Magnesium sulfate = MgSO4 injectable
Magnesium sulfate injectable guidance for severe pre-eclampsia and eclampsia with close monitoring requirements.
Therapeutic action
Calcium antagonist, anticonvulsant.
Indications
- Severe pre-eclampsia for prevention of eclamptic seizures.
- Eclampsia for treatment of eclamptic seizures and prevention of recurrence.
Forms and strengths, route of administration
This drug should only be used by well trained personnel in well-equipped hospitals. During and after administration, have ventilation equipment, calcium gluconate, and solutions for fluid replacement ready for use.
- 5 g ampoule (0.5 g/ml, 10 ml) for IM injection or IV infusion.
Dose and duration
Continue treatment for 24 hours after delivery or the last seizure.
If seizures persist or recur, administer a further 2 g in patients under 70 kg or 4 g by IV infusion, without exceeding 8 g total during the first hour.
Reduce the dose in patients with renal impairment and do not administer to patients with severe renal impairment.
IV/IM protocol
- 4 g by IV infusion in 100 ml of 0.9% sodium chloride over 15 to 20 minutes then 10 g by IM route, 5 g in each buttock, then 5 g by IM route every 4 hours, changing buttock for each injection.
IV protocol
- 4 g by IV infusion in 100 ml of 0.9% sodium chloride over 15 to 20 minutes then 1 g per hour by continuous IV infusion.
Contra-indications, adverse effects, precautions
- May cause pain at the injection site, warm flushes, and decreased foetal heart rate.
- In overdosage with hypermagnesaemia, the mother may develop diminished then absent patellar reflex, hypotension, drowsiness, confusion, difficulty in speaking, bradycardia, and respiratory depression.
- In neonates of treated mothers, hypotonia, neurobehavioural impairment, apnoea, and respiratory depression may occur.
- Do not combine with nifedipine.
- Check urine output every hour. If urine output is under 30 ml/hour or 100 ml/4 hours, stop magnesium sulfate and perform delivery as soon as possible.
- Check patellar reflex, blood pressure, heart rate, and respiratory rate every 15 minutes during the first hour, then every hour if no signs of overdose are observed.
- If signs of overdose are observed, stop magnesium sulfate and give 1 g calcium gluconate by slow IV route as an antidote.
- Breast-feeding: no contra-indication.
- Magnesium sulfate is also used as an adjunctive treatment in severe asthma attack in children and adults: 40 mg/kg, maximum 2 g, by IV infusion over 20 minutes.
- Also comes in ampoules containing 1 g and in many other dosages. Check the strength of the ampoule carefully before use.
- 1 g magnesium sulfate contains approximately 4 mmol (8 mEq) of magnesium.
- Do not mix with other drugs in the same syringe or infusion fluid.
Source
MSF Essential drugs practical guidelines (January 2026)
This page reproduces the structured reference information for this batch while leaving out the Storage and Remarks sections.
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