Non-steroidal anti-androgen Pregnancy: Indicated for use in male patients only; contraceptive measures should be taken during treatment. May cause foetal harm if administered to a pregnant woman (US labelling: Pregnancy Category D). Safety in human pregnancy or lactation not established.

Flutamide

Brand names: Drogenil

Flutamide is a non-steroidal anti-androgen used, usually with a gonadotrophin-releasing hormone analogue or surgical castration, in the management of metastatic prostate cancer.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 250 mg (one tablet)

Route: Oral

Frequency: Three times daily

Flutamide 250 mg tablet, one tablet three times daily. When used as initial treatment with an LHRH-agonist, it is recommended to start flutamide at least three days before the LHRH-agonist and continue thereafter at the same dose (to reduce the LHRH-agonist flare reaction). Tablets are preferably taken after meals. Only indicated for use in male patients. In impaired liver function, long-term treatment should only be initiated after careful benefit-risk assessment; administer with caution in impaired renal function. Liver function tests before treatment and monthly for the first 4 months, then periodically.

Dose adjustments

Renal

Administer with caution in patients with impaired renal function (no specific dose given in SPC).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to flutamide or any other component of the preparation (withdraw immediately if hypersensitivity reactions occur)
Severe hepatic impairment (per US labelling; baseline hepatic enzymes should be evaluated prior to treatment)

Side effects

Gynaecomastia, breast tenderness, galactorrhoea (very common; resolve on discontinuation or dose reduction)
Nausea, vomiting, diarrhoea (common)
Increased appetite, insomnia (common)
Somnolence, tiredness (common); transient abnormal liver function (common)
Hepatitis and liver function test abnormalities; hepatotoxicity may be fatal (see warnings)

Interactions

Warfarin - increases in prothrombin time noted after flutamide initiated; monitor prothrombin time and adjust anticoagulant dose as necessary
Medicinal products that prolong the QT interval - assess benefit-risk (including Torsade de pointes potential) before initiating

Clinical monograph

How it works

It competitively blocks androgen receptors in target tissues, preventing dihydrotestosterone and testosterone from stimulating prostate tumour growth.

Prescribing in practice

Hepatotoxicity, including fatal hepatic failure, is the key risk; check liver function before and periodically during treatment and stop promptly if jaundice or transaminase rise occurs.
When used for prostate cancer it is typically combined with castration (medical or surgical) to achieve complete androgen blockade.
Counsel that it is not indicated in women or children and review interacting drugs, including warfarin, against current prescribing references.

Monitoring

Monitor liver function tests at baseline and at regular intervals, with prompt re-checking if symptoms of hepatic dysfunction arise.

Counselling the patient

Report yellowing of the skin or eyes, dark urine, nausea or right-sided abdominal pain straight away.
Gynaecomastia and breast tenderness are common; tell your team if troublesome.
Urine may take on an amber or greenish discolouration, which is harmless.

Evidence & guidelines

Anti-androgens combined with castration are established in prostate cancer management as reflected in UK and international oncology guidance.

Reference: NICE NG131; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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