Pharmacology of bumetanide

The diuretic action of bumetanide was compared with that of furosemide following oral and intravenous administration of equipotent doses in the rat, mouse, cat, rabbit, and dog. The onset of the bumetanide-induced diuresis was rapid and lasted 4 to 6 hours. In studies of selective renal uptake, the ratio of tissue concentration to plasma concentration of bumetanide was three times greater than that of furosemide. Protein binding and metabolism studies did not reveal significant differences between the two diuretics. Bumetanide and Furosemide were excreted in dog urine as unchanged drug. Data obtained by various procedures to determine renal sites of action indicate a direct action of bumetanide at the ascending limb of Henle's loop and the proximal convoluted tubule. The altered blood flow induced by bumetanide does not per se account for the natriuretic response, but the increase in renal electrolyte excretion is thought to be linked to a prostaglandin--reninbradykinin system.