Flutamide
PronunciationPronunciation: FLEW-tuh-mide
Class: Antiandrogen
Trade Names
Flutamide
- Capsules 125 mg
Euflex (Canada)
Pharmacology
Flutamide inhibits androgen uptake or inhibits nuclear binding of androgen in target tissues or both.
Pharmacokinetics
Absorption
Flutamide is rapidly and completely absorbed. T max is approximately 2 h (for the active metabolite).
Distribution
The parent drug and the active metabolite are 94% to 96% and 92% to 94% protein bound at steady state, respectively.
Metabolism
Flutamide is rapidly and extensively metabolized to at least 6 metabolites. The active metabolite is hydroxyflutamide.
Elimination
The t ½ is about 6 h (active metabolite). The drug is excreted primarily in the urine with 4.2% excreted in feces.
HemodialysisThe parent drug and active metabolite are not well dialyzed.
Special Populations
Renal Function ImpairmentThe t ½ is slightly prolonged. No dosage adjustment is necessary.
ElderlyThe t ½ and T max are slightly prolonged.
Indications and Usage
Metastatic prostate cancer, combination therapy with a luteinizing hormone-releasing hormone (LHRH) analog (eg, goserelin, leuprolide).
Unlabeled Uses
Treatment of hirsutism in women (250 mg/day).
Contraindications
Patients with severe hepatic function impairment.
Dosage and Administration
Prostate CancerAdults
PO 250 mg (2 capsules) every 8 h.
Stage B 2 -C Prostatic CarcinomaAdults
PO Start treatment at 8 wk prior to initiating radiation therapy and continue during radiation therapy.
Stage D 2 Metastatic CarcinomaAdults
PO Initiate flutamide capsules with the LHRH agonist and continue until progression.
General Advice
- For patients unable to swallow capsules, open the capsule and mix the contents with applesauce, pudding, or other semi-solid foods. Administer immediately.
Storage/Stability
Store between 2° and 30°C (36° and 86°F). Protect unit dose packages from excessive moisture.
Drug Interactions
Prothrombin time may increase when flutamide therapy is initiated in patients stabilized on chronic warfarin therapy.
Laboratory Test Interactions
Elevated AST, ALT, bilirubin, SGGT, BUN, and serum creatinine.
Adverse Reactions
CNS
Decreased libido.
Endocrine
Hot flashes, gynecomastia.
GI
Low potential for nausea and vomiting; diarrhea; hepatocellular necrosis; cholestatic jaundice; elevated LFTs.
Genitourinary
Impotence; reduced sperm count.
Precautions
WarningsHepatic injuryHospitalization and rarely death from liver failure. Evidence of hepatic injury included elevated serum transaminase levels, jaundice, hepatic encephalopathy, and death related to acute hepatic failure. The hepatic injury was reversible after discontinuation of therapy in some patients. Approximately 50% of the reported cases occurred within the initial 3 mo of treatment. |
MonitorMonitor serum transaminase levels at baseline and monthly during the first 4 mo of treatment. Monitor periodically during continued treatment, especially if the patient experiences signs and symptoms of liver dysfunction. Immediately discontinue flutamide if ALT increases more than 2 times above the upper limit of normal. Monitor methemoglobin levels in patients susceptible to aniline toxicity (eg, people with glucose-6-phosphate dehydrogenase deficiency or hemoglobin M disease as well as patients who smoke). |
Pregnancy
Category D .
Aniline exposure
A metabolite of flutamide, 4-nitro-3-fluoro-methylaniline, may cause methemoglobinemia, hemolytic anemia, and cholestatic jaundice in patients treated with flutamide.
Women
Flutamide is used only in men.
Overdosage
Symptoms
Hypoactivity; piloerection; slow respiration; ataxia; lacrimation; anorexia; tranquilization; emesis; methemoglobinemia.
Patient Information
- The urine was noted to change to an amber or yellow-green appearance.
- Photosensitization may occur.
- Flutamide and LHRH-agonists should be administered concomitantly; and do not interrupt dosing or stop taking these medications without consulting the health care provider.
Copyright © 2009 Wolters Kluwer Health.
More Flutamide resources
- Flutamide Prescribing Information (FDA)
- Flutamide Monograph (AHFS DI)
- flutamide Advanced Consumer (Micromedex) - Includes Dosage Information
- flutamide Concise Consumer Information (Cerner Multum)
- flutamide MedFacts Consumer Leaflet (Wolters Kluwer)
- Eulexin Prescribing Information (FDA)
