Bicalutamide is a drug used in the treatment of metastatic prostate cancer. It is used as a combination therapy, along with gonadotropin-releasing hormone agonists (GnRH) like Leuprolide and Goserelin. It belongs to a class of medicines called non-steroidal antiandrogens. It works by blocking the actions of a male hormone called androgen that stops the growth and spread of cancer cells. Bicalutamide is available as tablets to be taken orally along with an injection of luteinizing hormone-releasing hormone (LHRH). The combination therapy does not cure cancer; however, it stops the growth and spread of cancer cells. Bicalutamide is manufactured by the AstraZeneca group of companies. FDA (Food and Drugs Administration) approved for the use of the drug on the 19th of December 2008.
How Does Bicalutamide Work?
The prostate cancer cells need a male hormone called androgen or testosterone to grow. Bicalutamide belongs to a group of medications called antiandrogens. It works by stopping the testosterone from reaching the cancer cells. This is believed to slow the growth of cancer cells and even shrink their size.
Indications and Uses:
Bicalutamide 50 mg daily is indicated to treat stage D2 metastatic carcinoma of the prostate. It is indicated for use in a combination therapy along with LHRH (luteinizing hormone-releasing hormone). A daily dose of 150 mg of Bicalutamide is not recommended for use alone or as a combination therapy.
Dosage and Administration:
Recommended Dose and Schedule:
The recommended dose of Bicalutamide along with LHRH analog is a 50 mg tablet to be taken orally in the morning or evening, either with or without food. It is recommended to take the dose at the same time every day. Also, treatment with Bicalutamide must be started at the same time as treatment with LHRH analog. If a dose is missed, the next scheduled dose must be taken. It is not advised to take the missed dose or double the next dose to make up for the missed dose.
Dose Adjustment in Renal Impairment:
A dose adjustment is not required in patients with renal impairment.
Dose Adjustment in Hepatic Impairment:
No dose adjustment is required in patients with mild and moderate hepatic impairment. In patients with severe hepatic impairment, it was noted that there was a 76 % increase in the half-life, which increased from 5.9 days to 10.4 days when compared to normal people; still, no dosage adjustment is necessary.
Dosage Forms and Strengths:
Bicalutamide is available in a dosage of 50 mg tablets to be administered orally.
Bicalutamide is contraindicated in the following conditions:
Bicalutamide is a contraindication for patients with a history of hypersensitivity to the drug or its ingredients. Hypersensitivity reactions like urticaria and angioneurotic edema have been reported.
Bicalutamide is not required in females and should not be used in this population group.
Bicalutamide use is contraindicated in pregnancy as it can cause fetal harm.
Warnings and Precautions:
Cases of hospitalization and death have been reported during post marketing due to the use of Bicalutamide. The reason for the serious instances was a severe liver injury or hepatic failure. Hepatotoxicity was noted within the first three to four months of the start of treatment. In controlled clinical trials, hepatitis or an elevation of the liver enzymes led to the discontinuation of drug use in approximately 1 % of patients on Bicalutamide.
In case of signs and symptoms that suggest a liver dysfunction like nausea, vomiting, abdominal pain, anorexia, lethargy, dark urine, jaundice, tenderness of the right upper abdominal quadrant, or "flu-like" symptoms, the serum transaminases, mainly the serum ALT (alanine transaminase) levels must be checked. Levels of serum transaminases should be checked before starting treatment with Bicalutamide, at regular intervals during the first four months of treatment, and periodically throughout the treatment phase. The use of Bicalutamide should be stopped immediately in cases where the patients present with symptoms of jaundice or in whom the ALT levels have doubled when compared to the normal upper limit. Also, a close follow-up of the liver functioning is recommended.
Hemorrhage With a Consequent Use of Coumarin Anticoagulant:
Cases of elevated prothrombin time (PT) and International Normalized Ratio (INR) days to weeks after introducing Bicalutamide in patients who were previously stable on coumarin anticoagulants have been noted. Patients have reported severe bleeding, including intracranial, retroperitoneal, and gastrointestinal bleeding. They required blood transfusion or Vitamin K administration. It is advised to monitor PT and INR closely and adjust the anticoagulant dose when needed.
