Bumetanide interferes with renal cAMP and/or inhibits the sodium-potassium ATPase pump. Bumetanide appears to block the active reabsorption of chloride and possibly sodium in the ascending loop of Henle, altering electrolyte transfer in the proximal tubule. This results in excretion of sodium, chloride, and water and, hence, diuresis.
Bumetanide is a loop diuretic of the sulfamyl category to treat heart failure. It is often used in patients in whom high doses of furosemide are ineffective. There is however no reason not to use bumetanide as a first choice drug. The main difference between the two substances is in bioavailability. Bumetanide has more predictable pharmacokinetic properties as well as clinical effect. In patients with normal renal function, bumetanide is 40 times more effective than furosemide.
45% is secreted unchanged. Urinary and biliary metabolites are formed by oxidation of the N-butyl side chain.