Bicalutamide Drug Information

• Bicalutamide tablets, USP 50 mg daily are indicated for use in combination therapy with a luteinizing hormone-releasing hormone (LHRH) analog for the treatment of Stage D 2 metastatic carcinoma of the prostate. Bicalutamide tablets, USP 150 mg daily are not approved for use alone or with other treatments.
• Bicalutamide tablet 50 mg is an androgen receptor inhibitor indicated for use in combination therapy with a luteinizing hormone-releasing hormone (LHRH) analog for the treatment of Stage D 2 metastatic carcinoma of the prostate.
• Bicalutamide tablet 150 mg daily is not approved for use alone or with other treatments.

Recommended Dose and Schedule

The recommended dose for bicalutamide tablets therapy in combination with an LHRH analog is one 50 mg tablet once daily (morning or evening), with or without food. It is recommended that bicalutamide tablets be taken at the same time each day. Treatment with bicalutamide tablets should be started at the same time as treatment with an LHRH analog.

If a dose of bicalutamide tablets is missed, take the next dose at the scheduled time. Do not take the missed dose and do not double the next dose.

Dosage Adjustment in Renal Impairment

No dosage adjustment is necessary for patients with renal impairment.

Clinical Trials Experience

In patients with advanced prostate cancer treated with bicalutamide in combination with an LHRH analog, the most frequent adverse reaction was hot flashes (53%). In the multi-center, double-blind, controlled clinical trial comparing bicalutamide 50 mg once daily with flutamide 250 mg three times a day, each in combination with an LHRH analog, the following adverse reactions with an incidence of 5% or greater, regardless of causality, have been reported. Table 1 Incidence of Adverse Reactions (≥ 5% in Either Treatment Group) Regardless of Causality 15 32 Other adverse reactions (greater than or equal to 2%, but less than 5%) reported in the bicalutamide-LHRH analog 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 bicalutamide-LHRH analog treated and flutamide-LHRH analog treated patients.

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of bicalutamide. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Respiratory disorders: Interstitial lung disease (some fatal) including interstitial pneumonitis and pulmonary fibrosis, most often at doses greater than 50 mg.

Hemorrhage: Increased PT/INR due to interaction between coumarin anticoagulants and bicalutamide. Serious bleeding reported. Skin and subcutaneous tissue disorders: Photosensitivity

• Clinical studies have not shown any drug interactions between bicalutamide and LHRH analogs (goserelin or leuprolide). There is no evidence that bicalutamide induces hepatic enzymes. In vitro studies have shown that R-bicalutamide is an inhibitor of CYP 3A4 with lesser inhibitory effects on CYP 2C9, 2C19 and 2D6 activity. Clinical studies have shown that with coadministration of bicalutamide, mean midazolam (a CYP 3A4 substrate) levels may be increased 1.5-fold (for C max ) and 1.9-fold (for AUC). Hence, caution should be exercised when bicalutamide is coadministered with CYP 3A4 substrates. In vitro protein-binding studies have shown that bicalutamide can displace coumarin anticoagulants from binding sites. PT/INR should be closely monitored in patients concomitantly receiving coumarin anticoagulants and bicalutamide. Adjustment of the anticoagulant dose may be necessary.
• R-bicalutamide is an inhibitor of CYP 3A4; therefore, caution should be used when bicalutamide is coadministered with CYP 3A4 substrates.
• PT/INR should be closely monitored in patients already receiving coumarin anticoagulants who are started on bicalutamide.

Pregnancy Risk Summary Bicalutamide is contraindicated for use in pregnant women because it can cause fetal harm. Bicalutamide is not indicated for use in females. There are no human data on the use of bicalutamide in pregnant women.

In animal reproduction studies, oral administration of bicalutamide to pregnant rats during organogenesis caused abnormal development of reproductive organs in male fetuses at exposures approximately 0.7 to 2 times the human exposure at the recommended dose (see Data). Data Animal Data In an embryo-fetal development study in pregnant rats dosed during the period of organogenesis from gestation days 6-15, male fetuses had reduced anogenital distance at doses of 10 mg/kg/day and above (approximately 0.7 to 2 times the human exposure at the recommended dose). In a pre- and post-natal development study, female rats were dosed from gestation day 7-16 and allowed to litter and rear their offspring to weaning.

Male offspring of rats receiving doses of 10 mg/kg/day (approximately 0.7 times the human exposure at the recommended dose) and above, were observed to have reduced anogenital distance. Survival and weights of offspring during lactation were reduced for litters from maternal rats receiving doses of 250 mg/kg/day (approximately 2 times the human exposure at the recommended dose). Female offspring of rats receiving doses of 10 mg/kg/day (approximately 0.7 times the human exposure at the recommended dose) and above had reduced pregnancy rates.

