Eplerenone

About Eplerenone

Eplerenone is a mineralocorticoid receptor antagonist: it blocks the binding of aldosterone, and it can raise blood potassium. The current label, revised in June 2025, covers improving survival in stable adults with symptoms of heart failure and a reduced ejection fraction after an acute heart attack, and treating high blood pressure in adults. In heart failure it starts at 25 mg once daily and is raised to 50 mg once daily, ideally within four weeks, with each step set by the potassium level. For blood pressure it starts at 50 mg once daily, its full effect appears within four weeks, and it can be raised to 50 mg twice daily, the highest recommended dose. Safety and effectiveness in children have not been established; in a study of ages 4 to 16 it did not lower blood pressure effectively.

There is no boxed warning. The main risk is high potassium, which is more likely with kidney impairment, protein in the urine, diabetes, age 65 or older, and ACE inhibitors, ARBs, NSAIDs or moderate CYP3A inhibitors, so potassium is measured before starting, within the first week and one month after starting or changing the dose, then periodically. It must not be taken when potassium is above 5.5 mEq/L at the start, when creatinine clearance is 30 mL/min or less, or with strong CYP3A inhibitors such as ketoconazole, itraconazole, clarithromycin, ritonavir or nelfinavir. For high blood pressure it is also ruled out in type 2 diabetes with microalbuminuria, with a creatinine clearance under 50 mL/min or serum creatinine above 2.0 mg/dL in men or 1.8 mg/dL in women, and with potassium supplements or potassium-sparing diuretics such as amiloride, spironolactone or triamterene.

In the heart failure trial, high potassium and a rise in creatinine occurred more often than with placebo; in blood pressure studies, breast enlargement in men and abnormal vaginal bleeding occurred and became more frequent with longer use, and headache, dizziness, diarrhea and tiredness are among other reported effects. Moderate CYP3A inhibitors such as erythromycin, verapamil, fluconazole and saquinavir limit the dose to 25 mg once daily in heart failure, or to a start of 25 mg and at most 25 mg twice daily for blood pressure, and potassium and creatinine are rechecked three to seven days after starting one of them, an ACE inhibitor, an ARB or an NSAID. In the heart failure trial, people over 75 did not appear to benefit. Inspra’s 100 mg tablet is discontinued; the 25 and 50 mg tablets are still sold.

Taking Eplerenone

How to take it

Once or twice a day as prescribed, with or without food, at the same times each day. The full effect on blood pressure can take four weeks; keep taking it even if you feel well, and keep every blood test appointment.

If you miss a dose

Take it as soon as you remember, unless it is almost time for the next dose; then skip the missed dose and continue your regular schedule. Do not take a double dose.

Storage

At room temperature in a closed container, away from heat and moisture and not in the bathroom, out of reach of children. Use a take-back program for unused tablets.

Interactions to know about

Ketoconazole, itraconazole, clarithromycin, ritonavir and nelfinavir must not be taken with it; erythromycin, verapamil, fluconazole and saquinavir call for a lower dose. ACE inhibitors, ARBs, NSAIDs, potassium supplements and potassium salt substitutes raise the risk of high potassium, St. John’s wort lowers its levels, and lithium levels are checked often if the two are combined. Ask the prescriber about grapefruit.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Eplerenone differs from pharmacy to pharmacy

Generic eplerenone, rated equivalent to Inspra, is made by several companies, so quotes for the generic differ with each pharmacy’s cost, markup and dispensing fee, while a prescription that names Inspra and blocks substitution is filled at the brand price. In heart failure the dose may be lowered to 25 mg every other day when potassium runs high, so a month can be a small number of tablets, and the dispensing fee can then be a large part of the quote.

Ways to pay less for Eplerenone without insurance

• Make sure the prescription allows generic substitution rather than naming Inspra only.
• Ask whether eplerenone is on the pharmacy’s flat-price generic list, and compare more than one pharmacy.
• Ask for a ninety-day supply once your dose and potassium are stable.
• If it is quoted high, ask the prescriber whether spironolactone, an older generic that also blocks aldosterone, would suit you.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Eplerenone

1. 1.When will my potassium and kidney function be checked?
2. 2.Do any of my antibiotics, antifungals or heart medicines change my dose?
3. 3.Should I avoid potassium supplements, salt substitutes, ibuprofen or naproxen?
4. 4.Which symptoms of high potassium mean I should call?

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