Ibutilide arrhythmia with

Newly developed class III drugs comprise dofetilide, a specific Ik, blocker, and ibutilide, which blocks IKl and activates the slow iNa- Both drugs lack hemodynamic side effects. These drugs are scheduled for the treatment of atrial fibrillation and atrial flutter. As with class HI drugs, they can induce torsade de pointes arrhythmia. 

Ibutilide Ibutilide (Corvert) is an blocker that in some systems also activates an inward Na current. The action-potential-prolonging effect of the drug may arise from either mechanism. Ibutilide is administered as a rapid infusion (1 mg over 10 minutes) for the immediate conversion of atrial fibrillation or flutter to sinus rhythm. The drug s efficacy rate is higher in patients with atrial flutter (50 to 70%) than in those with atrial fibrillation (30 to 50%). In atrial fibrillation, the conversion rate is lower in those in whom the arrhythmia has been present for weeks or months compared with those in whom it has been present for days. The major toxicity with ibutilide is torsade de pointes, which occurs in up to 6% of patients and requires immediate... 

Ibutilide, a class in antiarrhythmic, is known to increase the QT interval, so increasing the risk of torsade de pointes arrhythmia. Class Ic antiarrhythmics such as propafenone and flecainide generally shorten the QT interval. It is possible that class Ic antiarrhythmics may usefully attenuate the risk of torsade de pointes with ibutilide, and ibutilide may be... 

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