Burns and Suxamethonium — FRCA Final MCQ

Correct answer: E — Suxamethonium

E. Suxamethonium is contraindicated because this patient has confirmed pre-existing hyperkalaemia. Depolarisation of skeletal muscle by suxamethonium normally increases serum potassium by about 0.5 mmol/L; in a patient starting at 5.8 mmol/L, this may precipitate dangerous dysrhythmia or cardiac arrest. At only 2 hours after the burn, burn-related proliferation of extrajunctional acetylcholine receptors is not itself the decisive contraindication: the exaggerated potassium response develops later, with the SmPC identifying greatest risk approximately 5–70 days after severe burns or major trauma. Rocuronium, atracurium, cisatracurium and pancuronium are non-depolarising blockers and do not produce the same depolarisation-mediated potassium efflux. Rocuronium is suitable when rapid-onset blockade is required; pancuronium is less suitable for rapid sequence induction because of its slower onset and long duration, but it is not contraindicated by the stated findings.

Reference: Martindale Pharma, Suxamethonium Chloride 50 mg/ml Solution for Injection/Infusion, Summary of Product Characteristics, sections 4.3–4.4, updated 2025. https://www.medicines.org.uk/emc/product/3401/smpc