Nifekalant (INN) is a class III antiarrhythmic agent approved in Japan for the treatment of arrhythmias and ventricular tachycardia. It has the brand name Shinbit. Nifekalant (INN) is a class III antiarrhythmic agent approved in Japan for the treatment of arrhythmias and ventricular tachycardia. It has the brand name Shinbit.