Description

What Is Xtandi 40 mg?

Xtandi 40 mg is an oral soft capsule containing enzalutamide, an androgen receptor inhibitor used to treat prostate cancer in adult men. It is supplied as liquid-filled soft gelatin capsules, commonly in packs of 112 or 120 capsules. Made by Astellas, it targets the androgen (male hormone) signalling that drives prostate cancer growth.

Xtandi is a prescription-only medicine used across several stages of prostate cancer, including hormone-sensitive and castration-resistant disease. Because prostate cancer cells depend on androgens such as testosterone to grow, blocking the androgen receptor slows or halts the cancer’s progression and can extend the time before the disease worsens.

Active Ingredient & Mechanism of Action

The active ingredient is enzalutamide, an androgen receptor signalling inhibitor. Its main metabolite, N-desmethyl enzalutamide, has similar activity.

Enzalutamide acts at several steps in the androgen receptor pathway: it competitively blocks androgens (such as testosterone) from binding to the androgen receptor, prevents the receptor from moving into the cell nucleus, and stops its interaction with DNA. By interrupting this signalling, enzalutamide reduces prostate cancer cell growth and can induce cancer cell death, decreasing tumour volume.

Approved Indications

Xtandi is indicated for adult men with prostate cancer in several settings: metastatic castration-resistant prostate cancer (mCRPC); non-metastatic castration-resistant prostate cancer (nmCRPC) at high risk of metastasis; metastatic castration-sensitive (hormone-sensitive) prostate cancer (mCSPC / mHSPC); and non-metastatic castration-sensitive prostate cancer with high-risk biochemical recurrence. In many of these settings it is used together with medical or surgical castration (an LHRH analogue).

Dosage & Administration

The recommended dose is 160 mg once daily, taken as four 40 mg capsules at the same time each day, with or without food. Medical castration with an LHRH analogue should generally be continued during treatment in men who are not surgically castrated. Treatment continues until the disease progresses or side effects become unacceptable. In certain high-risk recurrence cases, therapy may be paused based on PSA response, as directed by the specialist. Do not adjust or stop the dose without medical advice.

How to Take Xtandi

Swallow the capsules whole with water — do not chew, dissolve, or open them. Take all four capsules together once a day, at the same time each day, with or without food. If you are also receiving GnRH/LHRH therapy by injection, continue it as prescribed. Keep to your daily routine to maintain steady drug levels, and follow your oncology team’s instructions closely.

Missed Dose

If you miss your dose at the usual time, take it as soon as you remember on the same day. If you miss a whole day, skip the missed dose and take the next dose at your normal time the following day — do not take extra capsules to make up for it. Do not take more than the prescribed 160 mg in a single day. If unsure, contact your doctor.

Overdose

In overdose there is no antidote; treatment is stopped and general supportive measures are given, taking into account enzalutamide’s long half-life of about 5.8 days. The risk of seizure may be higher after an overdose. Seek medical help immediately if substantially more than the prescribed dose is taken, and monitor closely under medical supervision.

Storage Conditions

Store Xtandi capsules at room temperature, ideally 20°C to 25°C (excursions 15–30°C are permitted), in a dry place with the container tightly closed. Do not use capsules that are damaged or leaking. Keep the medicine out of the reach and sight of children, and do not use it after the expiry date. Dispose of unused capsules according to local guidance.

Contraindications

Xtandi is contraindicated in women who are or may become pregnant and in patients with hypersensitivity to enzalutamide or any excipient. It is intended only for adult men with prostate cancer and must not be handled by pregnant women (capsules should not be opened or crushed). The prescriber must confirm suitability, including reviewing seizure risk factors, before treatment.

Warnings & Precautions

The most important warning is the risk of seizures; enzalutamide should be used with great caution, or avoided, in men with a history of seizures or other predisposing factors, and stopped if a seizure occurs. Posterior reversible encephalopathy syndrome (PRES) — a rare brain disorder with seizures, headache, confusion, and visual disturbance — requires immediate discontinuation. There is also a risk of ischaemic heart disease, falls and fractures, hypersensitivity reactions, and severe skin reactions. Cardiovascular risk factors should be managed.

Common & Serious Side Effects

Common side effects include fatigue, hot flushes, high blood pressure, headache, and falls, along with musculoskeletal pain, weakness, and reduced appetite. Serious effects requiring urgent attention include a seizure or loss of consciousness, symptoms of PRES (rapidly worsening headache, confusion, vision loss), chest pain or breathlessness (possible heart problems), signs of a severe allergic or skin reaction, and significant falls or fractures.

