Onset of action of captopril, enalapril, enalaprilic acid and lisinopril in normal man.

The effects of orally administered captopril, enalapril and lisinopril on plasma concentrations of angiotensin converting enzyme (ACE), angiotensin II (ANGII) and renin (PRC) were studied over a period of 6 hours in 6 normal subjects. A further 4 subjects received intravenous enalapril and enalaprilic acid (enalaprilat). Captopril (25 mg) by mouth caused a fall in pANGII that reached a nadir 30 to 40 minutes after administration but an effect was hardly apparent after 6 hours. Enalapril (10 mg) by mouth had less marked effects on pACE and pANGII with a decline in levels first apparent 1 hour after administration and the lowest levels reached between 3 and 6 hours. Lisinopril (10 mg) produced a progressive fall in pACE and pANGII from 1 hour to reach the lowest values 6 hours after treatment. Intravenous enalaprilat (5 mg) produced an immediate sustained fall in both pACE and pANGII but intravenous enalapril (7 mg) had a biphasic inhibitory effect.