Gynecomastia and Breast pain:
Clinical trials on Bicalutamide 150 mg, which was used as a single therapy for prostate cancer, showed that there were gynecomastia and breast pain in 38% and 39% of patients, respectively.
Reduced glucose tolerance was noted in patients receiving LHRH agonists. This leads to the development of diabetes or a loss of glycemic control in people with prediabetes. Glucose monitoring is therefore necessary for patients receiving Bicalutamide and LHRH agonists.
Regular testing of serum prostate-specific antigen (PSA) is required to monitor for a rise in PSA levels. If, during treatment, the PSA levels rise along with a clinical progression of the disease, it is suggested to go for a treatment-free period while only continuing the LHRH analog.
The most common adverse reaction noted with Bicalutamide was hot flashes accounting for 53 % of the adverse effects. In a multi-center, double-blind, controlled clinical trial that compared Bicalutamide 50 mg once daily dose and Flutamide 250 mg thrice daily, the following adverse effects were noted, that included:
In the Body as a Whole:
Cardiovascular Adverse Effects:
Digestive Adverse Effects:
Musculoskeletal Adverse Effects:
Metabolic and Nutritional Adverse Effects:
Nervous Adverse Effects:
Respiratory Adverse Effects:
Adverse Effects on the Skin:
Special Senses Adverse Effects:
Urogenital Adverse Effects:
Abnormalities in the laboratory findings included an elevated AST (aspartate aminotransferase), ALT (alanine transaminase), bilirubin, creatinine, and BUN. Also, there was a decrease in the hemoglobin and white blood cell count in patients on Bicalutamide-LHRH analogs and Flutamide-LHRH analogs.
What Is Prostate Cancer?
Prostate cancer is a type of cancer that occurs in a small gland called the prostate gland in males. The prostate gland produces the seminal fluid that nourishes and helps transport the sperm.It is a common type of cancer that is mostly benign, with the cancer cells confined to the gland. However, some types of prostate cancers are aggressive, divide fast, and spread to different body parts. Early detection and the start of treatment can help in a better cure.
What Are the Causes and Symptoms of Prostate Cancer?
The exact cause of prostate cancer is unknown. However, it is believed that mutations in the cancer cells' genetic material can lead to a tumor's development. The risk factors for developing prostate cancer include age older than 50, black race, family history, and obesity.
The early stages of prostate cancer do not have any signs and symptoms. However, advanced and aggressive forms present with the following symptoms that include:
Difficulty in urination.
Decreased force in the stream of urine.
Blood in the urine.
Blood in the semen.
Pain in bones.
Unexplained weight loss.
How Is Prostate Cancer Diagnosed and Treated?
Prostate screening is done by digital rectal examination in which the doctor inserts a lubricated, gloved finger into the patient's rectum and checks the back part of the prostate for any lumps or growths. Another test to diagnose prostate cancer is a PSA (prostate-specific antigen) test. It detects the levels of elevated PSA in blood. High levels can occur due to an infection, inflammation, or tumors of the prostate. An ultrasound scan, MRI (magnetic resonance imaging), or biopsy can help diagnose the condition.
Prostate cancer that is not aggressive can be left untreated with active surveillance and periodic checkups. However, severe cases are treated with different treatment modalities like radiation, surgery, chemotherapy, medications that reduce testosterone levels in the body, immunotherapy, and targeted drug therapy. Bicalutamide is one medicine that, when given in conjunction with LHRH, blocks testosterone from reaching the cancer cells, thereby decreasing their growth.
