Quick Facts

• Is indicated for the management of castration-resistant prostate cancer (CRPC).
• Is a therapeutic option for metastatic castration-sensitive prostate cancer (mCSPC).
• May be used for non-metastatic castration-sensitive prostate cancer (nmCSPC) that is at high risk for metastasis.

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Кстанди (enzalutamide) is an approved therapeutic option used in the management of several specific types of prostate cancer. The medication is indicated for patients diagnosed with castration-resistant prostate cancer (CRPC), which is prostate cancer that continues to progress despite hormone treatments aimed at lowering testosterone levels.

This drug may also support patient well-being and is part of the approved treatment plan for metastatic castration-sensitive prostate cancer (mCSPC), where the disease has spread to other parts of the body but still generally responds to hormone therapy.

Furthermore, this treatment is an option for certain patients with non-metastatic castration-sensitive prostate cancer (nmCSPC) who have a high-risk for the cancer spreading following a biochemical recurrence.

Eligibility Map: Who can and cannot use Кстанди — official regulatory information

Eligibility scope

Category	Official Regulatory Statement
Populations for whom use is allowed (as stated in label)	Adult Men for the approved prostate cancer indications.
Populations for whom use is not recommended (if applicable)	Paediatric population (< 18 years); Women who are lactating.
Populations for whom use is contraindicated	Women who are or may become pregnant; patients with known hypersensitivity to enzalutamide or its excipients.
Age-related eligibility rules	Geriatric Patients (ge 65 years): No dose adjustment is necessary. Paediatric Population (< 18 years): No relevant use; safety and efficacy are not established.
Condition-specific eligibility rules	Hepatic/Renal Impairment: No dose adjustment is needed for mild/moderate impairment.
Pregnancy and lactation eligibility status (if explicitly documented)	Pregnancy/Lactation: Contraindicated.
Eligibility-related restrictions	Caution is advised in severe renal impairment or end-stage renal disease due to insufficient study data. Patients with a history of seizures or recent severe cardiovascular disease were generally excluded from clinical trials.

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Eligibility classifications (high-level)

Classification Detail	Summary Statement from Regulatory Sources
Eligibility severity classification (as defined in official documents)	Classified as Contraindicated (e.g., Pregnancy), Caution Advised (e.g., Severe Renal Impairment), or Use Not Established (e.g., Paediatric).
Regulatory basis (EMA / FDA / etc.)	Based on the official regulatory labeling (e.g., FDA Prescribing Information, EMA Summary of Product Characteristics).
Eligibility-context constraints (as defined in official documents)	Determined by gender, specific historical comorbidities, and limitations in clinical study data.

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Resulting eligibility structure

Official eligibility statements:

• The medicine is contraindicated in women who are or may become pregnant and in patients with known hypersensitivity to the active substance.
• Use is restricted to adult men; there is no relevant use in the paediatric population, where safety and efficacy are not established.
• Caution is required in patients with severe renal impairment because the medicine has not been formally studied in this population.

Connection to the overall eligibility profile (2–4 sentences):

The official documentation defines eligibility by establishing absolute prohibitions based on gender and allergy, strictly limiting use to adult men. The profile also advises caution or non-use in populations, such as those with severe renal disease, where formal study data is insufficient or where specific historical comorbidities like seizures present an increased risk. These statements dictate who can and who must not use the drug according to regulatory standards.

Xtandi (enzalutamide) is a drug with complex interactions, primarily because it is a strong inducer of the enzyme CYP3A4 and a moderate inducer of CYP2C9 and CYP2C19. These enzymes are responsible for metabolizing (breaking down) many other medications. Co-administering Xtandi can therefore lower the concentration of these other drugs in the body, potentially making them less effective.

Key Medication Interactions

Drug Class/Example	Potential Effect of Xtandi	Management Consideration
Anticoagulants (e.g., warfarin, apixaban, rivaroxaban)	Reduced blood levels, potentially reducing effectiveness and increasing risk of clotting.	Closely monitor the effects and consider dosage adjustment or alternative agents.
Opioids (e.g., fentanyl, oxycodone, hydrocodone)	Reduced pain relief due to lower opioid concentration.	Monitor for pain control; dose adjustments may be needed.
Statins (e.g., atorvastatin, simvastatin)	Lowering of statin levels.	Monitor cholesterol and adjust statin dose as necessary.
Anti-seizure Medications (e.g., phenytoin, carbamazepine)	Reduced effectiveness of anti-seizure drugs.	Monitor closely for seizures; dose change or substitution may be required.

