&NA;Dofetilide (UK 68, UK 68798, Tikosyn®, Xelide®) is a cardioselective potassium channel antagonist that selectively blocks the rapidly-activating component of the delayed rectifier potassium current.[1] A methanesulfonanilide derivative, dofetilide is related to sotalol and sematilide. Dofetilide is under development with Pfizer as a broad spectrum ‘pure’ class III antiarrhythmic agent (it has no class I, II or IV effects), and has demonstrated a low incidence of proarrhythmia and no cardiac inhibitory effects. Dofetilide (Tikosyn®) has been recommended for approval by the US Food and Drug Administration for the conversion of atrial fibrillation (AF) or atrial flutter to sinus rhythm and maintenance of sinus rhythm. The drug is also undergoing phase III trials in Europe, Australia and Japan. Dofetilide is an investigational agent in Canada. Preclinical development in ischaemic heart disorders may be proceeding in Norway.