Enalapril and lisinopril in renovascular hypertension--antihypertensive and hormonal effects of two new angiotensin-converting-enzyme (ACE) inhibitors. A preliminary report.

We assessed the antihypertensive and hormonal effects of two new angiotensin converting enzyme (ACE) inhibitors, enalapril (MK-421) and lisinopril (MK-521) in 22 patients with renovascular hypertension. All patients had angiographically verified renal artery lesions, 3 had bilateral renal artery stenosis and one a stenosis in a single kidney, and the rest had unilateral renal artery stenosis. After placebo treatment for 3 days in hospital, increasing doses from 5 to 40 mg daily, of both ACE-inhibitors were given. Both drugs induced a significant fall in blood pressure (BP). Significant BP reductions were seen after 2 h with a maximum fall for the enalapril group at a dose of 40 mg 4 h after drug intake (mean supine BP decrease - 31/24 mm Hg, standing - 29/16 mmHg). The corresponding maximal BP reductions were for the lisinopril group at a dose of 40 mg o.d. at 6 h: mean supine BP fall - 25/28 mmHg and standing - 33/31 mm Hg. Both drugs significantly inhibited serum ACE to about 5 to 10% of initial values and with a duration for more than 24 h. Both drugs also caused a decrease in plasma-AII levels and also in plasma aldosterone concentrations. There were not toxic effects and no serious side effects. Careful monitoring of biochemical variables showed no significant changes. We conclude that both enalapril and lisinopril are effective and very safe agents for the treatment of renovascular hypertension and with a long duration of action and with very good tolerance.