To characterize the anti-arrhythmic properties of a new calcium antagonist, monatepil [corrected], AJ-2615, the preventive effects of AJ-2615 were compared with those of the existing calcium antagonists, diltiazem and verapamil, in experimental models of arrhythmia. 2. AJ-2615 (0.1-3.0 mg/kg, i.v.) suppressed ventricular arrhythmias induced by adrenaline (10 micrograms/kg, i.v.) in rats. AJ-2615 (0.1 mg/kg per min for 2 min, i.v.) also suppressed atrial tachycardia induced by aconitine (0.01% aconitine solution) in rats. 3. In these activities, AJ-2615 was comparable to or more potent than diltiazem and verapamil which are widely used for the treatment of arrhythmia. 4. In pro-arrhythmic activity, AJ-2615 was less potent than diltiazem and verapamil. 5. These results suggest that AJ-2615 would be a safer anti-arrhythmic agent, with less proarrhythmic liability than diltiazem and verapamil.
