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Indications and uses Pharmacokinetics Side effects
Letrozole structure
Chemical Name:
Letroz;FEMARA;Lelrozol;Lerozole;LETROZOL;LETRAZOLE;CGS-20267;LETROZOLE;letrozolex;To letrozole
Molecular Formula:
Formula Weight:
MOL File:

Letrozole Properties

Melting point:
Boiling point:
563.5±60.0 °C(Predicted)
1.21±0.1 g/cm3(Predicted)
storage temp. 
-20°C Freezer
DMSO: >50mg/mL
White powder
white to off-white
CAS DataBase Reference
112809-51-5(CAS DataBase Reference)
  • Risk and Safety Statements
Hazard Codes  Xi
Risk Statements  36/37/38
Safety Statements  26-36
WGK Germany  3
RTECS  DI4957000
HS Code  2933997500

Letrozole price More Price(10)

Manufacturer Product number Product description CAS number Packaging Price Updated Buy
Sigma-Aldrich 182541 Aromatase Inhibitor II, Letrozole 112809-51-5 25mg $119 2019-12-02 Buy
Sigma-Aldrich 1356971 Letrozole United States Pharmacopeia (USP) Reference Standard 112809-51-5 200mg $352.8 2019-12-02 Buy
Cayman Chemical 11568 Letrozole ≥98% 112809-51-5 10mg $35 2018-11-13 Buy
Cayman Chemical 11568 Letrozole ≥98% 112809-51-5 25mg $74 2018-11-13 Buy
Sigma-Aldrich PHR1540 Letrozole Pharmaceutical Secondary Standard; Certified Reference Material 112809-51-5 1g $74.7 2019-12-02 Buy

Letrozole Chemical Properties,Uses,Production

Indications and uses

Letrozole is part of a new generation of highly selective aromatase inhibitors and is an artificially synthesized benzotriazole derivative. Letrozole inhibits aromatase to lower estrogen levels, thus preventing estrogen from stimulating tumor growth. Its in vivo activity is 150-250 times stronger than that of first generation aromatase inhibitor Amarante. As it is highly selective, it will not impact glucocorticoid, mineralocorticoid and thyroid functions; even at high dosages, it will not have any inhibiting effects on adrenal corticosteroid secretion, giving it a high treatment index. Letrozole has no latent toxicity towards any bodily systems and target organs, has no mutagenicity and carcinogenic effects, has minimal toxic side effects, is well-tolerated, and has stronger anticancer effects than other aromatase inhibitors and antiestrogen drugs. Letrozole is suitable for advanced breast cancer postmenopausal patients who have not responded to estrogen-suppressing treatment and for early breast cancer treatment. It is used to treat postmenopausal patients with advanced breast cancer and serves as a second-line treatment to follow unsuccessful antiestrogen treatment. Compared to the current standard Tamoxifen treatment, Letrozole can better prevent the risk of breast cancer recurrence.


Absorption of oral letrozole is rapid and complete and steady state is achieved in 2–6 weeks with administration of letrozole 2.5mg once daily. The major route of elimination of letrozole is via metabolism to a pharmacologically inactive carbinol metabolite. The cytochrome P450 (CYP) 3A4 and CYP2A6 isozymes metabolize letrozole to a pharmacologically inactive carbinol metabolite. Renal excretion of a glucuronide conjugate of the carbinol metabolite of letrozole represents the major route of drug clearance.

Side effects

Randomized grouping studies have shown that daily oral ingestion of 2.5mg Letrozole leads to a 33% rate of drug-related negative reactions, a percentage much lower than AG group’s 46%. Negative reactions to Letrozole are mostly mild or moderate, consisting mostly of nausea (2-9%), headache (0-7%), bone pain (4-10%), hot flashes (0-9%) and weight gain (2-8%). Other uncommon side effects include constipation, diarrhea, itching, rash, joint pain, chest pain, abdominal pain, fatigue, insomnia, dizziness, edema, high blood pressure, arrhythmia, thrombosis, dyspnea, vaginal bleeding, etc.


