DESCRIPTION
MECHANISM OF ACTION
• Nonsteroidal antiandrogen agent that binds to androgen receptor and inhibits androgen uptake as well as inhibiting androgen binding in the nuclei of androgen-sensitive prostate cancer cells.
• Affinity to androgen receptor is 4-fold greater than flutamide.
ABSORPTION
Well absorbed by the GI tract. Peak plasma levels observed 1–2 hours after oral administration. Absorption is not affected by food.
DISTRIBUTION
Distribution is not well characterized. Extensively bound to plasma proteins (96%).
INDICATIONS
Stage D2 metastatic prostate cancer.
DOSAGE RANGE
Recommended dose is 50 mg PO once daily, either alone or in combination with a luteinizing hormone–releasing hormone (LHRH) analog.
DRUG INTERACTIONS
Warfarin—Bicalutamide can displace warfarin from its protein-binding sites, leading to increased anticoagulant effect. Coagulation parameters (PT and INR) must be followed closely, and dose adjustments may be needed.
SPECIAL CONSIDERATIONS
1. Use with caution in patients with abnormal liver function. Monitor LFTs at baseline and during therapy.
2. Caution patients about the potential for hot flashes. Consider the use of clonidine 0.1–0.2 mg PO daily, megestrol acetate 20 mg PO bid, or soy tablets 1 tablet PO tid for prevention and/or treatment.
3. Instruct patients on the potential risk of altered sexual function and impotence.
4. Pregnancy category D. Breastfeeding should be avoided.
TOXICITY 1
Hot flashes, decreased libido, impotence, gynecomastia, nipple pain, and galactorrhea. Occur in 50% of patients.
TOXICITY 2
Constipation observed in 10% of patients. Nausea, vomiting, and diarrhea occur rarely.
TOXICITY 3
Transient elevations in serum transaminases are rare.
SPECIFICATION
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