What is the mechanism of action for Furosemide?

Furosemide, known as a loop diuretic, exerts its action primarily by inhibiting the sodium-potassium-chloride cotransporter (NKCC2) located in the thick ascending limb of the loop of Henle within the nephron. This inhibition results in a significant reduction in the reabsorption of sodium, potassium, and chloride ions, leading to increased excretion of these electrolytes in the urine. This mechanism also affects the osmotic gradient necessary for water reabsorption, ultimately resulting in increased urine output and a decrease in fluid retention.

The effectiveness of furosemide in treating conditions such as edema associated with heart failure or kidney disease stems from this unique mechanism that differentiates it from other diuretics that may work at different sites in the nephron or through different pathways.