What is the role of magnesium sulphate (MgSO4) in the management of acute exacerbation of Chronic Obstructive Pulmonary Disease (COPD)?

Magnesium Sulphate in Acute Exacerbation of COPD

Intravenous magnesium sulphate can be used as an adjunctive therapy in acute exacerbations of COPD, particularly in severe cases with poor response to standard bronchodilator therapy, as it modestly improves pulmonary function and may reduce hospitalization rates. 1

Mechanism and Evidence

• Magnesium causes relaxation of bronchial smooth muscle independent of serum magnesium levels, with only minor side effects such as flushing and light-headedness 2
• A 2022 meta-analysis demonstrated that IV magnesium was associated with significant improvements in FEV₁, peak expiratory flow rate (PEFR), decreased residual volume, and reduced odds of hospital admission in patients with COPD exacerbations 1
• Studies have shown that magnesium sulfate (1.2g over 20 minutes) administered after beta-agonist treatment provides modest but significant bronchodilator effects beyond what is achieved with beta-agonists alone 3

Clinical Application

When to Consider Magnesium Sulphate

• For patients with severe COPD exacerbations who show inadequate response to initial standard bronchodilator therapy 1
• As an adjunct to standard treatment including short-acting bronchodilators and systemic corticosteroids 2
• Typical dosing is 1.2-2g IV administered over 20 minutes 3, 4

Standard Treatment Approach for COPD Exacerbations

1. First-line therapy:

   • Short-acting inhaled β2-agonists with or without short-acting anticholinergics are the initial bronchodilators recommended 2
   • Systemic corticosteroids to improve lung function, oxygenation, and shorten recovery time (typically 40mg prednisone daily for 5 days) 2
   • Antibiotics when indicated (purulent sputum) to reduce recovery time and risk of early relapse 2

2. Second-line/adjunctive therapy:

   • Consider IV magnesium sulfate in severe cases with suboptimal response to initial therapy 1, 4
   • Note that methylxanthines are not recommended due to side effects 2

Evidence Quality and Considerations

• While magnesium has been well-studied in asthma exacerbations, the evidence in COPD is more limited but growing 2, 1
• Results from different studies show some variability:
  • A 2015 pilot study showed significant improvements in FEV₁ with IV magnesium (27.07% improvement vs 11.39% in placebo) 4
  • However, a 2013 study found nebulized magnesium had no effect on FEV₁ when used as an adjuvant to salbutamol 5
  • The strongest evidence supports IV rather than nebulized administration 1

Important Caveats

• Magnesium sulfate should be considered an adjunctive therapy, not a replacement for standard treatments for COPD exacerbations 2, 1
• Monitor for side effects including flushing, light-headedness, and hypotension 2
• The GOLD guidelines do not specifically mention magnesium sulfate in their treatment recommendations for COPD exacerbations, focusing instead on bronchodilators, corticosteroids, and antibiotics as primary treatments 2
• Consider checking magnesium levels before administration, especially in patients with renal impairment 6