Vaughan-Williams Classification — FRCA Primary MCQ
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Correct answer: A — Lidocaine
The best answer is “Lidocaine”. Lidocaine is a class-Ib antiarrhythmic that preferentially binds inactivated fast sodium channels; blockade becomes more prominent at higher activation frequencies, producing use dependence. This favours effects in depolarised ventricular tissue. Flecainide is class Ic, sotalol is predominantly class III with beta blockade, amiodarone has multiple actions centred on class III effects, and verapamil is class IV.
Reference: Lidocaine Injection BP 2% w/v, Summary of Product Characteristics: https://www.medicines.org.uk/emc/product/15150/smpc