Magnesium Sulphate (Obstetric — Eclampsia/Neuroprotection)

SPC §4.2 (Magnesium Sulfate 10% w/v solution for infusion). RECURRENT CONVULSIONS: if convulsions recur, a further 2–4 g (8–16 mmol) of magnesium ions (20–40 mL of a 10% solution, depending on the woman's weight; 2 g (8 mmol) if less than 70 kg) is given IV over 5 minutes. Dosage should be tailored to the individual patient's needs and responses; plasma magnesium concentrations should be measured to determine the rate and duration of infusion and should be monitored throughout therapy. Serum calcium levels should be routinely monitored. Respiratory depression may occur — caution in patients with respiratory disease; caution in myasthenia gravis (risk of myasthenic crisis). OTHER INDICATION IN THE SAME SPC — treatment of magnesium deficiency in hypomagnesaemia: up to 40 g or 160 mmol of magnesium ions (400 mL of a 10% solution) by slow intravenous infusion in glucose 5% over up to 5 days. FETAL NEUROPROTECTION: this UK SPC does NOT contain a fetal/neonatal neuroprotection regimen — only eclampsia seizure prophylaxis and hypomagnesaemia. A neuroprotection regimen must be sourced separately from national guidance by the clinician. PAEDIATRIC: SPC states 'no special recommendation' — no paediatric dose given. US LABELLING (Magnesium Sulfate in 5% Dextrose Injection, cross-check only — verify against UK SPC): loading dose 4 to 6 grams over 15 minutes followed by maintenance 1 to 2 grams every hour in eclampsia or preeclampsia; consider targeting serum magnesium of 3 to 6 mg per 100 mL (2.5 to 5 mEq per litre); an additional 2 gram intravenous bolus for recurrent eclampsia; maximum recommended dosage 30 to 40 grams over 24 hours; administration beyond 5 to 7 days is not recommended.