Double-blind controlled study of rilmenidine versus hydrochlorothiazide in mild hypertension: clinical and renal haemodynamic evaluation.

Clinical and renal haemodynamic parameters were evaluated in 20 mild hypertensive patients after rilmenidine (RIL) administration during a one month double-blind randomised study compared with hydrochlorothiazide (HCT). At the beginning and at the end of the study, BP, heart rate and renal haemodynamic parameters were evaluated. Renal haemodynamic parameters included effective renal plasma flow (ERPF) evaluated by radionuclide study utilising 131I-Hippuran according to Schlegel's method, effective renal blood flow (ERBF = ERPF/(1-Ht)), glomerular filtration rate (GFR) by creatinine clearance, filtration fraction (FF = GFR/ERPF) and renal vascular resistances (RVR = DBP x 80/ERBF). RIL and HCT significantly (P < 0.01) reduced systolic, diastolic and mean blood pressure without relevant change in ERPF, ERBF, GFR and FF. RVR was significantly reduced both in the RIL group (P < 0.002 vs. baseline) and in the HCT group (P < 0.001 vs. baseline). No relevant side-effects were observed in either group. In conclusion, rilmenidine was effective in reducing BP in mild hypertensive patients and produced favourable effects on renal function.