Eplerenone, sold under the brand name Inspra, is an aldosterone antagonist type of

potassium-sparing diuretic Potassium-sparing diuretics refers to drugs that cause diuresis without causing potassium loss in the urine. They are typically used as an adjunct in management of hypertension, cirrhosis, and congestive heart failure. The steroidal aldostero ...

that is used to treat chronic heart failure and high blood pressure, particularly for patients with resistant hypertension due to elevated aldosterone. It is a steroidal

antimineralocorticoid An antimineralocorticoid, also known as a mineralocorticoid receptor antagonist (MRA or MCRA) or aldosterone antagonist, is a diuretic drug which antagonizes the action of aldosterone at mineralocorticoid receptors. This group of drugs is ofte ...

of the

spirolactone Spirolactones are a class of functional group in organic chemistry featuring a cyclic ester attached spiro to another ring system. The name is also used to refer to a class of synthetic steroids, called steroid-17α-spirolactones, 17α-spiro ...

group and a selective aldosterone receptor antagonist (SARA). Eplerenone is more selective than spironolactone at the

mineralocorticoid receptor The mineralocorticoid receptor (or MR, MLR, MCR), also known as the aldosterone receptor or nuclear receptor subfamily 3, group C, member 2, (NR3C2) is a protein that in humans is encoded by the ''NR3C2'' gene that is located on chromosome 4q31 ...

relative to binding at

androgen An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...

, progestogen,

glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every verteb ...

, or

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...

receptors.

Medical uses

Heart failure

Eplerenone reduces risk of death in patients with heart failure, particularly in patients with recent myocardial infarction (heart attack).

Hypertension

Eplerenone lowers blood pressure in patients with primary hypertension. Eplerenone also reduces arterial stiffness and vascular endothelial dysfunction. For persons with resistant hypertension, eplerenone is safe and effective for reducing blood pressure, particularly in persons with resistant hypertension due to hyperaldosteronism.

Central serous chorioretinopathy

Eplerenone is often prescribed for people with central serous chorioretinopathy (CSC). However, the most recent and largest

randomized controlled trial A randomized controlled trial (or randomized control trial; RCT) is a form of scientific experiment used to control factors not under direct experimental control. Examples of RCTs are clinical trials that compare the effects of drugs, surgical te ...

showed that eplerenone has no significant effect on chronic CSC.

Adverse effects

Common

adverse drug reaction An adverse drug reaction (ADR) is a harmful, unintended result caused by taking medication. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs. The meaning of this term ...

s (ADRs) associated with the use of eplerenone include:

hyperkalaemia Hyperkalemia is an elevated level of potassium (K+) in the blood. Normal potassium levels are between 3.5 and 5.0mmol/L (3.5 and 5.0mEq/L) with levels above 5.5mmol/L defined as hyperkalemia. Typically hyperkalemia does not cause symptoms. Occasi ...

hypotension Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dia ...

, dizziness, and reduced renal clearance. Eplerenone may have a lower incidence than spironolactone of sexual side effects such as feminization,

gynecomastia Gynecomastia (also spelled gynaecomastia) is the abnormal non-cancerous enlargement of one or both breasts in males due to the growth of breast tissue as a result of a hormone imbalance between estrogens and androgens. Updated by Brent Wisse ( ...

impotence Erectile dysfunction (ED), also called impotence, is the type of sexual dysfunction in which the penis fails to become or stay erect during sexual activity. It is the most common sexual problem in men.Cunningham GR, Rosen RC. Overview of mal ...

, low sex drive and reduction of size of male genitalia. This is because other antimineralocorticoids have structural elements of the progesterone molecule, causing progestogenic and antiandrogenic outcomes. When considering taking these medicines, it is important to note the variations in their ability to offset the nongenomic effects of aldosterone. Currently, there is not enough evidence available from the randomized controlled trials on side effects of eplerenone to do a benefit versus risk assessment in people with primary hypertension.

Interactions

Eplerenone is primarily metabolized by the

cytochrome P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various co ...

enzyme CYP3A4. Thus the potential exists for adverse drug interactions with other drugs that induce or inhibit CYP3A4. Specifically, the concomitant use of the CYP3A4 potent inhibitors ketoconazole and

itraconazole Itraconazole, sometimes abbreviated ITZ, is an antifungal medication used to treat a number of fungal infections. This includes aspergillosis, blastomycosis, coccidioidomycosis, histoplasmosis, and paracoccidioidomycosis. It may be given by mo ...

is contraindicated. Other CYP3A4 inhibitors including erythromycin,

saquinavir Saquinavir (SQV), sold under the brand names Invirase and Fortovase, is an antiretroviral drug used together with other medications to treat or prevent HIV/AIDS. Typically it is used with ritonavir or lopinavir/ritonavir to increase its effect ...

, and

verapamil Verapamil, sold under various trade names, is a calcium channel blocker medication used for the treatment of high blood pressure, angina (chest pain from not enough blood flow to the heart), and supraventricular tachycardia. It may also be ...

should be used with caution. Other drugs that increase

potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosph ...

concentrations may increase the risk of hyperkalemia associated with eplerenone therapy, including salt substitutes, potassium supplements and other

Pharmacology

Eplerenone is an

, or an antagonist of the

(MR). Eplerenone is also known chemically as 9,11α-epoxy-7α-methoxycarbonyl-3-oxo-17α-pregn-4-ene-21,17-carbolactone and "was derived from spironolactone by the introduction of a 9α,11α-epoxy bridge and by substitution of the 17α-thoacetyl group of spironolactone with a carbomethoxy group." The drug controls high blood pressure by blocking the binding of aldosterone to the mineralocorticoid receptor (MR) in

epithelial Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercell ...

tissues, such as the kidney. Blocking the action of aldosterone decreases blood volume and lowers blood pressure. It has 10- to 20-fold lower affinity for the MR relative to spironolactone, and is less potent ''

in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and ...

'' as an antimineralocorticoid. However, in contrast to spironolactone, eplerenone has little affinity for the

, progesterone, and

glucocorticoid receptor The glucocorticoid receptor (GR, or GCR) also known as NR3C1 (nuclear receptor subfamily 3, group C, member 1) is the receptor to which cortisol and other glucocorticoids bind. The GR is expressed in almost every cell in the body and regulates ...

s. It also has more consistently observed non-genomic antimineralocorticoid effects relative to spironolactone (see membrane mineralocorticoid receptor). Eplerenone differs from spironolactone in its extensive metabolism, with a short half-life and inactive metabolites. Eplerenone seems to be about 50 to 75% as potent as spironolactone as an antimineralocorticoid. Hence, 25 mg/day spironolactone may be equivalent to approximately 50 mg/day eplerenone.

Regulatory and Patent History

Eplerenone was patented in 1983 and approved for medical use in the United States in 2002. Eplerenone is currently approved for sale in Canada, the US, EU, Netherlands and Japan. Eplerenone costs an estimated $2.93 per day when treating

congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...

and $5.86 per day when treating hypertension.

References

{{Mineralocorticoid receptor modulators Antimineralocorticoids Epoxides Lactones Methyl esters Pfizer brands Pregnanes Spirolactones