Randomized, controlled study of the effects of losartan versus enalapril in small doses on proteinuria and tubular injury in primary glomerulonephritis.

BACKGROUND: Pharmacological blockade of the renin-angiotensin-aldosteron system ameliorates glomerular and tubulointerstitial damage. For optimal renoprotection, high doses of angiotensin II converting enzyme inhibitors and angiotensin II subtype 1 receptor antagonists are commonly recommended, but cannot always be administered. The aim of this study was to evaluate the effects of low-dose (25 mg) losartan on proteinuria and tubular injury extent.

MATERIAL/METHODS: This was an open, randomized, 12-month study on the effects of 25 mg of losartan (n=19) vs. 10 mg of enalapril (n=14) as a control on proteinuria, urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG), and blood pressure in patients with primary glomerulonephritis. The second part of the study was an uncontrolled assessment of the renal effects of 50-mg administration of losartan.

RESULTS: There were no significant differences between the groups in the effects on proteinuria and NAG excretion. Losartan and enalapril reduced proteinuria by 32.8% (p<0.029) and 40.9% (p<0.021), respectively, but did not affect NAG excretion. The antiproteinuric effect of losartan, achieved without changes in blood pressure, was particularly evident in subjects with proteinuria >1.5 g/24 h and normal blood pressure. 50 mg of losartan caused a significant decrease in NAG excretion vs. the baseline (p<0.027).

CONCLUSIONS: 25 mg of losartan and 10 mg of enalapril equally reduce proteinuria. The significant antiproteinuric effect of losartan was achieved despite no changes in blood pressure. There were no differences between the drugs regarding their influence on tubular injury extent. 50 mg of losartan seems to be the minimal dose to improve tubular status.