Inspra (Eplerenone)

Inspra (eplerenone) is used in cardiovascular conditions that involve aldosterone‑mediated fluid retention and blood‑pressure elevation.

• Hypertension: lowers systolic and diastolic blood pressure by antagonizing aldosterone‑driven sodium retention.
• Heart failure with reduced ejection fraction: improves survival and reduces hospitalizations by decreasing cardiac remodeling.
• Post‑myocardial infarction: reduces the risk of cardiovascular death and heart‑failure progression when added to standard therapy.

• Eplerenone selectively blocks the mineralocorticoid (aldosterone) receptor in the distal nephron, preventing aldosterone from binding and stimulating sodium reabsorption. This inhibition promotes natriuresis and potassium retention, leading to reduced extracellular fluid volume and lower arterial pressure. The drug’s receptor selectivity minimizes off‑target binding to androgen or progesterone receptors, contributing to its cardiovascular protective effects. By attenuating the aldosterone‑induced fibrotic response, eplerenone also helps limit myocardial and vascular remodeling.

Eplerenone may be associated with a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Hyperkalaemia: elevated serum potassium levels, often mild.
• Dizziness or light‑headedness, especially after the first dose.
• Headache.
• Fatigue.
• Gastrointestinal discomfort such as nausea or abdominal pain.

Serious or Rare Side Effects

• Severe hyperkalaemia leading to cardiac arrhythmia.
• Acute kidney injury or worsening renal function.
• Angioedema affecting the face, lips or airway.
• Hepatic dysfunction with elevated transaminases.

When prescribing eplerenone, clinicians should observe several precautionary measures to ensure patient safety.

• Monitor serum potassium: check baseline and periodic levels to avoid hyperkalaemia.
• Assess renal function: evaluate creatinine and eGFR before initiation and during therapy.
• Use caution in patients with diabetes: increased risk of electrolyte disturbances.
• Avoid in severe hepatic impairment: limited metabolism may raise drug exposure.
• Adjust dose in elderly patients: consider reduced renal clearance.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Eplerenone can interact with other medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Potassium‑rich supplements or salt substitutes: may cause dangerous hyperkalaemia.
• ACE inhibitors or ARBs: additive effect on potassium and renal function, requiring close monitoring.
• Cytochrome P450 3A4 inhibitors (e.g., ketoconazole, itraconazole): increase eplerenone plasma concentrations.

Moderate Interactions (Monitor Closely)

• Diuretics (especially thiazides): may exacerbate electrolyte shifts.
• NSAIDs: can impair renal function and potentiate hyperkalaemia.
• Digoxin: altered potassium levels may affect digoxin toxicity risk.