Posted on April 28th, 2009 by

Class: Hormonal Therapy

Generic Name: anastrozole (ah-NAS-tre-zole)

Trade Name: Arimidex®

For which conditions is this drug approved? Anastrozole is indicated for the treatment of postmenopausal women with hormone-positive breast cancer either as an adjuvant treatment for the early stages of the disease; or for first-line treatment or secondary treatment after tamoxifen for postmenopausal women with advanced stages of disease.

What is the mechanism of action? Anastrozole belongs to a group of drugs referred to as aromotase inhibitors. Anastrozole produces its anti-cancer effects by inhibiting the production of the female hormone estrogen in the body. A significant portion of breast cancers, referred to as estrogen- or hormone-positive, are stimulated to grow by estrogen, which circulates in the blood stream and binds to cancer cells. By inhibiting estrogen production, the growth stimulus of the cancer cells is removed, causing cancer cells to stop growing and/or die.

How is anastrozole typically given (administered)? Anastrozole is administered as a pill once daily. It is eliminated in the body through the urine and feces.

How are patients typically monitored? Patients will usually have scheduled meetings with their healthcare provider while they are being treated with anastrozole. Typically, blood will be drawn to check levels of blood cells and to monitor functions of some organ systems, such as the kidneys or liver. Patients may also undergo physical examinations, scans or other measures to assess side effects and response to therapy. If a physician feels that a patient is at risk for osteoporosis (reduction in bone density), scans to determine bone density may be ordered prior to or during treatment with anastrozole, as the risk of bone fractures may be increased during treatment.

What are the common (occur in 30% or more of patients) side effects of treatment with anastrozole?

  • Hot flashes

What are the less common (occur in 10% to 29% of patients) side effects of treatment with anastrozole?

  • Joint aches or pain
  • Weakness
  • Mood changes
  • Nausea and vomiting
  • Pain
  • Sore throat
  • Cough
  • Headache
  • Back pain, bone pain

This is not a complete list of side effects. Some patients may experience other side effects that are not listed here. Patients may wish to discuss with their physician the other less common side effects of this drug, some of which may be serious.

Some side effects may require medical attention. Other side effects do not require medical attention and may go away during treatment. Patients should check with their physician about any side effects that continue or are bothersome.

What can patients do to help alleviate or prevent discomfort and side effects?

  • Pay careful attention to the physician’s instructions and inform the physician of any side effects.
  • Maintain adequate rest and nutrition.
  • For hot flashes, light clothing, cool environment and cool cloths on the body or head may help relieve these symptoms.
  • Over the counter pain medications may help to alleviate the aches or pains that may be caused by treatment; it is important to thoroughly discuss these options with a physician.
  • Eat small meals frequently to help alleviate nausea.
  • If patients have been prescribed an anti-nausea medication, they should be sure to take the prescribed doses.
  • Wear sunscreen and protective clothing and try to minimize sun exposure.
  • Drink plenty of fluids. (Patients should ask their physician about the amount of liquid to consume during a day.)

Are there any special precautions patients should be aware of before starting treatment?

  • If an oral dose is missed, do not double up on doses. Patients should contact their physician in this event.
  • Keep tablets out of reach of children and return to the pharmacy for safe disposal if treatment is terminated.
  • Patients should inform their physician if they are pregnant or breastfeeding as anastrazole is not administered to women who are pregnant.
  • It is important that patients inform their physician of any pre-existing conditions (chicken pox, heart disease, kidney disease, liver disease, lung disease, etc.) as they may worsen with this drug.
  • Patients should inform their physician of any other medication they are taking (whether prescription or over-the-counter, including vitamins, herbs, etc.) as they may interfere with treatment.
  • Patients should check with their physician before starting any new drug or nutritional supplement.
  • Patients should inform their physician of any known drug or food allergies or any reactions to medications they have experienced in the past.

When should patients notify their physician?

  • Prolonged or severe nausea or vomiting
  • Severe weakness
  • Bone pain after a fall or trauma, as this may indicate a bone fracture
  • Extreme pain

What is a package insert?

A package insert is required by the FDA and contains a summary of the essential scientific information needed for the safe and effective use of the drug for healthcare providers and consumers. A package insert typically includes information regarding specific indications, administration schedules, dosing, side effects, contraindications, results from some clinical trials, chemical structure, pharmacokinetics and metabolism of the specific drug. By carefully reviewing the package insert, you will get the most complete and current information about how to safely use this drug. If you do not have the package insert for the drug you are using, your pharmacist or physician may be able to provide you with a copy.

Last updated on 09/16.

Important Limitations of Use

The information provided above on the drug you have selected is provided for your information only and is not a substitute for consultation with an appropriate medical doctor. We are providing this information solely as a courtesy and, as such, it is in no way a recommendation as to the safety, efficacy or appropriateness of any particular drug, regimen, dosing schedule for any particular cancer, condition or patient nor is it in any way to be considered medical advice. Patients should discuss the appropriateness of a particular drug or chemotherapy regimen with their physician.

As with any printed reference, the use of particular drugs, regimens and drug dosages may become out-of-date over time, since new information may have been published and become generally accepted after the latest update to this printed information. Please keep in mind that health care professionals are fully responsible for practicing within current standards, avoiding use of outdated regimens, employing good clinical judgment kin selecting drugs and/or regimens, in calculating doses for individual patients, and verifying all dosage calculations.



The prescribing physician is solely responsible for making all decisions relating to appropriate patient care including, but not limited to, drugs, regimens, dose, schedule, and any supportive care.

Tags: A, Drug Dictionary, Hormonal Therapy

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