Trade Name: PureLetrozole 2.5mg

Substance: Letrozole 20 tabs

Production: PureGear Laboratories, EU

Form: 1 mg / tbl.

Letrozole (common trade name Femara) is an oral non-steroidal aromatase inhibitor for the treatment of hormonally-responsive breast cancer after surgery.

Estrogens are produced by the conversion of androgens through the activity of the aromatase enzyme. Estrogens then bind to an estrogen receptor, which causes cells to divide.

Letrozole prevents the aromatase from producing estrogens by competitive, reversible binding to the heme of its cytochrome P450 unit. The action is specific, and letrozole does not reduce production of mineralo- or corticosteroids.

In contrast, tamoxifen interferes with the estrogen receptor. Tamoxifen is also used to treat hormonally- responsive breast cancer. However, letrozole is effective only in post-menopausal women, in whom estrogen is produced predominantly in peripheral tissues (i.e. in adipose tissue, like that of the breast) and a number of sites in the brain.In pre-menopausal women, the main source of estrogen is from the ovaries not the peripheral tissues, and letrozole is ineffective.

In the BIG 1-98 Study, of post-menopausal women with hormonally-responsive breast cancer, letrozole improved the recurrence of cancer, but not survival, compared to tamoxifen