Eplerenone

Eplerenone is a prescription medication that acts as a selective antagonist of the mineralocorticoid receptor, reducing the effects of aldosterone. It is used in adults to treat hypertension and to improve outcomes in heart failure with reduced ejection fraction (HFrEF). It is also prescribed for patients after myocardial infarction who have left ventricular dysfunction to lower the risk of cardiovascular death. Eplerenone was developed to provide the therapeutic benefits of aldosterone blockade with a lower risk of antiandrogen and gynecomastia-related side effects compared with spironolactone.

Mechanism of action and effects: By blocking the mineralocorticoid receptor in the distal nephron, eplerenone decreases sodium reabsorption and potassium excretion, contributing to blood pressure reduction and improved fluid balance. In heart failure, it can reduce cardiac remodeling and potassium-sparing diuresis, contributing to improved outcomes.

Pharmacokinetics and administration: Eplerenone is taken orally and is metabolized in the liver, mainly by the CYP3A4 enzyme, with excretion through urine and feces. Peak concentrations occur within a few hours of dosing, and the drug has a relatively dose-dependent effect on potassium and renal function. Dosing is individualized by indication and patient tolerance, with careful monitoring.

Safety and monitoring: Hyperkalemia is the most important potential adverse effect, especially in patients with renal impairment or those taking other potassium-sparing drugs or ACE inhibitors/ARBs. Other risks include hypotension and renal function changes. Before starting and after dose changes, potassium and creatinine should be checked, and ongoing monitoring is recommended. It is contraindicated in hyperkalemia or significant renal impairment and used with caution with strong CYP3A4 inhibitors.