Known brand names include Aldactone.
A potassium-sparing "water pill" that blocks aldosterone. It treats heart failure with reduced ejection fraction, resistant high blood pressure, swelling from cirrhosis or nephrotic syndrome, and primary hyperaldosteronism.
Labeled use. Cirrhosis or nephrotic syndrome; may help when other diuretics have caused hypokalemia.
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Labeled use. Short term before surgery, or long term for adenoma not suited to surgery or bilateral adrenal hyperplasia.
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Labeled use. NYHA class III to IV with reduced ejection fraction, usually with other heart failure therapies.
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Labeled use. Edema from cirrhosis not responsive to fluid and sodium restriction; start in the hospital.
Add for heart failure with reduced ejection fraction on top of standard therapy, since it lowers mortality. A preferred fourth agent for resistant hypertension and the diuretic of choice for cirrhotic ascites, often paired with furosemide. Choose eplerenone when gynecomastia is a problem. Avoid with hyperkalemia or poor renal function.
Spironolactone and its active metabolites compete with aldosterone for its receptor at the sodium-potassium exchange site in the distal tubule. The kidney then excretes more sodium and water while holding on to potassium. It also counters the secondary aldosteronism driven by edema states and other diuretics.
The label does not describe a narrow therapeutic index or direct dosing by measured blood levels of the drug.
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Doses come from the FDA label. Study tool, not for clinical decisions.
Hyperkalemia risk rises with renal impairment, so monitor potassium closely. In heart failure, start at 25 mg every other day when eGFR is 30 to 50 mL/min/1.73 m2.
No specific antidote. Overdose may cause drowsiness, confusion, rash, nausea, vomiting, dizziness, or diarrhea; hyperkalemia is most likely with renal impairment. Give supportive care for fluids, electrolytes, and vital functions, and stop the drug if hyperkalemia develops.
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Its anti-androgen effects may disrupt sexual development of a male fetus, based on animal data; limited human case reports have not shown major malformations. Avoid in pregnancy or explain the risk to a male fetus.
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Spironolactone itself is not found in breast milk; its active metabolite canrenone appears in small amounts expected to be clinically insignificant. Long-term infant effects are unknown.
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Mostly cleared by the kidney, and older adults are more likely to have reduced renal function, so monitor renal function and watch for adverse reactions.
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