Spironolactone
- Class: Aldosterone antagonist
- Used for: fluid buildup from heart failure
- Say it: speer-on-oh-LAK-tohn
- Forms: tablet, oral liquid
Remember the name – SPIRO → spiral
SPIRONOLACTONE = the water SPIRALS down the drain — but the potassium stays behind.
Blocking aldosterone sends sodium and water out, while potassium is held back. That is why it is called potassium-sparing, and why hyperkalaemia is the danger.
SPIRONOLACTONE = the water SPIRALS down the drain — but the potassium stays behind.
Blocking aldosterone sends sodium and water out, while potassium is held back. That is why it is called potassium-sparing, and why hyperkalaemia is the danger.
Mnemonic: SpironoLACTONE spares potassium
It blocks aldosterone at the very end of the tubule, so unlike other diuretics it holds potassium in. It blocks androgen receptors too — which is why men can develop breast tenderness.
It blocks aldosterone at the very end of the tubule, so unlike other diuretics it holds potassium in. It blocks androgen receptors too — which is why men can develop breast tenderness.
Side effects
Common: high potassium, breast tenderness, menstrual changes
Serious: dangerous hyperkalemia
Typical dose
25–50 mg once daily in heart failure
25 mg is the heart failure dose; ascites needs 100–400 mg, four to sixteen times higher. Increase no faster than every four weeks.
Check yourself
Which diuretic raises potassium instead of lowering it?
- Spironolactone
- Furosemide
- Hydrochlorothiazide
- None — every diuretic lowers potassium
Show answer
A. Spironolactone
Aldosterone's job is to trade potassium away in order to keep sodium. Blocking it means potassium stays in the body — hence 'potassium-sparing'.
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