Spironolactone
A potassium-sparing aldosterone antagonist used for heart failure, resistant hypertension, primary hyperaldosteronism and edema in cirrhosis.
Drug card
- How it works
- Blocking aldosterone receptors, so sodium is lost and potassium kept
- Used for
- Heart failure with reduced ejection fraction
- Add-on treatment for resistant high blood pressure
- Edema and ascites in liver cirrhosis
- Edema in nephrotic syndrome
- Known for
- High potassium (hyperkalemia)
- Breast enlargement in men (gynecomastia)
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does spironolactone work?
A steroid that, with its active metabolites, competes with aldosterone for the mineralocorticoid receptor in the distal tubule, so sodium and water are lost while potassium is kept. It also has antiandrogen activity, whereas eplerenone binds the mineralocorticoid receptor more selectively.
Like other mineralocorticoid receptor antagonists: They bind to mineralocorticoid receptors in the late distal tubule and collecting duct and stop aldosterone from switching them on. Less sodium and water are reabsorbed while potassium is kept, so they are potassium-sparing diuretics. They also block aldosterone in the heart and blood vessels, and in heart failure with reduced ejection fraction they improve survival.
Uses
What is spironolactone used for?
- Heart failure with reduced ejection fraction
- Add-on treatment for resistant high blood pressure
- Edema and ascites in liver cirrhosis
- Edema in nephrotic syndrome
- Primary hyperaldosteronism
Side effects
Side effects of spironolactone
- High potassium (hyperkalemia)Known forSerious
- Breast enlargement in men (gynecomastia)Known for
- Breast and nipple pain
- Irregular periods, low libido or erection problems
- Worsening kidney functionSerious
- Low sodium
- Low blood pressure and dehydration
- Nausea, vomiting and diarrhea
- Leg cramps
- Stomach bleeding or ulcersSerious
- Liver injury (rare)Serious
- Severe skin reactions (Stevens-Johnson syndrome, DRESS)Serious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Contraindicated in hyperkalemia and Addison's disease, and together with eplerenone.
- Potassium is checked within a week of starting and regularly after.
- ACE inhibitors, ARBs, NSAIDs, potassium supplements and salt substitutes add to the risk of hyperkalemia.
- Liver impairment, cirrhosis and ascites: impaired neurological function or coma can occur.
Good to know: Its most common side effect is gynecomastia: about 9% of men in a heart failure trial; the risk grows with dose and it usually reverses.
Remember it
A way to remember it
Block aldosterone, keep potassium.
Aldosterone makes the kidney hold on to sodium and let potassium go. Blocking its receptor reverses this, so these diuretics spare potassium, and hyperkalemia is their main danger, above all alongside ACE inhibitors or ARBs.
Written for biofideX
Its class
Mineralocorticoid receptor antagonists
Other mineralocorticoid receptor antagonists with a card:
Easily mixed up with loop diuretics and thiazide and thiazide-like diuretics.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Heart failure, rhythm and angina
Spironolactone is one of 10 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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