Letrozol Heumann 2,5 mg

Description

Pharmacodynamics

Letrozole is an anticancer drug, a non-steroidal selective inhibitor of aromatase, an enzyme of estrogen synthesis, and has anti-estrogenic activity. Aromatase activity is reduced due to competitive binding to the prosthetic part (heme) of cytochrome P450 (a subunit of this enzyme). In postmenopausal women, oestrogens are mainly formed by the enzyme aromatase, which converts androgens synthesised in the adrenal glands (mainly androstendione and testosterone) into oestrone and oestradiol.

Administration of the drug in the postmenopausal period at a dose of 0.1-5 mg/day leads to a reduction in plasma concentrations of oestradiol, oestrone and oestrone sulphate by 75-95% of the initial value. Low estrogen concentrations are maintained throughout the treatment period in all patients. In women with oestrogen-dependent malignant breast tumours arising during menopause, the drug, by reducing the concentration of circulating oestrogens and inhibiting their synthesis in tumour tissue, leads to tumour regression (in 23% of cases) and a reduction in recurrence and mortality. Possessing high specificity for the aromatase enzyme, it does not interfere with the synthesis of steroid hormones in the adrenal glands.

Indications for use

• adjuvant therapy of breast cancer in postmenopausal women with hormone-positive early-stage breast cancer
• early-stage breast cancer in postmenopausal women who have received standard adjuvant therapy with tamoxifen
• breast cancer in postmenopausal women who have previously received anti-estrogen therapy
• localised estrogen receptor-positive breast cancer in postmenopausal women who have received organ-sparing surgery, if organ-sparing surgery was not initially indicated.