What to Know About Inspra (Eplerenone)

A Potassium-Sparing Diuretic for High Blood Pressure and Heart Failure

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Inspra (eplerenone) is a drug used for the treatment of high blood pressure and heart failure after a heart attack. Inspra is in a class of drugs called mineralocorticoid receptor antagonists or selective aldosterone receptor antagonists. Aldosterone antagonists are also considered water pills (diuretics).

Simply put, they work to block the action of a steroid in the body called aldosterone (a substance that is a key determinant of fluid volume in the body, thereby influencing blood pressure). Eplerenone is available as an oral (by mouth) tablet; it can be taken alone, or it is also available in combination with other drugs that treat high blood pressure.

eplerenone is used for high blood pressure and heart failure
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The FDA has approved eplerenone as a medication to treat conditions including:

  • Improving the survival rate for people (with specific symptoms) experiencing heart failure after a heart attack
  • The treatment of hypertension to reduce the risk of heart attacks or primary strokes

Studies have shown that eplerenone is linked with a 15% reduction of blood pressure and an improved survival rate for those with heart failure—in stable condition—who have experienced a heart attack (myocardial infarction).

Off-Label Uses

Oral eplerenone has been studied for its potential in treating a condition of the eye called chronic (long-term) central serous chorioretinopathy (CSCR). This is a condition involving an abnormal accumulation of fluid under the retina of the eye, which could lead to detachment of the retina and vision loss.

A 2015 study discovered that 25 milligrams (mg) to 50 mg of eplerenone given daily, resulted in significant visual improvements in those with CSCR.

Before Taking

Before taking eplerenone, it’s important to inform your healthcare provider:

  • If you are allergic to eplerenone or any other medications
  • If you are taking any prescription medications, over-the-counter (OTC) drugs, herbal or natural supplements (including vitamins or St. John's wort), or medicated topical (on the skin) preparations such as lotions, creams, gels, or patches
  • If you have a history of liver or kidney disease
  • If you have diabetes
  • If you are pregnant, plan to become pregnant, or are breastfeeding

Precautions and Contraindications

There are several precautions that you should be aware of before taking eplerenone.


Eating grapefruit can result in a buildup of eplerenone in the body; this can result in unwanted side-effects that are more impactful than when normal levels of eplerenone are present. Ask your healthcare provider about eating grapefruit or drinking grapefruit juice while taking eplerenone.

Eating just one grapefruit or drinking a single glass of grapefruit juice can cause too much potassium in the blood (which can interfere with the normal heart rhythm).

Excess Sodium

Excess sodium (salt) in the diet is a major factor in the development of hypertension. Studies show a significant link between the level of salt intake, blood pressure, and the frequency that a person has hypertension. Ask your healthcare provider about any special dietary precautions while taking eplerenone; a low sodium diet may be ordered.


Products that have potassium have the potential to raise your blood potassium to dangerous levels when taking eplerenone. Use caution when using salt substitutes as many of these products have potassium listed as a primary ingredient and should be avoided.


Eplerenone and other aldosterone-blocking medications have a potential to interfere with fertility in some people. Be aware that there are some preliminary animal studies that show the potential for eplerenone to compromise fertility in males.


A contraindication is a specific situation in which a medication, procedure, or treatment should not be given or performed because it could cause harm. Eplerenone is contraindicated in several instances, including in those with:

  • A high potassium level in the blood (above 5.5 mEq/L) when eplerenone is initially prescribed (because an unwanted side effect of eplerenone is high potassium levels [hyperkalemia]) 
  • A serum (blood) creatinine clearance less than or equal to 30 ml/min (low serum creatinine clearance levels could indicate serious or long-term kidney damage)

Contraindications for Those with Hypertension

Although eplerenone is FDA-approved to treat high blood pressure, there are some instances in which the drug is considered contraindicated in people with hypertension, including when a person has high blood pressure along with:

