Antiarrhythmic agents

Antiarrhythmic agents are a group of pharmaceuticals that are used to suppress abnormal rhythms of the heart (cardiac arrhythmias), such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation.

Many attempts have been made to classify antiarrhythmic agents. The problem arises from the fact that many of the antiarrhythmic agents have multiple modes of action, making any classification imprecise.

The Singh-Vaughan Williams classification was introduced in 1970. As a doctoral candidate at Oxford University, Dr. Bramah N. Singh determined that amiodarone and sotalol had antiarrhythmic properties and belonged to a new class of antiarrhythmic agents (what would become the class III antiarrhythmic agents). Singh developed part of the classification system while working in the lab of Miles Vaughan Williams and part of the system after leaving Oxford. Singh subsequently pioneered the use of these agents at bedside over the next several decades of practice in the United States.

With regards to management of atrial fibrillation, classes I and III are used in rhythm control as medical cardioversion agents, while classes II and IV are used as rate-control agents.

The five main classes in the Singh-Vaughan Williams classification of antiarrhythmic agents are:

Sotalol is also a beta blockerAmiodarone has Class I, II, III & IV activity

The class I antiarrhythmic agents interfere with the sodium channel. Class I agents are grouped by what effect they have on the Na⁺ channel, and what effect they have on cardiac action potentials.

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