The administration of an ACE-I or angiotensin receptor blocker (ARB) decreases proteinuria in patients at high risk for renal damage (e.g., diabetes mellitus), but does not fully halt the progression of renal disease. One meta-analysis of 11 studies found that the addition of spironolactone or eplerenone to an ACE-I or ARB, however, significantly decreased 24 hr urinary protein excretion beyond single agent therapy alone.37 While this may be attributed to improved blood pressure control, in contrast to ACE-I drugs, aldosterone receptor antagonists do not mediate efferent renal arterial pressure and thus do not induce nephrotoxicity. Overall, data linking aldosterone receptor antagonists with renal function improvement are, to date, derived mainly from numerous small studies limited by brief follow-up periods. The long-term effect of these drugs on renal disease-associated outcomes is under investigation.