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Bicalutamide
CASODEX® (bicalutamide) Tablets for oral administration contain 50 mg of bicalutamide, a nonsteroidal antiandrogen with no other known endocrine activity. The chemical name is propanamide, N-[4-cyano-3-(trifluoromethyl)phenyl]-3-[(4-fluorophenyl) sulfonyl]-2-hydroxy-2-methyl-,(+-). Bicalutamide has a following molecular formaula: C18H14N2O4F4S. Bicalutamide has a molecular weight of 430.37. The pKa is approximately 12. Bicalutamide is a fine white to off-white powder which is practically insoluble in water at 37°C (5 mg per 1000 mL), slightly soluble in chloroform and absolute ethanol, sparingly soluble in methanol, and soluble in acetone and tetrahydrofuran. CASODEX is a racemate with its antiandrogenic activity being almost exclusively exhibited by the R-enantiomer of bicalutamide; the S-enantiomer is essentially inactive. The inactive ingredients of CASODEX Tablets are lactose, magnesium stearate,
methylhydroxypropylcellulose, polyethylene glycol, polyvidone, sodium
starch glycollate, and titanium dioxide.
Mechanism of Action: CASODEX is a non-steroidal antiandrogen. It competitively inhibits the action of androgens by binding to cytosol androgen receptors in the target tissue. Prostatic carcinoma is known to be androgen sensitive and responds to treatment that counteracts the effect of androgen and/or removes the source of androgen. When CASODEX is combined with luteinizing hormone-releasing hormone (LHRH) analogue therapy, the suppression of serum testosterone induced by the LHRH analogue is not affected. However, in clinical trials with CASODEX as a single agent for prostate cancer, rises in serum testosterone and estradiol have been noted. Pharmacokinetics Absorption: Bicalutamide is well-absorbed following oral administration, although the absolute bioavailability is unknown. Co-administration of bicalutamide with food has no clinically significant effect on rate or extent of absorption. Distribution: Bicalutamide is highly protein-bound (96%). See Drug-Drug Interactions below. Metabolism/ Elimination: Bicalutamide undergoes stereo specific metabolism. The S (inactive) isomer is metabolized primarily by glucuronidation. The R (active) isomer also undergoes glucuronidation but is predominantly oxidized to an inactive metabolite followed by glucuronidation. Both the parent and metabolite glucuronides are eliminated in the urine and feces. The S-enantiomer is rapidly cleared relative to the R-enantiomer, with the R-enantiomer accounting for about 99% of total steady-state plasma levels. Special Populations Geriatric: In two studies in patients given 50 or 150 mg daily, no significant relationship between age and steady-state levels of total bicalutamide or the active R-enantiomer has been shown. Hepatic Insufficiency: No clinically significant difference in the pharmacokinetics of either enantiomer of bicalutamide was noted in patients with mild-to-moderate hepatic disease as compared to healthy controls. However, the half-life of the R-enantiomer was increased apprpximately 76% (5.9 and 10.4 days for normal and impaired patients, respectively) in patients with severe liver disease (n= 4). Renal Inefficiency: Renal impairment (as measured by creatinine clearance) had no significant effect on the elimination of total bicalutamide or the active R-enantiomer. Women, Pediatrics: Bicalutamide has not been studied in women or pediatric subjects. Drug-Drug Interactions: Clinical studies have not shown any drug interactions between bicalutamide and LHRH analogues (goserelin or leuprolide). There is no evidence that bicalutamide induces hepatiç enzymes. In vitro protein-binding studies have shown that bicalutamide can displace coumarin anticoagulants from binding sites. Prothrombin times should be closely monitored in patients already receiving coumarin anticoagulants who are started on CASODEX. Pharmacokinetics of the active enantiomer of CASODEX in normal males and patients with prostate cancer are presented in Table 1. Table 1.
