Letrozol Accord 2,5 mg

Description

Anticancer drug, estrogen synthesis inhibitor. Letrozole has anti-estrogenic activity, selectively inhibiting aromatase (an enzyme of estrogen synthesis) through highly specific competitive binding to the haem subunit of the cytochrome P450 of this enzyme. It blocks estrogen synthesis in both peripheral and tumour tissues.

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.

Daily administration of letrozole at a daily dose of 0.1-5 mg leads to a reduction in plasma concentrations of oestradiol, oestrone and oestrone sulphate by 75-95% of the initial value. The suppression of oestrogen synthesis is maintained throughout the treatment period.

No impairment of steroid hormone synthesis in the adrenal glands is observed during the use of letrozole in the dose range of 0.1 to 5 mg, and the test with ACTH shows no impairment of aldosterone or cortisol synthesis. Additional prescription of glucocorticoids and mineralocorticoids is not required.

Blockade of oestrogen biosynthesis does not lead to accumulation of androgens, which are precursors of oestrogen.

Changes in plasma LH and FSH concentrations, changes in thyroid function, changes in lipid profile, increased incidence of myocardial infarction and stroke were not observed during the use of letrozole. Against the background of letrozole treatment, the incidence of osteoporosis increases slightly (6.9 per cent versus 5.5 per cent against placebo). However, the incidence of bone fractures in patients receiving letrozole does not differ from that in healthy individuals of the same age.

Adjuvant treatment with letrozole in early-stage breast cancer reduces the risk of recurrence, increases 5-year disease-free survival, and reduces the risk of secondary cancers.

Extended adjuvant therapy with letrozole reduces the risk of recurrence by 42%. A significant disease-free survival advantage was observed in the letrozole-treated group, irrespective of lymph node involvement. Treatment with letrozole reduces mortality in patients with lymph node involvement by 40%.