[Effect of efonidipine hydrochloride on myocardial oxygen balance in anesthetized dogs]

The aim of the present study was to investigate the effect of efonidipine hydrochloride (efonidipine) on myocardial oxygen balance in anesthetized open-chest dogs, and the results were compared to those of nifedipine or nisoldipine. Efonidipine (10 and 30 micrograms/kg) lowered the mean blood pressure, and the extent of the hypotension was similar to those induced by nifedipine (1 and 3 micrograms/kg) and nisoldipine (1 and 3 micrograms/kg). The hypotensive effect of efonidipine was very slow in onset and long-lasting as compared with that of nifedipine. Efonidipine and nisoldipine decreased the heart rate, but nifedipine increased it. Efonidipine (30 micrograms/kg) and nifedipine (1 and 3 micrograms/kg) slightly increased myocardial oxygen consumption. Nisoldipine (3 micrograms/kg) tended to increase myocardial oxygen consumption. Since efonidipine, nifedipine and nisoldipine decreased the arterio-venous oxygen difference and increased coronary sinus outflow, these drugs increased the oxygen supply to the myocardium. Furthermore, these drugs decreased myocardial oxygen demand. From these results, it is suggested that efonidipine may be useful for improving myocardial oxygen balance.