EFFECT OF RAMIPRIL ON BLOOD-PRESSURE AND PROTEIN EXCRETION RATE IN NORMOTENSIVE NONDIABETIC PATIENTS WITH PROTEINURIA

Angiotensin-converting enzyme inhibitors reduce proteinuria in both no rmotensive end hypertensive patients with proteinuric renal disease. H owever, the mechanism of the antiproteinuric effect has not been clari fied. We performed a prospective, double-blind, placebo-controlled, ra ndomized crossover trial to test the hypothesis that the antiproteinur ic effect of ramipril was due to an improvement in glomerular permsele ctivity independent of blood pressure and glomerular filtration rate, The effect of tow-dose (1.25 mg/d) and high-dose (5 mg/d) ramipril was assessed in 15 normotensive nondiabetic patients with proteinuria (> 150 mg/d). The study was divided into four 12-week periods: placebo, h igh- or low-dose ramipril, crossover to low- or high-dose ramipril, an d placebo, Blood pressure, glomerular filtration rate, renal plasma fl ow rate, urinary protein excretion rate, and plasma angiotensin II lev els were measured at the end of each period, Mean arterial pressure, u rine protein to creatinine ratio, and albumin excretion rate decreased significantly during low- and high-dose ramipril. Glomerular filtrati on rate and renal plasma flow rate were not changed significantly, Pla sma angiotensin II levels decreased with both low- and high-dose ramip ril, There were no episodes of hypotension and only one subject develo ped cough during ramipril that did not require discontinuation of the study drug. In conclusion, administration of ramipril in both low and high doses lowered blood pressure and reduced proteinuria in this coho rt of normotensive patients with a variety of proteinuric renal diseas es. The antiproteinuric effect of ramipril is probably mediated by a r eduction in glomerular capillary pressure. (C) 1996 by the National Ki dney Foundation, Inc.