Azimilide is a class III antiarrhythmic agent that prolongs cardiac repolarisation by blocking both the rapidly and slowly activating components of the delayed rectifier potassium channel. The most important consequence of this is apparent rate-independent activity, so that, unlike other class III antiarrhythmics, azimilide does not lose efficacy at high heart rates. Azimilide has very predictable pharmacokinetics, is predominantly hepatically metabolized, and has no significant drug interactions with digoxin or warfarin. The most common adverse effects reported by patients on azimilide were approximately equal in frequency with those on placebo: headache, asthenia, infection, diarrhea and dizziness. Azimilide is in phase III clinical trials for the treatment both supraventricular and ventricular tachyarrhythmias.