Overview
DESCRIPTION Ibutilide Fumarate Injection is an antiarrhythmic drug with predominantly class III (cardiac action potential prolongation) properties according to the Vaughan Williams Classification. Each milliliter of Ibutilide Fumarate Injection contains 0.1 mg of ibutilide fumarate, USP (equivalent to 0.087 mg ibutilide free base), 0.189 mg sodium acetate trihydrate, USP, 8.
Mechanism of Action
CLINICAL PHARMACOLOGY Mechanism of Action Ibutilide fumarate injection prolongs action potential duration in isolated adult cardiac myocytes and increases both atrial and ventricular refractoriness in vivo , ie, class III electrophysiologic effects. Voltage clamp studies indicate that ibutilide fumarate, at nanomolar concentrations, delays repolarization by activation of a slow, inward current (predominantly sodium), rather than by blocking outward potassium currents, which is the mechanism by which most other class III antiarrhythmics act. These effects lead to prolongation of atrial and ventricular action potential duration and refractoriness, the predominant electrophysiologic properties of ibutilide fumarate in humans that are thought to be the basis for its antiarrhythmic effect.
Indications
- INDICATIONS AND USAGE Ibutilide fumarate injection is indicated for the rapid conversion of atrial fibrillation or atrial flutter of recent onset to sinus rhythm. Patients with atrial arrhythmias of longer duration are less likely to respond to ibutilide fumarate. The effectiveness of ibutilide has not been determined in patients with arrhythmias of more than 90 days in duration. LIFE-THREATENING ARRHYTHMIAS—APPROPRIATE TREATMENT ENVIRONMENT Ibutilide fumarate can cause potentially fatal arrhythmias, particularly sustained polymorphic ventricular tachycardia, usually in association with QT...
Common Doses
- 1 mg
- 0.1 mL
- 0.01 mg
- 2 mg
Dosage
DOSAGE AND ADMINISTRATION The recommended dose based on controlled trials (see CLINICAL STUDIES ) is outlined in the Table below. Ibutilide infusion should be stopped as soon as the presenting arrhythmia is terminated or in the event of sustained or nonsustained ventricular tachycardia, or marked prolongation of QT or QTc. Recommended Dose of Ibutilide Fumarate Injection Patient Weight Initial Infusion (over 10 minutes) Second Infusion 60 kg (132 lb) or more One vial (1 mg ibutilide fumarate) If the arrhythmia does not terminate within 10 minutes after the end of the initial infusion, a...
Contraindications
- CONTRAINDICATIONS Ibutilide fumarate injection is contraindicated in patients who have previously demonstrated hypersensitivity to ibutilide fumarate or any of the other product components.
Side Effects
- ADVERSE REACTIONS Ibutilide fumarate injection was generally well tolerated in clinical trials. Of the 586 patients with atrial fibrillation or atrial flutter who received ibutilide fumarate in phase II/III studies, 149 (25%) reported medical events related to the cardiovascular system, including sustained polymorphic ventricular tachycardia (1.7%) and nonsustained polymorphic ventricular tachycardia (2.7%). Other clinically important adverse events with an uncertain relationship to ibutilide fumarate include the following (0.
Interactions
- Drug Interactions No specific pharmacokinetic or other formal drug interaction studies were conducted. Digoxin Supraventricular arrhythmias may mask the cardiotoxicity associated with excessive digoxin levels. Therefore, it is advisable to be particularly cautious in patients whose plasma digoxin levels are above or suspected to be above the usual therapeutic range. Co-administration of digoxin did not have effects on either the safety or efficacy of ibutilide in the clinical trials.