Bicalutamide (2 brand names, 1 dosage form, 1 route)
Available dosage forms: TABLET.
Routes of administration: ORAL.
Brand Names
- BICALUTAMIDE
- CASODEX
Indications and Usage
Bicalutamide tablets 50 mg daily is indicatedfor use in combination therapy with a luteinizing hormone-releasing hormone (LHRH) analog for the treatment of Stage D 2metastatic carcinoma of the prostate. Bicalutamide tablets 150 mg daily is not approvedfor use alone or with other treatments [see Clinical Studies (14.2)].
Contraindications
Bicalutamide tablets are contraindicated in: Hypersensitivity Bicalutamide tablets are contraindicated in any patient who has shown a hypersensitivity reaction to the drug or any of the tablet’s components. Hypersensitivity reactions including angioneurotic edema and urticaria have been reported. Women Bicalutamide tablets have no indication for women, and should not be used in this population. Pregnancy Bicalutamide tablets can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)] .
Adverse Reactions
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Drug Interactions
Clinical studies have not shown any drug interactions between bicalutamide and LHRH analogs (goserelin or leuprolide). There is no evidence that bicalutamide induces hepatic enzymes. In vitrostudies have shown that R-bicalutamide is an inhibitor of CYP 3A4 with lesser inhibitory effects on CYP 2C9, 2C19 and 2D6 activity. Clinical studies have shown that with co-administration of bicalutamide, mean midazolam (a CYP 3A4 substrate) levels may be increased 1.5-fold (for C max) and 1.9-fold (for AUC). Hence, caution should be exercised when bicalutamide is co-administered with CYP 3A4 substrates. In vitroprotein binding studies have shown that bicalutamide can displace coumarin anticoagulants from binding sites. PT/INR should be closely monitored in patients concomitantly receiving coumarin anticoagulants and bicalutamide. Adjustment of the anticoagulant dose may be necessary [see Warnings and Precautions (5.2)and Adverse Reactions (6.2)].
Mechanism of Action
Bicalutamide is a non-steroidal androgen receptor inhibitor. It competitively inhibits the action of androgens by binding to cytosol androgen receptors in the target tissue. Prostatic carcinoma is known to be androgen sensitive and responds to treatment that counteracts the effect of androgen and/or removes the source of androgen. When bicalutamide is combined with LHRH analog therapy, the suppression of serum testosterone induced by the LHRH analog is not affected. However, in clinical trials with bicalutamide as a single agent for prostate cancer, rises in serum testosterone and estradiol have been noted. In a subset of patients who have been treated with bicalutamide and an LHRH agonist, and who discontinue bicalutamide therapy due to progressive advanced prostate cancer, a reduction in Prostate Specific Antigen (PSA) and/or clinical improvement (antiandrogen withdrawal phenomenon) may be observed.
Overdosage
Long-term clinical trials have been conducted with dosages up to 200 mg of bicalutamide daily and these dosages have been well tolerated. A single dose of bicalutamide that results in symptoms of an overdose considered to be life threatening has not been established. There is no specific antidote; treatment of an overdose should be symptomatic. In the management of an overdose with bicalutamide, vomiting may be induced if the patient is alert. It should be remembered that, in this patient population, multiple drugs may have been taken. Dialysis is not likely to be helpful since bicalutamide is highly protein bound and is extensively metabolized. General supportive care, including frequent monitoring of vital signs and close observation of the patient, is indicated.