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Home > Drug Category > Blood Pressure Medication (Angiotensin Receptor Blocker) > Inspra and Equivalent

Inspra (Eplerenone) Information

Inspra, which contains the active ingredient eplerenone, is a selective aldosterone receptor antagonist (SARA) often grouped with potassium-sparing diuretics. It is primarily indicated for the treatment of hypertension (high blood pressure), typically used in combination with other agents. Critically, it is also shown to improve the survival of stable patients with left ventricular systolic dysfunction (LVSD) and signs of heart failure (HF) after an acute myocardial infarction (MI), by reducing the risk of cardiovascular death and hospitalization. Eplerenone is administered orally, usually once or twice daily.

The mechanism of action for eplerenone involves selectively blocking the binding of aldosterone to the mineralocorticoid receptors (MR) in the kidney, heart, blood vessels, and brain. Aldosterone, a hormone involved in the renin-angiotensin-aldosterone system (RAAS), promotes the retention of sodium and water and the excretion of potassium. In conditions like heart failure and post-MI, elevated aldosterone levels contribute to fibrosis, inflammation, and worsening cardiac function. By selectively blocking the mineralocorticoid receptor, eplerenone prevents these detrimental effects, leading to a mild diuretic effect (sodium and water loss), preservation of potassium (potassium-sparing effect), and most importantly, a reduction in cardiovascular remodelling and improved long-term outcomes in heart failure.

Inspra Side Effects

Inspra is generally well-tolerated, but side effects related to its specific action on aldosterone receptors and potassium balance may occur. Common side effects often reported include dizziness, cough, flu-like symptoms, and fatigue.

However, more serious side effects can occur, leading to significant monitoring protocols. If any of the following symptoms are experienced, the patient should stop taking the medication and seek immediate medical attention:
• Gynecomastia (Breast Enlargement): Although less common with eplerenone than with the non-selective antagonist spironolactone, male breast enlargement can occur.
• Risk of Hyperkalemia (Severe High Potassium) (Boxed Warning): The most serious risk is that significantly elevated serum potassium levels can lead to dangerous and potentially fatal cardiac arrhythmias. This risk is highest in patients with impaired renal function, concurrent use of potassium supplements or potassium-sparing diuretics, or diabetes.
• Renal Impairment/Failure: The drug should be used with extreme caution or avoided in patients with existing renal impairment, as the risk of life-threatening hyperkalemia is substantially increased.
• Symptomatic Hypotension: Excessive lowering of blood pressure, especially when initiating therapy in patients with heart failure, which may lead to fainting (syncope).

Inspra Precautions

Due to the significant risk of severe hyperkalemia, Inspra carries a Boxed Warning. It is contraindicated in patients with hyperkalemia (serum potassium greater than 5.0 mEq/L at baseline), severe renal impairment (creatinine clearance less than 30 mL/min), co-administration with potent CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin), which can significantly increase eplerenone concentration, and in patients with Type 2 diabetes with microalbuminuria and creatinine clearance of 50 mL/min. Serum potassium levels and renal function (serum creatinine) must be checked before starting treatment, within the first week of starting or adjusting dose, and periodically thereafter. Patients should be cautioned against using potassium supplements or potassium-containing salt substitutes while on Inspra.

Do I need a prescription to order Inspra?

Yes, a prescription is required from your physician to order Inspra.