LA Sodium Channel Intracellular — FRCA Primary MCQ
Instant feedback + full explanation. One question, done properly.
Educational content. Not a substitute for clinical judgement or local policy.
Reveal the answer and explanation
Correct answer: C — They block voltage-gated sodium channels from the intracellular side
Local anaesthetics block voltage-gated sodium channels from the intracellular side of the cell membrane. The unionised form crosses the membrane then the ionised form (cation) binds to the intracellular aspect of the sodium channel in the open or inactivated state (use-dependent block). This prevents sodium influx and action potential propagation.
Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care