Last reviewed 2026-04-20 · How we verify

Aldactone (Spironolactone)

Aldosterone antagonist causing increased sodium and water excretion while retaining potassium.

Spironolactone is a potassium-sparing diuretic and aldosterone antagonist indicated for heart failure with reduced ejection fraction, hypertension, edema management, and primary hyperaldosteronism. It demonstrates strong efficacy through competitive aldosterone receptor antagonism, increasing sodium and water excretion while retaining potassium. The primary risk is severe hyperkalemia, particularly when combined with ACE inhibitors, ARBs, NSAIDs, or potassium supplementation, requiring careful monitoring of serum potassium levels. Long-term metabolite half-lives (13.8-16.5 hours) support once-daily dosing and sustained therapeutic effects in heart failure and hypertension management.

At a glance

Mechanism of action

Spironolactone and its active metabolites are specific pharmacologic antagonists of aldosterone, acting primarily through competitive binding of receptors at the aldosterone-dependent sodium-potassium exchange site in the distal convoluted renal tubule. This mechanism causes increased amounts of sodium and water to be excreted, while potassium is retained. Spironolactone acts both as a diuretic and as an antihypertensive drug by this mechanism and may be given alone or with other diuretic agents that act more proximally in the renal tubule.

Approved indications

• NYHA Class III-IV heart failure with reduced ejection fraction
• Hypertension as add-on therapy
• Edema in cirrhotic patients unresponsive to fluid and sodium restriction
• Edema in nephrotic syndrome with inadequate response to other treatments
• Short-term preoperative treatment of primary hyperaldosteronism
• Long-term maintenance therapy for discrete aldosterone-producing adrenal adenomas in non-surgical candidates
• Long-term maintenance therapy for bilateral micro or macronodular adrenal hyperplasia

Common side effects

• Hyperkalaemia
• Hypokalaemia
• Diarrhoea
• Hypomagnesaemia
• Hypotension
• Glomerular filtration rate decreased
• Anaemia
• Constipation
• Cardiac failure
• Back pain
• Hyperglycaemia
• Iron deficiency anaemia

Drug interactions

• Potassium supplementation, salt substitutes containing potassium, ACE inhibitors, angiotensin II antagonists, NSAIDs, heparin, low molecular weight heparin, trimethoprim
• Lithium
• NSAIDs
• Digoxin
• Cholestyramine
• Acetylsalicylic acid (ASA)
• Abiraterone

Key clinical trials

• Regulating Blood Pressure During Recovery From Intracerebral Hemorrhage and Ischemic Stroke (PHASE2)
• Spironolactone for Pulmonary Arterial Hypertension (PHASE2)
• Spironolactone Improved Children With Gene Mutations Related to NCOR (PHASE2, PHASE3)
• Venous Congestion And Cognitive Dysfunction After Cardiac Surgery
• HEART: Pilot Randomized Controlled Trial (PHASE1, PHASE2)
• Topical 5% Spironolactone Gel Versus 0.1% Adapalene Gel for Acne Vulgaris: A Randomized Split-Face Study (PHASE2)
• Bioavailability and Bioequivalence Study of Extended Release Torsemide and Spironolactone (PHASE3)
• A Study Comparing the Clinical Benefit of Finerenone Versus a Fixed Dose Combination (FDC) of Extended-Release Torsemide and Spironolactone in Patients With Hypertension and Chronic Kidney Disease (PHASE3)

Patents

Primary sources

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Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Aldactone CI brief — competitive landscape report
• Aldactone updates RSS · CI watch RSS
• Pfizer Inc. portfolio CI