Drug Interactions

Enzalutamide is a strong inducer of liver enzymes (CYP3A4, CYP2C9, CYP2C19) and can reduce the levels and effectiveness of many other medicines, including certain anticoagulants (warfarin), antiepileptics, and other drugs. It should be avoided or used cautiously with medicines that lower the seizure threshold and with strong CYP2C8 inhibitors, which raise enzalutamide levels. Tell your doctor about all medicines, including herbal products, so interactions and doses can be reviewed.

Required Tests & Monitoring

Treatment response is followed with PSA (prostate-specific antigen) levels and imaging as appropriate. Blood pressure should be monitored and controlled, and patients watched for signs of ischaemic heart disease, seizures, and neurological symptoms suggesting PRES. Blood counts may be checked, as neutropenia can occur. Falls and fracture risk should be assessed, especially in older or frailer men.

Diet & Lifestyle Support

No specific diet is required, and Xtandi can be taken with or without food. Because of the seizure and falls risk, avoid activities where a sudden loss of consciousness could cause serious harm until you know how you respond. Managing blood pressure, staying active within your ability to protect bone and muscle, and attending regular reviews all support treatment. Report new neurological or heart symptoms promptly.

Expected Timeline for Improvement

Response is judged over weeks to months, mainly through falling PSA levels and stable or improved imaging, rather than an immediate change in how you feel. Treatment is continued as long as it controls the cancer and side effects remain acceptable. Your oncology team assesses benefit at regular intervals and decides whether to continue, pause, or change therapy based on PSA and scans.

Effect on Other Medications & Conditions

As a potent enzyme inducer, enzalutamide can weaken many co-prescribed medicines, so doses may need adjusting and some combinations avoided. Conditions such as a history of seizures, brain injury, uncontrolled hypertension, or heart disease strongly influence its safety and monitoring. All coexisting conditions and concurrent medicines — including anticoagulants and seizure-threshold-lowering drugs — should be reviewed by the prescriber before and during treatment.

When to See a Doctor

Seek emergency care immediately for a seizure or loss of consciousness, or for rapidly worsening headache, confusion, or vision changes (possible PRES). Get urgent help for chest pain, breathlessness, or signs of a severe allergic or skin reaction such as facial swelling or a widespread blistering rash. Contact your doctor about a serious fall, persistent very high blood pressure, or any new or worrying symptoms.

Use in Special Populations

Xtandi is for adult men only. It is contraindicated in pregnancy and must not be handled by women who are or may become pregnant; men with female partners of childbearing potential should use effective contraception during and for a period after treatment as advised. Caution and monitoring apply in older men (higher fall and fracture risk), and in those with heart disease or seizure risk factors. Dose adjustment may be considered in severe hepatic impairment.

Who Should Avoid Xtandi?

Xtandi must be avoided in pregnant women and in anyone hypersensitive to enzalutamide. It requires great caution — and is often avoided — in men with a history of seizures, significant brain injury, recent stroke or TIA, brain metastases, or on medicines that lower the seizure threshold. Particular care is needed in those with significant cardiovascular disease. It is not used to treat any condition other than prostate cancer.

Frequently Asked Questions

What is Xtandi used for? Xtandi (enzalutamide) treats several stages of prostate cancer in men, including hormone-sensitive and castration-resistant disease, by blocking androgen receptor signalling.

How is it taken? The dose is 160 mg once daily — four 40 mg capsules together, at the same time each day, swallowed whole with or without food.

Does it cause seizures? Seizures are an uncommon but important risk; men with seizure risk factors need caution, and treatment is stopped if a seizure occurs.

Do I continue hormone injections while on Xtandi? In many cases yes — LHRH/GnRH therapy is usually continued alongside Xtandi unless you have had surgical castration.

Can the capsules be opened or crushed? No. Swallow them whole; they should not be chewed, dissolved, or opened, and must not be handled by pregnant women.

Medical Review & Author Note

This page was medically reviewed by Dr. Abdallah Fouad, Clinical Nutrition Specialist with over 25 years of experience. The content is provided for educational purposes to help patients and caregivers understand how Xtandi (enzalutamide) is used, its benefits, and its risks. It does not replace the personalized advice of your treating physician or pharmacist.

Medical Disclaimer

Xtandi is a prescription-only anticancer medicine that must be prescribed and monitored by a qualified oncologist. This content is for general information only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your doctor or pharmacist before starting, changing, or stopping any medication.