Bumetanide is a loop diuretic with a rapid onset and short duration of action. Pharmacological and clinical studies have shown that 1 mg Bumetanide has a diuretic potency equivalent to approximately 40 mg furosemide. The major site of Bumetanide action is the ascending limb of the loop of Henle.
Bumetanide inhibits sodium reabsorption in the ascending limb of the loop of Henle. Reabsorption of chloride in the ascending limb is also blocked by Bumetanide.
Bumetanide may have an additional action in the proximal tubule. Since phosphate reabsorption takes place largely in the proximal tubule, phosphaturia during Bumetanide induced diuresis is indicative of this additional action. This proximal tubular activity does not seem to be related to an inhibition of carbonic anhydrase. Bumetanide does not appear to have a noticeable action on the distal tubule.