Antiarrhythmic use of cibenzoline, a new class 1 antiarrhythmic agent with class 3 and 4 properties, in patients with recurrent ventricular tachycardia

Oral cibenzoline reduces postoperative atrial fibrillation in coronary artery bypass grafting

OBJECTIVE

The objective of the present study was to investigate the effectiveness of postoperative oral administration of cibenzoline for the prevention of atrial fibrillation (AF) in coronary artery bypass grafting (CABG).

METHODS

A total of 39 patients who underwent isolated CABG from September 2000 to February 2001 and who took oral cibenzoline (300 mg per day for 10 days beginning immediately after surgery) were compared to 59 patients who underwent surgery in our department 8 months prior to the study and who did not take cibenzoline for incidence of postoperative AF. Exclusion criteria encompassed age (>80 years), low ejection fraction (<30%), high serum creatinine level (>2.0 mg/dL), and history of supraventricular arrhythmia with or without treatment by anti-arrhythmic drugs.

RESULTS

Postoperative AF occurred in 2 patients in the cibenzoline group (2/35, 5.7%) and 20 patients in the control group (20/59, 33.9%). There were significant differences in the incidence of postoperative AF (p = 0.002). Multivariate analysis revealed that the administration of cibenzoline reduced the incidence of AF significantly, and that a large number of bypass grafts significantly contributed to postoperative AF in CABG. The number of bypass grafts was significantly larger in the cibenzoline group, indicating that cibenzoline administration significantly suppresses the incidence of AF after CABG in high-risk patients.

CONCLUSIONS

Postoperative administration of oral cibenzoline for 10 days is one effective method for the prevention of AF after CABG.

Effects of the Na+ antagonist cibenzoline on left ventricular function of postischemic hearts

The negative inotropic effect of antiarrhythmic drugs is a major drawback in antiarrhythmic drug therapy, especially in patients with reduced contractile function of the left ventricle. The circulatory and myocardial effects of the new class I antiarrhythmic drug (a Na+ antagonist), cibenzoline (2 mg/kg i.v.), were investigated in 47 open-chest rats with normal and postischemic myocardium (3 x 4 minutes of global ischemia). Hemodynamic measurements in the intact circulation and isovolumic registrations (peak isovolumic left ventricular systolic pressure and peak isovolumic dP/dtmax) were compared to saline controls. In rats with postischemic myocardium, cibenzoline caused a significant (p < 0.001) decrease in the cardiac output for 38%, in the dP/dtmax for 30%, and in the peak isovolumic dP/dtmax for 19% at the end of infusion (compared to the control). The heart rate was reduced by 22% (p < 0.001), the mean aortic pressure by 22% (p < 0.001), and the calculated systemic resistance by 20% (p < 0.001). In contrast to the results with postischemic myocardium, no important changes in the hemodynamics were detectable after an identical dose in normal animals without left ventricular dysfunction. The results indicate that standard doses of the Na+ antagonist cibenzoline may induce significant cardiodeperessant effects on postischemic left ventricles with reduced function.

Cibenzoline. A review of its pharmacological properties and therapeutic potential in arrhythmias

Cibenzoline is a class I antiarrhythmic drug with limited class III and IV activity which can be administered orally or intravenously. An elimination half-life of about 8 to 12 hours permits twice daily administration, although age and renal function must be considered when determining dosage. Cibenzoline has some activity in ventricular and supraventricular arrhythmias, including drug-refractory ventricular tachycardia or ventricular arrhythmias following recent acute myocardial infarction, although results in patients with sustained ventricular tachycardia are less promising. In comparative trials, cibenzoline has demonstrated efficacy similar to or better than that of a variety of other class I antiarrhythmic drugs and was at least as well tolerated, with a more convenient dosage schedule. However, further studies to clarify the proarrhythmic effects of cibenzoline and its use in patients with impaired left ventricular function are required, and the use of cibenzoline (and other class I antiarrhythmic agents) in patients with other than potentially lethal ventricular arrhythmias should be avoided following the results of the CAST studies. Thus, cibenzoline is an effective antiarrhythmic agent with a favourable pharmacokinetic profile that may be considered with other class I drugs in patients requiring therapy for high risk arrhythmias.

