Eplerenone Tablets (Inspra): Benefits, Dosage & Side Effects
Comprehensive guide to eplerenone (Inspra) for hypertension and heart failure treatment, dosage, side effects, and precautions.
About eplerenone tablets
Eplerenone tablets, marketed under the brand name Inspra, belong to a class of medications known as selective aldosterone receptor antagonists (SARAs). These drugs work by blocking the action of aldosterone, a hormone produced by the adrenal glands that promotes sodium and water retention in the body. By inhibiting aldosterone, eplerenone helps reduce fluid buildup, lowers blood pressure, and protects the heart from further damage in conditions like heart failure.
Aldosterone contributes to hypertension by increasing sodium reabsorption in the kidneys and can lead to cardiac hypertrophy, fibrosis, and worsening heart function. Unlike non-selective antagonists like spironolactone, eplerenone is more selective for the aldosterone receptor, reducing the risk of sex hormone-related side effects such as gynecomastia in men or vaginal bleeding.
Approved by the FDA in 2002 for hypertension and 2003 for heart failure post-myocardial infarction, eplerenone has demonstrated significant benefits, including a 15% reduction in total mortality in stable heart failure patients after a heart attack.
Key facts about eplerenone tablets
- Brand name: Inspra
- Type of medicine: Selective aldosterone receptor antagonist
- Used for: Essential hypertension; heart failure with reduced ejection fraction (HFrEF) post-acute myocardial infarction
- Also called: Generic eplerenone
- Available as: Tablets (25 mg, 50 mg)
- Is it available as a generic? Yes
How eplerenone works
Eplerenone selectively binds to the mineralocorticoid receptor in epithelial (e.g., kidney) and nonepithelial (e.g., heart, blood vessels) tissues, blocking aldosterone’s effects. This prevents sodium retention and potassium loss, leading to diuresis, reduced blood volume, and lower blood pressure. In heart failure, it counters aldosterone-mediated cardiac remodeling, fibrosis, and hypertrophy, improving survival and reducing hospitalizations.
The drug is metabolized via the CYP3A4 pathway with a half-life of 4-6 hours, reaching steady state in 2 days. It increases plasma renin and serum aldosterone levels due to feedback inhibition.
About hypertension
Hypertension, or high blood pressure, affects millions worldwide and is a major risk factor for stroke, heart attack, kidney disease, and heart failure. Normal blood pressure is below 120/80 mmHg; hypertension is defined as consistently ≥130/80 mmHg. Lifestyle changes like diet, exercise, and weight management are first-line, but medications like eplerenone are used when needed.
Eplerenone lowers systolic and diastolic pressure effectively, with studies showing significant reductions vs. placebo (e.g., 12-week trial: 50-200 mg doses reduced diastolic BP significantly).
About heart failure
Heart failure occurs when the heart cannot pump blood effectively, often post-myocardial infarction (heart attack). Eplerenone is indicated for stable, symptomatic patients with left ventricular systolic dysfunction (ejection fraction ≤40%) to reduce cardiovascular mortality and hospitalization. Clinical trials like EPHESUS showed benefits when added to standard therapy (ACE inhibitors, beta-blockers).
How and when to take eplerenone
Take eplerenone exactly as prescribed. Swallow tablets whole with water, with or without food. For hypertension: start at 50 mg once daily, increase to 50 mg twice daily after 4 weeks if needed (max 100 mg/day). For heart failure: start at 25 mg once daily, titrate to 50 mg over 4 weeks if tolerated.
Dosage table:
| Condition | Starting Dose | Target Dose | Max Dose |
|---|---|---|---|
| Hypertension | 50 mg once daily | Adjust after 4 weeks | 50 mg twice daily |
| Heart Failure (post-MI) | 25 mg once daily | 50 mg once daily (over 4 weeks) | 50 mg once daily |
Missed dose: Take as soon as remembered unless near next dose; do not double up. Do not stop suddenly without doctor advice.
Dosage for eplerenone tablets
Standard dosages
- Hypertension: 50 mg daily; max 100 mg/day
- Heart failure: 25-50 mg daily
How to take it
Consistent daily timing aids adherence. Monitor blood pressure and potassium regularly.
Common questions about dosage
How long does it take to work?
Blood pressure reductions seen within 1-2 weeks; full effect in 4 weeks.
Can you overdose?
Overdose may cause hyperkalemia, hypotension. Seek emergency help.
