Furosemide and bumetanide: a study of responses in normal English and German subjects

Diuretic responses to oral administration of 1 mg bumetanide and 40 mg furosemide were determined in double-blind, crossover balanced trials in 10 normal English subjects and 6 normal German subjects. In each experiment the 0- to 8-hr urine volume and sodium excretion were significantly higher after bumetanide, potassium excretion did not differ, and the Na/K ratio, although higher after bumetanide, was not significantly different by analysis of variance. In German subjects the diuretic and natriuretic responses to both drugs were greater and the potassium excretion less than in English subjects. In the English, the pretreatment 24-hr urinary Na/K ratio correlated with the urinary Na/K ratio response to both drugs and with the potassium excretion after furosemide. The mean plasma uric acid before treatment correlated with the Na/K ratio and potassium excretion after furosemide. Aldosterone excretion did not correlate with response to either diuretic. The mean pretreatment 24-hr log10 Na/K ratio in the two treatment periods of the English and German subjects correlated with the mean sodium excretion, potassium excretion, and log10 Na/K after the two diuretics, thus providing a partial explanation for intersubject and interstudy variation. Pretreatment log10 Na/K could also explain intrasubject variation, justifying its use as a covariate in covariance analysis. This demonstrated that at this dose ratio the urinary log10 Na/K ratio response to bumetanide was significantly higher than that to furosemide.