Table 2.

The Vaughan Williams classification

Class	Mechanism	Examples
Ia	Na+ channel block (moderate)	•Quinidine •Ajmaline •Procainamide •Disopyramide
Ib	Na+ channel block (weak)	•Lidocaine •Phenytoin •Mexiletine •Tocainide
Ic	Na+ channel block (strong)	•Flecainide •Propafenone •Encainide •Moricizine
II	Beta-blocker	•Propranolol •Carvedilol •Esmolol •Timolol •Metoprolol •Atenolol •Bisoprolol •Nebivolol
III	K+ channel blocker	•Amiodarone •Dronedarone •Sotalol •Ibutilide •Dofetilide •Vernakalant
IV	Ca2+ channel blocker	•Verapamil •Diltiazem
V	Variable	•Adenosine •Digoxin •Magnesium sulphate