Magnesium Sulphate

Question 1

Drug class

Answer 1

Electrolyte

Question 2

Pharmacology

Answer 2

Important cofactor in multiple processes. It causes vasodilation & bronchodilation through inhibition of smooth muscle contraction. Magnesium ions also possess anticonvulsant & anti-dysrrhythmic properties

Question 3

Metabolism

Answer 3

Filtered in the kidneys & excreted predominantly in urine with small amounts of faeces & saliva

Question 4

Indications

Answer 4

• Box jellyfish envenomation (unresponsive to antivenom therapy)
• Eclampsia
• Irukanji syndrome (with intractable pain unrelieved by narcotic analgesia AND/Or systolic BP > 160
• Torsades de Pointes
• Severe life-threatening asthma (only pts who have required IM/IV adrenaline)

Question 5

Contraindications

Answer 5

• Allergy and/or adverse drug reaction
• Atrioventricular (AV) block
• Renal failure

Question 6

Precautions

Answer 6

Renal impairment

Question 7

Side effects

Answer 7

• Pain at cannulation site
• Magnesium toxicity
- hypotension / respiratory depression
- loss of deep tendon reflexes

Question 8

Presentation

Answer 8

10mmol (2.5g)/5ml amp

*mmol = millimole

Question 9

Onset

Duration

Answer 9

Immediate

30min

Question 10

Routes of admin

Answer 10

IV

IV INF

Question 11

Adult dosages

Answer 11

• Irukanji syndrome
• Box jellyfish envenomation

▪︎IV 10mmol over 20min, repeated once @ 20mins, total max dose 20mmol

• syringe prep: mix 10mmol (5ml) with 15ml sodium chloride 0.9% in a 30ml springfusor to equal 10mmol/20ml; admin at rate of 60ml/jr over 20mins

Question 12

Paediatric dosages

Answer 12

• Irukanji syndrome
• Box jellyfish

▪︎IV 0.1mmol/kg over 15min (rounded to nearest 0.5mml), single dose not to exceed 5mmol, repeated once @ 10min. Total max dose 10mmol

• syringe prep: mix 0.1mmol with sodium chloride 0.9% in a 30ml springfusor to equal 0.1mmol/15ml; admin at rate of 60ml/hr over 15mins