It is also recommended to avoid the herbal supplement St. John’s wort as it can significantly decrease enzalutamide levels, potentially reducing its effectiveness. Conversely, strong CYP2C8 inhibitors, such as gemfibrozil, can increase the concentration of enzalutamide, raising the risk of side effects like seizures. Your healthcare provider will need to review all prescription, over-the-counter, and herbal products you use to manage these potential interactions.

The mechanism of action for Кстанди (Enzalutamide) is defined by a systematic, multi-step inhibition of the Androgen Receptor ( AR) signaling pathway and an off-target interaction in the central nervous system (CNS).

Targeted Androgen Receptor Signaling Inhibition

Кстанди's core function is the physical and functional inhibition of the Androgen Receptor ( AR) protein. The active molecule, Enzalutamide, acts as a competitive antagonist by binding to the AR's ligand-binding domain. This key interaction prevents natural hormones like Dihydrotestosterone ( DHT) from binding to the receptor, thereby blocking the initial step of the entire signaling cascade. This functional blockade results in the systematic suppression of growth signals that rely on androgen hormones, leading to a limitation of cellular replication.

Multi-Stage Cascade Blockade

The mechanistic cascade extends beyond simple binding, as the Enzalutamide- AR complex inhibits three subsequent critical steps within the cell, suppressing gene transcription. It blocks the movement of the receptor complex into the nucleus (nuclear translocation), prevents its binding to DNA (Androgen Response Elements), and inhibits the recruitment of co-activator proteins. This multi-stage interference systemically suppresses the expression of pro-growth genes. This mechanistic domain results in the modulation of the cellular life-cycle by shifting the balance toward apoptosis (programmed cell death) in target tissue.

Modulation of CNS Inhibitory Tone

In addition to its primary AR action, Enzalutamide exhibits an off-target activity on the GABA A receptor, an inhibitory ion channel in the CNS. The molecule acts as a functional inhibitor of this receptor, reducing the flow of chloride ions that typically dampen neuronal activity. This reduction results in an increase in CNS excitability, which is a mechanism-linked physiological consequence that modulates central nervous system excitability.

Кстанди (enzalutamide) is consistently administered through the oral route across all approved indications. The standard recommended dose is 160 mg, which is taken once daily (QD). The medication is supplied as soft capsules (40 mg) and film-coated tablets (40 mg or 80 mg), with the prescribed 160 mg dose obtained using the appropriate combination of these forms.

Administration Guidelines

Entity	Description
Dosing Schedule	Standard recommended adult dose is 160 mg once daily.
Timing & Intake	May be taken with or without food. The capsules and tablets must be swallowed whole with water and must not be chewed, crushed, or opened.
Missed Dose Rule	If a dose is missed, it should be taken as soon as remembered, unless it is less than 12 hours before the next scheduled dose, in which case the missed dose should be skipped.

Use Protocol and Adjustments

Treatment with enzalutamide is intended for continuous long-term administration until the patient experiences confirmed disease progression or develops unacceptable toxicity. For specific populations, no initial dose adjustment is typically required for older adults or patients with mild-to-moderate renal impairment. However, a dose reduction or interruption may be necessary for individuals with moderate-to-severe hepatic impairment (e.g., reduction to 120 mg or 80 mg daily). This guidance ensures the drug's use is standardized while accounting for systemic processing constraints.

Research evidence / Overview of studies for Кстанди

Evidence for use in Castration-Resistant Prostate Cancer (CRPC)

Research exploring the use of Кстанди was evaluated in several large-scale, randomized clinical trials involving men with Castration-Resistant Prostate Cancer (CRPC). These studies primarily focused on populations where the cancer had progressed despite previous hormone-lowering treatments. The research examined important metrics related to how the disease evolved, such as radiographic progression-free survival (rPFS) and overall survival. Studies monitored patterns related to the time until new disease spread was detected in the study populations, when compared to the placebo group. Research describes patterns related to overall survival that were monitored in the study populations over defined time intervals. What remains uncertain for this population is the full characterization of long-term metrics, as follow-up durations were limited in the primary research settings.

Evidence for use in Metastatic Castration-Sensitive Prostate Cancer (mCSPC)

For men whose prostate cancer has spread but is still responsive to standard hormone treatment, research has explored the use of Кстанди in combination with conventional hormone therapy. These studies monitored overall survival and the measured duration of disease control. Studies reported how survival patterns evolved in the observed populations when this combination was used compared to the standard hormone treatment alone. Findings describe patterns observed in the studies related to the measured time to disease progression. Certainty remains low regarding the very long-term patterns, especially for patients with specific characteristics, such as those with low-volume disease as defined in some studies.

