Bicalutamide

Approved Indications:

• Prostate Cancer:
• In combination with a luteinizing hormone-releasing hormone (LHRH) analog or surgical castration for the treatment of locally advanced prostate cancer.
• As monotherapy for metastatic prostate cancer in patients who are not candidates for surgical or medical castration.
• Off-label / Clinically Accepted Uses:
• Used as an antiandrogen in androgen deprivation therapy (ADT).
• Sometimes used in female-to-male transgender hormone therapy for androgen suppression (off-label).
• Occasionally prescribed off-label in hirsutism or other androgen-related disorders, but not widely accepted.

Route: Oral

Adult Dosage:

• Standard Dose for Prostate Cancer:
• 50 mg once daily orally, with or without food.
• Typically administered in combination with LHRH analog therapy.
• Monotherapy Dose:
• Higher doses (up to 150 mg daily) may be used in some cases of metastatic disease.

Pediatrics:

• Safety and efficacy not established.

Elderly:

• No dosage adjustment required; monitor for hepatic function.

Renal/Hepatic Impairment:

• Use with caution in moderate to severe hepatic impairment; avoid in severe cases.
• No dosage adjustment needed for renal impairment.

Bicalutamide is a nonsteroidal antiandrogen that competitively inhibits androgen binding to androgen receptors (AR) in target tissues such as the prostate gland. By blocking the AR, it prevents androgen-mediated transcriptional activation of genes involved in prostate cancer cell growth and survival. This inhibits tumor growth and induces apoptosis. Bicalutamide does not reduce androgen production but blocks androgen receptor activation.

• Absorption: Well absorbed orally; peak plasma concentrations within 1–2 hours.
• Bioavailability: Approximately 70%.
• Distribution: Highly protein-bound (~96%), large volume of distribution.
• Metabolism: Extensively metabolized in the liver via CYP3A4 to inactive metabolites.
• Elimination: Primarily excreted in feces (~80%) and urine (~10%).
• Half-life: Approximately 6 days, allowing once-daily dosing.
• Steady State: Achieved after 4 weeks of daily dosing.

• Pregnancy: Category X — contraindicated in pregnancy due to risk of fetal harm (antiandrogen effects).
• Lactation: Unknown if excreted in human milk; breastfeeding is not recommended during treatment.

• Primary Class: Antiandrogen
• Subclass: Nonsteroidal androgen receptor antagonist

• Known hypersensitivity to bicalutamide or any excipients.
• Women who are or may become pregnant.
• Severe hepatic impairment (due to metabolism and risk of toxicity).

• Hepatotoxicity: Cases of severe liver injury and fatal hepatic failure reported; monitor liver function tests before and during therapy.
• Gynecomastia and breast pain: Common in men; counsel patients accordingly.
• Cardiovascular Risk: Potential risk of QT prolongation; use cautiously in patients with pre-existing cardiac conditions or on QT-prolonging drugs.
• Interstitial Lung Disease: Rare but serious; discontinue if symptoms develop.
• Tumor Flare: Initial therapy may cause worsening symptoms due to androgen receptor blockade; often managed with concurrent LHRH analogs.
• Use caution in patients with severe renal impairment or hepatic disease.

Common:

• Hot flashes
• Gynecomastia
• Breast tenderness or pain
• Gastrointestinal symptoms: nausea, diarrhea
• Fatigue
• Dizziness

Serious / Rare:

• Hepatotoxicity (jaundice, elevated liver enzymes)
• Interstitial lung disease
• QT prolongation and arrhythmias
• Anemia
• Depression

Onset: Side effects typically appear within weeks of starting therapy; hepatotoxicity may occur anytime but often within first 6 months.

• CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): May increase bicalutamide levels and toxicity risk.
• CYP3A4 inducers (e.g., rifampin, carbamazepine): May reduce effectiveness by decreasing plasma levels.
• Warfarin and other anticoagulants: Monitor INR closely as bicalutamide may enhance anticoagulant effect.
• QT-prolonging drugs: Use cautiously due to additive risk of arrhythmias.
• No significant interaction with food or alcohol reported.

• Current prostate cancer treatment guidelines (e.g., NCCN, ESMO) recommend bicalutamide as part of combined androgen blockade for locally advanced disease.
• Recent data favor second-generation antiandrogens for advanced metastatic prostate cancer but bicalutamide remains standard for early-stage combined therapy.
• Warnings regarding liver toxicity have been emphasized in updated labeling.
• No major changes in dosing or indications recently.

• Store tablets at 20°C to 25°C (68°F to 77°F).
• Protect from moisture and light.
• Keep in tightly closed container.
• Do not freeze.
• Keep out of reach of children.