What is the dose of magnesium for acute asthma exacerbation?

From the Guidelines

For acute asthma exacerbation, the recommended dose of magnesium is 2 grams administered over 20 minutes in adults, as this has been shown to moderately improve pulmonary function when combined with nebulized β-adrenergic agents and corticosteroids 1.

Key Considerations

• The dose for children is 25 to 75 mg/kg (up to a maximum of 2 g) 1.
• Magnesium causes relaxation of bronchial smooth muscle independent of serum magnesium level, with only minor side effects such as flushing and light-headedness 1.
• A Cochrane meta-analysis of 7 studies concluded that IV magnesium sulfate improves pulmonary function and reduces hospital admissions, particularly for patients with the most severe exacerbations of asthma 1.

Administration and Monitoring

• Magnesium sulfate should be administered in a monitored setting due to potential side effects including hypotension, flushing, and rarely respiratory depression.
• Patients with renal impairment may require dose adjustment.
• The onset of action is relatively quick, but the duration is limited, making it primarily useful for acute management rather than long-term control.

Treatment Context

• Magnesium sulfate is not a first-line treatment but rather an adjunct therapy when standard treatments (such as albuterol, ipratropium, and systemic corticosteroids) have not provided sufficient improvement 1.
• It is essential to consider the patient's overall clinical picture and adjust treatment accordingly, taking into account the potential benefits and risks of magnesium sulfate administration 1.

From the Research

Dose of Magnesium for Acute Asthma Exacerbation

• The dose of magnesium for acute asthma exacerbation is not explicitly stated in the provided studies, but the studies discuss the use of magnesium sulfate in the treatment of acute asthma.
• According to the study 2, intravenous MgSO4 is effective in reducing admissions and improving pulmonary functions in severe asthma exacerbations, but the dose is not specified.
• The study 3 uses a 3.2% solution of MgSO4 (95 mg) in nebulized form, while the study 4 uses a 260 mmol/L solution of MgSO4 (3 ml) every 20 to 60 minutes.
• The study 5 discusses the use of intravenous magnesium sulfate, but does not specify the dose.
• The study 6 recommends the use of intravenous magnesium sulfate in selected cases, particularly in severe exacerbations, but does not specify the dose.

Administration of Magnesium

• Magnesium can be administered intravenously or via nebulizer, with intravenous administration appearing to be more effective in severe cases 2, 5.
• Nebulized magnesium sulfate has been shown to have a significant bronchodilatory effect in acute asthma, comparable to nebulized salbutamol 3, 4.

Efficacy of Magnesium

• The studies suggest that magnesium sulfate can be beneficial in the treatment of acute asthma, particularly in severe cases 2, 4, 5.
• However, the evidence for routine use of magnesium sulfate in all patients with acute asthma is not strong, and it should be reserved for selected cases 5, 6.