Double-blind, placebo-controlled study on the effect of the aldosterone receptor antagonist spironolactone in patients who have persistent proteinuria and are on long-term angiotensin-converting enzyme inhibitor therapy, with or without an angiotensin II receptor blocker

Abstract

Studies have shown that dual therapy with angiotensin-converting enzyme inhibitors (ACEI) and either angiotensin II receptor blockers or aldosterone receptor antagonists is more effective in reducing proteinuria than either agent used alone. The questions that remain are as follows: (1) Which of these agents should be used as dual therapy with the ACEI? (2) Does a higher level of blockade of the renin-angiotensin-aldosterone system with triple therapy offer an advantage over dual blockade? A 3-mo randomized, double-blind, placebo-controlled study was performed in 41 patients with proteinuria >1.5 g/d. Four treatment groups were compared: (1) Ramipril + spironolactone placebo + irbesartan placebo, (2) ramipril + irbesartan + spironolactone placebo, (3) ramipril + irbesartan placebo + spironolactone, and (4) ramipril + irbesartan + spironolactone. The percentage change in protein excretion differed according to treatment arm (ANOVA: F(3,35) = 8.6, P < 0.001). Pair-wise comparison showed that greater reduction in protein excretion occurred in treatment regimens that incorporated spironolactone. The reduction in proteinuria at 3 mo was as follows: Group 1, 1.4%; group 2, 15.7%; group 3, 42.0%; and group 4, 48.2%. The reduction in proteinuria among patients who were taking spironolactone-containing regimens was sustained at 6 and 12 mo. This study suggests that aldosterone receptor blockade offers a valuable adjuvant treatment when used with ACEI therapy for the reduction of proteinuria. Results suggest no advantage of triple blockade over dual blockade of the renin-angiotensin-aldosterone system to reduce proteinuria.