Clinical studies did not show any drug interactions between Bicalutamide and LHRH analogs like Goserelin and Leuprolide. Also, Bicalutamide did not induce hepatic enzymes. In vitro studies have shown that Bicalutamide is an inhibitor of the CYP3A4 enzyme system. Co-administration of Bicalutamide with Midazolam thereby increased its activity to 1.5 times. Therefore, care must be taken when Bicalutamide is co-administered with medications metabolized by the CYP3A4 enzyme. Also, care must be exercised when Bicalutamide and coumarin anticoagulants are administered together. Regular monitoring of PT and INR is mandatory, and an anticoagulant dose adjustment is necessary in case of bleeding episodes. The inhibitory effects of Bicalutamide on CYP2C9, CYP2C19, and CYP 2D6 were comparatively lesser.
Use in Specific Populations:
Bicalutamide is not indicated for use in females. Also, it is contraindicated in pregnancy as it can cause fetal harm. Animal studies were conducted on rats, during which male rats administered Bicalutamide showed abnormal development of the reproductive organs. They were administered 0.7 to 2 times the maximum human recommended dose.
There is no sufficient data available on the presence of Bicalutamide in human milk, nor the milk production or adverse effects on the breastfed infant. However, traces of Bicalutamide have been detected in the milk of rats.
Males of Reproductive Potential:
There is evidence that antiandrogen therapy can affect the morphology of spermatozoa. Based on animal studies, female partners of male patients are advised to use effective contraception during and 130 days after the final dose of Bicalutamide.
The long-term effects on male fertility with Bicalutamide use are yet to be studied. However, animal studies have shown an inhibitory effect on spermatogenesis, affecting male fertility.
Bicalutamide's safe and effective use on pediatric patients has not yet been studied.
Patients administered 50 mg and 150 mg Bicalutamide in two separate studies did not show any significant relationship between the age of the patient and the steady-state levels of total Bicalutamide.
Bicalutamide is metabolized extensively by the liver. The drug must be used cautiously in patients with mild to moderate hepatic impairment. Regular administration in hepatic impairment patients led to delayed excretion and further accumulation. Also, long-term therapy advises liver function tests regularly in patients with hepatic impairment. There was not much difference in the drug's pharmacokinetics in patients with mild to moderate hepatic impairment.
No significant difference in the creatinine clearance impacted the elimination of Bicalutamide.
Clinical trials conducted on patients who were administered up to 200 mg of Bicalutamide did not show any symptoms of overdosage, and the medicine was found to be well tolerated. Also, life-threatening effects caused due to ingestion of a single dose of Bicalutamide have not been reported.
There is no specific antidote medicine to treat Bicalutamide overdosage, and the management must be symptomatic. Vomiting can be induced in a conscious patient. However, dialysis is not suitable as Bicalutamide is highly protein bound. Therefore, supportive therapy in the form of close monitoring of the patient and checking on vitals is advised.
The common side effects of Bicalutamide include:
Swelling of the arms, legs, ankles, and feet.
Blood in the urine.
Frequent urination at night.
The severe side effects of Bicalutamide include:
Liver problems like jaundice, nausea, vomiting, fever, chills, appetite loss, dark urine, fatigue, upper right abdominal pain, and liver failure.
Bleeding problems like excessive bleeding or unexplained bruising.
Breast complaints like gynecomastia and breast pain.
Blood sugar problems like uncontrolled blood sugars.
Bicalutamide is available as a 50 mg tablet. It is a non-steroidal androgen receptor inhibitor.
Propanamide, N [4 cyano-3- (trifluoromethyl)phenyl]-3-[(4-fluorophenyl)sulfonyl]-2-hydroxy-2-methyl-,(+-).
Bicalutamide is a fine powder, white to off-white in color.
Bicalutamide is insoluble in water, sparingly soluble in methanol, slightly soluble in chloroform and absolute ethanol, and soluble in acetone and tetrahydrofuran.
Lactose, Magnesium stearate, Hypromellose, Polyethylene Glycol, Polyvidone, Sodium starch glycolate, and Titanium dioxide.
