Aldosterone Antagonists: Potassium-Sparing Diuretics
Aldosterone antagonists block the hormone aldosterone, helping the body excrete sodium and water while retaining potassium. They're essential for heart failure and can also treat high blood pressure and hormonal conditions like PCOS.
Key Benefits
Taking This Medicine
Dosage Form
Spironolactone: 25mg, 50mg, 100mg tablets; Eplerenone: 25mg, 50mg tablets
When to Take
Once or twice daily, with or without food
Food Instructions
Can be taken with or without food
Common Side Effects
- High potassium (hyperkalemia)
- Frequent urination
- Dizziness
- Breast tenderness (spironolactone)
- Irregular periods (spironolactone)
- Erectile dysfunction (spironolactone)
When to Call Your Doctor
- •Hyperkalemia (dangerously high potassium)
- •Kidney dysfunction
- •Pregnancy (especially spironolactone)
- •Tumor risk in animal studies
What This Medicine Does
Aldosterone antagonists block aldosterone, a hormone that causes the kidneys to retain sodium and water while excreting potassium. By blocking aldosterone, these medications:
- Increase sodium and water excretion (diuretic effect)
- Retain potassium (unlike most diuretics)
- Block fibrosis in heart muscle (prevents scarring)
- Reduce sympathetic nervous system activation
This unique combination makes them valuable in heart failure beyond just diuresis.
Heart Failure Game Changer
In major heart failure trials, spironolactone reduced mortality by 30% and hospitalizations by 35%.RALES Trial, NEJM 1999 Eplerenone showed similar benefits with fewer hormonal side effects.EPHESUS Trial, NEJM 2003 These medications are now standard of care for HFrEF (reduced ejection fraction heart failure).ACC/AHA HF Guidelines, 2022
The benefit extends beyond fluid removal—aldosterone blockade prevents heart muscle scarring and remodeling.
Two Aldosterone Antagonists
Spironolactone:
- Older, more potent aldosterone blockade
- Additional effects on other hormones (androgen, progesterone receptors)
- Causes hormonal side effects (gynecomastia, menstrual irregularities)
- Inexpensive, widely available
- Also used for hormonal acne, hirsutism, PCOS
Eplerenone:
- Newer, more selective for aldosterone receptor
- Fewer hormonal side effects
- More expensive than spironolactone
- Specific indications: post-MI heart failure, HFrEF
- Less potent than spironolactone
Common Things You Might Notice
Side Effects:
Side Effects
| Side Effect | More Common With | Management |
|---|---|---|
| High potassium (hyperkalemia) | Both | Regular monitoring, avoid potassium supplements |
| Breast enlargement/tenderness (men) | Spironolactone | Usually resolves with discontinuation or dose reduction |
| Irregular periods | Spironolactone | Expected with spironolactone, may need dose adjustment |
| Decreased libido, erectile dysfunction | Spironolactone | Spironolactone-specific, eplerenone alternative |
| Frequent urination | Both | Expected diuretic effect, take earlier in day |
| Dizziness, lightheadedness | Both | From BP lowering, rise slowly, stay hydrated |
Hyperkalemia: The Main Concern
Symptoms of severe hyperkalemia:
- Muscle weakness or paralysis
- Heart rhythm abnormalities
- Nausea, fatigue
- Tingling sensations
Risk factors:
- Kidney dysfunction
- Combination with ACE inhibitors/ARBs
- Diabetes
- Older age
Regular monitoring is essential—catch rising potassium before it becomes dangerous.
When to Call Your Doctor
Seek Immediate Care For:
- Muscle weakness or paralysis: Could indicate severe hyperkalemia
- Chest pain, irregular heartbeat: Potassium affecting heart rhythm
- Fainting: From low blood pressure or hyperkalemia
Contact Your Doctor For:
- Muscle cramps: Could indicate electrolyte imbalance
- Breast changes: Enlargement, tenderness (spironolactone)
- Menstrual changes: Irregular periods, spotting (spironolactone)
- Erectile dysfunction: Spironolactone-specific
- Significant dizziness: Blood pressure may be too low
Daily Practical Tips
- Take earlier in day: Prevents nighttime urination
- Consistent timing: Same time daily maintains steady levels
- Potassium awareness: Don't take potassium supplements without approval
- Regular lab work: Potassium and kidney function monitoring essential
- Rise slowly: Prevents dizziness from low BP
- Report side effects: Especially hormonal changes (spironolactone)
Food Sources of Potassium
You Don't Need to Avoid All Potassium
You don't need to eliminate potassium-rich foods, but be aware of them:
High Potassium Foods:
- Bananas, oranges, avocados
- Potatoes, tomatoes, spinach
- Beans, lentils
- Nuts, seeds
- Salt substitutes (often potassium-based)
If your potassium is normal, eat these foods. If your potassium is elevated, moderate intake and avoid supplements.
For Healthcare Professionals
Clinical InformationDosing
Heart Failure (HFrEF):
- Spironolactone: 12.5-25 mg daily, titrated to target dose 25-50 mg daily
- Eplerenone: 25 mg daily, titrated to 50 mg daily
- Start low if renal impairment or risk of hyperkalemia
Hypertension:
- Spironolactone: 25-100 mg daily
- Eplerenone: 50-100 mg daily
Primary Hyperaldosteronism:
- Spironolactone: 100-400 mg daily
- Surgical treatment (adrenalectomy) may be preferred
Dose Adjustment:
- CrCl 30-50 mL/min: Start at low dose, monitor closely
- CrCl ＜ 30 mL/min: Contraindicated
References
- FDA Aldactone (spironolactone) and Inspra (eplerenone) Prescribing Information. U.S. Food and Drug Administration. https://www.accessdata.fda.gov/scripts/cder/daf/
- Heidenreich PA, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure. Journal of the American College of Cardiology. 2022;79:e263-e421. https://www.acc.org/guidelines
- ESC Guidelines for the Diagnosis and Treatment of Acute and Chronic Heart Failure. European Heart Journal. 2021;42:359-421. https://www.escardio.org/Guidelines
- Pitt B, et al. The Effect of Spironolactone on Morbidity and Mortality in Severe Heart Failure (RALES Trial). New England Journal of Medicine. 1999;341:709-717. https://pubmed.ncbi.nlm.nih.gov/10477761/
- Pitt B, et al. Eplerenone in Patients with Heart Failure (EPHESUS Trial). New England Journal of Medicine. 2003;348:1309-1321. https://pubmed.ncbi.nlm.nih.gov/12668699/
- Circulation: Heart Failure. Aldosterone Antagonists in HFrEF. 2021;14:e007854. https://www.ahajournals.org/journal/circheartfailure
- Journal of the American College of Cardiology. Mineralocorticoid Receptor Antagonists. 2022;79:1123-1135. https://www.acc.org/
- American Heart Association Scientific Statements. Hyperkalemia Management. 2022. https://www.heart.org/
- NIH National Center for Biotechnology Information. Spironolactone and Eplerenone Drug Information. https://www.nih.gov/
- Endocrine Society. Aldosterone Antagonists Clinical Practice Guidelines. 2021. https://www.endocrine.org/
Medical Disclaimer: This content is for educational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider before starting, stopping, or changing any medication.
🧪Key Lab Tests to Monitor
Doctors often check these values to ensure Aldosterone Antagonists: Potassium-Sparing Diuretics is safe and effective:
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⚠️ Safety Disclaimer
This information is for educational purposes only and does not constitute medical advice. Always consult your healthcare provider before making any changes to your medication regimen. Dosages and recommendations may vary based on individual health factors.