Suzhou Excellentbiotech Co.,Ltd

Top Grade Biotechnology Manufacturer In China

Quality Product Safe Delivery Professional Service

Home ProductsAnabolic Steroid Powder

CAS 566-48-3 Pharmaceutical Intermediates Anti Estrogen Steroids BodyBuilding Formestane

CAS 566-48-3 Pharmaceutical Intermediates Anti Estrogen Steroids BodyBuilding Formestane

  • CAS 566-48-3 Pharmaceutical Intermediates Anti Estrogen Steroids BodyBuilding Formestane
  • CAS 566-48-3 Pharmaceutical Intermediates Anti Estrogen Steroids BodyBuilding Formestane
  • CAS 566-48-3 Pharmaceutical Intermediates Anti Estrogen Steroids BodyBuilding Formestane
CAS 566-48-3 Pharmaceutical Intermediates Anti Estrogen Steroids BodyBuilding Formestane
Product Details:
Place of Origin: CHINA
Brand Name: Excellentbiotech
Certification: GMP, ISO 9001, USP, BP
Model Number: 566-48-3
Payment & Shipping Terms:
Minimum Order Quantity: 10g
Price: Negotiable
Packaging Details: Discreet ways of packing for customs guaranteed
Delivery Time: MonthWithin 8 hours after payment
Payment Terms: T/T, , ,Bitcoin,Paypal
Supply Ability: 2000kg Per Month
Contact Now
Detailed Product Description
Name: Aromatase Suitable For: Adult
Purity: >99% Appearance: White Powder
MF: C19H26O3 E-mail:
MW: 302.41 Catalogy: Steroidal Aromatase Inhibitor
Usage: An Antineoplastic
High Light:

anabolic bodybuilding steroids


athletes anabolic steroids

Product name: Formestane,Lentaron,4-hydroxyandrostenedione
Other name: Lentaron;FORMESTAQNE;hydroxyandrostenedione
Chemical Name(s): 4-Hydroxyandrost-4-ene-3, 17-dione;4-hydroxy-4-androstene-3,17-dione;4-Hydroxyandrostenedione
CAS: 566-48-3
Molecular Formula: C19H26O3
Molecular Weight: 302.41
Appearance: White crystalline powder
Assay: 99%
Delivery: EMS,DHL,FedEx ,TNT,ect
Grade : Pharmaceutical Grade
Application : Used for natural or artificial postmenopausal breast cancer patients, including tamoxifen and other endocrine treatment of patients is invalid. Used for breast cancer.



2. Description:


1.Lentaron, a.k.a. formestane, belongs to a class of drugs known as 2 (or second generation) aromatase inhibitors which are primarily used in the treatment of estrogen-receptor positive breast and ovarian cancers in post-menopausal women. Some cancers require estrogen to grow, and aromatase is an enzyme that synthesizes estrogen. Aromatase Inhibitors (AIs) are a class of drugs that effectively block this synthesis thereby lowering estrogenic levels, and slowing the growth of cancers.

2.AIs are categorized into two types: 1) non-steroidal inhibitors such as Arimidex (anastrozole) and Femara (letrozole) which inhibit the enzyme by reversible competition and; 2) irreversible steroidal inhibitors such as Aromasin (exemestrane) which form a permanent bond with the aromatase enzyme complex. Lentaron is classified in the second group as a selective irreversible steroidal aromatase inhibitor. Derived from androstenedione (the same except for the addition of a 4-hydroxyl group), formestane forms an irreversible bond with the aromatase enzyme which permanently deactivates it. It takes several days (following formestane discontinuation) for aromatase to become active again. These types of drugs are often referred to as suicidal aromatase inhibitors because the drugs seemingly sacrifice themselves (their structural independence) in the process of blocking estrogen.


3. Fuction of Formestane/ Lentaron:


Formestane (Lentaron,4-hydroxyandrostenedione ) is a steroidal aromatase inhibitor used in the treatment of estrogen-receptor positive breast cancer in post-menopausal women.


Formestane is often used to suppress estrogen production from anabolic steroids or prohormones. It also acts as a prohormone to 4-hydroxytestosterone, an active steroid which displays weak androgenic activity in addition to acting as a mild aromatase inhibitor.