Pediatric Use The safety and effectiveness of bicalutamide in pediatric patients have not been established. Bicalutamide orodispersible tablet was studied in combination with Arimidex # (anastrozole) orodispersible tablet in an open-label, non-comparative, multi-center study that assessed the efficacy and safety of this combination regimen over 12 months in the treatment of gonadotropin-independent precocious puberty in boys with familial male-limited precocious puberty, also known as testotoxicosis. Patients were enrolled in the study if they had a baseline age ≥2 years and a diagnosis of testotoxicosis based on clinical features of progressive precocious puberty, symmetrical testicular enlargement, advanced bone age, pubertal levels of serum testosterone, prepubertal pattern of gonadotropin secretion following a GnRH stimulation test, and absence of other clinical and biochemical causes of testosterone excess.

Thirteen out of the 14 patients enrolled completed 12 months of combination treatment (one patient was lost to follow-up). If central precocious puberty (CPP) developed, an LHRH analog was to be added. Four patients were diagnosed with CPP during the 12-month study and received LHRH analog treatment and 2 additional patients were diagnosed at the end of the 12 months and received treatment subsequently.

The starting bicalutamide dose was 12.5 mg. Bicalutamide was titrated in each patient until steady-state R-bicalutamide (the active isomer of bicalutamide) trough plasma concentration reached 5 mcg/mL to 15 mcg/mL, which is the range of therapeutic concentrations achieved in adults with prostate cancer following the administration of the currently approved bicalutamide dose of 50 mg. The starting daily dose of anastrozole was 0.5 mg.

Anastrozole was independently titrated in each patient until it reached at steady-state a serum estradiol concentration of <10 pmol/L (2.7 pg/mL). For anastrozole there were two ascending doses: 0.5 mg and 1 mg. In the majority of patients, steady-state trough concentrations of R-bicalutamide appeared to be attained by Day 21 with once daily dosing.

Steady-state trough plasma anastrozole concentrations appeared to be attained by Day 8. The primary efficacy analysis of the study was to assess the change in growth rate after 12 months of treatment, relative to the growth rate during the ≥6 months prior to entering the study. Pre-study growth rates were obtained retrospectively.

There was no statistical evidence that the growth rate was reduced during treatment. Table 2 shows descriptive data for growth rates for the overall population and for subgroups defined by history of previous treatment for testotoxicosis with ketoconazole, spironolactone, anastrozole or other aromatase inhibitors. Table 2.

Growth Rates Endpoint Analysis Population Pre-study Mean Change from pre-study to 12 months % patients with growth reduction Change compared to pre-study growth rate. Mean Median (Min, Max) Growth rate (cm/yr) All treated (n=13) PT PT = Previous treatment for testotoxicosis with ketoconazole, spironolactone, anastrozole or other aromatase inhibitors. (n=6) 10.3 -0.2 -2.6 Median calculated as midpoint of 3rd and 4th ranked observations. NPT NPT = no previous treatment for testotoxicosis with ketoconazole, spironolactone, anastrozole, or other aromatase inhibitors. (n=7) Growth rate (SD units) All treated (n=13) PT (n=6) NPT (n=7) Total testosterone concentrations increased by a mean of 5 mmol/L over the 12 months of treatment from a baseline mean of 10 mmol/L.

Six of the 12 patients started treatment at an estradiol concentration below the level of quantification. There were no deaths, serious adverse events, or discontinuations due to adverse events during the study. Of the 14 patients exposed to study treatment, 13 (92.9%) experienced at least one adverse event.

Headache was the only adverse reaction considered possibly related to anastrozole by investigators. For the patient who developed elevated ALT and AST, the elevation was <3X ULN, and returned to normal without stopping treatment; there was no concomitant elevation in total bilirubin.

• Bicalutamide is contraindicated in:
• Hypersensitivity Bicalutamide is contraindicated in any patient who has shown a hypersensitivity reaction to the drug or any of the tablet’s components. Hypersensitivity reactions including angioneurotic edema and urticaria have been reported.
• Women Bicalutamide has no indication for women, and should not be used in this population.
• Pregnancy Bicalutamide can cause fetal harm when administered to a pregnant woman.
• Hypersensitivity
• Women
• Pregnancy

Long-term clinical trials have been conducted with dosages up to 200 mg of bicalutamide daily and these dosages have been well tolerated. A single dose of bicalutamide that results in symptoms of an overdose considered to be life threatening has not been established. There is no specific antidote; treatment of an overdose should be symptomatic.

In the management of an overdose with bicalutamide, vomiting may be induced if the patient is alert. It should be remembered that, in this patient population, multiple drugs may have been taken. Dialysis is not likely to be helpful since bicalutamide is highly protein bound and is extensively metabolized.

General supportive care, including frequent monitoring of vital signs and close observation of the patient, is indicated.