Css= Mean Steady-State Concentration Clinical Studies In a multicenter, double-blind, controlled clinical trial, 813 patients with previously untreated advanced prostate cancer were randomized to receive CASODEX 50 mg once daily (404 patients) or flutamide 250 mg (409 patients) three times a day, each in combination with LHRH analogues (either goserelin acetate implant or leuprolide acetate depot). In an analysis conducted after a median follow-up of 160 weeks was reached, 213 (52.7%) patients treated with CASODEX-LHRH analogue therapy and 235 (57.5%) patients treated with flutamide-LHRH analogue therapy had died. There was no significant difference in survival between treatment groups. The hazard ratio for time to death (survival) was 0.87 (95% confidence interval 0.72 to 1.05). There was no significant difference in time to objective tumor progression between treatment groups. Objective tumor progression was defined as the appearance of any bone metastases or the worsening of any existing bone metastases on bones can attributable to metastatic disease, or an increase by 25% or more of any existing measurable extra skeletal metastases. The hazard ratio for time to progression of CASODEX plus LHRH analogue to that of flutamide plus LHRH analogue was 0.93 (95% confidence interval, 0.79 to 1.10). Quality of life was assessed with self-administered patient questionnaires
on pain, social functioning, emotional well-being, vitality, activity
limitation, bed disability, overall health, physical capacity, general
symptoms, and treatment related symptoms. Assessment of the Quality of
Life questionnaires did not indicate consistent significant differences
between the two treatment groups.
CASODEX is indicated for use in combination therapy with a luteinizing hormone-releasing hormone (LHRH) analogue for the treatment of Stage D2 metastatic carcinoma of the prostate.
The recommended dose for CASODEX therapy in combination with an LHRH analogue is one 50 mg tablet once daily (morning or evening), with or without food. It is recommended that CASODEX be taken at the same time each day. Treatment with CASODEX should be started at the same time as treatment with an LHRH analogue. Dosage Adjustment in Renal Impairment: No dosage adjustment is necessary for patients with renal impairment (See CLINICAL PHARMACOLOGY, Special Populations, Renal Insufficiency). Dosage Adjustment in Hepatic Impairment: No dosage adjustment is necessary for patients with mild to moderate hepatic impairment. Although there is a 76% (5.9 and 10.4 days for normal and impaired patients, respectively) increase in the half-life of the active enantiomer of bicalutamide in patients with severe liver impairment (n = 4), no dosage adjustment is necessary (see CLINICAL PHARMACOLOGY, Special Populations, Hepatic Impairment and PRECAUTIONS sections). HOW SUPPLIED 50 mg Tablets. (NDC 0310-0705) White, film-coated tablets (identified on one side with “CDX50” and on the reverse with the “CASODEX logo”) are supplied in unit dose blisters of 30 tablets per carton (0310-0705-39), bottles of 30 tablets (0310-0705-30) and bottles of 100 tablets (0310-0705-10). Store at controlled room temperature, 20°-25°C (68°-77°F).
In patients with advanced prostate cancer treated with CASODEX in combination with an LHRH analogue, the most frequent adverse experience was hot flashes (53%). In the multicenter, double-blind, controlled clinical trial comparing CASODEX 50 mg once daily with flutamide 250 mg three times a day, each in combination with an LHRH analogue, the following adverse experiences with an incidence of 5% or greater, regardless of causality, have been reported. Table 2 Incidence of Adverse Events (ł5% In Either Treatment Group) Regardless of Causality
† Increased liver enzyme test includes increases in AST, ALT or both. ‡ Anemia includes anemia, hypochromic-and iron deficiency anemia Other adverse experiences (greater than or equal to 2%, but less than 5%) reported in the CASODEX-LHRH analogue treatment group are listed below by body system and are in order of decreasing frequency within each body system regardless of causality. Body as a Whole: Neoplasm; Neck pain; Fever; Chills; Sepsis; Hernia; Cyst Cardiovascular: Angina pectoris; Congestive heart failure; Myocardial infarct; Heart arrest; Coronary artery disorder; Syncope Digestive: Melena; Rectal hemorrhage; Dry mouth; Dysphagia; Gastrointestinal disorder; Periodontal abscess; Gastrointestinal carcinoma Metabolic and Nutritional: Edema; BUN increased; Creatinine increased; Dehydration; Gout; Hypercholesteremia Musculoskeletal: Myalgia; Leg cramps Nervous: Hypertonia; Confusion; Somnolence; Libido decreased; Neuropathy; Nervousness Respiratory: Lung disorder; Asthma; Epistaxis; Sinusitis Skin and Appendages: Dry skin; Alopecia; Pruritus; Herpes zoster; Skin carcinoma; Skin disorder Special Senses: Cataract specified Urogenital: Dysuria; Urinary urgency; Hydronephrosis; Urinary tract disorder Abnormal Laboratory Test Values: Laboratory abnormalities including elevated AST, ALT, bilirubin, BUN, and creatinine and decreased hemoglobin and white cell count have been reported in both CASODEX-LHRH analogue treated and flutamide LHRH analogue treated patients.
