Table 2 The Vaughan Williams classification

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