Inotropic and electrophysiological effects of tolbutamide in normal subjects

The acute cardiac effects of tolbutamide on myocardial contractility, evaluated with systolic time intervals (ST), and on the atrio-ventricular conduction system have been studied in a group of five volunteer normal subjects. The intravenous administration of 1 g of tolbutamide showed no considerable changes of STI and of electrophysiologic parameters. Glycemia decreased whereas there was a statistically significant increase in plasmatic levels of catecholamines at the 10th and 20th min. Our findings suggest that the intravenous administration of tolbutamide has no effect either on the atrio-ventricular conduction system or on myocardial contractility in normal men.