Efficacy and safety of oral cibenzoline for ventricular arrhythmias.

This study evaluates acute and chronic therapy with cibenzoline, a new class I antiarrhythmic drug, in 49 patients with ventricular arrhythmias. Acute therapy with 260 to 330 mg/day of cibenzoline resulted in a significant reduction in the number of hourly ventricular premature complexes (VPCs) (from 377 +/- 60 to 116 +/- 33, p less than 0.001), total paired VPCs in 24 hours (from 531 +/- 196 to 101 +/- 66, p less than 0.02), and total episodes of ventricular tachycardia in 24 hours (from 31 +/- 10 to 4 +/- 3, p less than 0.01). Among this group, acute therapy resulted in more than 75% suppression of VPC frequency in 29 of 49 patients, more than 90% suppression of paired VPCs in 31 of 42 patients, and complete suppression of ventricular tachycardia in 21 of 27 patients. Radionuclide evaluation of ventricular function revealed no deleterious effect of cibenzoline on ventricular function. Significant suppression of VPC frequency was maintained during 6 months of therapy in 16 of 19 patients and during 12 months of therapy in 9 of 10 patients. Trough plasma cibenzoline levels were measured during the acute dosing period. These levels did not differ among the group of responders (326 +/- 140 ng/ml) compared with nonresponders (354 +/- 282 mg/ml). Cibenzoline therapy resulted in adverse effects 18 patients and necessitated discontinuing therapy in 12. No patient had a proarrhythmic effect. In conclusion, cibenzoline appears to be as efficacious as the available antiarrhythmic drugs in treating chronic complex ventricular arrhythmias. Drug-related adverse effects occur with a frequency similar to that of other antiarrhythmic drugs.