Ibutilide, antiarrhythmic agent

Ibutilide (Corvert) is a structural analog of sotalol and produces cardiac electrophysiological effects similar to those of the antiarrhythmic agents in class III. 

Ibutilide is an antiarrhythmic agent that prolongs atrial and ventricular action potential duration and refractoriness by activation of a slow inward current (predominantly sodium). It is indicated for rapid conversion of recent onset atrial fibrillation or atrial flutter to sinus rhythm. 

Other class III antiarrhythmics include sotalol, ibutilide, and dofetilide. These agents do not have a role in the acute treatment of ventricular fibrillation. 

Ibutilide. Ibutilidc, A - 4- 4-(cthylheptylaminoH-hy-droxybutyllphenyllmethanesulfonamidc (Corvert), a class III antiarrhythmic belonging to the mcthancsulfonanilidc class of agents, is indicated for rapid conversion of atrial Hbrillation or atrial flutter to normal sinus rhythm. Unlike dofetilide, it is not highly. specific for the delayed a clificr potassium currents (Ikr) and does have some affinity for. sodium channels. 

Type III antiarrhythmics include agents that specifically prolong refractoriness in atrial and ventricular tissue. This class includes very different drugs bretylium, amiodarone, sotalol, ibutilide, and recently, dofetilide they share the common effect of delaying repolarization by blocking potassium channels. The electrophysiologic actions of bretylium are related to its multifaceted pharmacology. 

Antiarrhythmic drugs in Phase III clinical trials are shown in Figure 26.16. Nifekalant is a pyrimidinone Class III agent. Sematilide is a Class III agent that is a benzamide derivative of ibutilide, and SSR-149744c and dronedarone are noniodinated analogues of amiodarone, reportedly with fewer adverse effects than amiodarone. 

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