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Prilocaine cyanosis — FRCA Primary MCQ

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ModeratePharmacologyPrilocaine cyanosisFRCA Primary

A patient has cyanosis with normal PaO2 after a high-dose local anaesthetic technique. Which drug is most likely?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: A — Prilocaine

Prilocaine is a recognised cause of methaemoglobinaemia. Ketamine is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Magnesium sulphate is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Neostigmine is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Etomidate is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. In Primary FRCA pharmacology, link the clinical effect to the receptor, distribution or elimination mechanism rather than memorising isolated facts.

Reference: Peck, Hill & Williams Pharmacology for Anaesthesia and Intensive Care; BNF; Primary FRCA textbooks