Effects of amlodipine on renal haemodynamics in mild to moderate hypertensive patients. A randomized controlled study versus placebo.

In this study the efficacy and safety of short-term amlodipine administration on renal haemodynamics were evaluated in mild to moderate hypertensive subjects. Our final goal was to evaluate whether the reduced blood pressure induced by treatment was associated with maintenance of renal function. After a run-in period with placebo, 30 hypertensive patients without cardiac or renal diseases were randomly allocated to a double-blind 4 weeks controlled study with amlodipine 10 mg once a day (15 patients) or placebo (15 patients). Renal haemodynamic measurements included effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) by radionuclide study using 131I-hippuran and 99mTc, with methods described by Schlegel and Gates, respectively. In addition, effective renal blood flow [ERBF = ERPF/(1-Ht)], filtration fraction (FF = GFR/ERPF) and renal vascular resistance (RVR = MBP x 80/ERBF) were calculated. Plasma renin activity (PRA), serum aldosterone (ALD) and urinary excretion of sodium (NaU) were evaluated. At the end of amlodipine administration a significant decrease (P < 0.001) in SBP, DBP and MBP from baseline values was observed. A significant decrease (P < 0.01) in RVR and significant increases (P < 0.05) in ERPF, ERBF and in NaU were also found, without relevant changes in GFR, FF, PRA and ALD. No significant variation in clinical and renal measurements was observed in the placebo group. No relevant side effects were observed in either group. In conclusion, amlodipine was effective in lowering blood pressure in mild to moderate hypertension and exerted favourable effects on renal haemodynamics and function.