Local anaesthetic action — FRCA Primary MCQ
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Correct answer: C — It blocks voltage-gated sodium channels
Local anaesthetics prevent nerve action potential propagation by blocking voltage-gated sodium channels. It inhibits adrenal 11-beta hydroxylase is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. It encapsulates aminosteroid neuromuscular blocker is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. It prolongs cardiac repolarisation is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. It enhances GABA-A receptor chloride channel activity 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