A 58-year-old man on spironolactone for heart failure develops bilateral breast tenderness and enlargement. The mechanism underlying spironolactone-induced gynecomastia is:
- A Direct estrogen receptor agonism
- B Blockade of androgen receptors and increased testosterone aromatization ✓
- C Inhibition of 5-alpha reductase
- D Prolactin excess due to pituitary disinhibition
Correct answer: B. Blockade of androgen receptors and increased testosterone aromatization
Explanation
Spironolactone causes gynecomastia by blocking androgen receptors and inhibiting testosterone synthesis. It also increases the conversion of testosterone to estradiol via aromatization, creating a relative estrogen excess. This anti-androgenic effect is dose-dependent and more common in men. Eplerenone, a selective aldosterone antagonist, has fewer hormonal side effects.
Reference: Katzung Basic & Clinical Pharmacology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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