5-alpha reductase inhibitor
- Blocks testosterone → dihydrotestosterone conversion
- ↓ DHT → prostate shrinkage and less androgen-driven hair loss
- Can cause sexual dysfunction
- Lowers PSA
- Lowers PSA by about half
Drugs with this mechanism (2)
- Dutasteride — Dual 5-alpha-reductase inhibitor for BPH; longer-acting than finasteride.
- Finasteride — Type-II 5-alpha-reductase inhibitor for BPH and hair loss.
Self-check
- Which testosterone metabolite falls with 5α-reductase inhibition?
Dihydrotestosterone (DHT). - About how much can 5α-reductase inhibition lower PSA?
About half.
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