Casodex: Uses, Dosage & Side Effects

What Is Casodex and What Is It Used For?

Casodex contains the active substance bicalutamide, which belongs to a class of medications known as non-steroidal antiandrogens. Prostate cancer is one of the most common cancers in men worldwide, and the majority of prostate cancers are hormone-sensitive, meaning they depend on androgens (male sex hormones, primarily testosterone and its more potent derivative dihydrotestosterone) to grow. By blocking the androgen receptor, bicalutamide removes this growth signal and helps control tumor progression.

The androgen receptor is a nuclear receptor protein that, when activated by androgens, translocates to the cell nucleus and binds to specific DNA sequences called androgen response elements (AREs). This binding activates the transcription of genes that promote cell growth, survival, and proliferation in prostate tissue. Bicalutamide competitively inhibits the binding of androgens to this receptor. Specifically, it binds to the androgen receptor with high affinity, preventing testosterone and dihydrotestosterone (DHT) from activating the receptor signaling cascade. Without androgen-driven gene expression, the growth and survival of androgen-dependent prostate cancer cells is impaired, leading to tumor regression or stabilization.

However, androgen blockade at the receptor level alone is not sufficient to fully suppress androgen-driven prostate cancer growth. While Casodex blocks the receptor in target tissues, the testes continue to produce testosterone. Furthermore, when LHRH analogues are first administered, they can cause an initial surge of testosterone (known as the “flare” phenomenon) before suppression occurs. Casodex 50 mg is therefore specifically designed to be used in combination with an LHRH analogue (such as goserelin, leuprorelin, or triptorelin) or surgical castration (bilateral orchiectomy). This dual approach — reducing circulating androgen levels through castration and blocking any remaining androgen action at the receptor level with bicalutamide — is known as combined androgen blockade (CAB) or maximal androgen blockade (MAB).

Casodex 50 mg is approved by regulatory authorities worldwide, including the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA), for the following indication:

• Advanced prostate cancer: Treatment of advanced prostate cancer in combination with an LHRH analogue or surgical castration. Casodex is indicated to provide combined androgen blockade for patients with locally advanced or metastatic prostate cancer who are being treated with hormonal therapy. It may also be used to cover the initial testosterone flare that occurs when LHRH analogues are first started.

The evidence base for combined androgen blockade with bicalutamide has been established through large-scale randomized controlled trials. The pivotal studies demonstrated that the addition of Casodex 50 mg to castration therapy provided a statistically significant improvement in progression-free survival compared with castration alone. Meta-analyses, including those published in the Cochrane Database and by the Prostate Cancer Trialists’ Collaborative Group, have confirmed a modest but consistent overall survival benefit for combined androgen blockade, particularly in patients with metastatic disease.

Prostate cancer is the second most common cancer in men globally, with approximately 1.4 million new cases and 375,000 deaths per year according to the World Health Organization. Advanced prostate cancer — whether locally advanced (extending beyond the prostate capsule) or metastatic (spread to distant sites such as bone or lymph nodes) — often requires systemic hormonal therapy as a primary treatment approach. Casodex plays an important role in this therapeutic strategy, either as part of first-line combined androgen blockade or to prevent testosterone flare at the initiation of LHRH therapy.

What Should You Know Before Taking Casodex?

Contraindications

There are specific situations in which Casodex must not be used. Understanding these contraindications is essential before starting treatment.

• Hypersensitivity: Do not take Casodex if you are allergic to bicalutamide or any of the other ingredients in the tablet (including lactose monohydrate, sodium starch glycolate, povidone, magnesium stearate, methylhydroxypropylcellulose, polyethylene glycol, and titanium dioxide).
• Women: Casodex is indicated only for male patients with prostate cancer. It must not be given to women, and particularly not to women who are or may become pregnant, as it could interfere with hormonal balance and potentially harm an unborn child.
• Children: Casodex is not indicated for use in children or adolescents. It has no approved pediatric indications.
• Co-administration with terfenadine, astemizole, or cisapride: Bicalutamide should not be used with these medications due to the potential for clinically significant drug interactions (some of these medications have been withdrawn from the market in many countries).