Evidence for use in Non-Metastatic Castration-Sensitive Prostate Cancer (nmCSPC) with High-Risk Biochemical Recurrence

Кстанди was also evaluated in studies focusing on a population of men who had undergone initial treatment and subsequently had a rise in their PSA (biochemical recurrence) without evidence of cancer spread on scans. These trials were designed to assess whether adding Кстанди to standard hormone therapy influenced the time until the cancer was detected in a distant location (metastasis-free survival). Findings describe patterns observed in these specific settings, providing insight into short-term changes monitored over the defined study period. Results apply only to the high-risk populations studied. Comparative evidence is lacking for certain treatment sequences, and data regarding the consequences of treatment interruptions or extended usage are not well characterized.

What is Still Uncertain about Кстанди

The existing body of research highlights key areas where more data are needed. Comparative evidence is lacking in head-to-head trials against all other available treatment options. Follow-up durations were limited in key randomized trials, and therefore, long-term patterns on patient-reported metrics describing perceived discomfort are not fully established. Limited data are available for special populations, such as those with particular genetic profiles. Research is ongoing to provide more insight into which patients may or may not show the observed patterns.

Common questions about Кстанди (FAQ)

Q: How is Кстанди different from other prostate cancer medications?

A: According to official product information, Кстанди (enzalutamide) is classified as a potent, second-generation Androgen Receptor (AR) inhibitor. Regulatory documents describe its mechanism as systematically blocking the AR signaling pathway in multiple ways. This action not only prevents male hormones from binding to the AR protein, but also affects later steps like the receptor's movement into the cell's nucleus.

Q: How long can a person stay on Кстанди treatment?

A: Treatment with Кстанди is intended for continuous, long-term administration. Regulatory documents state that treatment is generally continued until there is confirmed evidence of disease progression or the patient develops an unacceptable toxicity.

Q: What if a common cold medicine has an interaction listed with Кстанди?

A: Кстанди is known to be a strong inducer of several liver enzymes that break down many other medicines. Co-administration with certain cold medicines or other common drugs may reduce their concentration, which could potentially make them less effective. Official labeling emphasizes the need for a healthcare provider to review all medications, including non-prescription products, due to the potential for these interactions.

Q: What are the differences between using Кстанди before or after chemotherapy?

A: Official research evidence supports the use of Кстанди in different contexts. It is approved for metastatic Castration-Sensitive Prostate Cancer, where it is used in combination with standard hormone therapy. It is also approved for metastatic Castration-Resistant Prostate Cancer, which is indicated for patients whose cancer has progressed after initial hormone-lowering treatments.

Q: Is it normal to feel more tired when starting treatment with Кстанди?

A: Asthenia (weakness) and fatigue (tiredness) are classified as very common side effects in the medicine's regulatory documents, meaning they were frequently reported by patients in clinical trials. This is common to experience.

Q: Can Кстанди cause hair loss or changes in skin?

A: Hair loss is not listed among the common or very common side effects in the core regulatory documents. The official safety information indicates that skin changes such as pruritus (itching) are a reported side effect, though this was generally reported in less than 10% of patients in clinical studies.

Q: Are there any common over-the-counter pain relievers that interact with Кстанди?

A: As a potent enzyme inducer, Кстанди has the potential to interact with many drugs, including common over-the-counter (OTC) pain relievers. The safety information highlights the need to review all products with a healthcare professional before starting any new medications.

Q: Is Кстанди used for all stages of prostate cancer?

A: Кстанди is indicated for men with specific disease states only, including non-metastatic and metastatic castration-resistant prostate cancer (CRPC) and metastatic castration-sensitive prostate cancer (mCSPC). It is not generally indicated for all forms or all stages of the disease.

Q: Why do some people take Кстанди along with other treatments?

A: The medicine is often prescribed along with another type of hormone therapy (like a GnRH analog). This combination is intended to ensure continued suppression of male hormones, which is part of the established protocol for managing hormone-sensitive prostate cancer.

Q: What kind of studies support the use of Кстанди for prostate cancer?

A: The use of Кстанди is supported by large, randomized, placebo-controlled clinical trials. These studies compared the outcomes of patients receiving the drug against those receiving a placebo to measure benefits such as overall survival and radiographic progression-free survival.

Q: Does Кстанди affect bone density over time?

A: Clinical trials reported an increased incidence of falls and non-pathologic fractures (broken bones not due to injury) compared to those on placebo. Regulatory documents note the importance of evaluating patients for their individual risk of falls and fractures, given the observed increase in these events.

