Which statement is a correct Vaughan-Williams class pairing with an example?

• A. Class II (beta blockers) e.g., verapamil.
• B. Class I (sodium channel blockers) e.g., lidocaine.
• C. Class III (potassium channel blockers) e.g., nifedipine.
• D. Class IV (calcium channel blockers) e.g., propranolol.

Answer: (B)

The main idea is matching antiarrhythmic drugs to the Vaughan-Williams classes. Lidocaine is a classic example of a sodium channel blocker in Class I, specifically a Class Ib agent. Drugs in this class block fast sodium channels, reducing the slope of phase 0 and slowing conduction, which helps terminate or prevent ventricular arrhythmias. Verapamil and nifedipine are calcium channel blockers (Class IV), not beta blockers, so they don’t fit as Class II. Propranolol is a beta-blocker (Class II), not a calcium channel blocker, so it doesn’t fit Class IV. Therefore, pairing Class I with lidocaine is correct.