LA Sodium Channel Intracellular — FRCA Primary MCQ
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Correct answer: D — 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