Furosemide is a loop diuretic that acts primarily on the thick ascending limb of the loop of Henle in the nephron.
- It inhibits the Na⁺-K⁺-2Cl⁻ symporter, which is responsible for the reabsorption of sodium, potassium, and chloride ions from the tubular fluid back into the bloodstream.
- By blocking this transporter, furosemide increases the excretion of Na⁺, Cl⁻, and K⁺, along with water, leading to a potent diuretic effect.
- This inhibition also reduces the reabsorption of calcium and magnesium, contributing to additional electrolyte loss.
- Furosemide is useful in the management of edema, congestive heart failure, hypertension, and renal impairment.
- Unlike thiazide diuretics, which act on the distal convoluted tubule, furosemide works earlier in the nephron and has a more profound diuretic effect.