Bicalutamide is a prescription medication classified as a non-steroidal anti-androgen (NSAA). It is taken orally as a tablet and is used as part of androgen deprivation therapy (ADT). Bicalutamide works by interfering with the body’s natural male sex hormones, known as androgens. Its primary function is to block the effects of androgens, which stimulate the growth of certain cancers.
Therapeutic Applications of Bicalutamide
The primary medical use for Bicalutamide is in the management of prostate cancer. Prostate cancer cells require androgens, such as testosterone and dihydrotestosterone (DHT), to grow and divide. Bicalutamide works by acting as a competitive inhibitor at the cellular level. It binds to the androgen receptor (AR) inside the cancer cells, blocking natural androgens from attaching. By occupying the receptor without activating it, Bicalutamide prevents the cell from receiving growth signals, which slows the progression of the cancer.
Bicalutamide is frequently used as part of a combination therapy, particularly in the treatment of metastatic prostate cancer. It is administered alongside a luteinizing hormone-releasing hormone (LHRH) analog. LHRH analogs reduce testosterone production, and Bicalutamide blocks the effect of any remaining circulating androgens, creating a comprehensive hormone blockade. The drug is also used briefly to prevent “testosterone flare,” a temporary worsening of symptoms that occurs when an LHRH analog is first introduced. Furthermore, Bicalutamide has been used as a monotherapy for locally advanced prostate cancer, although this application may not be approved in all regions.
Standard Administration and Prescribing Guidelines
Bicalutamide is taken as a tablet once daily, preferably at the same time each day. It can be taken in the morning or evening, and absorption is not affected by food. Consistent adherence is important for maintaining stable drug levels, given the active component’s long half-life of about six days.
The dosage is determined by the patient’s cancer context and treatment strategy. The standard dose in combination with an LHRH analog is typically 50 milligrams (mg) once daily. This lower dose is effective because the LHRH analog significantly reduces overall androgen concentration. A higher dose of 150 mg once daily is used internationally when Bicalutamide is prescribed as monotherapy for locally advanced disease. Patients must follow their physician’s specific instructions and should not take a double dose if one is missed.
Monitoring and Managing Adverse Reactions
Common Adverse Effects
One of the most frequently reported adverse effects is the experience of hot flashes, which occurs in over half of patients in combination therapy. These episodes involve sudden feelings of warmth, often spreading across the upper body. Another common issue is the development of breast tenderness (mastalgia) and breast enlargement (gynecomastia). These breast changes can affect a majority of men receiving the 150 mg monotherapy dose. Other effects include general fatigue, weakness, and gastrointestinal symptoms such as nausea, diarrhea, or constipation. Patients may also report pain in the back or pelvis, or swelling in the extremities.
Serious or Rare Adverse Reactions
Bicalutamide carries a risk of serious reactions, including hepatotoxicity. This can manifest as abnormal liver function, which is typically detected through blood tests showing elevated liver enzymes (transaminases). Liver changes most often occur within the first few months of starting treatment. In rare instances, this liver dysfunction can become severe, leading to symptoms like jaundice (yellowing of the skin or eyes), dark urine, or upper right abdominal pain.
Due to this risk, liver function tests should be conducted before starting treatment, regularly during the initial four months, and periodically thereafter. If a patient develops jaundice or if the liver enzyme alanine aminotransferase (ALT) rises significantly, the drug may need to be discontinued immediately. Rarely, the medication has also been associated with pulmonary issues, such as interstitial pneumonitis, which is a form of lung inflammation. Symptoms of this include a persistent cough, shortness of breath, and fever, and they warrant immediate medical evaluation. Cardiovascular events, including changes in heart rhythm or chest discomfort, have also been reported and require careful monitoring, particularly in patients with pre-existing heart conditions.