Antiandrogen Drugs

Finasteride

• Mechanism of Action:
  • Inhibits 5 alpha reductase.
• Indications:
  • Benign prostatic hyperplasia (BPH).
  • Androgenetic alopecia.
• Adverse Effects:
  • Gynecomastia.
  • Sexual dysfunction.

Flutamide, Bicalutamide, Apalutamide, Enzalutamide

• Mechanism of Action:
  • Nonsteroidal competitive inhibition at androgen receptors (decreases steroid binding).
• Indications:
  • Metastatic prostate cancer (often in combination with GnRH analogs for medical castration).
  • Hirsutism (e.g., in Polycystic Ovary Syndrome - PCOS).
  • Androgenetic alopecia in female individuals.
• Adverse Effects:
  • Gynecomastia.
  • Hypogonadism in males.
  • Hepatotoxicity (particularly noted with Flutamide, requires monitoring).

Cyproterone

• Mechanism of Action:
  • Blocks androgen receptor.
  • Has progesterone-like effects.
• Indications:
  • Prostate cancer.
  • Hirsutism.
  • Precocious puberty.
  • Hypersexuality.
• Adverse Effects:
  • (Note: Specific adverse effects for Cyproterone were not listed separately in the provided text excerpt, but common antiandrogen effects like gynecomastia and potential progestogenic effects/mood changes can occur).

Spironolactone

• Mechanism of Action:
  • Blocks androgen receptor.
  • Inhibits 17,20-desmolase and 17 alpha-hydroxylase (steroid synthesis enzymes).
  • Inhibits 5-alpha reductase enzyme.
• Indications:
  • Androgenic effects of PCOS (e.g., hirsutism).
  • Androgenetic alopecia in female individuals.
  • (Also used commonly as a diuretic/for heart failure/hypertension due to its mineralocorticoid receptor antagonist activity, though not listed in this context).
• Adverse Effects:
  • Gynecomastia.
  • Breast tenderness.
  • Amenorrhea.
  • (Hyperkalemia is a significant risk due to its primary mineralocorticoid antagonist effect).

Ketoconazole

• Mechanism of Action:
  • Inhibits several steps of adrenal and gonadal steroid synthesis (e.g., 17,20-desmolase, 17 alpha-hydroxylase, 11β-hydroxylase, cholesterol side-chain cleavage).
• Indications:
  • Androgenic effects of PCOS (e.g., hirsutism) - (Use is limited due to toxicity).
  • Peripheral precocious puberty (e.g., McCune-Albright syndrome).
  • Cushing syndrome.
  • Advanced prostate cancer - (Less common now due to newer agents and toxicity).
  • (Primarily known as an antifungal agent).
• Adverse Effects / Characteristics:
  • Gynecomastia.
  • Amenorrhea.
  • Potent CYP 450 inhibitor (leading to numerous drug interactions).
  • Hepatotoxicity (Black Box Warning in some regions).
  • QTc prolongation.
  • Adrenal insufficiency (due to cortisol synthesis inhibition).