Comparative studies of the systemic hemodynamics and myocardial oxygen consumption of FRC 8653, a new Ca++ channel blocker, and nifedipine in anesthetized dogs.

Effects of FRC 8653, a new dihydropyridine derivative, on regional blood flow, cardiac function and myocardial oxygen consumption were examined and compared with those of nifedipine in anesthetized open-chest dogs. Intravenous administration of FRC 8653 at doses of 1, 3 and 10 micrograms/kg dose-dependently decreased aortic pressure and increased aortic, vertebral and coronary blood flow similar to nifedipine. No significant change was observed in left ventricular end-diastolic pressure, left ventricular positive dP/dt and heart rate following i.v. administration of FRC 8653. Myocardial oxygen consumption was dose-dependently decreased by FRC 8653. When changes in mean aortic pressure and aortic and coronary blood flow were compared at the same dose of 10 micrograms/kg i.v., both FRC 8653 and nifedipine showed almost the same degree of reduction of mean aortic pressure, but the time from drug administration to peak responses and the duration for which half the maximal effects were maintained, were significantly longer with FRC 8653 than nifedipine. Results suggest that FRC 8653 may be useful for the treatment of patients with hypertension and ischaemic heart disease.