Electrophysiological Effects of a Single Oral Administration of Pentisomide (ME3202) in Patients with Supraventricular Tachycardia.

The cardiac electrophysiological effects of pentisomide, a new class I antiarrhythmicagent, were studied in 14 patients with sunraventricular tachycardia.Pentisomide did not significantly change sinus cycle length, PA time, and AH and HVintervals at 1.5 hr after a single oral administration of 300, 400 or 600 mg. Furthermore, theantegrade and retrograde refractory periods of AV node and the accessory pathway were notsignificantly changed. However induction of supraventricular tachycardia was suppressed in 5out of 14 patients. Three of the 5 patients showed AV nodal reentrant tachycardia (AVNRT), 1 intra-atrial reentrant tachycardia (IART) and 1 concealed Wolff-Parkinson-White (WPW) syndrome. Pentisomide blocked the retrograde conduction in AV node in 3 patients with.AVNRT. The retrograde conduction in the accessory pathway was blocked in the patientwith concealed WPW syndrome. The plasma concentration of pentisomide at 1.5 hr afteradministration was 3.0±1.5 μg/ml in the effective cases and 2 .3±1.5 μg/ml in ineffectivecases (no statistically significance).Conclusion: A single oral administration of pentisomide showed no statistically significantinfluence on the electrophysiological parameters of human hearts, whereas it was effective insuppression of supraventricular tachycardia by the mechanism of retrograde conduction blockin several patients.