The antiarrhythmic efficacy of intravenous therapy with disopyramide phosphate

Disopyramide phosphate was administered i.v. to 57 patients with 60 episodes of arrhythmia (21 supraventricular and 39 ventricular) as a 2 mg/kg bolus. Conversion to sinus rhythm was achieved in 3 (38%) of 8 patients with atrial flutter, 2 (20%) of 10 patients with atrial fibrillation, 1 (33%) of 3 patients with paroxysmal atrial tachycardia, and 2 (50%) of 4 patients with sustained ventricular tachycardia. In 9 (75%) of 12 patients with nonsustained ventricular tachycardia, suppression of the arrhythmia was accomplished following the intravenous bolus of disopyramide. In 18 (78%) of 23 patients with frequent ventricular premature contractions, greater than 50% suppression of the ventricular premature contractions was achieved. These effects were satisfactorily maintained in 6 (86%) of 7 patients with nonsustained ventricular tachycardia and in 14 (88%) of 16 patients with frequent ventricular premature contractions in whom therapy with disopyramide phosphate was continued as a 20 mg/hr i.v. drip infusion for up to 24 hr. Side effects were observed in only 8 patients (14%) and were primarily anticholinergic in nature. Transient hypotension, not necessitating treatment with pressor agents, was observed in 3 patients (5%) in 2 of whom discontinuance of therapy with disopyramide was deemed necessary. I.v. therapy with disopyramide in the dosage regimen employed appears to be moderately effective against supraventricular arrhythmia and particularly effective against ventricular arrhythmia with minimal toxicity. It appears to be a suitable alternative to i.v. therapy with lidocaine and has the additional advantage of availability for oral administration.