Letrozole (trade name: Femara) is an orally active nonsteroidal aromatase inhibitor. As a competitive inhibitor of the aromatase, Letrozole inhibits the conversion of androgens to estrogen (estrogen stimulates breast tissues and breast cancer reoccurrence) and gonadal steroidogenesis. It can be used for the treatment of breast cancer that is hormonally-responsive or has an unknown receptor status in postmenopausal women. Besides this, Letrozole also has some off-label use such as ovarian stimulation, pretreatment of termination of pregnancy, treatment of gynecomastia, treatment of endometriosis, and promoting spermatogenesis for male patients of nonobstructive azoospermia.

Chemical Properties

white to light yellow crystal


Novartis (Switzerland)


A nonsteroidal aromatase inhibitor structurally related to Fadrozole. Antineoplastic

brand name

Femara (Novar tis).

General Description

Letrozole, 4,4'-(1H-1,2,4-triazol-1-ylmethylene)dibenzonitrile (Femara), is used for most of thesame indications as anastrozole. It reduces concentrations ofestrogens by 75% to 95%, with maximal suppressionachieved within 2 to 3 days. Letrozole is specific for aromataseinhibition, with no additional effects on adrenal corticoidbiosynthesis. CYPs 3A4 and 2A6 are involved in themetabolism of letrozole to the major carbinol metabolite,which is inactive. The loss of the triazole ring, which is involvedin coordination of the heme iron, would explain theloss of activity. Letrozole strongly inhibits CYP2A6 invitro, with moderate inhibition of CYP2C19. The effect ofthis in vitro inhibition on the pharmacokinetics of coadministereddrugs is unknown. Tamoxifen reduces the levels ofletrozole significantly if they are used together, so combinationtreatment with these agents is not recommended.

Clinical Use

Femara was launched in France and the UK for second-line treatment of advanced breast cancer. Letrazole can be synthesized in two steps from 4- bromomethyl-benzonitrile with 1,2,4-triazole and is a third generation aromatase inhibitor. It is a highly specific inhibitor of P450arom which prevents the conversion of androstenedione to estrone. The reduction of plasma estrogen was immediate and long lasting. This is accomplished with no inhibition of other steroid biosynthesis making it the most selective aromatase inhibitor tested. Letrazole has remarkable antitumor activity, is well tolerated and has no toxic side effects. It is 10,000 times more potent than aminoglutethimide, in vivo, the first well established aromatase inhibitor.


Letrozole Preparation Products And Raw materials

Raw materials

Preparation Products

Letrozole Suppliers

Global( 351)Suppliers
Supplier Tel Fax Email Country ProdList Advantage
Beijing Yibai Biotechnology Co., Ltd
0086-182-6772-3597 CHINA 420 58
Henan Tianfu Chemical Co.,Ltd.
0371-55170693 CHINA 22626 55
020-81716319 CHINA 2793 55
Shanghai Yingrui Biopharma Co., Ltd.
+86-21-34979012 CHINA 739 60
Nanjing Finetech Chemical Co., Ltd.
025-85710122 17714198479
025-85710122 CHINA 890 55
Shanghai Zheyan Biotech Co., Ltd.
18017610038 CHINA 3623 58
career henan chemical co
+86-371-86658258 CHINA 30050 58
Shenzhen Nexconn Pharmatechs Ltd
15013857715 CHINA 3035 58
08657186217390 CHINA 309 58
Chemwill Asia Co.,Ltd.
86-21-51861608;;; CHINA 23977 58

Related articles

View Lastest Price from Letrozole manufacturers

Image Release date Product Price Min. Order Purity Supply Ability Manufacturer
2020-04-29 Letrozole
US $0.00-0.00 / 公斤 1KG 99.0%+ 800 tons Shaanxi Dideu Medichem Co. Ltd
2019-08-26 Letrozole
US $0.00-0.00 / KG 1g 99% 100kg/month Beijing Yibai Biotechnology Co., Ltd
2019-04-22 Letrozole powder
US $1.00 / g 1g 99% 100kg Cangzhou Wanyou New Material Technology Co.,Ltd

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