Magnesium sulfate
Eclampsia: 4 g IV loading, then 1 g/hour (or Pritchard IM regimen). Acute severe asthma: 1.2–2 g IV over 20 minutes. Torsades: 2 g IV.
On this page
Dose
| Indication | Dose |
|---|---|
| Eclampsia (Zuspan, IV) | 4 g IV over 5–15 minutes, then 1 g/hour for 24 hours |
| Eclampsia (Pritchard, IM) | 4 g IV over 5–15 minutes plus 10 g IM (5 g each buttock), then 5 g IM every 4 hours |
| Recurrent fit on magnesium | 2 g IV (4 g if over 70 kg) over 5–15 minutes |
| Acute severe asthma (adult) | 1.2–2 g IV over 20 minutes |
| Acute severe asthma (child) | 40 mg/kg (max 2 g) IV over 20 minutes |
| Torsades de pointes | 2 g IV over 10–15 minutes |
| Low magnesium | 8–16 mmol IV over several hours |
Monitoring for toxicity
Reflexes, RR, SpO₂ and urine output hourly. Loss of reflexes, RR below 12 or urine output below 25–30 mL/hour: stop and give 10 mL of 10% calcium gluconate.
Frequently asked questions
What is the Pritchard regimen?
4 g IV plus 10 g IM loading (5 g in each buttock), then 5 g IM every 4 hours in alternate buttocks, if reflexes, breathing and urine output are adequate.
Used in these guides
Sources
Doses on this page are typical doses from the sources above. Always confirm with a current drug reference, the product leaflet and your hospital protocol, especially in children, pregnancy and kidney or liver disease.