Antiarrhythmic and electrophysiological effects of CH-200.

A new antiarrhythmic drug CH-200, 5-phenacyl-thieno[3,2-c]yridinium, was compared with procainamide and lidocaine in a two-stage coronary ligation arrhythmia model for its efficacy and electrophysiological properties. CH-200 suppressed arrhythmia in beagle dogs more effectively than did procainamide and lidocaine. The antiarrhythmic effects of CH-200 and procainamide developed slowly and lasted longer than those of lidocaine. Electrophysiological studies with CH-200 showed that it decreased max dV/dt of the action potential. This effect was dependent on the heart rate: the higher the rate, the stronger the effect. CH-200, procainamide and lidocaine prolonged the effective refractory period and this effect seemed to be responsible for suppressing the arrhythmia after coronary ligation. CH-200 and procainamide increased the frequency of ventricular pacemaker activity, while lidocaine decreased it. These effects appear to be unimportant for the antiarrhythmic effects.