SOTALOL - AN UPDATED REVIEW OF ITS PHARMACOLOGICAL PROPERTIES AND THERAPEUTIC USE IN CARDIAC-ARRHYTHMIAS

Sotalol is a nonselective beta-adrenoceptor antagonist which prolongs cardiac repolarisation independently of its antiadrenergic action (cla ss III antiarrhythmic properties). The antiarrhythmic action of sotalo l appears to arise predominantly from its class III properties, and th e drug exhibits a broader antiarrhythmic profile than the conventional beta-blockers. Sotalol is effective in controlling paroxysmal suprave ntricular tachycardias and the ventricular response to atrial fibrilla tion/flutter in Wolff-Parkinson-White syndrome, in maintaining sinus r hythm after cardioversion of atrial fibrillation/flutter, and in preve nting initiation of supraventricular tachyarrhythmias following corona ry artery bypass surgery. Sotalol shows promise in the control of nonm alignant and life-threatening ventricular arrhythmias, particularly th ose associated with ischaemic heart disease. It is effective in suppre ssing complex forms of ventricular ectopy, displaying superior antiect opic activity to propranolol and metoprolol. The acute efficacy of sot alol in preventing reinduction of sustained ventricular tachyarrhythmi as and suppressing spontaneous episodes of these arrhythmias on Holter monitoring is translated into long term prophylactic efficacy against arrhythmia recurrence in approximately 55 to 85% of patients with ref ractory life-threatening ventricular arrhythmias. In addition, sotalol offers the advantage over the class I agents of reducing cardiac and all-cause mortality in the high risk population with life-threatening ventricular arrhythmias. The adverse effects of sotalol are primarily related to its beta-blocking activity and its class III property of pr olonging cardiac repolarisation. Sotalol is devoid of overt cardiodepr essant activity in patients with mild or moderate left ventricular dys function. The overall arrhythmogenic potential is moderately low, but torsade de pointes may develop in conjunction with excessive prolongat ion of the QT interval due to bradycardia, hypokalaemia or high plasma concentrations of the drug. In summary, sotalol displays a broad spec trum of antiarrhythmic activity, is haemodynamically well tolerated, a nd confers a relatively low proarrhythmic risk. It is likely to prove particularly appropriate in the treatment and prophylaxis of life-thre atening ventricular tachyarrhythmias.