INHIBITION OF ANGIOTENSIN-CONVERTING ENZYME WITH LIBENZAPRIL IN NORMOTENSIVE MALES

The effect of intravenous (IV) libenzapril was studied in six healthy moles by administering IV angiotensin I [AI] administered in stepwise increments of 20 ng/kg/5 min until the subjects' systolic blood pressu re (SEP) had increased 20-30 mm Hg above baseline. The mean baseline i nfusion of 63 ng/kg/5 min resulted in a significant (P < 0.05) increas e in the ratio of AII to AI plasma levels from 0.52 +/- 0.46 to 7.92 /- 4.48 and a SEP increase of 120 +/- 7.1 to 147 +/- 5.6. Within 15 mi nutes of starting the 1-mg infusion of libenzapril over 1.5 hours, the AII/AI ratio decreased to baseline values, and the SEP had returned t o baseline in 1 hour. Repeat AI challenges at 3.5 and 5 hours postdose did not increase SEP significantly. Even the 6.5-hour challenge demon strated only a slight increase in SEP, with an AII/AI ratio of 0.26. A t 24 hours, SEP was only 40% of the baseline response, demonstrating t hat libenzapril is a potent long-acting ACE inhibitor.