Background: Loop diuretics are the drugs of choice for the treatment of hypertension in chronic renal failure patients. However, the adaptive changes in the distal nephron and the short half-life of these drugs may decrease their long-term efficacy. Thiazides are not believed to be efficient in advanced renal failure, but this is debated.
Methods: We compared the efficacy of long-acting furosemide (60 mg/day) and hydrochlorothiazide (25 mg/day) in a double-blind, randomized crossover trial in seven patients with severe renal failure and hypertension (seven men, 54+/-10 years old). The primary end-points were sodium and chloride fractional excretions after 1 month of each diuretic and then after their combination. During the trial, other treatments and the diet were controlled.
Results: A trend towards an increase in the fractional excretion of sodium and of chloride was observed with furosemide, but the difference did not reach the level of statistical significance (P = NS). Hydrochlorothiazide significantly increased fractional excretion of sodium and chloride from 3.7+/-0.9 to 5.5+/-0.3 and from 3.9+/-0.19 to 6.5+/-0.3, respectively (P<0.05). The combination of the two diuretics had no additional effect on the increase in sodium and chloride fractional excretion. Furosemide, hydrochlorothiazide and the combination of the two diuretics decreased mean arterial blood pressure by the same extent from 112 to 97, 99 and 97 mmHg, respectively (P<0.05).
Conclusions: Hydrochlorothiazide increased the fractional excretion of sodium and chloride more than furosemide did in hypertensive severe renal failure patients. Mean arterial blood pressure decreased by the same amount with both diuretics. Combining furosemide and hydrochlorothiazide did not increase the efficacy of hydrochlorothiazide.