Pharmacology · Antiandrogens and androgen synthesis inhibitors
Bicalutamide !
A once-daily antiandrogen tablet for prostate cancer, given with a GnRH analogue. It can cause breast swelling and, rarely, serious liver injury.
Updated 2026-11-01
The figure shows R-bicalutamide, the active enantiomer, in the ligand-binding domain of a human androgen receptor carrying the W741L mutation, which lets the drug fit in a crystal.
Mechanism of action
Bicalutamide is a non-steroidal competitive antagonist of the androgen receptor. It keeps testosterone and dihydrotestosterone from binding, so the receptor does not activate androgen-driven genes in prostate cancer cells. Given with a GnRH analogue, it blocks the remaining androgen and the initial testosterone flare.
- Binds the androgen receptor instead of testosterone
- The receptor does not switch on androgen genes
- Prostate cancer cells lose their growth signal
- With a GnRH analogue it blocks the testosterone flare
Pharmacokinetics
- Absorption
- Well absorbed by mouth
- Metabolism
- In the liver; the active R-enantiomer is metabolised slowly
- Elimination
- As inactive metabolites in bile and urine
- Half-life
- About 6 days for the active enantiomer, longer in severe liver disease
Indications
- Metastatic prostate cancer, combined with a GnRH (LHRH) analogue Prostate cancer →
Adverse effects
Common
- Hot flushes
- Gynaecomastia and breast pain
- Body pain, including back and pelvic pain
- Raised liver enzymes
Contraindications
- Hypersensitivity to bicalutamide
- Women
- Pregnancy
Key interactions
- Warfarin and other coumarin anticoagulants
- Bicalutamide displaces warfarin from protein binding; INR can rise greatly; monitored closely.
- CYP3A4 substrates
- Bicalutamide inhibits CYP3A4 and may raise their levels.
What is monitored
- Liver tests regularly, especially in the first months
- PSA
- INR in patients on warfarin
- Glucose with GnRH agonists
Administration and safety
- Oral tablet once a day, at the same time, with or without food.
- Given together with a GnRH analogue, which is continued.
Nursing care
- Teach the signs of liver injury and when to report them.
- Ask about warfarin and plan closer INR checks.
- Explain breast swelling or tenderness, which can occur.
- Teach that the GnRH injections continue alongside the tablet.
Pregnancy and breastfeeding
Contraindicated in pregnancy and not indicated for women; it can cause fetal harm.
Test yourself
Think of the answer, then tap the question to see it.
Why is bicalutamide combined with a GnRH agonist at the start of prostate cancer treatment?
It blocks the androgen receptor during the agonist's initial testosterone surge and also blocks the androgens that remain after castration.
A patient on warfarin starts bicalutamide. What should be expected?
The INR can rise markedly, with bleeding risk; INR is monitored closely and warfarin adjusted.
Which serious adverse effect requires regular liver tests with bicalutamide?
Hepatitis that can progress to liver failure and death.
Related drugs
Related conditions
← Back to the class: Antiandrogens and androgen synthesis inhibitors
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Bicalutamide: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2018); DailyMed - BICALUTAMIDE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Crystal Structure of the Androgen Receptor Ligand-binding Domain W741L Mutant Complex with R-bicalutamide (RCSB Protein Data Bank, 2005).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.