Enzalutamide

Generic name: enzalutamide

Brand name: Xtandi
Dosage forms: oral capsule (40 mg); oral tablet (40 mg; 80 mg)
Drug classes: Antiandrogens, Hormones / antineoplastics

Medically reviewed by  A Ras MD.

What is enzalutamide used for?

Enzalutamide is a prescription medicine that is used to treat prostate cancer. Enzalutamide may be given to you for other reasons.

Description

Enzalutamide is an androgen receptor inhibitor. The chemical name is 4-{3-[4-cyano-3-(trifluoromethyl)phenyl]-5,5-dimethyl-4-oxo-2-sulfanylideneimidazolidin-1-yl}-2-fluoro-N-methylbenzamide.

The molecular weight is 464.44 and molecular formula is C21H16F4N4O2S. The structural formula is:

Enzalutamide is a white crystalline non-hygroscopic solid. It is practically insoluble in water.

XTANDI is available as liquid-filled soft gelatin capsules for oral administration. Each capsule contains 40 mg of enzalutamide as a solution in caprylocaproyl polyoxylglycerides. The inactive ingredients are caprylocaproyl polyoxylglycerides, butylated hydroxyanisole, butylated hydroxytoluene, gelatin, sorbitol sorbitan solution, glycerin, purified water, titanium dioxide, and black iron oxide.

XTANDI is also available as film-coated tablets for oral administration. Each tablet contains 40 mg or 80 mg of enzalutamide. The inactive ingredients are hypromellose acetate succinate, microcrystalline cellulose, colloidal silicon dioxide, croscarmellose sodium, and magnesium stearate. The tablet film-coat contains hypromellose, talc, polyethylene glycol, titanium dioxide, and ferric oxide.

Mechanism of Action

Enzalutamide is an androgen receptor inhibitor that acts on different steps in the androgen receptor signaling pathway. Enzalutamide has been shown to competitively inhibit androgen binding to androgen receptors; and consequently, inhibits nuclear translocation of androgen receptors and their interaction with DNA. A major metabolite, N‑desmethyl enzalutamide, exhibited similar in vitro activity to enzalutamide. Enzalutamide decreased proliferation and induced cell death of prostate cancer cells in vitro, and decreased tumor volume in a mouse prostate cancer xenograft model.

Before taking enzalutamide, tell your doctor:

• If you are allergic to enzalutamide; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
• If you are taking any of these drugs: Alfentanil, clopidogrel, cyclosporine, dihydroergotamine, ergotamine, fentanyl, phenytoin, pimozide, quinidine, sirolimus, or tacrolimus.
• If you are a woman. This medicine is not approved for use in women. This medicine may cause harm to an unborn baby if it is taken during pregnancy. If you are a woman using enzalutamide, talk with your doctor if you are pregnant, plan on getting pregnant, or are breast-feeding.

This is not a list of all drugs or health problems that interact with enzalutamide.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take enzalutamide with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take enzalutamide?

• Tell all of your health care providers that you take enzalutamide. This includes your doctors, nurses, pharmacists, and dentists.
• Have blood work checked as you have been told by the doctor. Talk with the doctor.
• Some people have had seizures while taking enzalutamide. The chance of seizures may be raised if you have certain brain blood vessel problems, take other drugs that may raise the chance of seizures, or if you have ever had seizures, brain injury, stroke, or brain cancer. Avoid tasks or actions where passing out may cause harm to you or others. Talk with your doctor.
• Heart disease has happened with enzalutamide in some people. Rarely, this has been deadly. If you have questions, talk with the doctor.
• Use care if you have risks for heart disease (high blood pressure, high cholesterol, overweight, high blood sugar or diabetes, cigarette smoking, man older than 40 years of age, other family members with early heart disease, woman after change of life). Talk with your doctor.
• The chance of falling is raised with enzalutamide. Falls may lead to very bad problems like head injury and broken bones. The chance of falling is higher in older people. Talk with the doctor.
• High blood pressure has happened with enzalutamide. Have your blood pressure checked as you have been told by your doctor.
• This medicine interacts with many other drugs. The chance of side effects may be raised or how well enzalutamide works may be lowered. Check with your doctor and pharmacist to make sure that it is safe for you to take enzalutamide with all of your other drugs (prescription or OTC, natural products, vitamins).
• This medicine may affect being able to father a child. Talk with the doctor.
• This medicine may cause harm to an unborn baby. If you are a man and have sex with a female who could get pregnant, protect her from pregnancy during treatment and for 3 months after your last dose.
• If you are a man and your sex partner gets pregnant while you take enzalutamide or within 3 months after your last dose, call your doctor right away.
• If you are having sex and your partner is pregnant, use a condom while taking enzalutamide and for 3 months after your last dose.

How is enzalutamide best taken?

Use enzalutamide as ordered by your doctor. Read all information given to you. Follow all instructions closely.

• Take enzalutamide at the same time of day.
• Take with or without food.
• Swallow whole. Do not chew, break, open, or dissolve.
• Keep taking enzalutamide as you have been told by your doctor or other health care provider, even if you feel well.
• Females who are pregnant or may get pregnant must not handle enzalutamide.

What do I do if I miss a dose?

• Take a missed dose as soon as you think about it.
• If you do not think about the missed dose until the next day, skip the missed dose and go back to your normal time.
• Do not take 2 doses at the same time or extra doses.

What are the side effects of enzalutamide that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Signs of high blood pressure like very bad headache or dizziness, passing out, or change in eyesight.
• Signs of electrolyte problems like mood changes, confusion, muscle pain or weakness, a heartbeat that does not feel normal, seizures, not hungry, or very bad upset stomach or throwing up.
• Chest pain or pressure.
• Shortness of breath.
• A burning, numbness, or tingling feeling that is not normal.
• Blood in the urine.
• Seizures.
• Swelling in the arms or legs.
• Bone pain after a fall.
• Memory problems or loss.
• Not able to focus.
• Low white blood cell counts have happened with enzalutamide. This may lead to a higher chance of getting an infection. Call your doctor right away if you have signs of infection like fever, chills, or sore throat.
• A very bad and sometimes deadly brain problem called posterior reversible encephalopathy syndrome (PRES) has happened with enzalutamide. Call your doctor right away if you have signs like feeling confused, lowered alertness, change in eyesight, loss of eyesight, seizures, or very bad headache.

What are some other side effects of enzalutamide?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Feeling dizzy, tired, or weak.
• Back, muscle, or joint pain.
• Muscle weakness.
• Not hungry.
• Diarrhea or constipation.
• Hot flashes.
• Signs of a common cold.
• Weight loss.
• Headache.
• Trouble sleeping.
• Anxiety.
• Change in taste.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out enzalutamide?

• Store at room temperature in a dry place. Do not store in a bathroom.
• Keep lid tightly closed.
• Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
• Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.