A 62-year-old man on spironolactone 50 mg daily for heart failure develops painful bilateral gynecomastia after three months. Serum potassium remains normal. The most appropriate substitution is:

• A Eplerenone titrated to equivalent dose ✓
• B Amiloride 10 mg daily
• C Continue spironolactone, since gynecomastia is benign and dose related only at higher doses
• D Stop aldosterone blockade entirely and add furosemide

Explanation

Spironolactone antagonizes not only mineralocorticoid but also androgen and progesterone receptors, causing gynecomastia, breast tenderness and menstrual irregularities. Eplerenone is a selective mineralocorticoid receptor antagonist with minimal affinity for sex steroid receptors, so it provides aldosterone blockade without these effects. Amiloride blocks ENaC downstream but lacks the proven mortality benefit of aldosterone blockade in heart failure, and stopping aldosterone blockade sacrifices outcome benefit.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

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Written and medically reviewed by the StethoPrep medical team.