Renoprotective effects of adding angiotensin II receptor blocker to maximal recommended doses of ACE inhibitor in diabetic nephropathy: A randomized double-blind crossover trial

Abstract

OBJECTIVE - We evaluated the renoprotective effects as reflected by short-term changes in albuminuria of dual blockade of the renin-angiotensin system (RAS) by adding an angiotensin II receptor blocker (ARB) to treatment with maximal recommended doses of an ACE inhibitor (ACEI) in patients with type 2 diabetes and nephropathy. RESEARCH DESIGN AND METHODS - A total of 20 patients (17 men and 3 women) with type 2 diabetes along with hypertension and nephropathy were enrolled in this double-blind, randomized, two-period, crossover trial of 8 weeks of treatment with the ARB candesartan 16 mg daily and placebo added in random order to existing treatment with lisinopril/enalapril 40 mg daily or captopril 150 mg daily. At the end of each treatment period, we evaluated albuminuria in three 24-h urinary collections by turbidimetry, 24-h ambulatory blood pressure (ABP) using the Takeda-TM2420, and glomerular filtration rate (GFR) by the 51Cr-EDTA plasma-clearance technique. RESULTS - During monoblockade of the RAS by ACEI treatment, albuminuria was 706 (349-1,219) mg/24 h [geometric mean (IQR)]; 24-h ABP was 138 ± 3/72 ± 2 mmHg (mean ± SE); and GFR was 77 ± 6 ml · min-1 · 1.73 m-2 (mean ± SE). During dual blockade of the RAS by addition of candesartan 16 mg daily, there was a mean (95% CI) reduction in albuminuria of 28 (17-38) compared with ACEI alone (P < 0.001). There was a modest reduction in systolic/diastolic 24-h ABP of 3/2 mmHg (-2 to 8 systolic, -2 to 5 diastolic; NS). Changes in albuminuria did not correlate to changes in ABP. Addition of candesartan 16 mg daily induced a small, insignificant decrease in GFR of 4 (-1 to 9) ml · min-1 · 1.73 m-2. CONCLUSIONS - Dual blockade of the RAS provides superior short-term renoprotection independent of systemic blood pressure changes in comparison with maximally recommended doses of ACEI in patients with type 2 diabetes as well as nephropathy.