Introduction: We characterized in vivo electropharmacological profile of anti-atrial fibrillatory drug vernakalant.
Methods: Vernakalant was intravenously administered in doses of 0.3 and 3 mg/kg/10 min to the isoflurane-anesthetized beagle dogs (n=5). These results were compared with those of other anti-atrial fibrillatory drugs; ranolazine, dronedarone, amiodarone, bepridil and dl-sotalol.
Results: Vernakalant suppressed the sinus automaticity, ventricular contractility, and atrioventricular nodal and intraventricular conduction, whereas it increased the total peripheral vascular resistance, preload to the left ventricle and mean blood pressure.  Meanwhile, vernakalant delayed the repolarization in a reverse frequency-dependent manner; and the prolongation of early/late repolarization was 43 ms/12 ms when QT-interval prolongation was the greatest, whereas it prolonged the atrial/ventricular effective refractory period by 32 ms/44 ms, respectively.
Conclusion: The atrial effective refractory period prolongation by vernakalant was intermediate among the drugs, but its atrial selectivity was the lowest. Prolongation of the early repolarization by vernakalant was the greatest, whereas that of the late repolarization was in the middle, indicating greater risk for intracellular Ca²⁺ overload-based ventricular arrhythmias.