Q: Is it common to have nausea or diarrhea with Кстанди?

A: According to official safety information, diarrhea is listed as a common adverse reaction, with up to 22% of patients in some trials reporting it. Nausea is listed among the adverse reactions reported in clinical trials.

Q: Is Кстанди a type of chemotherapy?

A: No. Кстанди is classified as a potent Androgen Receptor (AR) inhibitor and a nonsteroidal antiandrogen. It is a form of endocrine (hormonal) therapy, not traditional cytotoxic chemotherapy.

Q: Do older patients respond differently to Кстанди than younger patients?

A: Based on the clinical data reviewed by regulatory agencies, the data did not indicate any major overall differences in safety or effectiveness when comparing older patients (ge 65 years) to younger patients.

Q: What is the potential impact of Кстанди on sexual function?

A: Based on findings from animal studies, there is a potential for the drug to impair fertility in males of reproductive age. Official labeling emphasizes the need for men with reproductive partners to be advised about using effective contraception.

Q: Can Кстанди be used by women (e.g., for off-label uses) or is it only for men?

A: Кстанди is only approved and indicated for use in adult men for the treatment of prostate cancer. The medicine is specifically contraindicated (prohibited) in women who are or may become pregnant due to the risk of serious harm to the developing fetus.

Q: Are there any known long-term side effects of Кстанди?

A: While the drug's safety profile is documented, primary clinical trial data had limited follow-up duration. Consequently, the full characterization of very long-term patterns and side effects from extended usage is not fully established.

Q: Is it safe to drive or operate machinery while taking Кстанди?

A: Due to the potential risk of seizure and dizziness associated with this medication, caution should be exercised regarding activities like driving or operating heavy machinery. Patients are generally advised to discuss the risks with their healthcare provider, especially if they have predisposing factors for seizure or experience dizziness.

Q: Are there any specific blood tests required while on Кстанди?

A: Official safety information recommends monitoring patients for several key indicators. This may include regular checks of PSA (Prostate-Specific Antigen) levels to track treatment response, and monitoring blood pressure and liver function tests.

Q: Why is monitoring liver function sometimes necessary with Кстанди?

A: This monitoring is performed because an increased drug half-life—the time it takes for the drug to clear from the body—has been observed in patients with severe hepatic (liver) impairment, which may necessitate a dose adjustment.

Q: What are the signs that Кстанди might not be working anymore?

A: Treatment is generally continued until confirmed disease progression is observed. This progression is typically indicated by a sustained rise in the patient's Prostate-Specific Antigen (PSA) levels, or through evidence of new tumor growth or spread on imaging scans.

Q: How quickly does Кстанди start to clear out of the system if treatment is stopped?

A: Кстанди (enzalutamide) has a long elimination half-life, meaning it takes an extended time to fully clear from the body. The mean half-life of the active ingredient is approximately 5.8 days.

Q: Are there published guidelines for starting and stopping Кстанди?

A: Yes, official prescribing information provides guidelines for managing treatment. This guidance includes information on the recommended starting dose, as well as specific instructions for dose reduction, interruption, or discontinuation as needed.

Q: Does alcohol consumption affect the safety or effectiveness of Кстанди?

A: While a specific alcohol interaction is not detailed, the official product information mentions that predisposing factors for seizure require careful evaluation by a healthcare provider. This includes a history of alcoholism.

Q: Does Кстанди interfere with general anesthesia if I need surgery?

A: Since Кстанди is a potent enzyme inducer, it can reduce the concentration of many other medicines, including substrates of CYP3A4, CYP2C9, or CYP2C19. Medications commonly used during anesthesia or surgery may be affected, which requires a healthcare provider to carefully review all drugs before the procedure.

Storage and Disposal of XTANDI (Enzalutamide)

Labeled Storage Temperature Requirements	Store at Controlled Room Temperature (CRT), defined as 20 C to 25 C (68 F to 77 F), with excursions permitted between 15 C and 30 C (59 F and 86 F).
Light/Moisture Protection Requirements	Keep the product dry and away from excess heat or moisture.
Packaging-Related Storage Rules	Store in the original container and ensure the bottle is kept tightly closed.

XTANDI must be kept out of the reach of children and pets, using the child-resistant packaging provided. The capsules or tablets must not be chewed, dissolved, or opened. As an antineoplastic agent, disposal must follow hazardous drug guidelines. Unused or expired medication should not be flushed down the toilet or thrown in household trash. Instead, dispose of the product through an official drug take-back program or follow local regulations for hazardous medicinal waste.