Warnings and Precautions

Before and during treatment with Casodex, the following precautions should be observed:

• Liver function monitoring: Bicalutamide is extensively metabolized in the liver. Regular monitoring of liver function tests (ALT, AST, bilirubin) is mandatory, particularly during the first 4 months. Transient elevations in transaminases are common and usually resolve spontaneously or after discontinuation. However, serious hepatotoxicity can occur unpredictably and may progress rapidly.
• Glucose tolerance: Androgen deprivation therapy (of which Casodex is a component when combined with an LHRH analogue) has been associated with impaired glucose tolerance and an increased risk of diabetes mellitus. Blood glucose levels should be monitored periodically, particularly in patients with pre-existing diabetes or risk factors for diabetes.
• Cardiovascular risk: Combined androgen blockade may increase the risk of cardiovascular events, including ischemic heart disease and heart failure. This risk should be carefully considered in patients with pre-existing cardiovascular conditions. Patients should be monitored for signs and symptoms of cardiovascular disease.
• Bone density: Long-term androgen deprivation therapy is associated with a decreased bone mineral density and an increased risk of fractures (osteoporosis). Baseline and periodic bone density assessments should be considered, along with appropriate preventive measures such as calcium and vitamin D supplementation.
• Photosensitivity: Cases of photosensitivity reactions have been reported with bicalutamide. Patients should be advised to avoid prolonged sun exposure and use sunscreen.
• Antiandrogen withdrawal syndrome: In some patients, discontinuation of antiandrogen therapy can paradoxically lead to a decline in PSA (prostate-specific antigen) levels and clinical improvement. This phenomenon, known as antiandrogen withdrawal syndrome, should be considered if the disease progresses during treatment with Casodex.
• QT prolongation: Androgen deprivation therapy may prolong the QT interval on electrocardiogram. Caution is advised in patients with a history of QT prolongation or those taking other QT-prolonging medications.
• Lactose intolerance: Casodex tablets contain lactose. Patients with rare hereditary problems of galactose intolerance, total lactase deficiency, or glucose-galactose malabsorption should not take this medicine.

Pregnancy and Breastfeeding

Casodex is indicated exclusively for male patients with prostate cancer and has no approved use in women. It is contraindicated in women, particularly during pregnancy, as the antiandrogen mechanism could potentially affect fetal development. Women who are pregnant or may become pregnant should not handle crushed or broken Casodex tablets, as bicalutamide could be absorbed through the skin.

Male patients receiving Casodex should be aware that androgen deprivation therapy may cause subfertility or infertility. If fertility preservation is a concern, sperm cryopreservation should be discussed with the treating physician before treatment initiation.

Driving and Operating Machinery

Casodex is unlikely to affect the ability to drive or operate machinery. However, dizziness and somnolence (drowsiness) have been reported as side effects. If you experience these symptoms, you should exercise caution when driving or operating machinery until you know how Casodex affects you.

How Does Casodex Interact with Other Drugs?

Drug interactions with Casodex are primarily related to its high protein binding (approximately 96% bound to plasma proteins) and its metabolism by the cytochrome P450 enzyme system, particularly CYP3A4. Bicalutamide can displace other highly protein-bound drugs from their binding sites, and it can inhibit the oxidative metabolism of certain CYP3A4 substrates. It is essential to inform your doctor about all medications, supplements, and herbal products you are currently taking.

Major Interactions

Minor Interactions

In vitro studies have shown that the (R)-enantiomer of bicalutamide (the pharmacologically active form) is an inhibitor of CYP3A4, with lesser inhibitory effects on CYP2C9, CYP2C19, and CYP2D6. While clinically significant interactions have been demonstrated primarily with warfarin, caution should be exercised when prescribing Casodex alongside any drug with a narrow therapeutic index that is metabolized by these enzymes.

Additionally, bicalutamide can displace other drugs from their protein binding sites. Since bicalutamide is approximately 96% bound to plasma proteins, co-administration with other highly protein-bound drugs may result in elevated free concentrations of either drug, potentially increasing pharmacological effects and side effects.

What Is the Correct Dosage of Casodex?

Casodex is formulated as a film-coated tablet containing 50 mg of bicalutamide. The dosing regimen is straightforward: one tablet taken once daily, every day. The tablet should be swallowed whole with a glass of water and can be taken with or without food. It is recommended to take Casodex at approximately the same time each day to maintain consistent plasma levels of the active drug.

