What is the recommended dose of magnesium sulfate (MgSO4) for pediatric patients with asthma?

Magnesium Sulfate Dosing for Pediatric Asthma

For pediatric patients with severe asthma exacerbations not responding to conventional therapy, the recommended intravenous magnesium sulfate dose is 25-50 mg/kg (maximum 2 grams) administered over 20 minutes 1, 2.

Indications for Use

Magnesium sulfate should be used in the following scenarios:

• Severe asthma exacerbations not responding to conventional therapy
• Life-threatening asthma exacerbations
• Patients who remain in severe distress after 1 hour of intensive conventional treatment 1

Dosing Protocol

Age Group	Recommended Dose	Administration Rate	Maximum Dose
Children	25-50 mg/kg	Over 20 minutes	2 grams
Adolescents	25-50 mg/kg	Over 20 minutes	2 grams

Treatment Algorithm

1. First-line treatment:

   • Inhaled short-acting beta-agonists (3 doses)
   • Systemic corticosteroids
   • Oxygen therapy as needed

2. If inadequate response after 60-90 minutes:

   • Consider IV magnesium sulfate 25-50 mg/kg (maximum 2 grams) over 20 minutes 1, 2

3. Monitor response:

   • Vital signs
   • Oxygen saturation
   • Peak expiratory flow rate (PEFR)
   • Clinical asthma scores

Evidence of Efficacy

Multiple studies support the use of IV magnesium sulfate in pediatric asthma:

• Research shows significant improvement in pulmonary function parameters including FEV1, PEF, and FEF25-75 after magnesium administration 3
• Children treated with IV magnesium are more likely to be discharged home from the emergency department than those receiving placebo 2
• Early administration of magnesium sulfate shows significant improvement in PEFR, oxygen saturation, and clinical asthma scores 4

Alternative Dosing Strategies

For patients with severe, non-infectious mediated asthma who fail to improve with standard therapy, a high-dose prolonged infusion protocol may be considered:

• 50 mg/kg/hour for 4 hours (maximum 8 grams over 4 hours) 5
• This approach has shown to expedite discharge and reduce healthcare costs

Safety Considerations

• Monitor blood pressure during administration
• Have calcium chloride available to reverse potential magnesium toxicity 1
• Rapid infusion may cause hypotension and bradycardia
• No significant side effects have been reported at recommended doses 6

Important Caveats

• Magnesium sulfate should not replace standard therapy but should be used as an adjunct
• The National Asthma Education and Prevention Program Expert Panel recommends selective use of IV magnesium sulfate for life-threatening exacerbations and those remaining severe after 1 hour of intensive conventional treatment 1
• Magnesium sulfate has no apparent value in patients with exacerbations of lower severity 1

Remember that magnesium sulfate is not a first-line treatment but should be considered early in the management of severe asthma exacerbations not responding to conventional therapy to improve outcomes and potentially reduce hospitalization rates.