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Enzalutamide

(en-zuh-loo-tuh-mide)

Trade/other name(s): Xtandi®, MDV3100

Why would this drug be used?

Enzalutamide is used to treat advanced prostate cancer. It is also being studied for other uses.

How does this drug work?

Enzalutamide is a type of hormone therapy known as an anti-androgen. It blocks the action of male hormones called androgens (such as testosterone).

In prostate cancer and some other cancers, the cells have androgen receptors on their surfaces. When androgens attach to these receptors, it helps the cells grow. This drug blocks the androgen receptors and prevents their signals from reaching the cell’s control center. Cancer cells that depend on androgens may no longer be able to grow.

Enzalutamide works in a slightly different way than other anti-androgens, and it may be effective even if these other drugs no longer work.

Before taking this medicine

Tell your doctor…

  • If you are allergic to anything, including medicines, dyes, additives, or foods.
  • If you have a history of seizures, brain injury, stroke, or brain tumors. This drug may raise your risk of seizures.
  • If you have any other medical conditions such as kidney disease, liver disease (including hepatitis), heart disease, diabetes, gout, or infections. These conditions may require more careful monitoring by your doctor.
  • If you have a partner who is pregnant, trying to get pregnant, or if there is any chance of pregnancy. This drug may cause birth defects if taken at the time of conception or during pregnancy. (See “Precautions” below.)
  • If you think you might want to have children in the future. This drug may reduce fertility. Talk with your doctor about the possible risk with this drug and the options that may preserve your ability to have children.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Enzalutamide can interact with a number of drugs and supplements, so it is important to be sure your health care team knows about all of your medicines and to check with them before starting or stopping any medicines.

The following drugs and supplements can lower the levels of enzalutamide in the blood and might make it less effective:

  • Anti-seizure drugs, such as carbamazepine (Tegretol), phenobarbital (Solfoton), and phenytoin (Dilantin)
  • Drugs to treat tuberculosis (TB), such as rifampin (Rifadin, Rimactane; also in Rifamate and Rifater), rifabutin (Mycobutin), and rifapentine (Prifin)
  • The steroid drug dexamethasone (Decadron)
  • St. John's wort (herbal dietary supplement)

Some drugs and supplements could cause enzalutamide to build up in your blood, which might worsen side effects and other problems:

  • Some drugs used to treat high cholesterol, such as gemfibrozil (Lopid)
  • Some antibiotics, such as erythromycin, clarithromycin (Biaxin), telithromycin (Ketek), and similar drugs
  • Anti-fungal medicines such as ketoconazole (Nizoral), itraconazole (Sporanox), voriconazole (Vfend), and posaconazole (Noxafil)
  • Some anti-depressant drugs, such as nefazodone (Serzone)
  • Anti-HIV drugs such as indinavir (Crixivan), ritonavir (Kaletra), nelfinavir (Viracept), atazanavir (Reyataz), saquinavir (Invirase), and others

Your doctor may need to adjust the dose of enzalutamide if you need to take some of these drugs.

Enzalutamide may also affect the blood levels of many other medicines. Some of these drugs may have a narrow range where they are safe and effective, so your doctor may need to watch you closely or even switch you to a different drug. Examples of drugs that could cause problems include warfarin (Coumadin), phenytoin (Dilantin), cyclosporine (Sandimmune, others), dihydroergotamine (Migranal), ergotamine (Cafergot, others), fentanyl (Actiq, others), pimozide (Orap), quinidine, sirolimus (Rapamune), and tacrolimus (Prograf).

The lists above do not include all of the drugs that might interact with enzalutamide. It is very important to check with your doctor, nurse, or pharmacist about all of your medicines, herbs, and supplements, and whether alcohol can cause problems with this medicine.

Interactions with foods

Grapefruit or grapefruit juice may change the level of this drug in your blood. Check with your doctor, nurse, or pharmacist about whether these or other foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Enzalutamide is taken once daily as capsules, with or without food. It should be taken at about the same time each day. The usual starting dose is 4 capsules for a dose of 160 milligrams (mg), but the dose may be lower if you are taking certain other medicines. Your doctor may need to delay your treatment for a time and/or reduce your dose if you have serious side effects.

Keep the medicine in a tightly closed container away from heat and moisture and out of the reach of children and pets.

Precautions

Enzalutamide may cause seizures in a small number of people. Be sure your doctor knows if you have a history of seizures, brain injury, stroke, or tumors in the brain. Talk to your doctor about whether you should avoid activities such as driving, where a sudden loss of consciousness could cause serious harm to you or to others. Tell your doctor or nurse right away if you have a loss of consciousness or a seizure.

This drug may also cause dizziness, trouble thinking, and changes in sensation in your hands and feet, which may increase your risk of serious falls and broken bones.

It is important to keep taking enzalutamide and your other medicines, even if you feel well. If you are bothered by side effects, talk to your doctor or nurse to find out if the problems are serious. Many side effects can be managed with help from your doctor.

This drug has not been tested in women or children and is not recommended for their use.

This drug could cause problems with the fetus if taken at the time of conception, or possibly even when a woman is already pregnant. Men who are having sex with women who are or could become pregnant should use a condom and another effective form of birth control during treatment and for at least 3 months after the last dose of this drug. Check with your doctor about what kinds of birth control can be used with this medicine.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.

Common

  • Feeling tired and weak
  • Back pain
  • Joint pain
  • Diarrhea
  • Hot flashes

Less common

  • Swelling in the hands or feet
  • Muscle pain
  • Muscle weakness
  • High blood pressure
  • Headache
  • Feeling dizzy*
  • Changes in or loss of sensation, especially in the hands or feet*
  • Damage to the spinal cord or spinal nerves caused by broken bones in the spine or pressure from tumor growth
  • Upper respiratory infection (such as a cold)
  • Pneumonia or bronchitis
  • Trouble sleeping
  • Feeling anxious
  • Blood in the urine
  • Low white blood cell counts, which might raise the risk of infection

Rare

  • Seizures*
  • Muscle stiffness
  • Memory loss or trouble thinking* or concentrating
  • Hallucinations
  • Frequent urination
  • Falls or injuries related to falls*
  • Broken bones (not related to the cancer)*
  • Itchy or dry skin
  • Nosebleeds
  • Death from serious infections

*See “Precautions” section for more detailed information.

Other side effects not listed above can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved in 2012.

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.


Last Medical Review: 09/07/2012
Last Revised: 09/07/2012