Amiloride

Amiloride is a potassium-sparing diuretic that acts on the late distal convoluted tubule and collecting duct of the kidney. It directly blocks epithelial sodium channels (ENaC) on the luminal side of tubular epithelial cells, thereby inhibiting sodium ion (Na⁺) entry into these cells. Because sodium reabsorption is reduced, the intracellular positive charge decreases, which in turn suppresses potassium ion (K⁺) secretion into the urine. As a result, it promotes the excretion of sodium and water while conserving potassium.