<unk>  is categorized as a class III antiarrhythmic agent, and prolongs phase 3 of the cardiac action potential, the repolarization phase where there is normally decreased calcium permeability and increased potassium permeability. It has numerous other effects, however, including actions that are similar to those of antiarrhythmic classes Ia, II, and IV.<unk>  is a blocker of voltage gated potassium (KCNH2) and voltage gated calcium channels (CACNA2D2).<unk>  slows conduction rate and prolongs the refractory period of the SA and AV nodes. It also prolongs the refractory periods of the ventricles, bundles of His, and the Purkinje fibres without exhibiting any effects on the conduction rate.<unk>  has been shown to prolong the myocardial cell action potential duration and refractory period and is a non-competitive β-adrenergic inhibitor. It also shows beta blocker-like and calcium channel blocker-like actions on the SA and AV nodes, increases the refractory period via sodium- and potassium-channel effects, and slows intra-cardiac conduction of the cardiac action potential, via sodium-channel effects. It is suggested that<unk>  may also exacerbate the phenotype associated with Long QT-3 syndrome causing mutations such as ∆KPQ. This effect is due to a combination of blocking the peak sodium current, but also contributing to an increased persistent sodium current.<unk>  chemically resembles thyroxine (thyroid hormone), and its binding to the nuclear thyroid receptor might contribute to some of its pharmacologic and toxic actions.
Amiodarone
Ibutilide
Colestilan
Flecainide
Verapamil
Acecainide
Sotalol
Dofetilide