Question

Consider the classification of anti-arrhythmic drugs
(A) Quinidine is a class I anti-arrhythmic drug
(B) Amiodarone is a class IV anti-arrhythmic drug
(C) Propranolol is a class ii anti-arrhythmic drug
(D) Lignocaine is a class I anti-arrhythmic drug
Choose the correct answer from the options given below:

• A. (A) and (D) only.
• B. (A), (C) and (D) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

Remember the Vaughan-Williams classes:
Class I = Sodium channel blockers (Quinidine, Lidocaine)
Class II = Beta-blockers (Propranolol)
Class III = Potassium channel blockers (Amiodarone)
Class IV = Calcium channel blockers (Verapamil)

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Anti-arrhythmic drugs are classified using the Vaughan-Williams classification system, which categorizes them into four main classes based on their primary mechanism of action.
Detailed Explanation:
Let us analyze each statement based on the Vaughan-Williams classification:
- (A) Quinidine is a class I anti-arrhythmic drug: Correct. Class I agents are sodium ($Na^+$) channel blockers. Quinidine is a Class IA agent.
- (B) Amiodarone is a class IV anti-arrhythmic drug: Incorrect. Amiodarone is a Class III agent, which acts primarily by blocking potassium ($K^+$) channels to prolong action potential duration. Class IV agents are calcium ($Ca^{2+}$) channel blockers (such as verapamil or diltiazem).
- (C) Propranolol is a class II anti-arrhythmic drug: Correct. Class II agents are beta-adrenergic blockers. Propranolol is a non-selective beta-blocker.
- (D) Lignocaine is a class I anti-arrhythmic drug: Correct. Lignocaine (lidocaine) is a Class IB sodium channel blocker commonly used to manage ventricular arrhythmias.
Therefore, the correct statements are (A), (C), and (D).

Step 2: Final Answer:
The correct combination is (A), (C) and (D) only, which corresponds to Option (B).