Spironolactone is used as an anti-androgen in female patients with polycystic ovarian syndrome (PCOS). Beyond its aldosterone-receptor blockade, its antiandrogenic mechanism is:
- A Competitive antagonism at androgen receptors (AR) and inhibition of testosterone biosynthesis via 17-alpha-hydroxylase ✓
- B Inhibition of 5-alpha-reductase enzyme reducing conversion of testosterone to DHT
- C Increased hepatic SHBG production reducing free testosterone levels
- D GnRH receptor antagonism reducing LH-driven androgen production in ovarian theca cells
Correct answer: A. Competitive antagonism at androgen receptors (AR) and inhibition of testosterone biosynthesis via 17-alpha-hydroxylase
Explanation
Spironolactone exerts antiandrogenic effects through two complementary mechanisms: (1) competitive antagonism at androgen receptors (blocking testosterone and DHT from binding), and (2) inhibition of steroidogenic enzymes including 17-alpha-hydroxylase and 17,20-lyase, reducing androgen synthesis in the adrenals and ovaries. These actions reduce hirsutism and acne in PCOS. Finasteride inhibits 5-alpha-reductase but does not block AR directly.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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