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[Pharmacology](https://durgical.com/en/pharmacology/) · [Antiandrogens and androgen synthesis inhibitors](https://durgical.com/en/pharmacology/classes/antiandrogens-and-androgen-synthesis-inhibitors/)

# Flutamide

An older antiandrogen tablet for prostate cancer, taken with a GnRH analogue. It can cause serious liver damage and turns the urine orange or green.

Updated 2026-11-01

- Class: [Antiandrogens and androgen synthesis inhibitors](https://durgical.com/en/pharmacology/classes/antiandrogens-and-androgen-synthesis-inhibitors/)
- Receptor: Androgen receptor (AR)
- ATC code: L02BB01

◎**Androgen receptor (AR)**Flutamide

ⓘ The figure shows hydroxyflutamide, the active metabolite of flutamide, in the ligand-binding domain of a human androgen receptor carrying the T877A mutation.

**Target in 3D:** Androgen receptor (AR). PDB structure 2AX6 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/2AX6) · Drag to rotate · pinch to zoom

## Mechanism of action

Flutamide is a non-steroidal androgen receptor antagonist. Its active metabolite, hydroxyflutamide, competes with testosterone and dihydrotestosterone for the receptor in prostate cancer cells and blocks androgen-driven growth. It is combined with a GnRH agonist.

- Converted in the liver to hydroxyflutamide
- Hydroxyflutamide binds the androgen receptor
- Androgens cannot activate their genes
- Prostate cancer growth slows

## Pharmacokinetics

**Absorption**
Taken by mouth several times a day

**Metabolism**
In the liver, to the active metabolite hydroxyflutamide

**Half-life**
Short, about 5 hours, so it is taken several times a day

## Indications

- Prostate cancer, together with a GnRH (LHRH) agonist [Prostate cancer →](https://durgical.com/en/conditions/prostate-cancer/)

## Adverse effects

### Common

- Diarrhoea
- Nausea and vomiting
- Hot flushes
- Breast enlargement and tenderness
- Loss of libido
- Blue-green or orange urine

### Serious (rare, important)

- Severe, sometimes fatal liver injury
- Breast cancer in men (rare)

## Contraindications

- Women, especially in pregnancy
- Hypersensitivity to flutamide

## Key interactions

**Alcohol**
Its use is discussed with the treating team because of the risk of liver injury.

**Other prescription and non-prescription medicines and supplements**
The team reviews them because doses may need changes or closer monitoring.

## What is monitored

- Liver tests before starting and regularly during treatment
- PSA

## Administration and safety

- Oral capsule every 8 hours, at about the same times each day, with or without food.
- Taken with a GnRH agonist, not alone.

## Nursing care

- Make sure liver tests are done before starting and at the scheduled intervals.
- Teach to report nausea, vomiting, loss of appetite, tiredness, right upper abdominal pain, yellow skin or dark urine.
- Explain that a blue-green or orange urine colour is expected and harmless.
- Teach that the GnRH injections continue alongside.
- Ask about smoking and inherited blood disorders such as G6PD deficiency or haemoglobin M disease.

## Pregnancy and breastfeeding

Only for men; it can harm a fetus if taken during pregnancy.

## Memory aid

FLUtamide FLUshes the urine green and can FLAre the liver.

## Test yourself

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

## What is the active metabolite of flutamide?

Hydroxyflutamide, formed in the liver; it is the molecule that blocks the androgen receptor.

## Which symptoms in a patient on flutamide suggest liver injury?

Nausea, vomiting, loss of appetite, tiredness, right upper abdominal pain, jaundice or dark urine.

## Why has bicalutamide largely replaced flutamide?

Bicalutamide is taken once a day and is generally better tolerated; flutamide needs several doses a day and causes more diarrhoea and liver toxicity.

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## Related drugs

- [Bicalutamide](https://durgical.com/en/pharmacology/bicalutamide/)
- [Enzalutamide](https://durgical.com/en/pharmacology/enzalutamide/)

## Related conditions

- [Prostate cancer](https://durgical.com/en/conditions/prostate-cancer/)

[← Back to the class: Antiandrogens and androgen synthesis inhibitors](https://durgical.com/en/pharmacology/classes/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: [Flutamide: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a697045.html) (MedlinePlus (U.S. National Library of Medicine), 2018); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L02BB01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 73 (McGraw Hill, 2023); [Crystal Structure Of The Androgen Receptor Ligand Binding Domain T877A Mutant In Complex With Hydroxyflutamide](https://www.rcsb.org/structure/2AX6) (RCSB Protein Data Bank, 2005).

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Representative model, for educational purposes only.

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