How Exemestane works
Exemestane is an irreversible aromatase inhibitor and as such suppresses the formation of female sex hormones (estrogens).
Estrogens (estrone, estradiol, and estriol) are female sex hormones. They are formed in the female body (in small quantities also in the male) from precursor substances, mainly in the ovaries.
The sex hormones are important for the formation of sexual characteristics and, together with other hormones (such as progesterone), keep the menstrual cycle going. During menopause, the ovaries gradually stop producing estrogen.
After that, the hormone is produced only in small amounts in other tissues (muscles, fatty tissue, mammary gland tissue). As a result, estrogen levels drop to very low levels.
In some cases of breast cancer, the tumor is hormone-sensitive, meaning that its growth is dependent on estrogen. Aromatase inhibitors such as Exemestane are used to suppress this hormone-controlled tumor growth.
They inhibit the enzyme aromatase, which is involved in converting estrogen precursors into the active hormones. This greatly lowers estrogen levels, often preventing further tumor growth.
Absorption, degradation and excretion
Exemestane is broken down in the liver and excreted in the urine and stool.
When is exemestane used?
Exemestane is approved for the adjuvant treatment of hormone-sensitive, early breast cancer after two to three years of treatment with the active ingredient tamoxifen.
It is also approved for the treatment of advanced breast cancer when tumor growth has not stopped with antiestrogen treatment.
Only post-menopausal women may be treated with exemestane. However, this can also be brought about prematurely with the help of medication.
How Exemestane is used
Exemestane is taken as a tablet once a day, after a meal, because it is then better absorbed into the body. The usual daily dose is 25 milligrams of exemestane.
The duration of use in patients with early breast cancer is determined individually by the doctor. In advanced breast cancer, the therapy is usually permanent as long as the tumor does not continue to grow.
What are the side effects of Exemestane?
Since the estrogen level drops suddenly and sharply with Exemestane, severe post-menopausal symptoms (“menopausal symptoms”) can occur, especially at the beginning of therapy.
Other common side effects include loss of appetite, decrease in blood platelets (thrombocytes), numbness, vomiting, diarrhea, constipation, indigestion, hair loss, skin rash, itching, decreasing bone density and fractures, and water retention and weakness.
What should be considered when taking Exemestane?
Contraindications
Exemestane should not be used in the following cases:
- hypersensitivity to the active substance or to any of the other ingredients of the drug
- women before menopause
- pregnancy
- Lactation
Drug interactions
Since Exemestane is broken down by liver enzymes that also break down other drugs, it may interact with some of them when used concomitantly:
Interactions have been observed with drugs that cause the liver to produce more of the enzymes that break down Exemestane. As a result, Exemestane is broken down more quickly, which reduces its effectiveness or prevents it from working at all. Examples of such agents include the antibiotic rifampicin, certain agents for epilepsy and seizures (such as phenytoin, carbamazepine), and the herbal antidepressant St. John’s wort.
In order not to jeopardize the therapeutic success of Exemestan, no estrogen-containing drugs should be taken or applied to the skin during treatment. This would cancel out the effect of exemestane.
Exemestane is indicated only in postmenopausal women. If necessary, this can be induced artificially.
Pregnancy and lactation
Exemestane is contraindicated during pregnancy and breastfeeding.
How to obtain medicines containing exemestane
Preparations containing Exemestan are available in Germany, Austria, and Switzerland in any dosage and package size on prescription and from pharmacies.
Since when is Exemestan known?
After the active ingredients anastrozole and letrozole, exemestane is the third orally active aromatase inhibitor developed for the treatment of hormone-sensitive breast cancer tumors. All three active ingredients are on the doping ban list because they can be taken by athletes to prevent side effects from banned doping agents (anabolic steroids).
Exemestane was approved in Germany in 1999. Since patent protection expired, numerous generics containing the active ingredient have come onto the market.
