USMLE

Finasteride

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Reproductive Pharm
  1. Leuprolide
  2. Anastrozole
  3. Estrogens
  4. Clomiphene
  5. Progestins
  6. Mifepristone
  7. Copper IUDs
  8. Danazol
  9. Terbutaline, Ritodrine
  10. Minoxidil
  11. Androgens (Testosterone, Methyltestosterone)
  12. Flutamide
  13. PDE-5 Inhibitors (Sildenafil, Vardenafil, Tadalafil)
  14. Finasteride

Summary

Finasteride is a drug that works by inhibiting the enzyme, 5-alpha reductase. This inhibition decreases the levels of dihydrotestosterone or DHT, which is a super-active form of testosterone that usually acts at androgen receptors. Finasteride therefore reduces  androgen receptor signaling by DHT, helping to treat prostate enlargement in benign prostatic hyperplasia as well as  male-pattern baldness.

Key Points

  • Finasteride 
    • Mechanism
      • Inhibits 5-Alpha Reductase
        • Reduces conversion of testosterone to dihydrotestosterone (DHT), which is a far more potent androgen
    • Indications
      • Benign Prostatic Hyperplasia (BPH)
        • DHT mediates many of testosterone’s effects, including prostate enlargement and male external genitalia
        • Promotes gradual shrinkage over one year; not useful for acute cases of bladder obstruction
      • Baldness (alopecia)
        • DHT contributes to male-pattern baldness
      • Polycystic Ovarian Syndrome
        • Treats masculinization symptoms (i.e. excessive facial hair) due to reduction of DHT
    • Adverse Effects
      • Gynecomastia
        • Low risk; seen in about 1-2% of patients
        • With decreased conversion of testosterone to DHT, more testosterone is converted to estradiol (estrogen) → increases breast development (gynecomastia)
      • Sexual Dysfunction
        • Due to decreased androgen activity from less DHT