14th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 2000

Jan. 29 - Feb. 5, 2000
Marilleva, Trento, Italy

RT-91

Electrophysiological interactions between sotalol and mexiletine in man

Roberto Padrini, Mohammad Al Bunni*, Monica Mollichelli*, Antonella Alberti**, Roberto Varotto**, Pietro Maiolino*, Mariano Ferrari**.
Department of Pharmacology and Anesthesiology and **Department of Clinical and Experimental Medicine, University of Padova, *Division of Cardiology, Cittadella Hospital, Cittadella, Italy

Introduction

Rac-sotalol is a non selective beta-adrenoceptor blocker with the additional property of prolonging the action potential duration and the QT interval on the surface ECG¹. The most serious adverse reaction to sotalol is polymorphic ventricular tachycardia (TdP), which is favoured by excessive QT interval prolongation and heart rate slowing². Various experimental studies in cardiac myocytes^3,4 and intact animals^5,6 have investigated the interaction between sotalol and mexiletine at an electrophysiological level and found that: a) mexiletine attenuated sotalol-induced action potential prolongation, but further prolonged cell refractoriness; b) sotalol-mexiletine combination had additive antiarrhythmic effect on electrically-induced ventricular tachycardia in dogs while preventing sotalol-induced TdP. On the basis of these experimental findings, we investigated whether mexiletine can interfere with the class III effect of sotalol also in man, at currently used doses.