Spironolactone
Summary
A potassium-sparing diuretic that competitively blocks aldosterone receptors in the collecting duct, preventing Na+ reabsorption and K+ excretion. Used for heart failure, hypertension, hyperaldosteronism, and cirrhotic ascites.
Detail
Spironolactone inhibits intracellular mineralocorticoid receptors in principal cells, preventing ENaC upregulation and Na-K-ATPase activity. Results in natriuresis with potassium retention. Diuretic effect is weak and delayed (2-3 days). Clinical value in combination with other diuretics to prevent hypokalemia. Improves survival in heart failure. Adverse effects: hyperkalemia (especially with ACE/ARBs), gynecomastia from anti-androgenic effects, metabolic acidosis.
Sources
- First Aid for the USMLE Step 1
- Katzung Basic & Clinical Pharmacology
- Harrison's Principles of Internal Medicine
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.