Eplerenone (Inspra and others)

How Medicare covers it

Part D (forms used at home). Part A during a covered inpatient stay. No Part B clinician-administered form in the CMS Part B spending file.

What it treats

Two uses: (1) heart failure with reduced pumping strength after a heart attack, to help patients live longer, and (2) high blood pressure in adults, to lower blood pressure and lower the risk of stroke and heart attack.

What it is for, in depth

Inspra (eplerenone) has two FDA-approved jobs. First, it improves survival in stable adults who have symptomatic heart failure with reduced ejection fraction — a heart that pumps weakly — after an acute heart attack (myocardial infarction). In that setting it is added to standard post-heart-attack care, starting at 25 mg once daily and working up to 50 mg once daily within 4 weeks as potassium levels allow. Second, it treats high blood pressure in adults, alone or combined with other blood pressure medicines; lowering blood pressure lowers the risk of fatal and nonfatal heart and blood vessel events, mainly strokes and heart attacks. Full benefit for blood pressure can take 4 weeks or longer. It is a long-term daily medicine, not a rescue treatment, and it should not be stopped without talking to your doctor. It comes as film-coated tablets in two strengths: 25 mg and 50 mg.

How it works

Eplerenone is an aldosterone antagonist. Aldosterone is a natural hormone that makes the body hold on to salt and water, which raises blood pressure and strains the heart. Eplerenone blocks aldosterone at its receptor, so the kidneys let go of more sodium and water while keeping potassium, which lowers blood pressure and eases the load on the heart.

How it is taken

Tablet by mouth, with or without food, at about the same time each day. After a heart attack with heart failure: start at 25 mg once a day and, if tolerated, raise to 50 mg once a day within 4 weeks. For high blood pressure: 50 mg once a day, alone or with other blood pressure drugs; if that is not enough, the dose may go up to 50 mg twice a day, and higher doses are not recommended. Blood potassium must be checked before starting and regularly during treatment, and the dose may change based on potassium levels.

Common side effects

Common effects include headache, dizziness, diarrhea, stomach pain, cough, feeling very tired, flu-like symptoms, and breast enlargement or tenderness. The most important problem to watch for is high blood potassium, which may cause tingling, muscle weakness or heaviness in the legs, confusion, low energy, and irregular heartbeat — call your doctor right away if these happen.

Serious warnings

This label has no boxed warning. The main serious risk is hyperkalemia — blood potassium that is too high — which can cause dangerous heart rhythm problems. The risk is higher in people with poor kidney function, diabetes, protein in the urine, and in people also taking ACE inhibitors, ARBs, NSAIDs (such as ibuprofen or naproxen), or moderate CYP3A inhibitors. Potassium levels must be measured before treatment starts and checked regularly, with the dose adjusted as needed.

Who should be careful

Do not start it if your blood potassium is above 5.5 mEq/L or your kidney function is very low (creatinine clearance 30 mL/min or less). For high blood pressure treatment, it must not be used by people with type 2 diabetes with protein in the urine (microalbuminuria), higher creatinine levels, or creatinine clearance below 50 mL/min. People with diabetes, kidney disease, liver disease, or gout should be watched closely, with regular potassium and kidney blood tests. Tell your doctor if you are pregnant or breastfeeding.

Major interactions

Never combine it with strong CYP3A inhibitors such as ketoconazole, itraconazole, nefazodone, troleandomycin, clarithromycin, ritonavir, or nelfinavir — this combination is not allowed. With moderate CYP3A inhibitors (such as verapamil, erythromycin, saquinavir, or fluconazole), the dose must be lowered and capped. ACE inhibitors, ARBs, NSAIDs, potassium supplements, potassium-based salt substitutes, and potassium-sparing diuretics (such as amiloride, spironolactone, or triamterene) all raise the risk of high potassium — for people taking eplerenone for high blood pressure, potassium supplements and potassium-sparing diuretics must not be used with it at all. Grapefruit juice and St. John's wort can also affect this drug, so ask your doctor about them.

Cost and saving notes

Eplerenone is widely available as a lower-cost generic under Medicare Part D, and the generic usually costs much less than the brand name Inspra. Ask your pharmacist to fill the generic unless your doctor has a reason to use the brand, and check your plan's drug list to confirm your cost.

Why it is in its tier

Eplerenone (Inspra and others) sits on Tier 3 in 47.03% of the plans that list it (2113 of 4493 listing plans). Tier 3 is the preferred brand tier — mid-level copays or coinsurance. The data-visible drivers: It is a generic product, and the CMS dashboard puts its average Part D spending at about $327 per beneficiary for 2024 — a relatively low-cost drug, which matches where plans place it. It is listed by 81.77% of Part D plans. The tier shown is the most common one; individual plans vary.

Sources

• INSPRA (EPLERENONE) TABLET, FILM COATED [VIATRIS SPECIALTY LLC] — DailyMed
• MedlinePlus — National Library of Medicine
• MedlinePlus — Eplerenone

What official patient guides say

Eplerenone (Inspra) comes as a tablet to take by mouth. Take it once or twice a day, with or without food, around the same time(s) every day. Take it exactly as directed — do not take more or less of it or take it more often than prescribed by your doctor. Your doctor may start you on a low dose and increase your dose after 4 weeks. It may take 4 weeks or longer before you feel the full benefit. Eplerenone controls high blood pressure but does not cure it. Continue to take it even if you feel well, and do not stop taking it without talking to your doctor. If you miss a dose, take it as soon as you remember. If it is almost time for the next dose, skip the missed dose and continue your regular schedule. Do not take a double dose. Keep it in the container it came in, tightly closed and out of reach of children. Store it at room temperature, away from excess heat and moisture, and not in the bathroom.

Source: MedlinePlus — Eplerenone

Part D formulary coverage

Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.

What you pay

Without insurance, the cash benchmark is 0.33137 per unit (EPLERENONE 25 MG TABLET) — about nan for 30 units. NADAC benchmark — the average price pharmacies pay (CMS, as of 2026-11-04). Pharmacy shelf prices vary.

A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.

Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-08

Coverage by plan and tier

Of the 5,495 Medicare drug plans we track for 2027, 4,493 list Eplerenone (Inspra and others) — 81.8% of plans. Most of those plans put it on Tier 3: 2,113 plans, 47.0% of the plans that list it. Other plans place it on Tier 4 (1,174 plans), Tier 2 (759 plans) or Tier 1 (447 plans). For example: Aetna Medicare Dual Extra (HMO D-SNP) puts it on Tier 4; Aetna Medicare Dual Extra Care (PPO D-SNP) puts it on Tier 4; Aetna Medicare Value Plus (PPO) puts it on Tier 4. You can compare these plans side by side on our Medicare Advantage hub. A tier is not a price. What you pay also depends on whether you have met your plan';s deductible, whether the drug costs a flat copay or a share of the price, and whether you get Extra Help or Medicaid.

Read next

• Part D in 2027: The $700 Deductible, the $2,400 Cap, and the $35 Insulin Rule
• Extra Help in 2027: Lower Drug Copays and Who Qualifies
• Checking Medicare Savings Programs and Extra Help

Part D spending averages (2024)

Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30

Companies covering this drug

Part D and Medicare Advantage plan sponsors that list this drug on a formulary, 50 at a time.