A woman presents with hirsutism and acne. She is started on spironolactone. The rationale for this use is:
- A Spironolactone is a progesterone receptor agonist that reduces LH and FSH secretion
- B Spironolactone is an aldosterone antagonist that also blocks androgen receptors and inhibits 5-alpha reductase, reducing androgenic effects on hair follicles and sebaceous glands ✓
- C Spironolactone inhibits CYP17 (17-alpha hydroxylase), blocking adrenal androgen synthesis
- D Spironolactone is a GnRH antagonist that reduces ovarian androgen secretion
Correct answer: B. Spironolactone is an aldosterone antagonist that also blocks androgen receptors and inhibits 5-alpha reductase, reducing androgenic effects on hair follicles and sebaceous glands
Explanation
Spironolactone competitively antagonises the mineralocorticoid (aldosterone) receptor but also has anti-androgen properties: it competitively blocks androgen (dihydrotestosterone) receptors in hair follicles and sebaceous glands and weakly inhibits 5-alpha reductase (the enzyme converting testosterone to DHT). These combined actions reduce androgen-driven hirsutism and acne. CYP17 inhibition is the mechanism of abiraterone (used in prostate cancer). GnRH antagonists (like cetrorelix) are used in fertility treatment.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.