Antineoplastic Letrozole Femara CGS-20267 Powder CAS 112809-51-5
oral non-steroidal aromatase inhibitor
|Synonyms||4,4'-(1H-1,2,4-TRIAZOL-1-YLMETHYLENE) BIS-BENZONITRILE; CGS-20267,
|storage temprature||-20°C Freezer|
What is Letrozole?
Letrozole (INN, trade name Femara) is an oral non-steroidal
aromatase inhibitor for the treatment of hormonally-responsive
breast cancer after surgery.It is a new generation of selective
How does Letrozole Work?
Letrozole is a new generation of selective aromatase inhibitors. It
is a synthetic benzyl triazole derivative, can inhibit aromatase
and decrease estrogen levels, further eliminates the stimulation of
estrogen on tumor growth. The activity of letrozole in the body is
150-250 times more than that of the first generation of aromatase
inhibitors-aminoglutethimide. Due to its high selectivity, and
shall not affect the ugar cortical hormone, mineralocorticoid and
thyroid functions, large dosage is of no inhibition for adrenal
orticosteroid secretions, therefore, it has a higher therapeutic
index. Preclinical studies have shown that Letrozole is of no
potential toxicity to each system and target organ in the body, no
mutagenic and carcinogenic effect, little side reaction, well
tolerated, and compared with other aromatase inhibitors and
anti-estrogen drugs, it has a stronger antitumor effect. Applicable
to the treatment of advanced breast cancer in postmenopausal
patients who anti-estrogen ineffective, and early breast cancer.
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 is an aromatase inhibitor.
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.
Usage of Letrozole
(1)A nonsteroidal aromatase inhibitor structurally related to
(2)Pyrrole type aromatization enzyme inhibitors. Used in the
treatment of breast cancer.
Adverse Reactions and Side Effects
Randomized trials show that orally take 2.5 mg of letrozole every
day, adverse reactions incidence may be related to the drug is 33%,
and is significantly less than that of the AG group which is 46%.
Most adverse reactions of letrozole are mild or moderate, mainly
include nausea (2%~9%), headache (0%~7%), bone pain (4%~10%), hot
flashes (0%~9%) and weight gain (2%~8%), and other rare reactions
like onstipation, diarrhea, itching, rash, joint pain, chest pain,
abdominal pain, fatigue, insomnia, dizziness, edema, hypertension,
arrhythmia, thrombosis, difficulty breathing, vaginal bleeding,