Inspra (Eplerenone)

Eplerenone is an aldosterone antagonist used in cardiovascular conditions that involve excess fluid retention.

• Hypertension: lowers systolic and diastolic blood pressure by promoting natriuresis while retaining potassium.
• Heart failure (reduced ejection fraction): improves survival and reduces hospitalisations by decreasing cardiac remodeling and fluid overload.
• Post‑myocardial infarction with left‑ventricular dysfunction: reduces the risk of cardiovascular death and heart‑failure progression.

• Eplerenone selectively binds to mineralocorticoid (aldosterone) receptors in the distal tubules and collecting ducts of the kidney. By antagonising aldosterone, it inhibits sodium reabsorption and potassium excretion, leading to increased urinary sodium loss (natriuresis) and potassium retention, which together contribute to reduced blood volume and lower arterial pressure.

Common Side Effects

• Dizziness: may occur due to blood‑pressure lowering effects.
• Hyperkalaemia: elevated serum potassium levels, especially when combined with other potassium‑sparing agents.
• Headache: mild to moderate intensity.
• Fatigue: general feeling of tiredness.
• Gastrointestinal discomfort: nausea, abdominal pain or dyspepsia.
• Increased serum creatinine: mild rise in renal markers.

Serious or Rare Side Effects

• Severe hyperkalaemia: can lead to cardiac arrhythmias.
• Acute renal failure: marked decline in kidney function.
• Angioedema: swelling of face, lips, tongue or airway.
• Hepatic dysfunction: elevated liver enzymes or hepatitis.
• Anaphylactic reaction: rare but potentially life‑threatening allergy.
• Severe hypotension: marked drop in blood pressure causing syncope.

Before initiating therapy, clinicians should consider the following precautions:

• Monitor potassium levels: regular blood tests to detect hyperkalaemia.
• Assess renal function: evaluate serum creatinine and eGFR prior to and during treatment.
• Avoid in severe renal impairment: contraindicated when eGFR is markedly reduced.
• Caution with concomitant potassium‑sparing diuretics: increased risk of hyperkalaemia.
• Use in pregnancy only if clearly needed: limited safety data are available.
• Store at room temperature: keep in the original pack, protect from moisture and light.

Eplerenone may interact with several medicines that affect potassium balance or renal function.

Major Interactions (Avoid)

• ACE inhibitors: additive risk of hyperkalaemia.
• Angiotensin‑II receptor blockers (ARBs): increase potassium levels.
• Potassium supplements or salt substitutes: may cause dangerous hyperkalaemia.

Moderate Interactions (Monitor Closely)

• NSAIDs: can reduce renal clearance and raise serum potassium.
• Non‑potassium‑sparing diuretics: may alter electrolyte balance.
• Digoxin: electrolyte shifts can increase digoxin toxicity risk.