Cibenzoline for treatment of ventricular arrhythmias: a double-blind placebo-controlled study

Cibenzoline, a new class I antiarrhythmic drug, was administered to 24 patients with frequent (greater than 30/h) premature ventricular complexes. Three patients discontinued the medication because of epigastric distress before repeat ambulatory electrocardiography. Of the remaining 21 patients, 13 responded to 130 mg twice daily by more than 75% suppression of premature ventricular complex frequency and 6 additional patients responded to 160 mg twice daily during an open-label titration phase. Events of ventricular tachycardia (greater than or equal to 3 beats) were totally suppressed in 9 of 10 patients and markedly diminished in the 1 remaining patient. During a double-blind placebo-controlled crossover phase in 16 patients (21 patients minus 2 nonresponders and 3 who developed side effects), cibenzoline suppressed the number of premature ventricular complexes per 24 hours (4,075 +/- 868 to 1,758 +/- 1,089, p = 0.02), the number of events of ventricular tachycardia (31 +/- 30 to 2 +/- 0, p = 0.01) and the number of premature ventricular complex pairs (61 +/- 28 to 25 +/- 21, p = 0.01). Cibenzoline plasma concentration was 59 to 421 ng/ml in responders and higher (387, 758 and 852 ng/ml, respectively) in the three subjects with side effects (right bundle branch block in one, hypotension in one, gastrointestinal upset and central nervous system complaints in one). Cibenzoline plasma concentration correlated with PR interval (r = 0.55, p = 0.0106) and corrected QT interval (r = 0.58, p = 0.0054). Further clinical investigation of this new antiarrhythmic agent is needed.