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[Pharmacology](https://durgical.com/en/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)

## Key points

- The key risk is hyperkalaemia, especially with ACE inhibitors, ARBs, potassium supplements, NSAIDs or kidney failure.
- Spironolactone also blocks androgen receptors: gynecomastia and menstrual changes; eplerenone is more selective.
- Spironolactone and eplerenone lower mortality in heart failure with reduced ejection fraction.
- Spironolactone is widely used for cirrhotic ascites and treats primary hyperaldosteronism.
- Triamterene can appear in kidney stones and is a weak folic acid antagonist.

## Drugs in this class

- [**Spironolactone** An aldosterone blocker: a potassium-sparing diuretic that lowers mortality in heart failure and treats ascites and… Mineralocorticoid (aldosterone) receptor](https://durgical.com/en/pharmacology/spironolactone/)
- [**Amiloride** A 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](https://durgical.com/en/pharmacology/amiloride/)
- [**Eplerenone** A selective aldosterone blocker that improves survival in heart failure after a heart attack, with fewer hormonal… Mineralocorticoid (aldosterone) receptor](https://durgical.com/en/pharmacology/eplerenone/)
- [**Triamterene** A potassium-sparing diuretic that blocks the ENaC sodium channel, often paired with hydrochlorothiazide. It can cause… Epithelial sodium channel (ENaC) of the collecting duct](https://durgical.com/en/pharmacology/triamterene/)

## 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.

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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](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=768563dc-a619-44dc-b97f-1a7e71fd56a0) (DailyMed (U.S. National Library of Medicine), 2026); [DailyMed - AMILORIDE HYDROCHLORIDE tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e0cc2d44-436a-47e8-a890-589882fff4c4) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=C03D) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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