Loop diuretic. Furosemide inhibits the coupled Na+/K+/2Cl- transport system in the luminal membrane of the thick ascending limb of the loop of Henle. Thus the loop diuretics reduce the reabsorption of NaCl and also diminish the normal lumen-positive potential that derives from K+ recycling.
Lowers blood pressure by depleting body sodium stores. Initially, blood volume and cardiac output declines; after 6-8 weeks, cardiac output returns toward normal while peripheral vascular resistance declines.