Pharmacology · Class
Potassium-sparing diuretics !
Weak diuretics that act on the collecting duct and keep potassium in the body. Some block aldosterone; others block the ENaC sodium channel.
Updated 2026-11-01
What they are
Two groups act in the late distal tubule and collecting duct: mineralocorticoid receptor antagonists (spironolactone, eplerenone) and ENaC sodium-channel blockers (amiloride, triamterene). They are weak diuretics but valuable in heart failure, hyperaldosteronism and cirrhotic ascites, and against the potassium loss caused by other diuretics.
Mechanism of action
Aldosterone antagonists stop aldosterone from switching on the genes for ENaC and the Na⁺/K⁺ pump; amiloride and triamterene plug ENaC directly. Either way less sodium enters the cell, the lumen becomes less negative, and less potassium and hydrogen are secreted.
Target: Mineralocorticoid receptor or epithelial sodium channel (ENaC)
Drugs in this class
- SpironolactoneAn aldosterone blocker: a potassium-sparing diuretic that lowers mortality in heart failure and treats ascites and…Mineralocorticoid (aldosterone) receptor
- AmilorideA potassium-sparing diuretic that blocks the ENaC sodium channel. Usually combined with a thiazide or loop diuretic to…Epithelial sodium channel (ENaC) of the collecting duct
- EplerenoneA selective aldosterone blocker that improves survival in heart failure after a heart attack, with fewer hormonal…Mineralocorticoid (aldosterone) receptor
- TriamtereneA potassium-sparing diuretic that blocks the ENaC sodium channel, often paired with hydrochlorothiazide. It can cause…Epithelial sodium channel (ENaC) of the collecting duct
Others in the class
- Finerenone
- Canrenone
Test yourself
Think of the answer, then tap the question to see it.
Which two mechanisms do potassium-sparing diuretics use?
Blocking the mineralocorticoid (aldosterone) receptor, as spironolactone and eplerenone do, or blocking the ENaC sodium channel, as amiloride and triamterene do.
Why is eplerenone less likely than spironolactone to cause gynecomastia?
It is more selective for the mineralocorticoid receptor and has little effect on androgen and progesterone receptors.
Which combination raises the risk of severe hyperkalaemia?
A potassium-sparing diuretic with ACE inhibitors or ARBs, potassium supplements or salt substitutes, NSAIDs, trimethoprim, or with kidney failure.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - SPIRONOLACTONE tablet (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - AMILORIDE HYDROCHLORIDE tablet (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.