Spironolactone

Diuretic / Antihypertensive — Aldosterone Antagonist

Nigerian brand names:AldactoneSpiractinSpilactoneBerlactone

Reviewed by the PMC Medical Team · Promise Medical Centre

Overview

Spironolactone is a potassium-sparing diuretic and aldosterone antagonist. It works by blocking the hormone aldosterone in the kidneys, which normally causes sodium (salt) and water retention and potassium excretion. By blocking aldosterone, spironolactone causes the kidneys to remove excess sodium and water while retaining potassium. It is used in the management of heart failure, high blood pressure, liver cirrhosis with fluid accumulation (ascites), and is an important component in treating primary hyperaldosteronism. Unlike most diuretics, it does not cause potassium loss.

Uses

Spironolactone is used to treat: - Heart failure: Reduces mortality and hospitalisation in moderate-to-severe heart failure alongside standard therapy (ACE inhibitor + beta-blocker + diuretic) - Hypertension (high blood pressure): Especially effective when other medicines have not worked adequately; useful when aldosterone excess is suspected - Oedema (swelling) associated with: Liver cirrhosis and ascites (fluid in abdomen), Nephrotic syndrome (kidney disease causing protein loss), Heart failure - Primary hyperaldosteronism (Conn's syndrome): Excess aldosterone production from the adrenal gland - Secondary hyperaldosteronism - Off-label: Hormonal acne and hirsutism (excess facial/body hair) in women — spironolactone blocks androgen (male hormone) receptors

How to Use

Take spironolactone exactly as prescribed. Dosage varies by condition: - Heart failure: Usually 25 mg once daily (may increase to 50 mg) - Hypertension/oedema: 25–100 mg daily in one or two divided doses - Ascites (liver cirrhosis): 100–400 mg daily, often combined with furosemide General guidelines: - Can be taken with or without food; taking with food may improve absorption - Take at the same time each day - If taking once daily, take in the morning to avoid needing to urinate at night - Effects (increased urination, oedema reduction) may take several days to become apparent - Do not stop suddenly without medical advice — especially in heart failure Potassium monitoring is essential: Your doctor will regularly check blood potassium levels (and kidney function).

Side Effects

Common side effects: - Increased urination (diuretic effect) - Elevated potassium levels (hyperkalemia) — may cause muscle weakness, irregular heartbeat if severe - Nausea, stomach cramps, or diarrhoea - Dizziness or lightheadedness (especially on standing) - Headache - Hormonal effects (due to anti-androgen activity): - In men: Gynaecomastia (breast enlargement/tenderness) — may be dose-dependent and reversible - Decreased libido, erectile dysfunction (in men, with long-term use) - Irregular menstrual periods (in women) Serious: - Severe hyperkalaemia (dangerous high potassium): Muscle weakness, numbness, irregular heartbeat — seek emergency care - Severe hyponatraemia (low sodium): Confusion, seizures - Worsening kidney function

Warnings & Precautions

Do not take spironolactone if you: - Have Addison's disease (adrenal insufficiency) - Have severely impaired kidney function (anuria or severe renal failure) - Have consistently high blood potassium (hyperkalemia) - Are taking other potassium-sparing diuretics (amiloride, triamterene) without close monitoring - Are pregnant: Risk of feminisation of a male foetus. Avoid in first trimester; use only if clearly necessary in later pregnancy under medical supervision Breastfeeding: Spironolactone is excreted in breast milk — generally avoided while breastfeeding. Important monitoring: - Potassium levels: Must be checked regularly (before starting, 1–2 weeks after starting, then at least every 3–6 months in stable patients, and after any dose change or illness). High potassium can be life-threatening - Kidney function: Creatinine and eGFR should be monitored - Blood pressure and fluid balance: Weigh yourself daily — sudden weight gain may indicate fluid retention

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Drug Interactions

Important interactions: - ACE inhibitors (lisinopril, enalapril) and ARBs (losartan): Triple therapy with spironolactone significantly increases potassium and risk of kidney damage — use with caution; close monitoring essential - NSAIDs (ibuprofen, diclofenac): Reduce diuretic effect and increase potassium and kidney risk - Potassium supplements and potassium-rich salt substitutes: Can cause dangerous hyperkalaemia — avoid unless specifically prescribed - Digoxin: Spironolactone can increase digoxin levels — risk of digoxin toxicity; monitor levels and signs of toxicity - Anticoagulants (warfarin): Spironolactone may reduce warfarin effect - Lithium: Spironolactone may increase or decrease lithium levels — monitor carefully - Fluconazole and other azole antifungals: May increase spironolactone levels - Cholestyramine: Reduces absorption of spironolactone - Carbenoxolone: Antagonises the effect of spironolactone

Storage

Store at room temperature (below 25°C) in a dry place, away from light and moisture. Keep out of reach of children.

Buy only NAFDAC-registered medications

Nigeria has a significant problem with counterfeit and substandard drugs. Always purchase medications from a licensed pharmacy and check the NAFDAC registration number on the package — verify at nafdac.gov.ng.