Paediatric Acute care Guidelines PMH Emergency Department



  • Used in treatment of severe asthma
  • Used in the treatment of magnesium deficiency
  • Can be used to treat arrhythmias, particularly Torsades de pointes resulting from magnesium deficiency
  • Has anti-convulsant properties if the seizures are as a result of acute uraemia, hypothyroidism or eclampsia


  • Excessive administration may result in hypermagnesaemia which leads to flushing, thirst, hypotension due to vasodilatation, drowsiness, confusion, loss of tendon reflexes, muscle weakness, respiratory depression, cardiac arrhythmia, coma and cardiac arrest
  • Treatment for hypermagnesaemia is ceasing the magnesium, administration of calcium gluconate, fluid resuscitation and in severe cases, dialysis


IV Administration:
    • Use 49.3% Magnesium Sulphate (= 2mmol/ml)


    • 0.2mmol/kg (0.1ml/kg), max 8 mmols (4 mls)
    • Add to 50ml bag 0.9% saline
    • Give over 20 minutes

In Emergency/ Polymorphic VT or VT caused by Hypomagnesaemia:

    • 0.1-0.2mmol/kg IV (0.05-0.1ml/kg)
    • Dilute with 2.5 times the volume of 0.9% saline
      eg. 2mls of MgSO4 added to 5ml of 0.9% saline
    • Give as slow IV push over 3 – 5 minutes

For Mg deficiency:

    • IV: 0.4mmol/kg/dose (0.2ml/kg/dose), max 20mmol (=10mls) 12 hourly
    • Can give over 20 minutes but preferably over 1 – 4 hours

Digoxin tachycardia, Pulmonary hypertension:

    • IV – 0.2mmol/kg (0.1ml/kg)
    • Give over 20 – 30 minutes

If infusion required (after stat dose given):

    • 0.12mmol/kg/hour (0.06ml/kg/hour)
    • Volume of MgSO4 = 0.06ml x pt wt kg x hrs infusion
    • Usually 4 – 6hrs, may be 24 hrs for myocardial infarction
    • Dilute with Normal Saline – 2.5mls to each 1ml MgSO4
    • Keep serum Mg 1.5-2.5mmol/L for digoxin tachycardia
    • Keep serum Mg 3-4mmol/L for pulmonary hypertension


  • Must have cardiac monitoring
  • Rapid administration may cause hypotension; if this occurs reduce rate
  • Administer with caution to patients with known renal impairment.; patients in severe renal failure should NOT be given magnesium
  • Parental administration may enhance effects of neuromuscular blocking agents
  • Careful monitoring of magnesium levels

Compatible with:

  • 5% glucose, Hartmann’s, normal saline, saline/glucose solutions
  • Aciclovir, amikacin, ampicillin, caspofungin, cefotaxime, cefoxitin, cephalothin, cephazolin, chloramphenicol sodium succinate, dexmedetomidine, erythromycin lactobionate, esmolol, gentamicin, heparin sodium, hydrocortisone sodium succinate, isoprenaline, labetalol, lignocaine, linezolid, metaraminol, metoclopramide, metronidazole, milrinone, morphine sulfate, noradrenaline, ondansetron, piperacillin, piperacillin-tazobactam, potassium chloride, sodium nitroprusside, trimethoprim-sulfamethoxazole, vancomycin, verapamil

Incompatible with:

  • Fat emulsion, soluble phosphates, alkali hydroxides and carbonates
  • Amiodarone, aminophylline, amphotericin B, azathioprine, calcium chloride, calcium gluconate, cefepime, ceftriaxone, chlorpromazine, ciprofloxacin, clindamycin, cylcosporin, dicloxacillin, dexamethasone sodium phosphate, diazepam, ketamine, methylprednisolone sodium succinate, pantoprazole, phenytoin, phosphate salts, salbutamol, sodium bicarbonate


PMH ED Guideline – Magnesium Sulphate:  Last updated September 2014
PICU Drug File Reviewed February 2013
The Extra Pharmacopoeia 35th Edition (2007) Martindale,
EMIMS 2012
Australian Injectable Drugs Handbook 5rthEdition (2011)
The Society of Hospital Pharmacists of Australia
Shann, F. Drug Doses (2010) 15th Edition
Paediatric Dosage Handbook International 17th Edition (2011)
Taketomo, CK, Hodding, JH & Kraus, DM. Drug Manufacturer Product Information
E/Clinical Pharmacology 2012
Intensive Care Manual 5th Edition (2003). T. Oh, Bersten & Son



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