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Ibutilide Fumarate (ibutilide fumarate)

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Last reviewed · Source: First Databank (FDB) drug data

Overview

Ibutilide fumarate is a class III antiarrhythmic agent.

Ibutilide fumarate is a class III antiarrhythmic agent. Like sotalol, ibutilide is a methanesulfonanilide derivative, and exhibits electrophysiologic effects characteristic of class III antiarrhythmic agents (e.g., prolongs repolarization and refractoriness without affecting conduction). However, unlike sotalol, ibutilide lacks beta-adrenergic blocking activity.

Ibutilide fumarate prolongs repolarization of cardiac tissue by prolonging the action potential duration (APD) and effective refractory period (ERP) in both atrial and ventricular cardiac tissue. In vitro studies of its electrophysiologic effects suggest that the antiarrhythmic action of ibutilide may result at least in part from activation of a slow, predominantly sodium, inward current at very low (i.e., less than nanomolar) concentrations, and/or from inhibition of the rapidly activating component of the potassium channel involved in repolarization of cardiac cells (i.e., the rapidly activated component of the delayed rectifier potassium current IKr) at higher (100-fold) concentrations. However, the exact mechanism of action of the drug remains to be more fully elucidated.

Like other class III antiarrhythmics, effects on cardiac repolarization induced by the drug can result in proarrhythmic effects (principally torsades de pointes). (See Uses.)

Ibutilide appears to be more selective in its cellular actions than some other currently available class III antiarrhythmic agents (e.g., amiodarone, sotalol), and therefore has been referred to as a ''pure'' class III antiarrhythmic. Ibutilide has negligible effects on heart rate, cardiac contractility, or blood pressure.

SumMon(R) (see Users Guide). For additional information on this drug until a more detailed monograph is developed and published, the manufacturer's labeling should be consulted. It is essential that the labeling be consulted for detailed information on the usual cautions, precautions, and contraindications.

Generic name: ibutilide fumarate

Reference product & biosimilars

No reference, biosimilar or interchangeable associated with this drug.

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Indications

The following indications are listed for Ibutilide Fumarate:

  • Cardioversion Of Atrial Fibrillation
  • Cardioversion Of Atrial Flutter

Dosing

Dosage of ibutilide fumarate is expressed in terms of the hemifumarate salt. Safety and efficacy of the drug in children younger than 18 years of age have not been established.

Proarrhythmic effects of ibutilide must be anticipated, and the drug should be administered only by skilled personnel in a setting in which proper equipment (e.g., cardiac monitors, intracardiac pacing, cardioverter/defibrillator) and therapy for sustained ventricular tachycardia such as polymorphic ventricular tachycardia are available during and after administration of ibutilide. In clinical trials, many initial episodes of such proarrhythmic effects were observed after completion of the ibutilide infusion but no later than 40 minutes after initiation of the infusion. However, instances of recurrent polymorphic ventricular tachycardia occurring about 3 hours after the initial infusion also were observed in these trials. Therefore, patients should be observed with continuous ECG monitoring for at least 4-6 hours after completion of ibutilide administration or until the corrected QT interval (QTc) has returned to baseline. Longer monitoring may be required if any arrhythmic activity is noted. Most cases of ventricular tachycardia observed in clinical trials responded to cardiac pacing and magnesium sulfate infusions, although degeneration to ventricular fibrillation requiring immediate defibrillation also can occur. If polymorphic ventricular tachycardia occurs in patients receiving ibutilide, the manufacturer recommends that the drug be discontinued and that electrolyte abnormalities (especially potassium and magnesium) be corrected and overdrive cardiac pacing, electrical cardioversion, and/or defibrillation be undertaken as necessary. Treatment with antiarrhythmic drugs generally should be avoided, although pharmacologic intervention with magnesium sulfate infusions may prove beneficial.

The safety, efficacy, and pharmacokinetics of ibutilide fumarate in patients with renal and/or hepatic impairment have not been established. The manufacturer states that it is unlikely that dosing adjustments based on renal or hepatic function are necessary. Nonetheless, because the drug undergoes substantial hepatic clearance, the manufacturer recommends that patients with abnormal liver function undergo continuous ECG monitoring that extends beyond the usual 4-hour period recommended for other patients.

Drug interactions

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Contraindications

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Adverse reactions

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Precautions

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ICD codes

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Formulary status

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Last reviewed · Source: First Databank (FDB) drug data