Magnesium Sulfate
Classification
Antiarrhythmic
Smooth muscle relaxant
Indications
ACP: Treatment of ventricular fibrillation and ventricular tachycardia refractory to first-line antiarrhythmics
ACP: Recurrent, intermittent episodes of wide-complex tachycardia
ACP: Treatment of Torsades de Pointes
ACP: Bronchospasm refractory to bronchodilation in acute asthma
ACP: Management of seizures in pregnancy associated with hypertension
Contraindications
- Hypersensitivity to magnesium sulfate
- Second or third-degree AV block
Adult dosages
ACP: Control of ventricular arrhythmias (including Torsades de Pointes)
- For perfusing rhythms: 2 g IV over 15 minutes
- In cardiac arrest: 4 g IV push
ACP: Bronchospasm refractory to bronchodilation
- 2 g IV over 20 minutes
ACP: Management of seizures in pregnancy associated with hypertension
Pediatric Considerations And Dosing
ACP: All indications
- In cardiac arrest: 50 mg/kg IV/IO push to maximum of 2 g
- All other causes: 50 mg/kg IV/IO infused over 15 minutes
Mechanism Of Action
The precise mechanism of action of magnesium sulfate is not entirely clear. It appears to alter membrane potential, slowing conduction and relaxing smooth muscle.
Pharmocokinetics
Following intravenous administration:
- Onset: 1-2 minutes
- Peak: < 5 minutes
- Duration: uncertain in most patients
Infusions may take up to 20-30 minutes to produce significant bronchodilation
Warning And Precautions
May prolong the effects of non-depolarizing neuromuscular blockers, and may potentiate the effects of calcium channel blockers