Exemestane sold under the brand name Aromasin among others, is a medicine used to treat breast cancer. It is a member of the class of anti-estrogens known as aromatase inhibitors. Some breast cancers require the growth of estrogen. These cancers have estrogen receptors (ERs), and are called ER-positive. They can also be called estrogen, hormonal or hormone-positive. Aromatase is an enzyme that synthesizes estrogen. Inhibitors of aromatase block estrogen synthesis. This reduces the level of estrogen and slows the growth of cancers.
Uses of Exemestane
Exemestane is indicated for the adjunctive treatment of postmenopausal women with early stage estrogen-receptor positive breast cancer who received tamoxifen for two to three years for a total of five consecutive years. adjuvant hormone therapy. The US FDA approval was in October 2005.
Exemestane is also indicated for the treatment of advanced breast cancer in postmenopausal women whose disease has progressed after tamoxifen therapy.
Side effects
The most common side effects (more than 10% of patients) are hot flashes and sweating, typical of estrogen deficiency caused by exemestane, as well as insomnia, headache and joint pain. Nausea and fatigue are mainly seen in patients with advanced breast cancer.
An occasional decrease in lymphocytes has been observed in approximately 20% of patients receiving Aromasin, particularly in patients with pre-existing lymphopenia.
Exemestane has androgenic properties similar to formestane and can produce androgenic side effects such as acne and weight gain, although they are usually associated with supratherapeutic doses of the drug.
Overdose of Exemestane
Single doses up to at least 32 times (800 mg), as well as continuous therapy with 24 times (600 mg) the usual daily dose are well tolerated. No life-threatening overdose is known in humans, but only in animal studies with doses from 2000 to 4000 times (adjusted to body surface area).
Interactions
Aromasin is metabolized by the CYP3A4 liver enzyme. While the CYP3A4 inhibitor has no significant effect on exemestane concentrations in a clinical trial, the strong rifampicin inducing CYP3A4 significantly reduced the levels of exemutane by 50% (AUC -54%, Cmax – 41% for a single dose), potentially compromising its effectiveness. Other 3A4 inducers such as carbamazepine and St. John’s wort should have similar effects. The clinical relevance of this effect has not been studied.
Estrogens probably reduce the effectiveness of exemestane: it would generally be counterproductive to reduce the estrogen synthesis of the body with exemestane and then replace the estrogen with drugs.