Pharmacology · Class
Antiandrogens and androgen synthesis inhibitors !
Prostate cancer tablets that block the androgen receptor or stop the body from making androgens, usually added to castration therapy.
Updated 2026-11-01
What they are
Hormonal therapy for prostate cancer. Androgen receptor antagonists (first generation: flutamide, bicalutamide; second generation: enzalutamide) keep testosterone and dihydrotestosterone off the receptor. Abiraterone blocks CYP17A1, the enzyme that makes androgens in the testes, the adrenal glands and the tumour. They are usually combined with a GnRH analogue or orchiectomy.
Mechanism of action
Prostate cancer cells grow under androgen-receptor signalling. Receptor antagonists compete with androgens for the receptor and reduce its nuclear translocation and gene transcription. On their own they do not lower LH, so testosterone stays normal or rises. Abiraterone instead cuts androgen production upstream by inhibiting the 17α-hydroxylase and C17,20-lyase activities of CYP17A1; because cortisol synthesis is also reduced, ACTH rises and mineralocorticoids build up, so prednisone is given with it.
Target: Androgen receptor (AR); CYP17A1 for abiraterone
Drugs in this class
- AbirateroneA prostate cancer tablet that shuts down androgen production in testes, adrenals and tumour. Given with prednisone; it…CYP17A1 (17α-hydroxylase/C17,20-lyase)
- BicalutamideA once-daily antiandrogen tablet for prostate cancer, given with a GnRH analogue. It can cause breast swelling and…Androgen receptor (AR)
- EnzalutamideA second-generation antiandrogen for prostate cancer that blocks the androgen receptor more strongly than older drugs…Androgen receptor (AR)
- FlutamideAn older antiandrogen tablet for prostate cancer, taken with a GnRH analogue. It can cause serious liver damage and…Androgen receptor (AR)
Others in the class
- apalutamida
- darolutamida
- nilutamida
Test yourself
Think of the answer, then tap the question to see it.
Why does an androgen receptor antagonist alone not lower testosterone?
It blocks the receptor but does not suppress LH; without negative feedback from androgen signalling, LH and testosterone stay normal or rise.
Why is abiraterone given together with prednisone?
Blocking CYP17A1 also lowers cortisol; ACTH rises and drives mineralocorticoid excess, causing hypertension, hypokalaemia and fluid retention. Prednisone replaces glucocorticoid and suppresses ACTH.
Why is a first-generation antiandrogen started alongside a GnRH agonist?
The agonist causes a temporary testosterone surge (flare); the antiandrogen keeps the surge from stimulating the tumour.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - BICALUTAMIDE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2025); DailyMed - ABIRATERONE ACETATE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2023); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 73 (McGraw Hill, 2023).
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Representative model, for educational purposes only.