Inhibition of angiotensin-I response by cilazapril and its time course in normal volunteers*

Cilazapril is a new angiotensin-converting enzyme (ACE) inhibitor. In a double-blind crossover study six normal male volunteers received single oral doses of cilazapril, 4 mg, captopril, 25 mg, enalapril, 10 mg, and placebo. The response of diastolic blood pressure to an intravenous infusion with increasing doses of angiotensin I (AT-I) (0.1 to 18 micrograms/min) was determined at control and up to 36 hours after oral drug intake. Additionally the response to AT-I was established before, during, and after cessation of a 15-day 2.5 mg/day cilazapril administration. The ACE inhibitors antagonized the AT-I effects and shifted the AT-I dose-effect curves rightward, whereas placebo was not effective. After single doses the effects of cilazapril and enalapril declined with a similar elimination half-life of approximately 4 hours; with captopril approximately 2 hours was observed. After multiple administration of cilazapril there was no evidence of cumulative effects. Cilazapril is an orally active ACE inhibitor that does not show pharmacodynamically relevant accumulation.