Using eplerenone with other medicines and herbal supplements
Eplerenone interacts with CYP3A4 inhibitors (e.g., ketoconazole, erythromycin: increase levels; avoid strong ones). Potassium-sparing diuretics, ACE inhibitors, ARBs raise hyperkalemia risk—monitor potassium. Avoid with potassium supplements.
- Moderate interactions: NSAIDs, lithium, certain antibiotics
- Herbals: Avoid St. John’s wort (induces CYP3A4)
Table of key interactions:
| Drug Class | Examples | Effect | Action |
|---|---|---|---|
| CYP3A4 Inhibitors | Ketoconazole, ritonavir | Increased eplerenone levels | Avoid or reduce dose |
| Potassium-sparing agents | Spironolactone, amiloride | Hyperkalemia | Monitor K+ closely |
| ACEI/ARB | Lisinopril, losartan | Hyperkalemia | Use with caution |
Common side effects
Most side effects are mild. Common (>1%): hyperkalemia (5-10%), dizziness, diarrhea, cough, fatigue.
| Side Effect | Frequency | Management |
|---|---|---|
| Hyperkalemia | Common | Monitor blood tests |
| Dizziness | Common | Rise slowly |
| GI upset | Uncommon | Take with food |
Serious side effects
Serious allergic reactions (rash, swelling), severe hyperkalemia (muscle weakness, arrhythmia), kidney issues. Seek immediate help for chest pain, irregular heartbeat.
Side effects table
(Detailed table as above)
Reporting side effects
In US, report to FDA MedWatch; UK, Yellow Card. Helps track safety.
Pregnancy and breastfeeding
Category B: No adequate human studies; animal data show no risk. Use only if benefit outweighs risk. Not recommended breastfeeding—excreted in milk.
Cautions of taking eplerenone tablets
Contraindicated in hyperkalemia (>5.5 mEq/L), severe renal impairment (CrCl <30 mL/min), type 2 diabetes with microalbuminuria. Caution in hepatic disease, elderly. Regular monitoring of potassium, renal function essential.
- Baseline K+ ≤5 mEq/L, creatinine ≤1.7 mg/dL (men)/1.5 (women)
- African Americans may respond less to monotherapy
Choosing between eplerenone and spironolactone
| Aspect | Eplerenone | Spironolactone |
|---|---|---|
| Selectivity | High (mineralocorticoid only) | Low (progesterone/androgen effects) |
| Sex side effects | Rare | Common (gynecomastia ~10%) |
| Cost | Higher | Lower (generic) |
| Efficacy | Similar in trials | Similar |
Eplerenone preferred if sex side effects occur with spironolactone.
Stopping eplerenone suddenly
Do not stop abruptly—may cause rebound hypertension or worsening heart failure. Taper under medical supervision.
Pharmacy advice
- Keep in original packaging, room temperature
- Check expiry; dispose properly
- 25 mg and 50 mg strengths available
Analogs
Spironolactone (main alternative).
Frequently asked questions (FAQs)
Can you take paracetamol with eplerenone?
Yes, no significant interaction.
Is eplerenone a blood thinner?
No, it’s a diuretic/antihypertensive.
Does eplerenone cause weight gain?
No, may cause mild fluid loss.
Can you drink alcohol with eplerenone?
Limit—may enhance hypotension.
What diet should you follow?
Low-sodium, potassium-moderate; avoid salt substitutes.
References
- Eplerenone (Inspra), a new aldosterone antagonist for the treatment of essential hypertension and heart failure — National Center for Biotechnology Information (PMC). 2004-09-15. https://pmc.ncbi.nlm.nih.gov/articles/PMC1200656/
- Eplerenone (Inspra): Uses, Side Effects, Interactions — WebMD. Accessed 2026. https://www.webmd.com/drugs/2/drug-64218/eplerenone-oral/details
- Inspra – Drug Summary — PDR.net. Accessed 2026. https://www.pdr.net/drug-summary/Inspra-eplerenone-1817
- Eplerenone (Inspra): Uses, Side Effects, Alternatives & More — GoodRx. Accessed 2026. https://www.goodrx.com/eplerenone/what-is
- Inspra Label — U.S. Food and Drug Administration. 2008-05-27. https://www.accessdata.fda.gov/drugsatfda_docs/label/2008/021437s006lbl.pdf
- Eplerenone (oral route) – Side effects & dosage — Mayo Clinic. Accessed 2026. https://www.mayoclinic.org/drugs-supplements/eplerenone-oral-route/description/drg-20063677
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