Potassiumsparing

Potassium-sparing refers to agents that promote diuresis without causing potassium loss, or that help retain potassium in the body. In clinical pharmacology, potassium-sparing diuretics are used to counteract potassium depletion caused by other diuretics and to treat conditions such as hypertension and edema.

There are two main mechanisms: aldosterone receptor antagonism and direct blockade of epithelial sodium channels (ENaC) in the collecting ducts. Aldosterone antagonists, including spironolactone and eplerenone, block the mineralocorticoid receptor, reducing sodium reabsorption and potassium excretion. ENaC blockers, such as amiloride and triamterene, decrease sodium reabsorption by directly inhibiting ENaC channels, thereby conserving potassium.

Common uses include combination therapy with loop or thiazide diuretics to prevent hypokalemia, management of edema in heart failure or cirrhosis, and treatment of resistant hypertension. Spironolactone has additional antiandrogen effects that can cause gynecomastia and menstrual irregularities, whereas eplerenone has fewer endocrine effects. Adverse effects center on hyperkalemia, especially in patients with renal impairment or those taking ACE inhibitors, ARBs, or NSAIDs. Other risks include kidney stones with some regimens and metabolic disturbances.

Cautions: monitor potassium and renal function; avoid concurrent use with potassium supplements unless directed. The term potassium-sparing is most commonly applied to diuretics, with limited application to other agents that alter potassium handling.