98% up by HPLC USP32 LETROZOLE 112809-51-5

Function of Letrozole
Letrozole is a new generation of highly selective aromatase inhibitors. It is a synthetic benztriazole derivative. By inhibiting aromatase, estrogen levels are reduced, thereby eliminating the stimulating effect of estrogen on tumor growth. The activity in the body is 150-250 times stronger than that of the first generation aromatase inhibitor amuromet. Because of its high selectivity, it does not affect glucocorticoids, mineralocorticoids, and thyroid function. Large doses have no inhibitory effect on the secretion of adrenal corticosteroids, so it has a high therapeutic index. Various preclinical studies have shown that letrozole has no potential toxicity, mutagenicity and carcinogenic effects on various systems and target organs in the whole body, and has less toxic and side effects, and is well tolerated. Compared with estrogen drugs, the anti-tumor effect is stronger. It is suitable for the treatment of postmenopausal patients with advanced breast cancer who are not responding to anti-estrogen therapy and early treatment of breast cancer.

In December 2005, the British drug and health product regulatory agency approved Letrozole (Fron) produced by Novartis of Switzerland to be used in the treatment of breast cancer patients, allowing it to be used in surgically treated, early menopausal hormone-positive mammary glands Cancer patients. This is the second aromatase inhibitor approved following the approval of AstraZeneca ’s Rainin in June 2005. Both drugs have shown in clinical trials that they can better prevent the risk of breast cancer recurrence compared to current standard tamoxifen treatment.