Ibutilide Amiodarone

III Block of repolarizing potassium channels, prolongation of action potential Amiodarone, Dronedarone, Sotalol, Dofetilide, Ibutilide... 

Class III drugs currently in use include amiodarone, bretylium, dofetilide, and ibutilide (see Table 23-2). These drugs all exert their primary effects by prolonging repolarization in cardiac cells. Amiodarone, however, also appears to have some properties similar to drugs in other classes, and may help control arrhythmias by inhibiting sodium channel function (class I effect), by beta blockade (class II effect), or even by blocking calcium channels (class IV effect).5... 

Bernard EO, et al. Ibutilide versus amiodarone in atrial fibrillation a double-blinded, randomized study. Crit Care Med 2003 3 I (4) 1031-1034. 

As with some other quinolones, moxifloxadn also prolongs the QTC interval [265], although the prolongation time of 4—6 ms (i.e., 1.4—1.6% of the starting interval) is relatively minimal. For safety reasons, the treatment of patients with QT interval prolongation and certain cardiac diseases is therefore contraindicated. Other medicaments with a potential for prolonging the QT interval may not be administered simultaneously with moxifloxacin. These indude anti-arrhythmic drugs of class IA (e.g., quinidine, hydroquinidine, disopyramide) and III (e.g., amiodarone, sotalol, dofetilide, ibutilide), intravenous erythromydn, tricyclic anti-depressives, and cisapride etc. 

An tiarrhy thmics Amiodarone, disopyramide, ibutilide procainamide, quinidine, sotalol... 

III Amiodarone Bretylium" Dofetilide SotaloF Ibutilide 0 tt 0 Potassium... 

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/vasodilating drugs Quinidine Procainamide N-Acety I p roca i na m ide Disopyramide Amiodarone Dofetilide Sotalol Ibutilide BepridiH Psychotropics Phenothiazines... 

Sotalol, Procainamide, Disopyramide, Dofetilide, Ibutilide, N oncardioacti ve , drugs (see text) Amiodarone (rare) interval (torsades de pointes) Isoproterenol Magnesium frequent Related to T plasma concentrations, except for quinidine... 

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. 

Amiodarone, Azimilide, Bretylium, Cibenzoline (Cifenline), Dofetilide, Dronedarone, Ibutilide, Sotalol... 

The concurrent use of ibutilide and amiodarone would be expected to further prolong the QT interval and increase the risk of torsade de pointes, but, despite this, one report describes their successful use for cardioversion. 

When intravenous ibutilide 2 mg was used for cardioversion of atrial fibrillation or flutter in 70 patients taking long-term amiodarone the QT interval was further prolonged (iiom 371 to 479 milliseconds). However, only one patient had an episode of non-sustained torsade de pointes. Ibutilide was effective within 30 minutes of infusion in 39% of patients with atrial flutter, and 54% of patients with fibrillation. Both amiodarone and ibutilide are class III antiarrhythmics and prolong the QT interval, with the consequent risk of torsade de pointes. The manufacturer recommends that they should not be used concurrently. However, the authors of the above report suggest that ibutilide may be useful for cardioversion in those already taking amiodarone. Combined use should be very well monitored. 

Glatter Yang Y, Chatteijee K, Mbdin G, Cheng J, Kayser S, Scheinman MM. Chemical car-dioveisicn of atrial fibrillation [Pg.261]

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