Ibutilide prolongs repolarization by inhibition of the delayed rectifier potassium current (Ikr) and by selective enhancement of the slow inward sodium current.
Ibutilide is a newer anti arrhythmic used in particularly for patients suffering from atrial fibrillation not responding to the commonly used medications.
Ibutilide is efficacious in the termination of atrial fibrillation (AF) and flutter with both single and repeated intravenous infusions.
It is as effective as amiodarone in cardioversion of atrial fibrillation. The proarrhythmic effect resulting in torsades de pointes is higher in individuals with heart failure, those with bradycardia, nonwhite subjects, women, and those given the drug for atrial flutter rather than atrial fibrillation.
The risk of this is greatest during or shortly after the infusion of the drug (within 1 hour) and rapidly wanes after administration since the half-life (2 to 12 hours) of this agent is short.
The patient should be monitored for at least 4 hours after the start of the Ibutilide infusion.