Loop Diuretics

Loop diuretics, including furosemide, bumetanide, and torsemide, act primarily on the thick ascending limb of the loop of Henle. This segment plays a critical role in urinary concentration, as it is impermeable to water. These diuretics exert their effect by blocking the sodium-potassium-2 chloride cotransporter (NKCC) located on the luminal membrane. This hinders the reabsorption of sodium chloride, leading to natriuresis. One distinguishing member of this class is ethacrynic acid, which is not a sulfonamide, making it an alternative for patients with sulfa allergies. By influencing the electrical potential in the renal tubules, loop diuretics indirectly affect the reabsorption of other cations such as magnesium and calcium. Furthermore, loop diuretics promote the synthesis of prostaglandins, compounds that boost salt excretion and enhance renal blood flow. Clinically, these diuretics are invaluable in managing conditions like heart failure, ascites in liver failure, and hypertension. However, they are not devoid of side effects, with concerns including hypokalemia, hypomagnesemia, ototoxicity, interstitial nephritis, hyperuricemia, contraction alkalosis, and rarely, hypocalcemia