MEDSURGE

What it is

MEDSURGE Magnesium Sulfate Heptahydrate 50% Concentrated Injection contains magnesium sulfate heptahydrate 500 mg per mL. It is a clear, colourless, slightly viscous, sterile solution. MEDSURGE is administered intravenously or intramuscularly.

Approved indications MEDSURGE is indicated for:

— treatment of acute hypomagnesaemia — prevention of hypomagnesaemia in patients receiving total parenteral nutrition — prevention and treatment of life-threatening seizures in the treatment of toxemias of pregnancy (pre-eclampsia and eclampsia) — emergency treatment of some arrhythmias such as Torsade de Pointes and those associated with hypokalemia

Dosing overview

Careful monitoring of plasma magnesium and other electrolyte concentration is essential, and dosage should be reduced in renal impairment. The total adult daily dose should not exceed 30–40 g of magnesium sulfate per day.

Key safety warnings

MEDSURGE may precipitate an acute myasthenic crisis, and sensitivity to parenteral magnesium has been reported. Respiratory depression is the most critical side effect of the medication; respiration rate should be determined and should be at least 16 per minute prior to each dose. Monitoring of serum magnesium levels is advised at periodic intervals during therapy to ensure that normal serum magnesium levels are not exceeded. The patellar reflex should be tested prior to administering repeat doses, as suppression of the reflex is an indication of magnesium intoxication. Urine output should be monitored and should be at least 100 mL during the four hours preceding dosing, to ensure adequate excretion of magnesium. Concurrent use of MEDSURGE and central nervous system depressant drugs may result in an enhanced central nervous system depressant effect. Concurrent use with neuromuscular blocking agents such as tubocurarine, suxamethonium and vercuronium may result in excessive neuromuscular blockade.

Contraindications

MEDSURGE is contraindicated in patients with heart block, since magnesium may exacerbate this condition, and in patients with renal failure (creatinine clearance less than 20 mL/min) or hepatic disorders, since there is an increased risk of hypermagnesaemia in these patients. MEDSURGE should not be administered to pregnant women in the two hours prior to delivery, unless it is the only therapy available to prevent eclamptic seizures, due to the risk that the neonate will be born with hypermagnesaemia and depressed breathing.

Regulatory history

MEDSURGE Magnesium Sulfate Heptahydrate 50% Concentrated Injection received initial approval on 14 October 1991. The MEDSURGE brand variants (1 g/2 mL, 2.5 g/5 mL and 5 g/10 mL concentrations) were first listed on the Australian Register of Therapeutic Goods on 5 August 2024.