Bretylium tosylate is an inhibitor of the presynaptic release of vasoconstrictor neurotransmitters, a available antiarrhythmic drug for ventricular arrhythmias.

Nine patients who had recurrent ventricular fibrillation following acute myocardial infarction or angina were given bretylium tosylate in a dose of 5 mg./kg. intramuscularly every eight hours after other measures had proved ineffective. Provided the patients were not in shock or in heart failure, there was a considerable reduction in the episodes of ventricular fibrillation.A second group of nine patients who developed recurrent ventricular fibrillation following open heart surgery were given bretylium intravenously, which controlled the arrhythmia in every instance.Bretylium did not completely abolish ventricular premature beats but the latter did not initiate ventricular fibrillation even when they occurred on the T wave[1].