In vitro studies have shown CASODEX can displace coumarin anticoagulants,
such as warfarin, from their protein-binding sites. It is recommended
that if CASODEX is started in patients already receiving coumarin anticoagulants,
prothrombin times should be closely monitored and adjustment of the anticoagulant
dose may be necessary (see CLINICAL
PHARMACOLOGY, Drug-Drug Interactions).
No information provided.
General 1. CASODEX should be used with caution in patients with moderate-to-severe hepatic impairment. CASODEX is extensively metabolized by the liver. Limited data in subjects with severe hepatic impairment suggest that excretion of CASODEX may be delayed and could lead to further accumulation. Periodic liver function tests should be considered for patients on long-term therapy. 2. In clinical trials with CASODEX as a single agent for prostate cancer, gynecomastia and breast pain have been reported in up to 38% and 39% of patients, respectively. 3. Regular assessments of serum Prostate Specific Antigen (PSA) may be helpful in monitoring the patient’s response. If PSA levels rise during CASODEX therapy, the patient should be evaluated for clinical progression. For patients who have objective progression of disease together with an elevated PSA, a treatment-free period of antiandrogen, while continuing the LHRH analogue, may be considered. 4. Since transaminase abnormalities and, rarely, jaundice have been reported with the use of CASODEX, periodic liver function tests should be considered. If clinically indicated, e. g., when the patient has jaundice or laboratory evidence of liver injury in the absence of liver metastases, CASODEX therapy should be discontinued. If transaminases increase over 2 times the upper limit of normal, treatment should be discontinued. Abnormalities are usually reversible upon discontinuation. Information for Patients See PATIENT INFORMATION section. Drug Interactions See DRUG INTERACTIONS section. Carcinogenesis, Mutagenesis, Impairment of Fertility Two-year oral carcinogenicity studies were conducted in both male and female rats and mice at doses of 5, 15 or 75 mg/kg/day of bicalutamide. A variety of tumor target organ effects were identified and were attributed to the antiandrogenicity of bicalutamide, namely, testicular benign interstitial (Leydig) cell tumors in male rats at all dose levels (the steady-state plasma concentration with the 5 mg/kg/day dose is approximately 2/3 human therapeutic concentrations*) and uterine adenocarcinoma in female rats at 75 mg/kg/day (approximately 11/2 times the human therapeutic concentrations*). There is no evidence of Leydig cell hyperplasia in patients; uterine tumors are not relevant to the indicated patient population. A small increase in the incidence of hepatocellular carcinoma in male mice given 75 mg/kg/day of bicalutamide (approximately 4 times human therapeutic concentrations*) and an increased incidence of benign thyroid follicular cell adenomas in rats given 5 mg/kg/day (approximately 2/3 human therapeutic concentrations*) and above were recorded. These neoplastic changes were progressions of non-neoplastic changes related to hepatic enzyme induction observed in animal toxicity studies. Enzyme induction has not been observed following bicalutamide administration in man. There were no tumorigenic effects suggestive of genotoxic carcinogenesis. A comprehensive battery of both in vitro and in vivo genotoxicity tests (yeast gene conversion, Ames, E. coli, CHO/HGPRT, human lymphocyte cytogenetic, mouse micronucleus, and rat bone marrow cytogenetic tests) has demonstrated that CASODEX does not have genotoxic activity. Administration of CASODEX may lead to inhibition of spermatogenesis. The long-term effects of CASODEX on male fertility have not been studied. In male rats dosed at 250 mg/kg/day (approximately 2 times human therapeutic concentrations*), the precoital interval and time to successful mating were increased in the first pairing but no effects on fertility following successful mating were seen. These effects were reversed by 7 weeks after the end of an 11-week period of dosing. No effects on female rats dosed at 10, 50 and 250 mg/kg/day (approximately 2/3, 1 and 2 times human therapeutic concentrations, respectively*) or their female offspring were observed. Administration of bicalutamide to pregnant females resulted in feminization of the male offspring leading to hypospadias at all dose levels. Affected male offspring were also impotent. *Based on a maximum dose of 50 mg/day of bicalutamide for an average 70 kg patient. Pregnancy: Pregnancy Category X (see CONTRAINDICATIONS). Nursing Mothers CASODEX is not indicated for use in women. It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when CASODEX is administered to a nursing woman. Pediatric Use Safety and effectiveness of CASODEX in pediatric patients have not been
established.
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