Pharmacology · Antiandrogens and androgen synthesis inhibitors

Abiraterone !

A prostate cancer tablet that shuts down androgen production in testes, adrenals and tumour. Given with prednisone; it can raise blood pressure.

Updated 2026-11-01

Class: Antiandrogens and androgen synthesis inhibitors
Enzyme: CYP17A1 (17α-hydroxylase/C17,20-lyase)
ATC code: L02BX03
WHO Model List of Essential Medicines

Also called: abiraterone acetate

CYP17A1 (17α-hydroxylase/C17,20-lyase)Abiraterone

The figure shows abiraterone in the active site of human CYP17A1, its pyridine nitrogen bound to the heme iron.

Target in 3D: CYP17A1 (17α-hydroxylase/C17,20-lyase). PDB structure 3RUK (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Abiraterone acetate is a prodrug converted to abiraterone, which inhibits CYP17A1, the enzyme with 17α-hydroxylase and C17,20-lyase activities needed to make androgens in the testes, adrenal glands and prostate tumour tissue. Androgens fall even below castration levels. Because the enzyme is also on the cortisol pathway, cortisol falls, ACTH rises and mineralocorticoids accumulate; prednisone is given to replace glucocorticoid and dampen ACTH.

Abiraterone acetate is converted to abiraterone
Abiraterone blocks CYP17A1 in testis, adrenal and tumour
Androgen production falls to very low levels
Cortisol falls too: prednisone is added

Pharmacokinetics

Absorption: Food raises absorption several-fold, so it is taken on an empty stomach
Metabolism: Prodrug hydrolysed to abiraterone; metabolised partly by CYP3A4; inhibits CYP2D6 and CYP2C8
Half-life: About 12 hours in metastatic prostate cancer, longer with liver impairment

Indications

Metastatic castration-resistant prostate cancer, with prednisone Prostate cancer →
Metastatic high-risk castration-sensitive prostate cancer, with prednisone Prostate cancer →

Adverse effects

Common

Hypertension
Hypokalaemia
Fluid retention and oedema
Fatigue and joint pain
Hot flushes
Raised liver enzymes

Contraindications

None listed on the label; it is not indicated for women and can cause fetal harm

Key interactions

Strong CYP3A4 inducers (rifampicin, phenytoin, carbamazepine, phenobarbital): Lower abiraterone exposure; avoided where possible.
CYP2D6 substrates with a narrow therapeutic index (for example thioridazine): Abiraterone raises their levels.
Pioglitazone and repaglinide (CYP2C8 substrates): Severe hypoglycaemia has been reported.
Radium-223: More fractures and higher mortality; the combination is not recommended.

What is monitored

Blood pressure, potassium and fluid retention, at least monthly
Liver tests before and regularly during treatment
Glucose in people with diabetes
PSA

Administration and safety

Oral tablet once a day on an empty stomach, with no food for some time before and after; swallowed whole with water, not crushed or chewed.
Women who are or may be pregnant handle broken or crushed tablets only with gloves.
Always given with a glucocorticoid (prednisone or prednisolone).

Nursing care

Check blood pressure, weight and potassium; correct low potassium and control hypertension before starting.
Teach that it is taken on an empty stomach and swallowed whole, and that prednisone must not be stopped suddenly.
Teach the signs of liver injury: yellow skin or eyes, dark urine, upper abdominal pain.
Teach the signs of adrenal insufficiency during illness or stress: weakness, dizziness, vomiting.
A GnRH analogue continues alongside unless the patient had an orchiectomy.

Pregnancy and breastfeeding

Not indicated in women; it can harm a fetus, and men with partners who could become pregnant use effective contraception.

Test yourself

Think of the answer, then tap the question to see it.

Which enzyme does abiraterone inhibit, and in which tissues?

CYP17A1 (17α-hydroxylase/C17,20-lyase), in the testes, adrenal glands and prostate tumour tissue.

A patient on abiraterone has new hypertension and hypokalaemia. What is the mechanism?

Mineralocorticoid excess: lower cortisol raises ACTH, which drives the build-up of mineralocorticoid precursors.

Why is abiraterone taken on an empty stomach?

Food increases its absorption a great deal, which would raise exposure and toxicity.

Add to my cards (3)

Prostate cancer

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Abiraterone: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2023); DailyMed - ABIRATERONE ACETATE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Human Cytochrome P450 CYP17A1 in complex with Abiraterone (RCSB Protein Data Bank, 2012).

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Representative model, for educational purposes only.