What is anastrozole?
Anastrozole is a prescription drug. It’s available as an oral tablet.
Anastrozole oral tablet is available as the brand-name drug Arimidex and as a generic drug. Generic drugs usually cost less. In some cases, they may not be available in the same strengths or dosage forms as the brand-name version.
This drug may be used with other medications to treat breast cancer.
Why it’s used
Anastrozole is used to treat breast cancer. It’s used only in women who have gone through menopause. Specifically, it’s used for:
Treatment of early breast cancer. It’s given to women with hormone receptor-positive or unknown breast cancer after surgery or in addition to other therapies.
Initial or first treatment of breast cancer that has metastasized (spread to other parts of the body). It’s used in women with hormone receptor-positive breast cancer, or women in whom the hormone receptors aren’t known.
Treatment of advanced breast cancer. It’s given when your disease has progressed, even after early response with the cancer drug tamoxifen.
How it works
Anastrozole belongs to a class of drugs called aromatase inhibitors. They block the production of estrogen, which is a key stimulator of breast cancer. A class of drugs refers to medications that work similarly. They have a similar chemical structure and are often used to treat similar conditions.
Heart disease warning: If you have early breast cancer and a history of blockage in your heart arteries, anastrozole may cause low blood flow to your heart. Call your doctor right away if you have symptoms, which may include:
- shortness of breath
- swelling in your legs and feet
- worsening chest pain
Low bone density risk: Anastrozole can decrease bone density in your lower spine and hips. Your doctor will monitor your bone mineral density while you’re taking this drug.
Cholesterol warning: Anastrozole may cause your cholesterol levels to rise. Higher cholesterol levels put you at increased risk of heart disease.
Embryo-fetal toxicity warning: Anastrozole may cause harm to the developing fetus and may lead to pregnancy loss. If you can become pregnant, you’ll need to use effective birth control while taking anastrozole and continue to do so for at least 3 weeks after taking your last dose of the drug.
This drug comes with several warnings.
Anastrozole can cause a severe allergic reaction. Symptoms may include:
- trouble breathing
- swelling of your throat or tongue
If you develop these symptoms, call 911 or go to the nearest emergency room.
Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal.
Contact with drug warning
Don’t share this medication with others, even if they have the same medical condition that you have. This drug could harm them.
Warnings for people with certain health conditions
For people with osteoporosis: Anastrozole lowers the estrogen levels in your body, which may cause your bones to become weak or thin. This could worsen your osteoporosis and further increase your risk for fractures. Your doctor will check your bone mineral density before starting and during treatment with this drug.
For people with high cholesterol: This medication may increase your cholesterol levels. This can raise your risk of serious heart problems. You doctor will check your cholesterol levels while you’re taking anastrozole.
For people with heart disease: If you have a history of blockage in your heart arteries, anastrozole may cause low blood flow to your heart. Talk to your doctor to weigh the risks and benefits of taking this medication to treat your breast cancer.
For people with liver problems: Anastrozole may cause inflammation of your liver. This can worsen liver problems. Your doctor may check your liver function before and during treatment with this drug.
How to take anastrozole
All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:
- your age
- the condition being treated
- how severe your condition is
- other medical conditions you have
- how you react to the first dose
Dosage for breast cancer
Form: oral tablet
Strengths: 1 mg
Form: oral tablet
Strengths: 1 mg
Adult dosage (ages 18 years and older)
The typical recommended dosage is one 1-mg tablet taken by mouth once per day.
Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always talk with your doctor or pharmacist about dosages that are right for you.
Take as directed
Anastrozole is used for long-term treatment. It comes with serious risks if you don’t take it as prescribed.
If you don’t take it at all, stop taking it, or don’t take it schedule: Your breast cancer may come back.
If you take too much: Call your doctor or go to the emergency room right away. Taking too much of this drug may cause serious side effects such as severe bleeding, death of tissues, or gastritis.
What to do if you miss a dose: If you forget to take your dose, take it as soon as you remember. If it’s just a few hours before the time for your next dose, then only take one dose at that time.
Never try to catch up by taking two doses at once. This could result in dangerous side effects.
How to tell if the drug is working: Your doctor will do tests to check if your breast cancer growth has slowed down or stopped.
Important considerations for taking anastrozole
Keep these considerations in mind if your doctor prescribes anastrozole for you.
Anastrozole can be taken with or without food.
Don’t crush, break, or chew anastrozole tablets. Swallow them whole.
If you can become pregnant, you must use birth control while taking anastrozole and continue to do so for some time after taking your last dose of the drug. Ask your doctor how long to use birth control for.
Store anastrozole at room temperature between 68°F and 77°F (20°C and 25°C).
Keep it away from high temperatures.
Don’t store this medication in moist or damp areas, such as bathrooms.
A prescription for this medication is refillable. You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.
When traveling with your medication:
- Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
- Don’t worry about airport X-ray machines. They can’t hurt your medication.
- You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
- Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.
Before starting and during treatment with anastrozole, your doctor will monitor your:
- heart function, including blood pressure and heart rate
- cholesterol levels
- liver function
- bone density
Your doctor will check to see if your breast cancer growth has decreased or stopped by doing a breast exam.
Not every pharmacy stocks this drug. When filling your prescription, be sure to call ahead to make sure they carry it.
Are there any alternatives?
There are other drugs available to treat your condition. Some may be more suitable for you than others. Talk to your doctor about possible alternatives.
Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
Usual Adult Dose for Breast Cancer
Initial dose: 1 mg orally taken once a day
Duration of therapy: Until tumor progression (treatment of advanced breast cancer); unknown (adjuvant treatment of early breast cancer)
Adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer;
First-line treatment of postmenopausal women with hormone receptor-positive or hormone receptor unknown locally advanced or metastatic breast cancer;
Second-line treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy.
Renal Dose Adjustments
No adjustment recommended.
Liver Dose Adjustments
Mild to moderate liver dysfunction: No adjustment recommended.
Stable hepatic cirrhosis: No adjustment recommended.
Severe liver dysfunction: Data not available.
CONTRAINDICATIONS:-Hypersensitivity to the active component or any of the ingredientsSafety and efficacy have not been established in patients younger than 18 years.Consult WARNINGS section for additional precautions.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.