Describe the mechanism of action of drugs commonly used to treat acute severe asthma.
Answers to this question needed to address drugs that target the pathophysiology of
asthma: bronchospasm, inflammation (oedema and hypersecretion), and hyperreactivity to inhaled stimuli. Not all drugs used to treat less severe forms of the
disease are relevant in the critical care context.
A discussion of efficacy versus toxicity was included in better answers.
As a minimum, sympathomimetics, antimuscarinics, corticosteroids and
methylxanthines should have been included. The role of inhaled Adrenaline as a B2
-agonist mediating bronchodilatation and an alpha-agonist constricting the bronchial
mucosa was relevant to the discussion. Ketamine and volatile anaesthetics could
have been discussed as adjuncts to therapy in ventilated patients. More
controversial therapies such as Magnesium and Heliox are less commonly
prescribed, however marks were awarded for more comprehensive answers.
Syllabus B2a 2a
Reference: Goodman and Gilman's the Pharmacological Basis of Therapeutics 11th
Ed p717-736
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.