Comparative study of the protective effects of terfenadine and amiodarone on barium chloride/aconitine-induced ventricular arrhythmias in rats: a potential role of terfenadine.

Terfenadine is a second generation histamine receptor antagonist which is widely used as a non‑sedating antihistamine to relieve allergic responses. However, terfenadine has been associated with a number of side effects on cardiac electrical activities through blocking multiple ion channels in the heart, particularly K+ channels. Previous studies have also implied that terfenadine may have a potential antiarrhythmic effect; however, the electrophysiological influence by which terfenadine exerts its antiarrhythmic action remains elusive. Based on evidence from previous studies, it was hypothesized that the antiarrhythmic effect of terfenadine may be similar to that of amiodarone. The present study aimed to examine the effect of terfenadine on the QTc interval and on experimental ventricular arrhythmia in rats by comparing with that of amiodarone. The effect of terfenadine and amiodarone on the QTc interval was evaluated by comparison of multiple electrocardiograms. Barium chloride/aconitine was intraperitoneally injected to induce ventricular arrhythmias. Normal saline was administered to control rats. In comparison with normal saline, terfenadine and amiodarone similarly dose‑dependently prolonged the QTc interval in rats. In the barium chloride/aconitine-induced ventricular arrhythmia model, terfenadine and amiodarone did not only similarly delay the onset time of arrhythmias induced by barium chloride (all P<0.05), but also increased the cumulative dosage of aconitine required to induce various arrhythmias (all P<0.05). Furthermore, the two drugs equivalently caused a significant decrease in the duration of ventricular tachycardia in comparison with the normal saline controls (all P<0.05). The present study suggested that terfenadine prolonged the QTc interval and decreased ventricular tachycardia duration. The potential protective effect of terfenadine in ventricular arrhythmia may be similar to that of amiodarone.