consider single dose of IV magnesium sulfate for life-threatening asthma exacerbations and severe exacerbations poorly responsive to initial bronchodilator therapy (NHLBI Evidence B; BTS/SIGN Grade B) – dosing varies by guideline

NHLBI guidelines recommend 25-75 mg/kg IV (maximum 2 g)

BTS/SIGN guidelines recommend 40 mg/kg/day IV

GINA guidelines recommend 40-50 mg/kg IV (maximum 2 g)

per BTS/SIGN and GINA guidelines, consider adding nebulized magnesium sulfate to SABA and ipratropium nebulizer treatments in the first hour of treatment for children ≥ 2 years old.

BTS/SIGN guidelines recommend considering adding magnesium sulfate 150 mg/dose to each nebulizer treatment in first hour in children with severe symptoms and oxygen saturation < 92% (BTS/SIGN Grade B)

magnesium nebulizer formulation not available in the United States; injection formulation may be given via nebulization,

but administration is considered off-label and not approved by FDA

MG SO4: IV, IM (1 g of magnesium sulfate = 98.6 mg elemental magnesium = 8.12 mEq magnesium).=4.06 mmol elemental magnesium.

Intravenous magnesium sulfate may be administered in the emergency department if there is clinical deterioration despite treatment with β2 agonists, ipratropium, and systemic corticosteroids.

The typical dose of magnesium sulphate 25–75 mg/kg (maximum 2.0 g) intravenously administered over 20 min.

Asthma, acute refractory exacerbation: Limited data available: Dose expressed as magnesium sulfate:

IV: Infants, Children, and Adolescents: 50 mg/kg/dose as a single dose (Ref); usual dose range: 25 to 75 mg/kg/dose; maximum dose: 2,000 mg/dose; recommended as adjunctive therapy in severe acute asthma for patients who have life-threatening exacerbations and in those whose exacerbations remain in the severe category after 1 hour of intensive conventional therapy . Efficacy results have been variable in trials; some have shown significant improvement with single doses of 25 mg/kg/dose and 40 mg/kg/dose  while others found no statistically significant difference compared to placebo . A pharmacokinetic modeling study of pediatric severe asthma suggested doses between 50 and 75 mg/kg to achieve concentrations within the hypothesized target range between 25 and 40 mg/L .

Oral inhalation: Severe exacerbation: Limited data available: Children ≥2 years and Adolescents: Nebulized 150 mg isotonic magnesium sulfate mixed with albuterol and ipratropium every 20 minutes for 3 doses in the first hour of treatment to patients with severe acute asthma who did not respond to standard inhalation treatment (Ref). In a large randomized, placebo-controlled trial (n=508, including 252 who received magnesium sulfate treatment; ages: 2 to 16 years) improvement was statistically significant, but clinically significant changes were only observed in the most severe patients (SaO2 <92% with symptoms lasting <6 hours

_We do not advocate the use of nebulized magnesium sulfate, due to lack of demonstrated clinically important benefits in randomized trials

Ref:

(Knightly R, Milan SJ, Hughes R, Knopp-Sihota JA, Rowe BH, Normansell R, Powell C ,

Cochrane Database Syst Rev. 2017;11(11):CD003898. Epub 2017 Nov 28)

Nelson Essentials for pediatrics,

Dynamed plus,

BNF for children,

Lexicomp monograph for pediatric