Bicalutamide is a nonsteroidal antiandrogen (NSAA) medication. It addresses hormone-sensitive conditions by interacting with specific hormone receptors. Its purpose is to manage medical conditions where the activity of male hormones, known as androgens, needs to be controlled.
Primary Medical Application
Bicalutamide is primarily used to treat prostate cancer, especially when it has spread to other parts of the body (metastatic prostate cancer). It is often combined with other therapies, such as gonadotropin-releasing hormone (GnRH) agonists, which reduce testosterone production. This combined approach aims for a more complete blockage of androgen activity.
The medication also manages localized prostate cancer. A typical dosage for metastatic prostate cancer in combination therapy is 50 mg once daily. The goal of bicalutamide treatment in prostate cancer is to slow the growth and spread of cancer cells, and potentially shrink existing tumors.
How Biclutamide Works
Bicalutamide functions as an anti-androgen by selectively blocking androgen receptors (AR). These proteins are found inside cells, including prostate cells, and normally bind to male hormones like testosterone and dihydrotestosterone (DHT). When androgens bind to these receptors, they stimulate the growth of certain cells, including prostate cancer cells.
Bicalutamide competes with natural androgens for binding to these receptors. It binds without activating them, preventing testosterone and DHT from attaching and exerting their growth-promoting effects. This inhibition reduces stimulatory signals for prostate cancer cells, slowing or halting their growth and spread. Bicalutamide does not lower the body’s androgen levels; instead, it blocks their action at the cellular level.
Managing Treatment and Potential Side Effects
Bicalutamide is taken as a tablet by mouth once a day. It is recommended to take the medication around the same time each day to maintain consistent levels. When used with a luteinizing hormone-releasing hormone (LHRH) agonist, bicalutamide is usually started on the same day the LHRH agonist injections begin.
Common side effects include hot flashes, which may improve as the body adjusts. Patients may also experience:
Breast tenderness or enlargement (gynecomastia)
Nausea
Fatigue
Bone, back, or pelvic pain
Muscle weakness
Swelling in the hands, feet, or ankles
Strategies like avoiding alcohol, spicy foods, and caffeine, or wearing layers of clothing, may help manage hot flashes.
Less common but more serious side effects require immediate medical attention. These include signs of liver problems such as yellowing of the skin or eyes, dark urine, upper stomach pain, or unusual tiredness. Other serious concerns are sudden chest pain, wheezing, or severe allergic reactions like facial swelling or difficulty breathing. Patients should report any new or worsening symptoms to their healthcare provider.
Important Considerations During Therapy
During bicalutamide therapy, regular monitoring is advised to assess effectiveness and detect potential complications. This includes periodic blood tests to check liver function, especially during the first four months of treatment and periodically thereafter. These tests help identify any signs of liver injury, which can be severe.
Bicalutamide can interact with other medications, particularly blood thinners like warfarin, potentially increasing bleeding risk. If taken concurrently, close monitoring of blood clotting times is necessary, and the anticoagulant dose may need adjustment. When used with LHRH agonists, bicalutamide therapy may reduce glucose tolerance in some males, requiring blood glucose monitoring, especially for individuals with diabetes.
Bicalutamide is not for use in women, particularly those who are pregnant, as it can cause fetal harm. Male patients with female partners of reproductive potential should use effective contraception during treatment and for at least 130 days after the final dose. The medication can also affect sperm production, potentially impairing male fertility.