Pharmacological-antitumor action, inhibiting the synthesis of estrogens.
It is active against estrogen-dependent breast tumors in postmenopausal women. Androstenedione-the main source of circulating estrogens in postmenopausal women, in peripheral tissues turns into estrone, and then into estradiol, this process occurs with the participation of the aromatase enzyme. The mechanism of action of anastrozole is associated with the inhibition of aromatase (non-steroidal selective inhibitor)in peripheral tissues, incl.adipose, which leads to a decrease in the amount of estradiol. In the treatment of anastrozole in the recommended dose - 1 mg per day-the level of estradiol decreases by 70% for 24 hours, by 80% - after 14 days. Suppression of serum estradiol is maintained for 6 days after discontinuation of daily administration of 1 g of anastrozole. Reducing the level of circulating estradiol has a therapeutic effect in breast tumors in postmenopausal women. When taken daily in doses of 3, 5 and 10 mg, anastrozole had no effect on the secretion of cortisol and aldosterone. Anastrozole showed no direct progestogenic, androgenic and estrogenic activity in animals, but altered circulating progesterone, androgen and estrogen levels.
After ingestion, 83-85% of the dose is absorbed, ingestion affects absorption (reduces absorption). Cmax is reached after 2 h (on an empty stomach). In the blood, plasma proteins bind 40%. The equilibrium concentration in the blood with a daily intake is reached after about 7 days, its value is 3-4 times higher than with a single intake. Anastrozole is extensively metabolized in postmenopausal women, less than 10% is excreted in the urine unchanged for 72 hours after administration, 60% is excreted as metabolites. Biotransformation in the liver is carried out by n-dealkylation, hydroxylation and glucuronization to form inactive metabolites, the main of which is triazole. Pharmacokinetics of anastrozole does not depend on the age of women in the range of 50-80 years.Method of administration and dose
Inside, 1 mg 1 once a day. The course of treatment depends on the form and severity of the disease