Any drug used in the treatment of cardiac arrhythmia is considered an antiarrhythmic medication. These include Ca plus plus antagonist, Beta blockers, cardiac glycosides, Class I antiarrhythmics and Class III antiarrhythmics.
Class I antiarrhythmics, such as Propafenone hydrochloride or Quinidine, impair the entry of Na+ ions into cardiac cells, slowing the rate of depolarisation and reducing the excitability of the muscle.
Class III antiarrhythmics, based on amiodarone such as Bretylium tosylate or Amiodarone hydrochloride, prolong the effective refractory period, the interval required for re-excitation is increased and arrhythmias are suppressed.
