Describe the mechanisms of action of drugs used to treat acute severe asthma
and give examples.
Asthma involves reversible bronchospasm, inflammation, and airway hyper-responsiveness to
inhaled stimuli. The main classes of drugs for acute therapy include sympathomimetics, antimuscarinic agents, corticosteroids, methylxanthines and magnesium. Candidates should have
a detailed knowledge of the mode of action of these mainstream drugs. Information about drugs
used for prevention and for chronic asthma was not asked for and answers which provided
details about long term inhaled steroids or leukotriene antagonists did not gain extra marks.
This question was well covered by some candidates in a semi-table format. A structured
approach worked well with details about drug class, mechanism of action and example(s).
Mechanism of action | Examples |
β-agonists (Waldeck, 2002) | |
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Antimuscarinic agents (Soler & Ramsdell, 2014) | |
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Corticosteroids (PJ Barnes, 1996) | |
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Methylxanthines (Tilley, 2011) | |
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Magnesium sulphate (Noppen, 1990; Irazuzta et al, 2017) | |
|
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Ketamine (Goyal & Agrawal, 2013; Sato et al, 1998) | |
|
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Volatile anaesthetics (Mondoñedo et al, 2015; Yamakage, 2002) | |
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Helium-oxygen mixtures | |
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|
Zdanowicz, Martin M. "Pharmacotherapy of asthma." American journal of pharmaceutical education 71.5 (2007).
Waldeck, Bertil. "β-Adrenoceptor agonists and asthma—100 years of development." European journal of pharmacology 445.1-2 (2002): 1-12.
Soler, Xavier, and Joe Ramsdell. "Anticholinergics/antimuscarinic drugs in asthma." Current allergy and asthma reports 14.12 (2014): 484.
Barnes, Peter J. "Molecular mechanisms of steroid action in asthma." Journal of allergy and clinical immunology 97.1 (1996): 159-168.
Tilley, Stephen L. "Methylxanthines in asthma." Methylxanthines. Springer, Berlin, Heidelberg, 2011. 439-456.
Noppen, Marc, et al. "Bronchodilating effect of intravenous magnesium sulfate in acute severe bronchial asthma." Chest 97.2 (1990): 373-376.
Irazuzta, Jose Enrique, and Nicolas Chiriboga. "Magnesium sulfate infusion for acute asthma in the emergency department." Jornal de pediatria 93 (2017): 19-25.
Goyal, Shweta, and Amit Agrawal. "Ketamine in status asthmaticus: a review." Indian journal of critical care medicine: peer-reviewed, official publication of Indian Society of Critical Care Medicine 17.3 (2013): 154.
Sato, Tetsumi, et al. "The role of the N-methyl-D-aspartic acid receptor in the relaxant effect of ketamine on tracheal smooth muscle." Anesthesia & Analgesia 87.6 (1998): 1383-1388.
Khan, Khurram Saleem, Ivan Hayes, and Donal J. Buggy. "Pharmacology of anaesthetic agents II: inhalation anaesthetic agents." Continuing Education in Anaesthesia, Critical Care & Pain 14.3 (2014): 106-111.
Mondoñedo, Jarred R., et al. "Volatile anesthetics and the treatment of severe bronchospasm: a concept of targeted delivery." Drug Discovery Today: Disease Models 15 (2015): 43-50.
Yamakage, M. "Editorial II: Effects of anaesthetic agents on airway smooth muscles." (2002): 624-627.