HEMODYNAMIC-EFFECTS OF BENAZEPRIL, AN ANGIOTENSIN-CONVERTING ENZYME-INHIBITOR, AS STUDIED IN CONSCIOUS NORMOTENSIVE DOGS

Hemodynamic effects and inhibitory effects on the pressor response to exogenous angiotensin I of benazepril (CGS 14824A), a new angiotensin-converting enzyme (ACE) inhibitor, were examined in conscious chronically instrumented normotensive dogs in comparison with those of captorpil. Oral administration of benazepril (1-10 mg/kg) and captopril (3 and 10 mg/kg) reduced the blood pressure and inhibited the pressor response to angiotensin I dose-dependently. The blood-pressure-lowering effect of benazepril was as potent as that of captopril. The onset of effects of benazepril was slower and the duration longer than that of captopril. There was no close correlation between the attenuation of pressor response to exogenous angiotensin I and the blood-pressure-lowering effect of these two agents. These results indicate that benazepril is a potent ACE inhibitor with a slow onset and a long duration. The slow onset of action may be explained by the necessity of prior conversion of this compound to an active metabolite. A mechanism or mechanisms other than that responsible for the inhibition of pressor response to exogenous angiotension I must be taken into consideration to explain the blood-pressure-lowering effects of benazepril and captopril.