18A10: Exam Report
Outline the advantages (15% of marks) and disadvantages (85% of marks) of the clinical use of suxamethonium.
46% of candidates passed this question.
This commonly used drug should be very well-known. The question asked for an outline, hence long explanations of various aspects of pharmacology (e.g. pseudocholinesterase deficiency) were unnecessary.
Headings should have included: advantages (e.g. rapid onset, rapid offset, short acting, IV or IM administration, not end organ dependent for metabolism, premixed, safe in pregnancy and neonates). The disadvantages section should have included the following headings: pharmaceutical, adverse drug reactions (including several potentially fatal ones), numerous contraindications, unpleasant side-effects and potential problems with repeat dosing.
L2i / 18A10: Outline the advantages (15 marks) and disadvantages (85 marks) of the clinical use of suxamethonium
Suxamethonium is a dicholine ester of succinic acid used for RSI
Vial 100mg/2ml – easy to draw up dose by weight. Also allows you to put 2 vials in 5ml red syringes which easily identifies muscle relaxant to avoid inadvertent drug administration.
Refrigerated – may be cumbersome to find in an emergency
IM & IV administration
Non-organ dependant elimination – very useful for ICU population
Plasma cholinesterase deficiency will result in SUX Apnoea – a prolonged block which will require prolonged ventilation and ICU admission to wear off
Rapid onset – can be used for RSI
Fast offset – cannot be used for ongoing paralysis
Fasciculations – can easily see what patient is paralysed and ready to intubate
Huge side effect profile, including side effects that can result in death; anaphylaxis & MH
Cardiovascular A/E – bradycardia, histamine release, hypotension
Numerous contraindications – burns, spinal injuries, critical illness myopathy, muscular dystrophies, renal failure
Tachyphylaxis – multiple doses progress to Ph II block