CLASS-III ANTIARRHYTHMIC AGENTS - THE NEXT WAVE

Class III antiarrhythmic agents are characterized by their ability to prolong action potential and increase refractoriness. The use of these drugs, namely sotalol hydrochloride and amiodarone hydrochloride, is rising. Both agents are effective for treating a range of ventricular arrhythmias, and amiodarone in particular has been linked with improve d mortality in certain patient populations compared with class I agent s. Sotalol and amiodarone have individual, complex pharmacologic profi les. As a result, there are also differences in their side effects and proarrhythmic actions. Sotalol is associated with side effects relate d to beta-adrenergic blockade and an incidence of proarrhythmia simila r to that of class Ia agents. Amiodarone is associated with pulmonary toxicity and other adverse events, but rarely induces torsades de poin tes. These agents must be differentiated from pure class III potassium channel blockers, such as the dextro isomer form of sotalol, which is linked to increased mortality compared with placebo in post-myocardia l infarction patients with reduced ventricular function or a history o f heart failure.