  • Type 2 diabetes with microalbuminuria, which is a sign that a person has diabetic nephropathy (a kidney-related complication of diabetes)
  • A serum creatinine level of more than 2.0 (for males) and more than 1.8 in females (indicating low blood volume, kidney dysfunction, or possibly that a person has dehydration)
  • A serum creatinine clearance of less than 50 ml/min
  • Taking potassium supplements or potassium-sparing diuretics (such as spironolactone or amiloride)
  • Severe kidney disease

Eplerenone has not been deemed safe and effective for the following uses:

  • Pediatric use
  • People who are pregnant or breastfeeding

Other Aldosterone Receptor Antagonists

Aldosterone is a steroid hormone that has been identified for some time as a key substance in the development of heart disease. High aldosterone levels are common in those with high blood pressure and heart failure. These findings led to the launch of aldosterone antagonists to treat these conditions.

The very first aldosterone antagonist on the market was a drug called Aldactone (spironolactone), initially used for treating hypertension. Today, spironolactone is also a standard treatment for systolic heart failure (involving weakness of the left ventricle of the heart).

Comparison of Aldosterone Receptor Antagonists

Aldactone (spironolactone) is considered a non-selective aldosterone receptor antagonist. Aldactone works just like eplerenone, except in addition to binding with the aldosterone receptor, it also binds with other steroid receptors (such as the hormone receptors for testosterone and progesterone).

This results in a higher instance of sex-hormone related side effects like gynecomastia (male breast development), breast pain, and impotence. Studies have shown that spironolactone has a higher risk of certain adverse effects, such as male gynecomastia and female vaginal bleeding than eplerenone.

Those who are taking spironolactone, who experience these side effects, may be switched to eplerenone. The overall effectiveness of both drugs (spironolactone and eplerenone) is considered the same. Both spironolactone and eplerenone can potentially cause severe, even life-threatening hyperkalemia (high potassium levels).


All listed dosages are according to the drug manufacturer. Check your prescription and talk to your doctor to make sure you are taking the right dose for you.

Eplerenone (Inspra) comes in 25 milligram (mg) and 50 mg tablets. The FDA-approved label information from the manufacturer recommends initially taking 25 milligrams (mg) one time per day.

The dose should be gradually increased over time (titrated). The maximum dose is 50 mg daily and, if a person tolerates it well (with no major adverse side effects) it should take four weeks to fully titrate the dosage.

The dosage should be adjusted if a person’s potassium level falls outside of the normal range. For high blood pressure (hypertension) the FDA-approved label recommends a dose of 50 mg daily, given alone or combined with other medications for high blood pressure. Dosages higher than 50 mg per day are not recommended.


The FDA-approved prescribing information recommends lowering the dose of eplerenone to 24 mg once a day for those taking certain drugs that are considered moderate CYP3A4 inhibitors, these include:

No adjustment is required in dosage for elderly people with mild to moderate liver impairment.

How to Take and Store

Eplerenone tablets are swallowed with or without food once or twice daily. The medication should be taken at approximately the same time each day. Follow the instructions on the bottle and take the prescription exactly as the prescription label instructs you to.

If you do not take eplerenone regularly, as scheduled, it may result in poor control of your blood pressure. This can result in an increased risk of a heart attack or stroke. Do not abruptly stop taking eplerenone without the approval of your healthcare provider.

If you forget to take your medication, take the missed dose as soon as you remember, but never try to catch up by doubling up on dosages (this could cause dangerous side effects). If it’s close to the time to take your next dose (if you are taking eplerenone twice per day), skip the next dose, then continue your regimen as usual afterward.

If you feel you may have accidentally taken too much medication, seek emergency medical care right away by calling 911 or go to the nearest hospital emergency room.

Keep the medication in its original container (that’s labeled from the pharmacy). Keep the lid closed tightly, store at room temperature away from moisture (not in the bathroom). Keep out of the reach of children.

