A 62-year-old man with symptomatic benign prostatic hyperplasia is started on a drug that shrinks the prostate by blocking the conversion of testosterone to dihydrotestosterone within prostatic tissue. The drug described is:
- A Tamsulosin
- B Finasteride ✓
- C Flutamide
- D Leuprolide
Correct answer: B. Finasteride
Explanation
Finasteride selectively inhibits the type II isoform of 5-alpha reductase, the enzyme converting testosterone to the more potent dihydrotestosterone in prostate, skin and liver. Reduced intraprostatic DHT causes gradual shrinkage of the gland over months and lowers serum PSA by about half. Tamsulosin relaxes smooth muscle without affecting size, flutamide blocks the androgen receptor itself, and leuprolide suppresses gonadotropin release centrally.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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