Inspra (Eplerenone)

Inspira (eplerenone) works within the renin‑angiotensin‑aldosterone system to treat conditions related to fluid overload and high blood pressure.

• Hypertension: lowers systolic and diastolic blood pressure by reducing sodium and water retention.
• Heart failure: improves cardiac function and reduces hospitalisation risk by antagonising aldosterone effects.
• Post‑myocardial infarction: helps prevent adverse cardiac remodeling and subsequent cardiovascular events.

• Eplerenone selectively blocks aldosterone receptors in the distal nephron, preventing aldosterone from binding and promoting sodium and water excretion while conserving potassium. This antagonism reduces extracellular fluid volume, lowers blood pressure, and mitigates the harmful cardiac remodeling associated with chronic aldosterone exposure.

Eplerenone may cause a range of adverse reactions, from mild to severe.

Common Side Effects

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

Serious or Rare Side Effects

• Severe hyperkalaemia leading to cardiac arrhythmia.
• Acute renal impairment or worsening kidney function.
• Allergic reactions including rash, pruritus, or angioedema.
• Hepatic dysfunction manifested by elevated liver enzymes.
• Anaphylactic shock (very rare).

Before initiating eplerenone therapy, several safety considerations should be observed.

• Monitor potassium levels: regular serum potassium testing is essential.
• Assess renal function: check creatinine and eGFR before and during treatment.
• Avoid use in severe renal impairment: contraindicated when eGFR is markedly reduced.
• Use with caution in pregnancy (Category B): benefits must outweigh potential risks.
• Do not combine with other potassium‑sparing agents without supervision.
• Store below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Eplerenone can interact with several medicines, requiring careful management.

Major Interactions (Avoid)

• Potassium supplements or high‑potassium diets: risk of severe hyperkalaemia.
• ACE inhibitors or ARBs: additive effect on potassium and renal function.
• NSAIDs: may impair renal clearance and increase potassium.
• Cyclosporine: can raise eplerenone plasma levels.

Moderate Interactions (Monitor Closely)

• Thiazide diuretics: may alter electrolyte balance.
• Digoxin: increased risk of digoxin toxicity with electrolyte shifts.
• Lithium: potential for lithium toxicity due to altered renal handling.
• Rifampin: may reduce eplerenone effectiveness by inducing metabolism.