive pulmonary disease) is the same as adult-onset asthma. See Answer

How are beta2 agonists used?

Beta2 agonists are available in various strengths and formulations that include:

  • Oral inhalations in the form of powders, aerosolized tiny particles or droplets, and solutions nebulized into a fine mist. Many types of inhalation devices such as metered dose inhalers and nebulizers are available on prescription.
  • Tablets
  • Syrups
  • Intravenous (IV) injections

Beta2 agonists are used in the treatment of the following conditions:

FDA-approved:

Off-Label:

Orphan designation:

What are side effects of beta2 agonists?

Side effects of beta2 agonists may include the following:

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

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What are names of beta2 agonist drugs?

Generic and brand names of beta2 agonist drugs include:

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References
https://reference.medscape.com/drugs/beta2-agonists

https://www.oindpnews.com/2020/03/fda-lists-arcapta-seebri-and-utibron-neohalers-as-discontinued/

https://ehlersdanlosnews.com/2020/03/26/fda-denies-acers-appeal-for-edsivo-a-potential-vascular-eds-therapy/

https://www.fda.gov/drugs/information-drug-class/phase-out-maxair-autohaler-questions-and-answers

https://www.ncbi.nlm.nih.gov/books/NBK559069/

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