Ibutilide Fumarate

 Action Prolongs atrial and ventricular action potential duration and refractoriness by activation of a slow inward current (predominantly sodium).

 Indications Rapid conversion of recent onset atrial fibrillation or atrial flutter to sinus rhythm.

 Contraindications Standard considerations.

 Route/Dosage

ADULTS: IV Initial infusion: ³ 60 kg (³ 132 lbs) 1 mg (1 vial) infused over 10 min; < 60 kg (< 132 lbs) 0.01 mg/kg (0.1 ml/kg) infused over 10 min. If the arrhythmia does not terminate within 10 min after the end of the initial infusion, a second 10 min infusion of equal strength may be administered 10 min after completion of the first infusion.

 Interactions Concomitant Class Ia and III antiarrhythmic agents (eg, amiodarone, disopyramide, procainamide, quinidine, sotalol): Do not give concurrently. Withhold for 5 half-lives prior to and for 4 hr after ibutilide infusion. Medications that prolong the QT interval (eg, phenothiazines, tricyclic and tetracyclic antidepressants): Potential for proarrhythmia may be increased. Digoxin: Cardiotoxicity (supraventricular arrhythmia) due to excessive digoxin concentrations may be masked.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Nonsustained monomorphic ventricular extrasystoles and ventricular tachycardia (VT); sinus; supraventricular sustained and nonsustained polymorphic VT; hypotension; postural hypotension; hypertension; bundle branch block; sustained polymorphic VT; AV block; sinus bradycardia; QT segment prolongation; palpitations. CNS: Headache. GI: Nausea.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Children: Safety and efficacy not established. Elderly patients: No age-related differences in safety and efficacy have been observed. Proarrhythmia: Potentially fatal ventricular arrhythmias may be induced or worsened. Ibutilide must be administered in a setting on continuous ECG monitoring by personnel trained in identification and treatment of acute ventricular arrhythmias, particularly polymorphic ventricular tachycardia. Hypokalemia/Hypomagnesemia: Should be corrected to reduce potential for proarrhythmia. Anticoagulation: Patients with atrial fibrillation > 2 to 3 days must be adequately anticoagulated, generally for ³ 2 weeks before attempted conversion.

 Administration/Storage

• Available for IV administration only.
• Store unopened vials at room temperature (59° to 77° F).
• May be administered undiluted or further diluted in 50 ml of either Normal Saline (NS) or D5W.
• Diluted medication may be stored for up to 24 hr at room temperature (59° to 86° F), or for 48 hr refrigerated (36° to 46° F), following which any unused solution should be discarded.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note use of antiarrhythmics (eg, Class Ia or III) or other agents (eg, phenothiazines, tricyclic antidepressants) which may increase arrhythmia risk.
• Obtain baseline 12-lead ECG, electrolytes, and liver function tests prior to treatment.
• Ensure that potassium and magnesium serum levels are within normal levels.
• Ensure that any Class Ia or III antiarrhythmics have been discontinued for ³ 5 half-lives.
• Observe patient with continuous ECG monitoring for ³ 4 hours following infusion or until QTc has returned to baseline. Longer monitoring is required if any arrhythmic activity is noted or if patient has abnormal liver function tests.
• Monitor blood pressure and pulse closely during administration.
• Have appropriate resuscitation equipment at bedside (eg, cardioverter/defibrillator, medications) during therapy.

 Patient/Family Education

• Advise patient that this is a short-term treatment for their arrhythmia and long-term oral medications will likely be required for control if this therapy is successful.
• Teach patient and family how to take blood pressure and pulse for home management with medications.
• Advise patient to report any chest pain, shortness of breath, palpitations, fluttering in the chest, headache, or faintness immediately to the nurse while the medication is infusing.