Formestane has poor oral bioavailability and as such is no longer popular as many orally active aromatase inhibitors have been identified.


4-hydroxyandrostenedione significantly reduces plasma levels of estrogen and has shown antitumour activity in postmenopausal women with breast cancer.


In comparative studies, the clinical efficacy of intramuscular (injected) formestane 250mg did not differ significantly from that of oral megestrol when administered as second-line endocrine therapy to patients with advanced disease in whom previous tamoxifen therapy had failed.


Formestane produced a response rate, duration of response and overall survival rate that was not significantly different from that of oral tamoxifen when administered as first-line endocrine therapy to patients with advanced disease, but tamoxifen was superior in some measures.


4. Characteristics:


Formestane is a steroidal aromatase inhibitor, known as a suicidal inhibitor because it permanently binds to the aromatase enzyme.


Formestane was originally used as an injectable for breast cancer patients, but due to its possible androgenic effects it has largely been replaced by non-steroidial AIs in the medical community. Most of its use is now is limited to the bodybuilding community since it is available as a legal dietary supplement for reducing estrogen and increasing testosterone production.


Although formestane can effectively reduce estrogen through oral consumption, its low oral bioavailability has lead to the development of several transdermal based products (which appear to offer higher efficacy at a lower dose).


Relative to 6-oxo and ATD, Formestane is a more potent aromatase inhibitor, which appears to effectively reduce natural estrogen levels by as much as 50% within several days (while higher doses may further suppress estrogen). Because of formestanes potent ability at reducing estrogen it will tend to reduce HDL levels, while increasing LDL levels, thus harming the cholesterol profile. For this reason, it is recommended to limit cycles of formestane to 8 weeks max.


Because formestane also has a strong affinity for the 5a-reductase enzyme it will reduce DHT levels in the body by effectively competing with testosterone for the 5a-reductase.


Formestane converts to the active androgen 4-hydroxytestosterone which has about half the anabolic potency, and about 25% of the androgenic potency as testosterone. This would suggest that fairly high doses of formestane (800-1000mg/day) could lead to some level of anabolic enhancement (although the amount required for this would surely lead to undesirably low estrogen levels).

Formestane is successfully used as a standalone during re-composition cycles to help reduce “bloat” and fat storage. It can also be used as an anti-estrogen to counter aromatization of aromatizing steroids.





Average Dose:


Aromatase inhibition
100-200mg/day (transdermal)
150-250mg/day (oral)

Anabolic effects
800-1000mg/day (oral)

Average Cycle Length:

4-8 weeks



6. COA:


Description White Crystalline Powder white powder
Identification Positive Positive
Assay 97.0~103.0% 99.31%
Melting Point 172~178℃ 172.0~176.0℃
Specific Rotation +34~ +38¡ã(C=2,in dioxane) +36.3¡ã
Loss On Drying 1.0%max in vacuum over P2O5 for 4h 0.26%
Residual Solvents meets the requirements. Conforms
Organic Volatile Impurities meets the requirements. Conforms
Conclusion The specification conform with USP30 standard



7. Our Adwantage:


High quality with competitive price:
1) Standard: Enterprise Standard
2) All Purity:>=99%
3) We are manufacturer and can provide high quality products with factory price.


Fast and safe delivery:
1) Parcel can be sent out in 24 hours after payment. Tracking number available
2) Secure and discreet shipment. Various transportation methods for your choice.
3) Customs pass rate: >=99%
4) We have our own agent/remailer/distributor who can help us ship our products very fast and safe, and we have stock in there for transferring.


We have clients throughout the world:
1) Professional service and rich experience make customers feel at ease, adequate stock and fast delivery meet their desire.
2) Market feedback and goods feedback will be appreciated, meeting customers's requirement is our responsibility.
3) High quality, competitive price, fast delivery, first-class service gain the trust and praise from the customers.


Everybody is talking the similar words, what I want to say is: Just give me a chance, Just have a try on me, maybe you will get a surprise from me!

Contact Details
Suzhou Excellentbiotech Co.,Ltd

Contact Person: lisa

Tel: +8613798562250

Send your inquiry directly to us
Other Products