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Flutamide (Monograph)

Brand name: Eulexin
Drug class: Antineoplastic Agents
- Antiandrogens
VA class: AN900
Chemical name: 2-Methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]-propanamide
Molecular formula: C11H11F3N2O3
CAS number: 13311-84-7

Medically reviewed by on Jun 21, 2023. Written by ASHP.


  • Severe liver injury (i.e., increased serum transaminase concentrations, jaundice, hepatic encephalopathy, acute hepatic failure) reported, sometimes resulting in hospitalization and/or rarely death; manifestations generally occurred within first 3 months and in some patients, were reversible after discontinuance.

  • Measure serum transaminase concentrations prior to initiation of therapy, monthly during first 4 months, and periodically thereafter.

  • Immediately measure serum transaminase (especially ALT) concentrations if manifestations suggestive of liver dysfunction (e.g., nausea, vomiting, abdominal pain, fatigue, anorexia, flu-like symptoms, hyperbilirubinuria, jaundice, right upper quadrant tenderness) occur.

  • Immediately discontinue if jaundice develops or serum ALT concentration is >2 times ULN; monitor liver function closely until resolves.


Antineoplastic agent; a nonsteroidal antiandrogen.

Uses for Flutamide

Prostate Cancer

First-line therapy in combination with a luteinizing hormone-releasing hormone (LHRH) analog (e.g., goserelin, leuprolide acetate, triptorelin) for prostate cancer.

Treatment of locally confined (stage B2 or C) and metastatic (stage D2) prostate cancer; should be used in conjunction with an LHRH analog.

Flutamide Dosage and Administration


  • In patients with stage B2 or C prostate cancer, initiate flutamide and LHRH analog 8 weeks prior to and continue during radiation therapy.

  • In patients with stage D2 metastatic prostate cancer, initiate flutamide and LHRH analog concomitantly and continue until disease progression.


Oral Administration

Administer orally 3 times daily at 8-hour intervals without regard to meals .



Prostate Cancer

250 mg 3 times daily, at 8-hour intervals.

Cautions for Flutamide


  • Known hypersensitivity to flutamide or any ingredient in the formulation.

  • Severe hepatic impairment.



Hepatic Effects

For warnings regarding hepatotoxicity, see Boxed Warning.

Use in Women

Not intended for use in women, particularly for nonserious or nonlife-threatening conditions.

Fetal/Neonatal Morbidity and Mortality

May cause fetal harm if used in pregnant women.

Aniline Toxicity

Metabolized in part to 4-nitro-3-fluoro-methylaniline; toxicities associated with aniline exposure (i.e., methemoglobinemia, hemolytic anemia, cholestatic jaundice) reported.

Monitor methemoglobin concentrations periodically in susceptible patients (e.g., those with glucose-6-phosphate dehydrogenase deficiency, hemoglobin M disease, smokers).

Sensitivity Reactions


Photosensitivity reactions (i.e., erythema, ulceration, bullous eruptions, epidermal necrolysis) reported.

General Precautions

Endocrine Effects

Possible gynecomastia.

Laboratory Monitoring

Regularly monitor serum PSA to assess response; if PSA increases, evaluate possible disease progression.

For patients with objective progression of disease and elevated serum PSA, consider temporarily withdrawing flutamide while continuing LHRH analog.

Specific Populations


Category D. (See Fetal/Neonatal Morbidity and Mortality under Warnings.)


Not intended for use in women.

Pediatric Use

Not studied in pediatric patients.

Hepatic Impairment

Contraindicated in patients with severe hepatic impairment. (See Boxed Warning.)


Not intended for use in women, particularly for nonserious or nonlife-threatening conditions.

Common Adverse Effects

Combined therapy with LHRH analog: hot flashes, loss of libido, impotence, diarrhea, nausea, vomiting, gynecomastia.

Cystitis, rectal bleeding, proctitis, skin rash, hematuria also frequent when flutamide combined with LHRH analog and radiation therapy.

Interactions for Flutamide

Specific Drugs





Increased risk of facial flushing

Avoid alcohol consumption during therapy

LHRH analog (e.g., goserelin, leuprolide)

Pharmacokinetic interaction unlikely


Increased PT reported

Closely monitor PT; adjust anticoagulant dosage as needed

Flutamide Pharmacokinetics



Rapidly and completely absorbed following oral administration, with peak plasma concentrations of active metabolite (2-hydroxyflutamide) attained within about 2 hours.


Food does not affect bioavailability.

Special Populations

In patients with chronic renal impairment, there appears to be no correlation between creatinine clearance and maximum plasma concentrations or AUC of flutamide; renal impairment did not affect maximum plasma concentrations or AUC of active metabolite.


Plasma Protein Binding

Flutamide: 94–96%; 2-hydroxyflutamide: 92–94%.



Rapidly and extensively metabolized to ≥6 metabolites, including an active α-hydroxylated derivative, 2-hydroxyflutamide.

Elimination Route

Excreted principally in urine and to lesser extent in feces (4.2%) as unchanged drug and metabolites.


2-Hydroxyflutamide: about 6 hours after a single 250-mg dose.

Special Populations

In patients with renal impairment (Clcr <29 mL/minute), half-life of active metabolite was slightly prolonged; no dosage adjustment necessary in chronic renal impairment.

In geriatric patients, half-life of active metabolite is about 8 hours after a single 250-mg dose.

Pharmacokinetics not studied in patients with hepatic impairment, women, or pediatric patients.





2–30°C. Protect unit dose packages from excessive moisture.


  • A selective antiandrogen with no estrogenic, antiestrogenic, progestational, antiprogestational, antigonadotropic, or adrenocortical activity in various animal models.

  • Competitively blocks nuclear androgen receptors in target tissues (e.g., prostate, seminal vesicles, adrenal cortex).

  • Blockade of androgen receptors in the hormone-sensitive tumor cells may result in growth arrest or transient tumor regression through inhibition of androgen-dependent DNA and protein synthesis.

  • Inhibits initial androgenic stimulation and potential exacerbation of symptoms (e.g., bone pain, urinary obstruction, liver pain, impending spinal cord compression) associated with the first month of LHRH analog therapy.

Advice to Patients

  • Risk of liver toxicity. Importance of adhering to schedule for laboratory monitoring of serum transaminases and reporting signs or symptoms of hepatic toxicity to clinician immediately.

  • Importance of initiating flutamide concomitantly with LHRH analog and of not interrupting or discontinuing therapy without consulting a clinician.

  • Risk of facial flushing, particularly if used in conjunction with alcohol. Avoidance of alcohol recommended if flushing occurs.

  • Not intended for use in women.

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well concomitant illnesses.

  • Importance of informing patients of other important precautionary information. (See Cautions.)


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name



Dosage Forms


Brand Names




125 mg*

Eulexin (with parabens and povidone;)


Flutamide Capsules

Barr, Genpharm, Sandoz, Teva

AHFS DI Essentials™. © Copyright 2023, Selected Revisions July 1, 2006. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

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Frequently asked questions