MAGNESIUM SULPHATE

Anticonvulsant, Antidysrhythmics, Electrolytes

Dosage Forms

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Solution for injection

500 mg/ml (50%)

Uses

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  • Eclampsia in pregnancy
  • Prevention of eclampsia (severe pre-eclampsia)
  • Hypomagnesaemia

Dose and Duration

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Hypomagnesaemia

Adult: by IM injection, 1 g every 6 hours for 4 doses in mild hypomagnesaemia (In severe cases, 5 g by IV infusion over 3 hours).
Maintenance dose 30–60 mg/kg/day

Child: by IV/IM injection, 25–50 mg/kg every 4–6 hours for 3–4 doses

Treatment and prevention of eclampsia

4 g as slow IV bolus over 10–15 minutes followed by IV infusion of 1–3 g/hour. Monitor respiration rate and knee jerk reflexes

Preparation

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  • Dilute 4 g (8 ml) to make up to a total volume of 20 ml with water for injection
  • Dilute solution with normal saline or dextrose 5% to 20% w/v for IM injection or to 20% or less for IV administration

Contraindications

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  • Severe kidney disease

Side Effects

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  • Pain at injection site
  • Warm flushes
  • Nausea, vomiting
  • Thirst
  • High blood magnesium levels

Interactions

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  • Nifedipine (risk of hypotension )

Pregnancy

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  • Can be used

Breast-feeding

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  • Can be used

⚠️ Caution

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  • Monitor respiratory rate, blood pressure, knee jerk reflex, and urine output every 30 minutes
  • Watch for signs of magnesium toxicity: low blood pressure, drowsiness, difficulty in speaking, double vision, confusion, irregular heartbeat, low respiratory rate (<16 breaths per minute), absent knee jerk reflex
  • Calcium gluconate is the antidote for magnesium sulphate toxicity
  • Reduce dose in patients with kidney disease