A 60-year-old man with metastatic castration-resistant prostate cancer is treated with abiraterone acetate. What is the mechanism of action of abiraterone?

• A Inhibitor of CYP17A1 (17-alpha-hydroxylase/17,20-lyase) blocking androgen biosynthesis ✓
• B Competitive antagonist at the androgen receptor
• C Inhibitor of 5-alpha reductase preventing DHT conversion
• D GnRH receptor antagonist suppressing LH and testosterone

Explanation

Abiraterone is a selective inhibitor of CYP17B1, a key enzyme in androgen biosynthesis in the testes, adrenal glands, and prostate tumor tissue. By blocking this enzyme, it reduces circulating and intratumoral androgen levels. It is always given with prednisolone to prevent mineralocorticoid excess from upstream steroid accumulation.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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