Classification: Aromatase Inhibitor
Exemestane is an aromatase inactivator, which works to decrease the overall levels of estrogen in a woman's body. In women who have gone through menopause, estrogen is mainly produced by the aromatase enzyme, which converts androgens (sex hormones produced by the adrenal glands) into estrogens. Exemestane binds to aromatase, changing the protein permanently. This change "turns off" aromatase so that it can no longer make estrogen. While estrogen may not actually cause breast cancer, it is necessary for the cancer to grow in certain breast cancers. With estrogen blocked, the cancer cells that feed off estrogen may not be able to survive.
How to Take Exemestane
Exemestane comes as a tablet to take by mouth. It should be taken once a day after a meal. Take exemestane at around the same time every day. If you miss a dose and it has been less than 12 hours since your regular dose time, take it as soon as you remember. If it is close to your next dose, skip the dose. Do not take 2 doses at once to make up for a missed dose.
Do not take your medication with a high fat meal, as this can increase the medication levels in your blood. The blood levels of this medication can also be affected by certain medications. These include: medications with estrogen including birth control pills or patches and hormone replacement therapy, rifampin, carbamazepine, phenobarbital, phenytoin and St. John’s wort. Be sure to tell your healthcare provider about all medications and supplements you take.
Storage and Handling
Store this medication at room temperature in the original container. If you prefer to use a pillbox, discuss this with your oncology pharmacist. Ask your oncology team where to return any unused medication for disposal. Do not flush down the toilet or throw in the trash.
Where do I get this medication?
Exemestane is available through both specialty pharmacies and retail/mail order pharmacy; depending on your prescription drug insurance plan. Your oncology team will work with your prescription drug plan to identify an in-network specialty/retail/mail order pharmacy for medication distribution.
This medication may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals without prescription drug coverage. Co-pay cards, which reduce the patient co-pay responsibility for eligible commercially (non-government sponsored) insured patients, are also available. Your care team can help you find these resources.
Possible Side Effects of Exemestane
There are a number of things you can do to manage the side effects of exemestane. Talk to your doctor or nurse about these recommendations. They can help you decide what will work best for you. These are some of the most common side effects:
There are a few things you can do to help with hot flashes. Several medications have been shown to help with symptoms, including clonidine (a blood pressure medication), low doses of certain antidepressants (such as venlafaxine and Prozac), and gabapentin. Non-medical recommendations include:
Weakening of the Bones (Osteoporosis)
Your doctor will check your bone health before starting therapy. This is done with a bone density scan (dexa scan). Women with no weakening of bones prior to aromatase inhibitor therapy will have a follow-up scan around one year after starting therapy, and then every one to two years.
If the scan shows that you already have some bone weakening, your doctor may order a type of medication called a bisphosphonate or calcium and vitamin D supplements to help strengthen the bones. These therapies have been shown to protect the bones from bone loss in women taking aromatase inhibitors. If the bone density remains stable, scans can then be done every two years. In addition, weight bearing exercise and a healthy diet rich in calcium and vitamin D can help protect bone health.
Muscle or Joint Pain/Aches and Headache
Aromatase inhibitor medications can cause joint or muscle aches and pains, which can interfere with quality of life. Be sure to talk to your oncology team if you develop this side effect. This pain is caused mainly by swelling in the joints, which is best treated by a non-steroidal anti-inflammatory (NSAID), such as ibuprofen, naproxen and celecoxib. Be sure to discuss which pain relievers you can safely take with your oncology team, as these are not without their own side effects. Studies have shown that acupuncture, gentle stretching, and exercise may also help reduce this pain.
Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.
Vaginal dryness and related painful intercourse is one of the more common side effects of cancer therapy in women. Vaginal lubricants and moisturizers (longer lasting form of moisturizers) can help with these concerns. Talk to your healthcare team for more suggestions in managing this side effect.
Nausea and/or Vomiting
Talk to your doctor or nurse so they can prescribe medications to help you manage nausea and vomiting. In addition, dietary changes may help. Avoid things that may worsen the symptoms, such as heavy or greasy/fatty, spicy or acidic foods (lemons, tomatoes, oranges). Try antacids, (e.g. milk of magnesia, calcium tablets such as Tums), saltines, or ginger ale to lessen symptoms.
Call your doctor or nurse if you are unable to keep fluids down for more than 12 hours or if you feel lightheaded or dizzy at any time.
Other Side Effects
In some studies, patients taking this medication had increased trouble sleeping (insomnia) and mood change, such as depression.
Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment and for at least 6 months after treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive. You should not breastfeeding while receiving this medication.
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