- Capsules 125 mg
Flutamide inhibits androgen uptake or inhibits nuclear binding of androgen in target tissues or both.
Flutamide is rapidly and completely absorbed. T max is approximately 2 h (for the active metabolite).
The parent drug and the active metabolite are 94% to 96% and 92% to 94% protein bound at steady state, respectively.
Flutamide is rapidly and extensively metabolized to at least 6 metabolites. The active metabolite is hydroxyflutamide.
The t ½ is about 6 h (active metabolite). The drug is excreted primarily in the urine with 4.2% excreted in feces.Hemodialysis
The parent drug and active metabolite are not well dialyzed.
Special PopulationsRenal Function Impairment
The t ½ is slightly prolonged. No dosage adjustment is necessary.Elderly
The 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).
Treatment of hirsutism in women (250 mg/day).
Patients with severe hepatic function impairment.
Dosage and AdministrationProstate Cancer
PO 250 mg (2 capsules) every 8 h.Stage B 2 -C Prostatic Carcinoma
PO Start treatment at 8 wk prior to initiating radiation therapy and continue during radiation therapy.Stage D 2 Metastatic Carcinoma
PO Initiate flutamide capsules with the LHRH agonist and continue until progression.
- For patients unable to swallow capsules, open the capsule and mix the contents with applesauce, pudding, or other semi-solid foods. Administer immediately.
Store between 2° and 30°C (36° and 86°F). Protect unit dose packages from excessive moisture.
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.
Hot flashes, gynecomastia.
Low potential for nausea and vomiting; diarrhea; hepatocellular necrosis; cholestatic jaundice; elevated LFTs.
Impotence; reduced sperm count.
Hospitalization 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.
Monitor 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).
Category D .
A metabolite of flutamide, 4-nitro-3-fluoro-methylaniline, may cause methemoglobinemia, hemolytic anemia, and cholestatic jaundice in patients treated with flutamide.
Flutamide is used only in men.
Hypoactivity; piloerection; slow respiration; ataxia; lacrimation; anorexia; tranquilization; emesis; methemoglobinemia.
- 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.
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