Side Effects

Common Side Effects

Common side effects of taking eplerenone may include:

  • Dizziness
  • Headache
  • Stomach upset or pain
  • Diarrhea
  • Body aches and other flu-like symptoms
  • Cough
  • Fatigue

If these symptoms do not go away, be sure to report them to your healthcare provider.

Severe Side Effects

Severe side effects of eplerenone may include:

  • Lethargy (lack of energy)
  • Loss of muscle tone (flaccidity)
  • Weakness in extremities
  • Confusion
  • Chest pain
  • Tingling in arms or legs
  • Swelling in the lower extremities
  • Skin that is cold, pale or gray in color
  • Irregular heart rate
  • Oliguria (a marked decrease in urination)

If you experience any of these serious side effects, seek emergency medical care right away.

Eplerenone may cause other, rare side effects, if you experience any unusual symptoms when taking eplerenone, be sure to consult with your healthcare provider about them as soon as possible.

Warnings and Interactions


Eplerenone can cause dangerous, life-threatening high levels of potassium, called hyperkalemia. High potassium levels can interfere with the ability of the heart rhythm and cause it to beat abnormally.

In those with renal (kidney) insufficiency, diabetes, advanced age, advanced heart failure, and those taking other medications that affect your potassium levels, the risk of hyperkalemia is higher. 

Symptoms of high potassium in the blood include:

  • Weakness and muscle fatigue
  • Paralysis (inability to move the muscles)
  • Arrhythmias (abnormal heart rhythms, such as skipping a beat)
  • Nausea

When taking eplerenone, it’s important to have your potassium levels closely monitored by your healthcare provider.

Although eplerenone and other drugs in its class are considered life-saving medications for people with advanced heart failure, it’s vital for potassium levels and kidney function to be monitored closely to lower the chance of severe hyperkalemia, which could potentially be fatal.

­­­­­­­­­­­­­­­­Drug Interactions

There are several drugs that should not be taken together with eplerenone. If you are taking any of these medications, it’s important to inform your healthcare provider before taking eplerenone:

  • Potassium supplements (such as Klor-Con, Ktab, K-Lyte)
  • Antibiotics (such as clarithromycin or erythromycin) which can increase levels of eplerenone and may result in severe adverse reactions
  • Antifungal drugs such as Onmel and Sporanox (itraconazole), Nizoral (ketoconazole), or Diflucan (fluconazole) which can increase the levels of eplerenone in the body and may result in severe adverse reactions
  • Spironolactone or Aldactazide (spironolactone and hydrochlorothiazide), when given along with eplerenone, may potentiate the antihypertensive action of eplerenone; this may result in dangerous levels of potassium in the body (hyperkalemia)
  • Diuretics that are considered potassium-sparing (such as triamterene, amiloride or amiloride and hydrochlorothiazide) which could raise potassium to dangerous levels in the blood 
  • Pain medications called nonsteroidal anti-inflammatory drugs (NSAIDs) such Motrin (ibuprofen) and Aleve (naproxen), which could affect potassium levels when taken with eplerenone
  • Medications for depression such as Serzone (nefazodone) or others, this type of antidepressant can potentially increase the levels of eplerenone in the body, thereby worsening any side effects of eplerenone.
  • Mood stabilizers such as Lithobid (lithium) and others
  • Antiretroviral drugs such as Kaletra (ritonavir) or others, which can increase the concentration of eplerenone in the body, thereby causing any side effects to worsen
  • Angiotensin-converting enzyme (ACE) inhibitors such as Capoten (captopril) and other antihypertensive medications, which can increase the risk of hyperkalemia as well as cause an increased risk of kidney problems.
  • St. John’s wort (an herbal supplement that is sometimes taken for depression), as studies have shown that some herbal products can adversely affect the pharmacological activity of medications taken at the same time. According to a 2019 study, some of these interactions could result in unexpected outcomes from eplerenone.

This list does not include every prescription or OTC drug that could interact with eplerenone; it’s important to give your prescribing healthcare provider a complete list of any type of medication, or natural supplement you are taking. 

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