Ibutilide

INTRODUCTION

Indications

Rapid conversion of recent-onset atrial flutter or fibrillation to normal sinus rhythm, including management of atrial flutter or fibrillation occurring within 1 wk of coronary artery bypass or cardiac valve surgery.

Action

Activates slow inward current of sodium in cardiac tissue, resulting in delayed repolarization, prolonged action potential duration, and increased refractoriness. Mildly slows sinus rate and AV conduction. Therapeutic Effects: Conversion to normal sinus rhythm.

Adverse Reactions/Side Effects

CNS: headache. CV: arrhythmias. GI: nausea.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Assess heart rate, ECG, and heart sounds, especially during exercise (See Appendices G, H). Although intended to treat certain arrhythmias, this drug can unmask or precipitate new arrhythmias (proarrhythmic effect). Report any rhythm disturbances or symptoms of increased arrhythmias, including palpitations, chest pain, shortness of breath, fainting, and fatigue/weakness.

Interventions

• Because of the risk of arrhythmias, use caution during aerobic exercise and other forms of therapeutic exercise. Assess exercise tolerance frequently (blood pressure, heart rate, fatigue levels), and terminate exercise immediately if any untoward responses occur (See Appendix L).

Patient/Client-Related Instruction

• Advise patient and family or caregivers about the signs of arrhythmias (see above under Examination and Evaluation) and to seek immediate medical assistance if these signs develop.

• Instruct patient and family/caregivers to report other side effects such as severe or prolonged headache or nausea.

Pharmacokinetics

Absorption: IV administration results in complete bioavailability.

Distribution: Unknown.

Metabolism and Excretion: Highly metabolized by the liver, 1 metabolite is active; metabolites excreted by kidneys.

Half-life: 6 hr (2–12 hr).

Contraindications/Precautions

Contraindicated in: Hypersensitivity.

Use Cautiously in: CHF or left ventricular dysfunction (↑ risk of more serious arrhythmias during infusion); Pregnancy, lactation, or children <18 yr (safety not established).

Interactions

Drug-Drug: Amiodarone, disopyramide, procainamide, quinidine, and sotalol should not be given concurrently or within 4 hr because of additive effects on refractoriness. Proarrhythmic effects may be ↑ by phenothiazines, tricyclic and tetracyclic antidepressants, some antihistamines, and histamine H₂ receptor blocking agents; concurrent use should be avoided.

Route/Dosage

Atrial Fibrillation/Flutter

IV (Adults ≥60 kg): 1 mg infusion; may be repeated 10 min after end of first infusion.