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Magnesium sulphate in asthma — DIPIMC MCQ

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ModeratePharmacology (Pre-Hospital)Magnesium sulphate in asthmaDIPIMCDipIMC

A 40-year-old with known asthma has a life-threatening attack with a silent chest and a poor response to back-to-back salbutamol nebulisers and ipratropium. Intravenous magnesium sulphate is being considered. What is the primary rationale for giving it here?

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Correct answer: E — It relaxes bronchial smooth muscle in severe asthma

A single dose of intravenous magnesium sulphate (commonly 1.2 to 2 g over about 20 minutes) is used in acute severe or life-threatening asthma that responds poorly to inhaled bronchodilators, acting as a smooth muscle relaxant with a bronchodilator effect. It does not replace nebulised beta-agonists, which remain the mainstay, and it has no role in reversing opioids or correcting glucose. Magnesium is also used in eclampsia, but that is a separate indication and not the reason for giving it in asthma. Pearl: senior help and consideration of critical care are warranted in life-threatening asthma with a silent chest or exhaustion.

Reference: BTS/SIGN Guideline (Asthma); JRCALC Clinical Guidelines