Magnesium Sulfate
Eclampsia/preeclampsia seizure prophylaxis, Torsades de Pointes, Severe asthma, Hypomagnesemia
Indications
- Eclampsia/preeclampsia seizure prophylaxis
- Torsades de Pointes
- Severe asthma
- Hypomagnesemia
Adult dosing
- eclampsia: dose: 4; unit: g IV over 20 min then 1-2g/hr; route: IV; fixed: true; torsades: dose: 2; unit: g IV over 2 min; route: IV; fixed: true; asthma: dose: 2; unit: g IV over 20 min; route: IV; fixed: true; hypomagnesemia: dose: 2; unit: g IV over 1 hr; route: IV; fixed: true
Pediatric dosing
- asthma: dose: 50; unit: mg/kg; maxDose: 2000; maxDoseAbsolute: true; route: IV over 20 min; weightBased: true; torsades: dose: 25; unit: mg/kg; maxDose: 2000; maxDoseAbsolute: true; route: IV over 2 min; weightBased: true
Contraindications
- Myasthenia gravis
- Heart block
Clinical pearls
- Torsades: 2g IV push over 2 min — can give faster if pulseless
- Eclampsia: 4g loading dose then 1-2g/hr maintenance — monitor patellar reflexes
- Toxicity signs: loss of patellar reflexes → respiratory depression → cardiac arrest
- Antidote for Mg toxicity: calcium gluconate 1g IV
Source and review
- ACLS Guidelines; ACOG Practice Bulletin; GINA Asthma Guidelines. Last reviewed: 2024-11-01