Your healthcare provider has prescribed anastrozole to help lower your estradiol levels or to prevent them from getting higher. Anastrozole is an oral medication (pill) that is most commonly used (and FDA-approved) to treat breast cancer. Anastrozole is the generic form of the brand name medication Arimidex. When it is used in men undergoing treatment for low testosterone, it is considered off-label prescribing.

Anastrozole comes in 1 mg tablets. Check your prescription for your dose (in your Ro account and on the package label)—most commonly, the starting dose is one tablet taken two or three times a week, with or without food.

What if you miss a dose?

If you miss a dose, take it as soon as you remember. If it is almost time for the next dose (within 1 hour or so), skip the missed dose and take the next regularly scheduled dose. Do not take two doses at the same time.

What if you take more than you are prescribed?

Tell your healthcare professional if you take more than the prescribed dose. A single dose of anastrozole that results in life-threatening symptoms has not been established, and there is no specific antidote to overdosage.

Your estradiol level will be checked regularly alongside other bloodwork for monitoring your progress while you are taking anastrozole and clomiphene. Generally, you will need to have a blood sample taken in person with our trusted lab partner, Quest Diagnostics, approximately every 6 months or as ordered by your doctor or nurse practitioner.

Symptoms of high estradiol are similar to symptoms of low testosterone and may include enlarged breasts (gynecomastia), nipple tenderness, trouble keeping an erection (erectile dysfunction), infertility, loss of libido, loss of muscle mass, and others. This is because the balance of testosterone and estradiol is what’s responsible for sex drive, secondary sex characteristics, and other functions. You may or may not notice symptoms of high estradiol (that is, you may have high estradiol without symptoms).

It is important to remember that your online visit with Roman does not replace routine in-person care with your primary healthcare provider, such as for an annual physical. While telemedicine has its benefits, there are some components of a health check-up that will not be completed via telemedicine, including the physical exam and some laboratory testing. There may also be recommended screening tests for you depending on your age, sex, and family history that require in-person evaluation.

For more details on the recommended check-in schedule, see your Treatment Plan for clomiphene under “What additional testing do I need?”.

If your estradiol stays high even after re-checking your levels while taking anastrozole, you may need to change your dose or you may need to stop taking anastrozole and clomiphene, since the risks of taking anastrozole might not outweigh the benefit. Your healthcare provider will help you make that decision. Talk to your Ro-affiliated healthcare provider if you think anastrozole isn’t working for you.

Common side effects of anastrozole include hot flashes, weakness, joint aches and pains, sore throat, and others.

The most serious potential side effects of anastrozole are:

• Bone thinning or weakness (osteoporosis).

• Skin reaction (ulcers, blisters).

• Severe allergic reactions, including swelling of the face, lips, tongue, or throat, or trouble swallowing or breathing.

• Liver problems.

These are not all of the possible side effects. You can see Important Safety Information for more information about side effects. If you have any questions about side effects, or if you’re experiencing any side effects, reach out to your Ro-affiliated provider.

Anastrozole is in a class of drugs called AIs (aromatase inhibitors). It helps lower levels of the hormone estradiol (the main form of estrogen in the body) in men who are undergoing treatment for low testosterone. It works by blocking the action of an enzyme called aromatase. Aromatase is responsible for converting testosterone into estradiol, a type of estrogen. Estrogens are normally found in adult men at low levels, but can increase with age or when testosterone levels are low. Estrogens may also increase (by conversion from testosterone) when people are treated for low testosterone, either with testosterone replacement therapy or with clomiphene.

The FDA requires that drugs go through a clinical testing process to establish that they’re safe and effective to treat a particular condition. Healthcare providers may prescribe a drug for an unapproved use if they judge that it is medically appropriate for their patient. This type of prescribing is called “off-label” prescribing. Off-label prescribing practices are sometimes validated by clinical experience and research and may be a widely recognized clinical practice. Healthcare providers have the discretion to prescribe drugs off-label based on a patient’s unique medical history, symptoms, and preferences.

The American Urological Association recommends testosterone replacement therapy as the first-line treatment for low testosterone in men. They have made a conditional recommendation that clinicians may use aromatase inhibitors like anastrozole in men with testosterone deficiency based on Level C (low level) evidence. This is a developing area of clinical understanding.

Talk to your Ro-affiliated provider if you have any concerns or questions about using anastrozole off-label. You can always message your healthcare provider through your Ro account.

Adapted from the Prescribing Information for anastrozole except where otherwise noted.

Read this information before you start taking anastrozole and each time you get a refill. There may be new information. This information does not take the place of talking with your healthcare provider about your medical condition or treatment. If you have any questions about anastrozole, ask your doctor, nurse practitioner, or pharmacist.

What is the most important information I should know about anastrozole?

Anastrozole is used to lower estradiol levels in some men undergoing treatment for low testosterone. This is an off-label use of anastrozole. Most clinical trials of anastrozole have been conducted in postmenopausal women undergoing treatment for breast cancer.

Anastrozole may cause serious side effects like worsening of heart disease. Get medical help right away if you have new or worsening pain in your chest or trouble breathing during treatment with anastrozole tablets.

Who should not take anastrozole?

Do not take anastrozole if you have had a severe allergic reaction to anastrozole or any of the ingredients in anastrozole tablets (see your package insert for details). Symptoms of a severe allergic reaction include swelling of the face, lips, tongue, or throat, trouble breathing or swallowing, hives, and itching.

Women who are pregnant, planning to become pregnant, or breastfeeding should not take anastrozole.

Before you take anastrozole, tell your healthcare provider if you have any of the following conditions:

• Heart problems. Patients with pre-existing ischemic heart disease have been observed to have worsening of heart disease on anastrozole.

• Bone thinning or weakness (osteoporosis). Lower levels of estrogen may lead to a loss of the mineral content of bones, which might decrease bone strength.

• Carpal tunnel. Some peopleexperienced tickling, tingling, or numbness of the wrists while taking anastrozole.

What are the possible side effects of anastrozole?

The most serious potential side effects of anastrozole are: – Bone thinning or weakness (osteoporosis). – Skin reaction (ulcers, blisters). – Severe allergic reactions, including swelling of the face, lips, tongue, or throat, or trouble swallowing or breathing. – Liver problems.

Common side effects of anastrozole include hot flashes, weakness, joint aches and pains, sore throat, and others.

Tell your healthcare provider if you have any side effect that bothers you or that does not go away.

This is not a complete list of reported side effects; see the Prescribing Information for more.