Randomized comparison of flecainide and cibenzoline in the conversion of atrial fibrillation

The efficacy of oral cibenzoline (260 mg/day and 320 mg/day) and flecainide (200 mg/day and 300 mg/day) in the conversion of chronic atrial fibrillation to sinus rhythm were compared in 31 patients in a randomized order. If sinus rhythm was not restored on the 5th day of oral treatment with either cibenzoline or flecainide (phase of initial treatment) patients were switched to a second phase of treatment with the drug not given in the first phase after a washout phase of 3 days. Sinus rhythm was restored in 7/28 treatment trials with cibenzoline and in 7/23 treatment trials with flecainide (not significant). Trough levels of cibenzoline and flecainide in the plasma were not significantly different between patients in whom sinus rhythm was restored and patients with persisting atrial fibrillation. In patients successfully converted to sinus rhythm, long-term treatment was instituted with flecainide (n = 6) or cibenzoline (n = 6). Atrial fibrillation developed in 2 patients in each group of patients within 3 months. In all other patients, sinus rhythm was maintained during the follow-up period of 12 months. Non-cardiac side effects were observed in 2 patients during treatment with cibenzoline and flecainide respectively. With flecainide, one patient developed sinus arrest up to 5.6 seconds.

Electrophysiologic effects and efficacy of cibenzoline on stimulation-induced atrial fibrillation and flutter and implications for treatment of paroxysmal atrial fibrillation

The effects of intravenous cibenzoline (1.5 mg/kg) on atrial vulnerability and electrophysiology were assessed in 25 patients with documented paroxysmal atrial fibrillation (AF), in whom sustained (greater than 30 seconds) AF was induced by atrial stimulation with up to 2 extrastimuli and paced rates between 100 and 180 beats/min. In 7 patients AF persisted despite the application of cibenzoline, and in 8 patients the induction of sustained AF was prevented by cibenzoline. Intraatrial conduction time, flutter cycle length and shortest ventricular cycle length during AF were increased by cibenzoline (p less than or equal to 0.01). Sinus cycle length was decreased (p less than or equal to 0.05), whereas sinus node recovery time remained unchanged. The effective refractory period of the right atrium was not significantly affected. Eight patients with frequent episodes of paroxysmal AF received oral cibenzoline for control of paroxysmal AF irrespective of the efficacy of intravenous cibenzoline. Prevention of stimulation-induced AF predicted successful treatment of paroxysmal AF (p = 0.018). Cibenzoline could be effective in the treatment of atrial arrhythmias, and selection of an antiarrhythmic therapy for recurrent AF seems to be useful.

Effect of oral cibenzoline on steady-state digoxin concentrations in healthy volunteers

The effect of oral cibenzoline on steady-state digoxin concentrations was studied in 12 healthy subjects ranging from 41 to 55 years of age. Each subject received an oral dose of 0.25 mg or 0.375 mg digoxin once daily for 27 days. On days 14 to 21, 160 mg of oral cibenzoline were administered concomitantly every 12 hours for a total of 15 doses. Plasma digoxin concentration-time profiles obtained before, during, and after cibenzoline coadministration were compared to determine the effect of oral cibenzoline on steady-state digoxin concentrations. The maximum plasma concentration, time of maximum concentration, area under the curve during a dosing interval and steady-state trough plasma concentration for digoxin, during and after concomitant doses of cibenzoline were similar to those before administration, indicating that cibenzoline did not affect the pharmacokinetics of digoxin. In addition, plasma cibenzoline concentration-time profiles after the first and last dose of cibenzoline were similar to those observed in previous studies in which multiple doses of cibenzoline alone were administered. The results of this study indicate that there is no pharmacokinetic interaction between digoxin and cibenzoline when the two drugs are coadministered to healthy subjects in multiple doses.

Electrophysiologic effects of cibenzoline in humans related to dose and plasma concentration

