MICROALBUMINURIA IN ESSENTIAL-HYPERTENSION - REDUCTION BY DIFFERENT ANTIHYPERTENSIVE DRUGS

The effects of four different antihypertensive drugs (the Ca2+-channel blocker felodipine, the beta-blocker metoprolol, the angiotensin converting enzyme inhibitor ramipril, and the alpha-blocking agent doxazosin) on microalbuminuria and renal hemodynamics were evaluated in a double-blind, crossover study in 17 patients (10 women, seven men, aged 39+/-14 years) with mild-to-moderate essential arterial hypertension and microalbuminuria. Patients were studied after a 2-week placebo phase preceded by 2 weeks off all medication and after 12 weeks of treatment with each drug. Between each drug treatment, there was another 14-day placebo washout period. At the end of the study, we performed two additional 2-week placebo periods. After each placebo and treatment period, we measured albumin excretion during a 3-day collecting period. Renal hemodynamics were assessed by clearance techniques (inulin and p-aminohippurate clearance) at the end of the first and last placebo periods and after each treatment period. All drugs reduced mean arterial pressure and microalbuminuria to a similar and statistically significant (p<0.05) extent (mean arterial pressure: placebo phase, 116+/-5 mmHg; felodipine, 101+/-4 mm Hg; metoprolol, 101+/-5 mm Hg; ramipril, 101+/-4 mm Hg; doxazosin, 102+/-5 mm Hg; urinary albumin excretion: placebo phase, 46+/-50 mg/day; felodipine, 18+/-23 mg/day; metoprolol, 14+/- 12 mg/day; ramipril, 16+/-16 mg/day; doxazosin, 14+/-14 mg/day). Mean arterial pressure levels and urinary albumin excretion returned to baseline after the last placebo period (110+/-6 mm Hg and 40+/-46 mg/day, respectively). Glomerular filtration rate and renal plasma flow were not significantly changed by any drug and were normal in all patients. Renal vascular resistance and filtration fraction were lowest during angiotensin converting enzyme inhibition, but these differences did not reach statistical significance. In conclusion, all types of antihypertensive drugs under investigation reduced microalbuminuria in patients with mild-to-moderate arterial hypertension and without an elevation in filtration fraction. In the case of essential arterial hypertension, reduction of blood pressure seems to be an important factor for treatment Of albuminuria.