What is Exemestane?
Exemestane more commonly known by the trade name Aromasin is used to treat early breast cancer in women who have experienced menopause (‘change of life’; end of monthly menstrual periods) and who have already been treated with a medication called tamoxifen (Nolvadex) for 2 to 3 years.
This medication is also used to treat breast cancer in women who have experienced menopause whose breast cancer has worsened while they were taking tamoxifen. The FDA approved the use of exemestane for adjuvant treatment of postmenopausal women with estrogen-receptor (ER)-positive early breast cancer following two-to-three years of tamoxifen for completion of five consecutive years of adjuvant hormonal therapy.
How Exemestane works
Exemestane is in a class of medications called aromatase inhibitors. It works by decreasing the amount of estrogen produced by the body. This can slow or stop the growth of some breast tumors that need estrogen to grow.
What special precautions should I follow?
Before taking exemestane,
• tell your doctor and pharmacist if you are allergic to exemestane or any other medications.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Be sure to mention any of the following: carbamazepine (Carbatrol, Epitol, Tegretol); medications that contain estrogens such as hormone replacement therapy and hormonal contraceptives (birth control pills, patches, rings, and injections); phenobarbital; phenytoin (Dilantin); and rifampin (Rifadin, in Rifater, in Rifamate). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor what herbal products you are taking, especially St John’s wort.
• tell your doctor if you have or have ever had osteoporosis (a condition in which the bones are fragile and break easily), liver, or kidney disease.
• tell your doctor if you are pregnant or plan to become pregnant. You will need to have a negative pregnancy test within 7 days before you begin to take exemestane. You should use birth control to avoid pregnancy during your treatment with exemestane and for 1 month after your final dose. If you become pregnant while taking exemestane, call your doctor immediately. Exemestane may harm the fetus.
• tell your doctor if you are breastfeeding. You should not breastfeed during your treatment with exemestane and for 1 month after your final dose.
How should this medicine be used?
Exemestane comes as a tablet to take by mouth. It is usually taken once a day after a meal. Take exemestane at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take exemestane exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
You may need to take exemestane for several years or longer. Continue to take exemestane even if you feel well. Do not stop taking exemestane without talking to your doctor.
How long does Exemestano take to work?
Exemestano starts to work soon after you take a dose. But it may take several weeks to see any improvement in your condition. Your doctor will order regular blood tests and imaging tests to see how Exemestano is working to treat your breast cancer.
How long does exemestane stay in your system?
There are several factors that come into play when estimating how long Exemestane will stay in your system because every patient has physiology unique to them. Here are some major factors you should consider when trying to understand how long Exemestane will stay in your body:
• Age: Typically, the younger you are, the more efficient your body functions are. The more efficient your body functions, the faster Exemestane will be removed from your system.
• Body height/weight/fat: Your specific prescribed Exemestane dosage corresponds to your body height, weight, and fat. Usually, larger people will be given a higher dosage of Exemestane. The higher the dose of Exemestane you have been taking, the longer Exemestane will take to be removed from your system.
• Genetics: Genes predispose people to different metabolic functions, which is a key factor in how your body processes medications like Exemestane. For this reason, your genetic makeup comes into play when estimating how long Exemestane will remain in your system.
• Kidney and liver functions: The liver and kidneys eliminate everything you ingest, and Exemestane is no exception. If your liver or kidneys are damaged, it will most likely take longer for your body to remove the Exemestane from your system.
• Metabolism: Your metabolism determines how quickly you process foods, liquids, and medications such as Exemestane. If your metabolism is slow, it will take longer for your body to process and eliminate Exemestane from its system than someone with a fast metabolism.
• Usage frequency: The longer you have been taking Exemestane, the longer it will remain in your system. For example, it will take longer for someone who has taken Exemestane for several years to remove Exemestane from the body than someone who has only been taking Exemestane for a few months.
Exemestane has a plasma elimination half-life of about 24 hours in humans. The half-life of a drug is the time it takes for the amount of a drug’s active substance in your body to reduce by half.
Half-life is used to estimate how long it takes for a drug to be removed from your body. It takes about 4 to 5 half-lives, for the plasma concentrations of a given drug to fall below a clinically relevant concentration and be considered eliminated. As a result, it can take about 48 hours (about 2 days) for a dose of Exemestane to be eliminated from the body.
Some foods and medications can also speed up how quickly Exemestano is removed from your body. If you take any of these, your doctor may adjust your dosage. Before starting treatment with Exemestano, share information about all your medications with your doctor.
What are the likely side effects of Exemestane?
Exemestane may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
• changes in vision
• difficulty falling asleep or staying asleep
• feeling worried or anxious
• hair loss
• hot flushes
• increased appetite
• muscle or joint pain
• red, itchy skin
• swelling of the arms, hands, feet, ankles, or lower legs
Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:
• chest pain
• shortness of breath
Your bone mineral density (BMD; a measure of the strength of the bones) may decrease while you are taking Exemestane. This may increase the chance that you will develop osteoporosis (a condition in which the bones are fragile and break easily). Talk to your doctor about the risks of taking Exemestane.
Exemestane may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.