Anastrozole (an-ASS-troh-zole ) is a medicine that is used to treat breast cancer.

Many breast cancer tumors grow in response to estrogen. This medicine interferes with the production of estrogen in the body. As a result, the amount of estrogen that the tumor is exposed to is reduced, limiting the growth of the tumor.

This medicine is available only with your doctor's prescription, in the following dosage form(s):

Oral
• Tablets (U.S. and Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For anastrozole, the following should be considered:

Allergies?Tell your doctor if you have ever had any unusual or allergic reaction to anastrozole. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy?Anastrozole has not been studied in pregnant women. However, studies in animals have shown that anastrozole causes miscarriages, decreased weight or death of the fetus, and problems with bone formation. Be sure that you have discussed this with your doctor before taking this medicine. Tell your doctor right away if you think you have become pregnant while taking anastrozole.

Breast-feeding?It is not known whether anastrozole passes into the breast milk. However, anastrozole is not recommended during breast-feeding because it may cause unwanted effects in nursing babies.

Children?Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of anastrozole in children with use in other age groups.

Older adults?This medicine has been tested in a limited number of patients 65 years of age or older and has not been shown to cause different side effects or problems in older people than it does in younger adults.

Other medicines?Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking anastrozole, it is especially important that your health care professional knows if you are taking any of the following:

• Medicines that contain estrogen (e.g., Alora, Climara, Mengest, Premarin, Prempro)?May cause anastrozole to not work as well

• Tamoxifen (e.g., Nolvadex)?May decrease the amount and effects of anastrozole

Take this medicine only as directed by your doctor. Do not use more or less of it, and do not use it more often than your doctor ordered.

Anastrozole sometimes causes nausea, vomiting, and diarrhea. However, it is very important that you continue to use the medicine, even if you begin to feel ill. Ask your doctor, nurse, or pharmacist for ways to lessen these effects.

Dosing?

The dose of anastrozole will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of anastrozole. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage form (tablets):
  • For breast cancer:
    • Adults?1 mg once a day. Your doctor will determine how long you need to take this medicine.
    • Children?Use and dose must be determined by your doctor.

Missed dose?

If you do miss a dose of this medicine, do not take the missed dose at all and do not double the next one. Instead, go back to your regular dosing schedule and check with your doctor.

Storage?

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Keep the medicine from freezing. Do not refrigerate.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is important that your doctor check your progress at regular visits to make sure this medicine is working properly and to check for unwanted effects.

It is important that your doctor check your progress at regular visits to make sure this medicine is working properly and to check for unwanted effects.