1985 Volume 145 Issue 2 Pages 125-135
OGAWA, K., MATSUNAGA, M., NAGAI, H., HARA, A., KOIDE, H., PAK, C.H., HIRAKAWA, A. and KAWAI, C. Effects of Enalapril Maleate (MK-421) on Renovascular Hypertension. Tohoku J. exp. Med., 1985, 145(2), 125-135-The effects of enalapril maleate (MK-421), a new angiotensin converting enzyme inhibitor, were studied on 5 patients with renovascular hypertension(RVH) due to unilateral renal artery stenosis. The therapeutic dosage was increased when the blood pressure (BP) was not controlled for more than 3 days. Blood sampling was performed before, and 5hr and 24hr after the first administration, and on the 3rd day with each dosage. The BP was normalized on 5mg/day in 1 case, 10mg in 1 case, 20mg in 2 cases, and 40mg plus mefruside in 1 case. Plasma renin activity (PRA) was significantly increased after 5hr and recoverd after 24hr with 2.5mg of the enalapril maleate, when the BP was not affected. This indicates that the increase in PRA is likely due to the reduced negative feedback of angiotensin II. When the blood pressure was lowered, PRA was increased and plasma aldosterone concentration (PAC) was decreased significantly. This rise of PRA may depend not only on the reduced negative feedback but also on the fall of BP. It is also considered that the PAC was decreased through the decrease in plasma angiotensin II. A fall of the glomerular filtration rate in one case and also a fall of the perfusion of the kidney of the stenotic side in another case were observed by radioisotope renograms. MK-421 administration was a useful treatment for RVH, and clearly normalized the BP of all the patients studied. However, there was a risk of a fall of renal function on the stenotic side due to the decrease in perfusion pressure.
