Ibutilide acts by

Ibutilide is a class III antiarrhythmic drug.The classes of antiarrhythmic action are:- Class I, Local anaesthetic effect due to blockade of Na+ currentClass I antiarrhythmics have been fuher subdivided based on the kinetics and potency of Na+ channel bindingClass Ia agents (quinidine, procainamide) are those with moderate potency and intermediate kinetics;Class Ib agents (lidocaine, mexiletine) are those with low potency and rapid kinetics; and Class Ic drugs (flecainide, propafenone) are those with high potency and the slowest kinetics.Class II: Interference with the action of catecholamines at the b-adrenergic receptor (Atenolol, Propranolol, Esmolol, Metoprolol)Class III: Delay of repolarization due to inhibition of K+ current or activation of depolarizing current (Amiodarone, Sotalol, Ibutilide, Dofetilide)Class IV: Interference with calcium conductance (Diltiazem, Verapamil)Harrison 19e pg: 273e-6