A 25-year-old man with androgenetic alopecia is started on finasteride. Which enzyme does this drug specifically inhibit to reduce hair follicle miniaturization?
- A Aromatase
- B 5-alpha reductase type 1
- C 5-alpha reductase type 2 ✓
- D 17-beta hydroxysteroid dehydrogenase
Correct answer: C. 5-alpha reductase type 2
Explanation
Finasteride is a competitive inhibitor of 5-alpha reductase type 2, which converts testosterone to dihydrotestosterone (DHT). DHT is the androgen responsible for follicular miniaturization in genetically predisposed scalps. Type 1 is primarily inhibited by dutasteride, not finasteride. Aromatase converts androgens to estrogens, and 17-beta hydroxysteroid dehydrogenase is involved in steroidogenesis.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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