Casodex (Bicalutamide) Dosing for Prostate Cancer
The FDA-approved dose of Casodex (bicalutamide) is 50 mg once daily when used in combination with an LHRH analog for Stage D2 metastatic prostate cancer. 1
Standard Dosing Regimen
Bicalutamide 50 mg once daily is the only FDA-approved dose for combination therapy with LHRH agonists in metastatic castration-resistant prostate cancer (mCRPC). 1
The 50 mg dose should be taken orally once daily, at approximately the same time each day, and can be taken with or without food. 2
Treatment should be initiated concurrently with an LHRH analog (such as goserelin or leuprolide) to achieve combined androgen blockade. 1, 2
Critical FDA Warning About Higher Doses
Bicalutamide 150 mg daily is NOT FDA-approved for use alone or with other treatments in the United States, despite being studied in clinical trials. 1
The 150 mg dose was evaluated as monotherapy in clinical trials for locally advanced disease, but this indication was not approved by the FDA. 2, 3
Rationale for 50 mg Dosing in Combination Therapy
The 50 mg dose is sufficient when combined with LHRH agonists because castration-level testosterone (achieved by LHRH therapy) reduces competition at androgen receptors, allowing lower antiandrogen doses to be effective. 3
Bicalutamide 50 mg demonstrates equivalent or superior efficacy compared to flutamide 250 mg three times daily (750 mg total daily) when both are combined with LHRH analogs. 4, 2
In the TERRAIN and STRIVE trials comparing newer agents, bicalutamide was dosed at 50 mg daily, confirming this as the standard comparator dose. 4
Important Clinical Considerations
Continue LHRH agonist therapy indefinitely even if disease progresses, as maintaining castrate testosterone levels remains important throughout treatment. 5
Common adverse effects at 50 mg include breast tenderness (most common), gynecomastia, and hot flushes—these are expected pharmacological effects of antiandrogen therapy. 6, 7
Bicalutamide 50 mg has minimal impact on sexual function compared to castration alone, with better preservation of libido and potency. 2, 6
Monitor liver function tests periodically, though clinically significant hepatotoxicity requiring discontinuation occurs in only 0.3% of patients. 6
When Bicalutamide May Not Be First Choice
Enzalutamide (160 mg daily) or apalutamide (240 mg daily) are now preferred over bicalutamide for mCRPC based on superior progression-free survival data from recent trials. 4, 8
Enzalutamide extended median PFS to 15.7 months versus 5.8 months with bicalutamide (HR 0.44), and reduced risk of progression or death by 76% (HR 0.24). 4, 8
However, bicalutamide remains a reasonable option for patients who cannot afford newer agents or prefer its more favorable side effect profile (particularly lower rates of fatigue, diarrhea, and no seizure risk). 4