Antiarrhythmic plasma concentrations of cibenzoline on canine ventricular arrhythmias

Using two-stage coronary ligation-, digitalis-, and adrenaline-induced canine ventricular arrhythmias, antiarrhythmic effects of cibenzoline were examined and the minimum effective plasma concentration for each arrhythmia model was determined. Cibenzoline suppressed all the arrhythmias, and the minimum effective plasma concentrations for arrhythmias induced by 24-h coronary ligation, 48-h coronary ligation, digitalis, and adrenaline were 1.9 +/- 0.9 (by 8 mg/kg i.v.), 1.6 +/- 0.5 (by 8 mg/kg i.v.), 0.6 +/- 0.2 (by 2 mg/kg i.v.), and 3.5 +/- 1.3 (by 5 mg/kg i.v.) micrograms/ml, respectively (mean +/- SDM, n = 6-7). The concentration for adrenaline-induced arrhythmia was significantly higher than those for the other types of arrhythmias. This pharmacological profile is similar to those of mexiletine and tocainide, and all three drugs have central nervous system (CNS) stimulant action. Because cibenzoline had only weak hypotensive and sinus node depressive effects and was found to be orally active when given to coronary ligation arrhythmia dogs, its clinical usefulness is expected.