Ibutilide Hemifumarate

DescriptionCovert was launched in the US and UK for treatment of atrial fibrillation and flutter and can be synthesized in three steps from N-phenyl rnethanesulfonamide. While ibutilide has an asymmetric center, it has been determined that the racemate is equipotent with either enantiomer. The antiarrhythmic action is derived from the compounds ability to prolong the action potential duration and lengthen the refractory period of myocardial tissue. Class Ⅲ antiarrhythrnic agents accomplish this by blocking outward potassium channels, however, ibutilide elicits the same effect by activation of slow inward sodium channels. Recent evidence indicates that it also is a potent blocker of the rapidly acting delayed rectifier potassium current (lkr)and may block the ATP-inhibited potassium channel.

Description(±)-Ibutilide is a class III antiarrhythmic agent. It inhibits the rapidly activating delayed-rectifier potassium current (IKr) in AT-1 myocytes with an IC50 value of 20 nM. (±)-Ibutilide also enhances the late inward sodium current (INa) and increases the action potential duration in isolated guinea pig ventricular cells. It decreases ventricular fibrillation induced by the ATP-dependent potassium channel activator pinacidil in Langendorff isolated perfused rabbit hearts when used at concentrations ranging from 3 to 30 μM. (±)-Ibutilide (15 μg/kg, i.v.) increases the effective refractory period (ERP) of the left and right atrium in anesthetized pigs. It prevents rapid pacing-induced atrial flutter in dogs when administered orally at doses ranging from 0.25 to 5 mg/kg. Formulations containing ibutilide have been used in the treatment of atrial arrhythmias.

UsesA methanesulfonanilide antiarrhythmic agent; prologns myocardial action potential duration, predominantly by activation of slow inward sodium current. Antiarrhythmic (class III).