Magnesium Sulphate (IV — ICU/Anaesthesia)

SOURCE: UK SPC (eMC) for Magnesium Sulfate 10% w/v solution for infusion, §4.2 (https://www.medicines.org.uk/emc/product/10502/smpc). SECOND SPC INDICATION — prevention of recurrent seizures in eclampsia: a loading dose of 4 g (16 mmol) of magnesium ions IV (40 ml of a 10% solution), or in some cases 5 g (20 mmol; 50 ml of a 10% solution), given over 5–15 minutes, followed by an infusion of 1 g (4 mmol)/hour (10 ml of a 10% solution) continued for 24 hours after the last fit. 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. TITRATION/MONITORING: 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 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). ELDERLY: no special recommendation — use with caution due to the risk of renal impairment in this age group. PAEDIATRIC POPULATION: the SPC states 'No special recommendation' and gives no paediatric regimen. GAP — this SPC covers only hypomagnesaemia and eclampsia. It does NOT contain the torsades de pointes or severe asthma regimens shown on this page, and it states no per-mmol bolus regimen (e.g. 8 mmol/2 g over 10–15 min) for hypomagnesaemia; those must be sourced separately and verified by the clinician. Note the SPC product is a 10% w/v solution. For instructions on dilution before administration see SPC §6.6.