What is eplerenone?

What is Eplerenone

Eplerenone is a selective mineralocorticoid receptor antagonist (MRA) that blocks aldosterone binding at the mineralocorticoid receptor, used primarily to treat heart failure with reduced ejection fraction post-myocardial infarction, hypertension, and primary aldosteronism—with the key advantage of lacking the antiandrogen effects that cause gynecomastia and sexual dysfunction seen with spironolactone. 1

Mechanism of Action

Eplerenone selectively binds to mineralocorticoid receptors and blocks aldosterone, a component of the renin-angiotensin-aldosterone system (RAAS). This blockade occurs in both epithelial tissues (kidneys) and non-epithelial tissues (heart, blood vessels, brain), preventing aldosterone-mediated sodium reabsorption and the harmful cardiovascular effects of aldosterone including inflammation, fibrosis, oxidative stress, and adverse tissue remodeling. 1, 2

The drug produces sustained increases in plasma renin and serum aldosterone levels (due to loss of negative feedback), but these increases do not overcome eplerenone's therapeutic effects. 1

Clinical Indications

FDA-Approved Uses:

• Heart failure post-myocardial infarction with left ventricular dysfunction 1, 3
• Primary (essential) hypertension 4, 1
• Heart failure after myocardial infarction 4

Guideline-Recommended Uses:

• Primary aldosteronism (bilateral disease or when surgery is not pursued) 5, 4
• Resistant hypertension 3

Key Pharmacologic Properties

Potency: Eplerenone has approximately 50% of the mineralocorticoid receptor antagonist potency of spironolactone in vivo. 4

Selectivity: Unlike spironolactone, eplerenone selectively binds mineralocorticoid receptors without significant binding to androgen, progesterone, or glucocorticoid receptors—eliminating the sexual side effects (gynecomastia, erectile dysfunction, menstrual irregularities) that occur with spironolactone. 4, 6

Pharmacokinetics:

• Half-life: 3-6 hours (shorter than spironolactone)
• Steady state reached within 2 days
• Peak plasma concentration: approximately 1 hour
• Metabolism: predominantly via CYP3A4
• Must be given twice daily due to shorter half-life 4, 1

Dosing

For Primary Aldosteronism/Hypertension:

• Starting dose: 25 mg twice daily
• Can titrate upward as needed 4

Critical Dosing Considerations:

• Use with caution in stage III chronic kidney disease (GFR <60 mL/min/1.73 m²) due to hyperkalemia risk
• Avoid in stage IV chronic kidney disease 4
• Requires dose adjustment with CYP3A4 inhibitors 1

Comparative Effectiveness

Versus Spironolactone in Primary Aldosteronism:

• Spironolactone is more effective for hypokalemia control and requires less intensive hypertension management 5
• Spironolactone may lower blood pressure more effectively than eplerenone 4
• However, eplerenone has superior tolerability due to lack of sexual side effects 4, 6

Clinical Context: Eplerenone is preferred when spironolactone's side effects (gynecomastia in men occurring in 52% at doses >150 mg/d, menstrual irregularities in women) prove intolerable. 4 The better tolerability must be balanced against higher cost and potentially lower blood pressure efficacy. 4

Major Adverse Effects

Hyperkalemia is the primary concern, especially in:

• Elderly patients (≥65 years) 1
• Patients with renal impairment 4
• Diabetics with microalbuminuria 7
• Those taking ACE inhibitors or other potassium-sparing medications 8, 7

Adequate patient selection and monitoring are essential. 6

Special Populations

Pediatrics: Not effective for hypertension in children ages 4-16 years despite achieving adult-equivalent exposures. Not studied in children <4 years or in pediatric heart failure. 1

Geriatrics: Patients >75 years did not appear to benefit in heart failure trials. Increased hyperkalemia risk due to age-related decline in creatinine clearance. 1

Pregnancy: Category B. No human data on presence in breast milk, though present in rat milk. May compromise male fertility based on animal data. 1, 9

Clinical Benefits Beyond Blood Pressure

Eplerenone provides cardiovascular protection through:

• Reduction in cardiovascular death and heart failure hospitalization (benefits seen as early as 26 days post-initiation in HFrEF) 10
• Attenuation of myocardial remodeling 6
• Regression of left ventricular hypertrophy 6
• Reduction in proteinuria 6

The drug's role is firmly established in post-MI left ventricular dysfunction and HFrEF, with evolving evidence in broader cardiorenal disease. 2