The electrophysiologic effects of a new antiarrhythmic agent, cibenzoline, were investigated in 25 patients with an average age of 62 years. The compound was administered intravenously, as a bolus given over 2 minutes, then as a slow infusion over 40 minutes. Each subject was randomly allocated to receive one of the following four doses: 1.55 mg/kg (six patients), 1.8 mg/kg (six patients), 2.2 mg/kg (six patients), or 2.6 mg/kg (seven patients). Plasma cibenzoline concentrations at these doses were 378 +/- 80,525 +/- 194, 618 +/- 72, and 731 +/- 196 ng/ml, respectively. Administration of 1.55 mg/kg cibenzoline significantly shortened the sinus cycle (60 msec on average; p less than 0.025) and increased intraatrial (+8 msec; p less than 0.05) and His-Purkinje conduction times (HV interval + 13 msec; p less than 0.001). At 1.80 mg/kg, prolongation occurred in the HV interval (+9 msec; p less than 0.02), the duration of the QRS complex (+20 msec; p greater than 0.05), and the QT interval (+18 msec; p less than 0.025). At the higher doses these changes became more marked (maximum increase: HV = +16 msec, p less than 0.001; QRS + 25 msec; p less than 0.001; QT + 26 msec, p less than 0.05), and additional effects on atrioventricular nodal conduction time (AH interval + 17 msec; p less than 0.05) and atrial (+20 msec; p less than 0.05) and ventricular (+10 msec; p greater than 0.05) effective refractory periods were observed. Prolongation of the QRS duration was the effect that correlated best with plasma cibenzoline levels (r = 0.47; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of cibenzoline after single and repetitive dosing in healthy volunteers

Twenty-five healthy, adult male volunteers entered two open-label parallel studies, each designed to define the pharmacokinetics of single and multiple oral doses of cibenzoline. Each volunteer received a single 160-mg oral dose of cibenzoline followed two or three days later by 160 mg of cibenzoline q12h for seven days. Plasma concentration-time profiles and urinary excretion rate data were used to determine pharmacokinetic parameters for unchanged drug. The apparent half-life following administration of the last dose (9.7 hours) was slightly longer than that observed after the first dose (8.4 hours). Total body clearance and nonrenal clearance were decreased after the last dose compared with the first dose, whereas renal clearance was not significantly altered. After both the first and last dose, the renal clearance greatly exceeded the glomerular filtration rate, suggesting that tubular secretion participates in the renal excretion of cibenzoline. Plasma concentrations from samples collected during the multiple-dose regimen suggest that a slight but statistically significant diurnal variation in the absorption and/or clearance of drug occurred during the course of the study. Overall, the pharmacokinetics of cibenzoline are characterized by a slightly longer half-life during multiple dosing than that observed following a single dose, due to a decrease in the nonrenal clearance. The multiple-dose pharmacokinetics reported herein are consistent with bid dosing for the maintenance of therapeutic plasma concentrations in patients taking chronic therapy.

Incidence of complex ventricular arrhythmias in asymptomatic patients with recent myocardial infarction

The incidence of ventricular extrasystoles (VES) was documented in 50 patients with recent uncomplicated myocardial infarction, with a 72-h two-channel ambulatory electrocardiogram. All patients were free of symptoms of arrhythmias; unstable angina pectoris and heart failure were absent. A total of 82% of the patients had VES: 23/50 patients had multiform or complex VES, 8/50 patients had ventricular tachycardia. VES were independent of heart rate and stable angina pectoris. Thus, frequent and complex VES are common in asymptomatic patients with uncomplicated recent myocardial infarction. Even in the absence of symptoms, ambulatory electrocardiography is useful. The prognostic significance of asymptomatic complex VES in these patients remains unsettled.

Antiarrhythmic effects of cibenzoline

Thirty-three patients with ventricular tachyarrhythmias were referred for evaluation of their arrhythmias using programmed electrical stimulation to guide antiarrhythmic therapy. Cibenzoline succinate, a new antiarrhythmic agent, was compared to procainamide in patients with ventricular tachycardia. Cibenzoline was given intravenously, initially 1.0 mg/kg, then in 1 mg/kg increments to a maximum of 3.0 mg/kg, during electrophysiologic testing. The results were compared to procainamide, which was also administered intravenously to 1000 and then to 1500 mg. Cibenzoline provided protection against ventricular tachycardia induction in 16 of 33 patients. The PR interval increased 13%, QRS duration widened 26%, and QTc interval was prolonged by 7%. There was a 9% fall in mean arterial blood pressure. Procainamide prevented ventricular tachycardia induction in 21 out of 31 patients tested. The PR interval increased 11%, QRS duration widened 27%, and QTc interval prolonged by 8%. Cibenzoline was given orally to 13 patients for chronic treatment. Chronic oral cibenzoline therapy after a mean follow-up of 8.8 months caused a reduction of ventricular ectopy from 666 to 190 beats/hr. Ventricular tachycardia events decreased per Holter monitor recording from 6 to 0.6. Cibenzoline therapy was discontinued in 5 of 13 patients due to break-through arrhythmias (nonsustained ventricular tachycardia on Holter monitor and recurrence of symptoms). Cibenzoline may be an effective antiarrhythmic agent in selected patients.