1. Introduction
Spironolactone is a potassium-sparing diuretic and aldosterone antagonist used to treat conditions such as heart failure, hypertension, oedema, and hyperaldosteronism. It works by blocking aldosterone receptors in the kidneys, reducing sodium and water retention while conserving potassium.
2. Indications
- Hypertension: As an adjunct therapy for resistant hypertension.
- Heart Failure (NYHA Class III-IV): To reduce mortality and hospitalisation risk.
- Oedema: Associated with liver cirrhosis, nephrotic syndrome, or heart failure.
- Primary Hyperaldosteronism (Conn’s Syndrome): Diagnosis and treatment.
- Polycystic Ovary Syndrome (PCOS): Off-label use to reduce androgenic symptoms.
- Hirsutism and Acne: Off-label use in women with androgen excess.
3. Dosage
Adults:
- Hypertension: 25–50 mg once daily.
- Heart Failure: 12.5–50 mg once daily; maximum dose: 100 mg/day.
- Oedema: 25–200 mg/day in divided doses.
- Primary Hyperaldosteronism: 100–400 mg/day in divided doses.
- PCOS, Acne, Hirsutism: 25–100 mg once daily.
Elderly:
- Start at the lower end of the dosing range due to increased risk of hyperkalaemia.
Children:
- Oedema: 1–3 mg/kg/day in divided doses.
- Hypertension: 1 mg/kg/day in divided doses.
Renal Impairment:
- Mild to moderate impairment (eGFR 30–60 mL/min): Use with caution; monitor potassium closely.
- Severe impairment (eGFR <30 mL/min): Avoid use due to hyperkalaemia risk.
Hepatic Impairment:
- No specific dose adjustment, but monitor electrolyte balance.
4. Administration
- Take with food to improve absorption and reduce stomach upset.
- Avoid potassium supplements or high-potassium foods unless directed by a doctor.
5. Forms Available
- Tablets: 25 mg, 50 mg, 100 mg
- Oral Suspension: 5 mg/mL
6. Side Effects
6.1 Common Side Effects:
- Hyperkalaemia
- Dizziness
- Nausea
- Breast tenderness or enlargement (gynaecomastia in men)
6.2 Less Common Side Effects:
- Menstrual irregularities
- Fatigue
- Dehydration
- Headache
6.3 Rare but Serious Side Effects:
- Severe hyperkalaemia (can lead to cardiac arrhythmias)
- Stevens-Johnson Syndrome
- Acute kidney injury
- Severe metabolic acidosis
7. Warnings
- Hyperkalaemia: Life-threatening potassium elevations can occur, especially in patients with kidney disease or those on other potassium-sparing medications.
- Gynaecomastia: Dose-dependent risk in male patients.
- Fluid & Electrolyte Imbalances: Monitor sodium, potassium, and renal function.
- Renal Dysfunction: Avoid use in severe kidney impairment.
8. Precautions
- Monitor potassium and kidney function regularly, especially in elderly or renally impaired patients.
- Avoid in Addison’s disease (risk of worsening hyperkalaemia).
- Use cautiously in patients on ACE inhibitors, ARBs, or potassium supplements.
9. Interactions
- ACE Inhibitors/ARBs (e.g., lisinopril, losartan): Increased risk of hyperkalaemia.
- NSAIDs (e.g., ibuprofen): May reduce diuretic efficacy and increase nephrotoxicity risk.
- Digoxin: Increased digoxin levels and toxicity risk.
- Lithium: Increased lithium toxicity risk.
- Potassium Supplements: High risk of hyperkalaemia.
10. Monitoring Parameters
- Serum potassium and sodium: Check at baseline and periodically.
- Renal function (eGFR, creatinine): Especially in elderly or renally impaired patients.
- Blood pressure: Monitor response in hypertension.
- Signs of hyperkalaemia: Muscle weakness, arrhythmias.
11. Use in Children
- Approved for paediatric hypertension and oedema with weight-based dosing.
- Requires careful electrolyte monitoring.
12. Use in Pregnancy
- Category C: Use only if the benefits outweigh risks. Limited data available.
13. Use in Elderly
- Increased risk of hyperkalaemia; use at the lowest effective dose and monitor closely.
14. Use in Kidney Disease
- Contraindicated in severe renal impairment (eGFR <30 mL/min) due to hyperkalaemia risk.
15. Use in Liver Disease
- Safe in cirrhosis-related ascites, but careful monitoring is required due to fluid balance shifts.
16. Patient Counselling Points
- Take spironolactone with food to minimise stomach upset.
- Avoid potassium-rich foods (e.g., bananas, spinach, potatoes) unless advised by your doctor.
- Inform your doctor of any signs of high potassium (e.g., muscle weakness, irregular heartbeat).
- If you miss a dose, take it as soon as possible, but do not double dose.
- Do not stop taking spironolactone suddenly without consulting your doctor.
17. Table of Brand Names, Manufacturer, and Prices in USD
Brand Name | Manufacturer | Strength/Dosage Form | Price (USD) |
---|---|---|---|
Aldactone | Pfizer | 25 mg Tablet | $40 (30 tablets) |
CaroSpir | CMP Pharma | 5 mg/mL Oral Suspension | $90 (150 mL) |
Generic Spironolactone | Various | 25 mg Tablet | $15 (30 tablets) |
18. 15 FAQs (Frequently Asked Questions)
1. What is Spironolactone used for?
Spironolactone treats hypertension, heart failure, oedema, hyperaldosteronism, and conditions like PCOS.
2. How does Spironolactone work?
It blocks aldosterone, reducing sodium retention and conserving potassium, leading to diuretic effects.
3. Can Spironolactone cause hyperkalaemia?
Yes, especially in patients with kidney disease or those taking other potassium-increasing drugs.
4. How long does Spironolactone take to work?
Diuretic effects occur within a few hours, but full benefits in conditions like heart failure may take weeks.
5. Can Spironolactone be used for acne?
Yes, it is often used off-label for acne in women with hormonal imbalances.
6. Does Spironolactone cause weight gain?
No, but it can cause water retention initially, which may mimic weight gain.
7. Can men take Spironolactone?
Yes, but long-term use may cause gynaecomastia (breast enlargement).
8. Is Spironolactone safe in pregnancy?
It is not typically recommended due to limited safety data.
9. Can I take Spironolactone with other blood pressure medications?
Yes, but avoid other potassium-sparing drugs to reduce hyperkalaemia risk.
10. Can Spironolactone cause dehydration?
Yes, especially if combined with other diuretics.
11. Does Spironolactone require regular blood tests?
Yes, to monitor potassium and kidney function.
12. Can Spironolactone interact with NSAIDs?
Yes, NSAIDs can reduce its effectiveness and increase kidney damage risk.
13. Can Spironolactone cause low blood pressure?
Yes, particularly in combination with other antihypertensives.
14. How should Spironolactone be stored?
Store at room temperature, away from moisture and heat.
15. What should I do if I miss a dose?
Take it as soon as possible unless it’s close to your next dose. Do not double the dose.