Exemestane (Aromasin) is a third-generation aromatase inhibitor used to treat hormone responsive breast cancers in women who are postmenopausal - have gone through menopause.

Some breast cancer cells need the hormone estrogen to grow. Exemestane works by blocking the enzyme aromatase, which converts androgen hormones into estrogen.

In premenopausal women the main source of estrogen is the ovaries. But in postmenopausal women, the main source of estrogen is from the conversion of androstenedione and testosterone - adrenal and ovarian androgen hormones - by the enzyme aromatase.

Exemestane is an irreversible, steroidal aromatase inactivator that works by binding to and and inactivating aromatase, an effect that is known as 'suicide inhibition'. This prevents aromatase from converting androgens into estrogen and cuts of the supply of estrogen that the breast cancer cells need to grow.

Exemestane was first approved by the US Food and Drug Administration (FDA) and in 1999 and marketed under the brand name Aromasin. Aromasin tablets are still available, but generic exemestane tablets have also been available for more than a decade.

What is exemestane used for?

Exemastane is used in women who are past menopause for the treatment of:

• Early breast cancer (cancer that has not spread outside the breast) in women who:
  • have cancer that needs the female hormone estrogen to grow, and
  • have had other treatments for breast cancer, and
  • have taken tamoxifen for 2 to 3 years, and
  • are switching to exemastane to complete 5 years in a row of hormonal therapy.
• Advanced breast cancer (cancer that has spread) after treatment with tamoxifen, and it did not work or is no longer working.

It is not known if exemastane is safe and effective in children.

• Take exemastane exactly as your doctor tells you.
• Take exemastane 1 time each day after a meal.
• If you take too much exemastane, call your doctor right away or go to nearest hospital emergency room.

The recommended dose of exemestane is one 25mg tablet taken once a day after a meal.

See full prescribing information for further information about exemestane dosing.

Do not take exemastane if you are allergic to exemastane or any of the ingredients in exemastane. See below for a complete list of ingredients in exemastane.

What should I tell my doctor before taking exemestane?

Before you take exemastane, tell your doctor about all your medical conditions, including if you:

• are still having menstrual periods (are not past menopause). Exemastane is only for women who are past menopause
• have weak or brittle bones (osteoporosis)
• have liver or kidney problems

If you miss a dose of exemastane, take it as soon as you remember if it is within 12 hours of the missed dose. If it has been more than 12 hours, skip the missed dose and take your next dose at the usual time.

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unless your doctor tells you otherwise, continue your normal diet.

Exemastane may cause serious side effects, including:

• Bone loss. Exemastane decreases the amount of estrogen in your body which may reduce your bone mineral density (BMD) over time. This may increase your risk for bone fractures or weak and brittle bones (osteoporosis). Your doctor may check your bones during treatment with exemastane if you have osteoporosis or at risk for osteoporosis.

The most common side effects of exemastane in women with early breast cancer include:

• hot flashes
• headache
• feeling tired
• trouble sleeping
• joint pain
• increased sweating

The most common side effects of exemastane in women with advanced breast cancer include:

• hot flashes
• increased sweating
• nausea
• increased appetite
• feeling tired

Your doctor will do blood tests to check your vitamin D level before starting treatment with exemastane.

Exemastane may cause decreased fertility in males and females. Talk to your doctor if you have concerns about fertility.

These are not all the possible side effects of exemastane. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins and herbal supplements.

Especially tell your doctor if you take medicines that contain estrogen, including other hormone replacement therapy or birth control pills or patches. Exemastane should not be taken with medicines that contain estrogen as they could affect how well exemastane works.

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your body's response to exemestane.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.