Bumetanide is a loop diuretic of the sulfamyl category. 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. Furosemide is incompletely absorbed in the intestine (40%), and there is substantial inter- and intraindividual differences in bioavailability (range 10-90%). Bumetanide is completely absorbed (80%), and the absorption is not altered when it is taken with food. It is said to be a more predictable diuretic, meaning that the predictable absorption is reflected in a more predictable effect.
Bumetanide is 40 times more potent than furosemide (for patients with normal renal function).