Adults

The duration of treatment with Casodex is typically long-term and continues for as long as the treating physician considers it clinically beneficial. In most cases, this means continuous treatment unless the disease progresses, unacceptable side effects occur, or the physician determines that a change in treatment strategy is warranted. Patients should not stop taking Casodex without consulting their doctor, as abrupt discontinuation without appropriate medical guidance could affect disease control.

Children

Elderly

Renal and Hepatic Impairment

Missed Dose

If you forget to take a dose of Casodex, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you frequently forget doses, consider setting a daily alarm or using a pill organizer to help maintain adherence.

Overdose

There is no specific antidote for bicalutamide overdose. In the event of an overdose, treatment should be symptomatic and supportive. Hemodialysis is unlikely to be effective in removing bicalutamide because of its high protein binding. General supportive measures should be initiated, including monitoring of vital signs and observation for adverse effects. Contact your local poison control center or seek emergency medical attention if an overdose is suspected.

In clinical trials and post-marketing experience, single doses of up to 200 mg have been taken without serious acute effects. There is no clinical experience with doses exceeding 200 mg as a single ingestion.

What Are the Side Effects of Casodex?

Like all medicines, Casodex can cause side effects, although not everybody gets them. Many of the side effects listed below are related to the overall androgen deprivation therapy (the combination of Casodex with an LHRH analogue or castration), rather than bicalutamide alone. The following side effects have been reported based on clinical trials and post-marketing surveillance:

It is important to distinguish between side effects caused directly by bicalutamide and those attributable to androgen deprivation therapy in general. Effects such as hot flushes, decreased libido, erectile dysfunction, weight gain, reduced bone mineral density, and increased cardiovascular risk are class effects of androgen deprivation therapy and are common to all forms of hormonal treatment for prostate cancer, whether involving LHRH analogues, surgical castration, or antiandrogens.

Gynecomastia and breast tenderness are particularly characteristic of antiandrogen monotherapy (typically with higher doses of bicalutamide, such as 150 mg), but also occur commonly when bicalutamide 50 mg is used as part of combined androgen blockade. The mechanism involves a shift in the estrogen-to-androgen ratio in breast tissue. In most cases, these symptoms are mild to moderate and manageable, but they can be distressing and may affect quality of life.

Liver function abnormalities deserve special attention. While transient elevations in liver enzymes are common (occurring in approximately 5–10% of patients in clinical trials), most are mild and resolve without discontinuation of therapy. However, rare cases of severe hepatotoxicity, including fulminant hepatic failure resulting in death, have been reported in post-marketing surveillance. This underscores the importance of regular liver function monitoring, particularly during the first four months of treatment.

How Should You Store Casodex?

Proper storage of Casodex is important to ensure the medication remains effective and safe to use throughout its shelf life. The following storage guidelines should be observed:

• Temperature: Store at room temperature, below 30°C (86°F). Do not refrigerate or freeze.
• Light protection: Keep in the original blister pack or container to protect from light until ready to use.
• Moisture: Store in a dry place. Avoid storing in bathrooms or other humid environments.
• Children: Keep out of the sight and reach of children.
• Expiry date: Do not use Casodex after the expiry date printed on the blister foil and the carton. The expiry date refers to the last day of that month.
• Disposal: Do not dispose of medications via household waste or wastewater. Ask your pharmacist how to dispose of medicines you no longer use. These measures help protect the environment.

If you notice any visible changes in the appearance of the tablets (discoloration, crumbling, or unusual odor), do not take them. Contact your pharmacist for a replacement.

What Does Casodex Contain?

Understanding the complete composition of Casodex is important, particularly for patients who have known allergies or intolerances to specific excipients.

Active Ingredient

• Bicalutamide: 50 mg per film-coated tablet. Bicalutamide is a racemic mixture, with the (R)-enantiomer being pharmacologically active. The chemical name is (RS)-N-[4-cyano-3-(4-fluorophenylsulfonyl)-2-hydroxyphenyl]-3,3,3-trifluoropropanamide. It appears as a white to off-white crystalline powder.

Inactive Ingredients (Excipients)

The tablet core and film coating contain the following inactive ingredients:

• Tablet core: Lactose monohydrate, sodium starch glycolate, povidone, magnesium stearate
• Film coating: Methylhydroxypropylcellulose (hypromellose), polyethylene glycol 300, titanium dioxide (E171)

The tablet is white, round, and biconvex with “CDX50” debossed on one side. It is film-coated for ease of swallowing and to protect the active ingredient.