Cilazapril is an inhibitor of angiotensin converting enzyme (ACE) with IC50 value of 1.93nM [1].
Cilazapril is a monoethyl prodrug of cilazaprilat. The latter shows an IC50 value of 1.93nM to rabbit lung ACE when using Hip-His-Leu substrate in vitro. Cilazaprilat is most potent among all the ACE inhibitors when the ACE is from rabbit lung, human plasma, hog kidney or human lung. Cilazaprilat is specific. It shows no inhibition to a variety of lipolytic and proteolytic enzymes even the concentration of it is up to more than 10000 fold higher than its IC50 value. Cilazapril and cilazaprilat also show inhibition of the angiotensin I (AI) pressor response with ED50 vallues of 0.44 and 0.06 mmol/kg. In addition, when cilazapril is treated as an antihypertensive drug, the maximum decrease in blood pressure relative to the control is 110mmHg on day 21 [1].
References:
[1] Waterfall JF. A review of the preclinical cardiovascular pharmacology of cilazapril, a new angiotensin converting enzyme inhibitor. Br J Clin Pharmacol. 1989;27