Class: Nonsteroidal antiandrogen (NSAA)
Mechanism of Action:
Competitively binds to androgen receptors, blocking the stimulatory effects of testosterone and dihydrotestosterone (DHT) on prostate cancer cells. Does not inhibit androgen production—therefore typically used in combination with androgen deprivation therapy (ADT) to achieve full androgen blockade.
Indications
- Metastatic prostate cancer (in combination with LHRH agonist/antagonist)
- Prevention of testosterone flare at initiation of LHRH agonists
- Occasionally used off-label in nonmetastatic settings (not first-line per guidelines)
Adult Dose
- 50 mg PO once daily
- Administer with or without food
- For flare prevention: Start bicalutamide at least 3 days before LHRH agonist and continue for 7 days after first LHRH dose.
- Absorption: Well absorbed orally
- Metabolism: Hepatic (CYP3A4 substrate)
- Half-life: ~6 days (long—allows once-daily dosing)
- Excretion: Feces and urine
Toxicities / Adverse Effects
- Gynecomastia, breast tenderness
- Hot flashes, decreased libido, impotence
- Hepatotoxicity: Monitor LFTs at baseline and periodically; rare severe hepatic failure
- Mild GI upset
- Fatigue
Monitoring
- Baseline & periodic LFTs
- Disease progression (PSA, imaging as appropriate)
- Adherence and tolerability
Clinical Pearls
- Well tolerated compared to older NSAAs (e.g., flutamide).
- Not effective as monotherapy in advanced disease—should be paired with ADT.
- If progression occurs on combined androgen blockade, discontinue bicalutamide and continue ADT (castration maintained).
- Long half-life means missing one dose is less likely to impact efficacy.
Synonyms
Casodex