Azimilide is a
potassium channel antagonist that, in contrast to existing class III antiarrhythmic agents, blocks both the rapidly (I(Kr)) and slowly (I(Ks)) activating components of the delayed rectifier
potassium current. In animal and clinical studies,
azimilide prolonged repolarisation by increasing the action potential duration and effective refractory period. In animal models,
azimilide was effective in terminating both atrial and ventricular arrhythmias.
Azimilide also demonstrated antifibrillatory efficacy in a canine model of
sudden cardiac death. In patients with a history of
atrial fibrillation/flutter, oral
azimilide controlled arrhythmias more effectively than placebo in a 6-month randomised double-blind study. At a dosage of 125 mg once daily,
azimilide significantly increased the time to first symptomatic recurrence of
atrial fibrillation/flutter. However, no significant difference between placebo and
azimilide was found in another study. Oral
azimilide 100 mg once daily demonstrated clinically significant treatment effects in patients with
paroxysmal supraventricular tachycardia. In clinical trials,
azimilide was generally well tolerated and
headache was the most commonly occurring adverse event.
Azimilide is associated with a low incidence of proarrhythmic events, such as
torsades de pointes, and few serious adverse events have been reported.