Diphenidol treatment of arrhythmias

The antiarrhythmic activity of diphenidol, an antiemetic, has been demonstrated both in electrophysiologic studies of patiens and in experimental arrhythmias in animals. Accordingly, 18 patients with tachyarrhythmias were treated with intravenous diphenidol in doses of 0.5 to 1.5 mg/kg. In six patients with atrial arrhythmias, there was no notable effect. Similarly, 12 patients with premature ventricular contractions were treated and studied. In six of them, ectopic beats were abolished, at least transiently; in three the number of ventricular premature contractions decreased; in two there was no effect; and in one, the number of premature beats was increased. Of the total number of 18 patients, 14 suffered adverse effects related to the central nervous system. These adverse effects were of such severity as to suggest that further studies with diphenidol as an antiarrhythmic are not warranted.