Mechanism of Action:
Bicalutamide is a non-steroidal androgen receptor inhibitor. It works by competitively inhibiting the actions of androgen by binding to cytosol androgen receptors in the target cells. As prostate cancer cell growth depends on the availability of androgens, Bicalutamide limits androgen availability reduces the growth of cancer cells. During a combination therapy of Bicalutamide and LHRH analogs, the suppression of testosterone caused by LHRH analogs was unaffected; however, single therapy with Bicalutamide caused a rise in testosterone and estradiol levels.
Though Bicalutamide's absolute bioavailability is unknown, the drug is well absorbed following oral administration. Also, there is no significant difference in the absorption rate of Bicalutamide when administered with food.
Bicalutamide is highly protein-bound, accounting for around 96 %.
Bicalutamide has an active isomer (R isomer) and an inactive isomer (S isomer). The inactive isomer is metabolized primarily by glucuronidation, whereas the active metabolite is first oxidized to the inactive metabolite, which is metabolized by glucuronidation.
The parent and metabolite compounds are eliminated both in the urine and feces. The S isomer is cleared more rapidly when compared to the R isomer, with the R-isomer accounting for around 99 % of steady-state plasma concentrations.
Two-year oral carcinogenicity studies conducted on animals showed their actions on the target organ, attributing to the antiandrogenecity effects of Bicalutamide. Administration of Bicalutamide also showed an increased occurrence of hepatocellular carcinoma and benign thyroid follicular cell adenoma in mice due to hepatic enzyme induction. However, tumorigenic effects and induction of hepatic enzymes have not been observed in humans. There is no evidence of Leydig cell hyperplasia and uterine tumors in humans. Studies also concluded that Bicalutamide does not cause genotoxicity.
Toxicology studies have shown the atrophy of seminiferous tubules that are believed to occur due to the antiandrogen effect of the drug. There was a decreased fertility in female rats and impotence in male rats upon Bicalutamide administration.
Safety Data from Clinical Studies:
Bicalutamide 150 mg is not recommended in patients with M1 cancer of the prostate due to an increased risk of death.
Bicalutamide 150 mg is not recommended in patients with locally advanced cancer of the prostate (T3-4, NX, M0).
Bicalutamide 150 mg is not recommended for use in patients with localized prostate cancer who are under watchful waiting.
How Is Bicalutamide Supplied?
Bicalutamide is supplied in a bottle containing 30 tablets. It is a white, film-coated tablet embossed with "CDX50" on one side and the "CASODEX" logo on the other.
How Is Bicalutamide Stored?
Bicalutamide has to be stored at a controlled room temperature of 20 degrees Celsius to 25 degrees Celsius.
Patient Counseling Information:
Patients must be advised to read the FDA-approved patient labeling before starting drug use thoroughly.
Dose and Schedule: Patients must be advised to start Bicalutamide and LHRH analogs simultaneously and avoid discontinuing either of the medicines without the doctor's consent.
Hepatitis: Patients must be advised about the risk of hepatitis with Bicalutamide use and warned about hepatic failure and death. Also, liver function tests must be done regularly to check on the liver function status.
Hemorrhage With Concomitant Use of Coumarin Anticoagulant: Patients must be informed about the severe bleeding due to increased anticoagulant effects of Bicalutamide. They must be advised to contact the doctor immediately during an episode of bleeding or spontaneous bruising.
Glucose Tolerance: Patients must be informed about the loss of glycemic index and predisposition to diabetes in people with prediabetes with drug use. The blood glucose levels must be monitored during the combination therapy of Bicalutamide and LHRH analogs.
Somnolence: Somnolence or drowsiness has been reported in patients taking Bicalutamide. Therefore, caution must be exercised while driving or operating machinery.
Photosensitivity: Patients must be informed about photosensitivity during therapy, be advised to avoid direct sunlight, and be encouraged to use sunscreen.
Contraception and Fertility: Female partners of male patients must be advised to use effective contraception during treatment and 130 days after the last dose of Bicalutamide. Also, male patients must be advised about an impairment of fertility.