CompoundList
Sign in
Oncology and immunology drugs

Formestane

Also known as 4-Hydroxyandrost-4-ene-3,17-dione, 4-Hydroxyandrostenedione, Lentaron

CAS 566-48-3Formula C19H26O3Molar mass 302.41 g/molEC 625-331-3
GHS signal word: Danger. Pictograms: Serious health hazard 15 suppliers listed
Get quotes Compare 15 suppliers
Formestane chemical structure, C19H26O3, CAS 566-48-3
2D chemical structure

Key facts

What buyers check first

All properties
CAS number
566-48-3
Formula
C19H26O3
Molar mass
302.41 g/mol
EC number
625-331-3
HS code
293729
Category
Oncology and immunology drugs

What is Formestane?

Plain description, key identifiers and synonyms

Formestane is a 17-oxo steroid that is androst-4-ene-3,17-dione in which the hydrogen at position 4 is replaced by a hydroxy group. Formestane was the first selective, type I steroidal aromatase inhibitor, suppressing oestrogen production from anabolic steroids or prohormones. It was formerly used in the treatment of oestrogen-receptor positive breast cancer in post-meopausal women. As it has poor oral bioavailability, it had to be administered by (fortnightly) intramuscular injection. It fell out of use with the subsequent development of cheaper, orally active aromatase inhibitors. Formestane is listed by the World Anti-Doping Agency as a substance prohibited from use by athletes. It has a role as an antineoplastic agent and an EC 1.14.14.14 (aromatase) inhibitor. It is a 17-oxo steroid, an enol, a hydroxy steroid and a 3-oxo-Delta(4) steroid. It derives from a hydride of an androstane.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
(8R,9S,10R,13S,14S)-4-hydroxy-10,13-dimethyl-2,6,7,8,9,11,12,14,15,16-decahydro-1H-cyclopenta[a]phenanthrene-3,17-dione
CAS number
566-48-3 CAS number cross-checked
EC number
625-331-3
Molecular formula
C19H26O3
UNII
PUB9T8T355
MDL number
MFCD00057814
InChIKey
OSVMTWJCGUFAOD-KZQROQTASA-N
InChI
InChI=1S/C19H26O3/c1-18-10-8-15(20)17(22)14(18)4-3-11-12-5-6-16(21)19(12,2)9-7-13(11)18/h11-13,22H,3-10H2,1-2H3/t11-,12-,13-,18+,19-/m0/s1
Canonical SMILES
CC12CCC3C(CCC4=C(O)C(=O)CCC43C)C1CCC2=O
Isomeric SMILES
C[C@]12CCC(=O)C(=C1CC[C@@H]3[C@@H]2CC[C@]4([C@H]3CCC4=O)C)O

Synonyms

  • 4-Hydroxyandrost-4-ene-3,17-dione
  • 4-Hydroxyandrostenedione
  • Lentaron
  • CGP 32349
  • 4-Hydroxy-4-androstene-3,17-dione
  • formestano
  • formestanum
  • 4-OHAD
  • 4-oh-androstene-3,17-dione
  • 4-hydroxy-Delta(4)-androstenedione
  • 4-hydroxyandrostene-3,17-dione
  • CGP 32 349
  • (8R,9S,10R,13S,14S)-4-hydroxy-10,13-dimethyl-2,6,7,8,9,11,12,14,15,16-decahydro-1H-cyclopenta(a)phenanthrene-3,17-quinone
  • (8R,9S,10R,13S,14S)-4-hydroxy-10,13-dimethyl-2,6,7,8,9,11,12,14,15,16-decahydro-1H-cyclopenta[a]phenanthrene-3,17-quinone
  • Androst-4-ene-3,17-dione, 4-hydroxy-
  • B, Aromatase inhibitor
  • (8R,9S,10R,13S,14S)-4-hydroxy-10,13-dimethyl-2,6,7,8,9,11,12,14,15,16-decahydro-1H-cyclopenta[a]phenanthrene-3,17-dione
  • Formestane (INN)
  • 4-Hydroxy-delta(sub 4)-androstenedione
  • SaveCream
  • Lentaron Depot
  • Formestane, solid
  • Lentaron (TN)
  • Lentaron(R)17-dione
  • Androst-4-ene-3, 4-hydroxy-
Show all 33 synonyms
  • 4-hydroxy-Delta4-androstenedione
  • 4-Hydroxyandrostendione (Formestane)
  • 4-hydroxy-androst-4-ene-3,17-dione
  • (8R,9S,10R,13S,14S)-4-hydroxy-10,13-dimethyl-7,8,9,10,11,12,13,14,15,16-decahydro-1H-cyclopenta[a]phenanthrene-3,17(2H,6H)-dione
  • Formestane Solution in Methanol, 100ug/mL
  • 4-Hydroxyandrost-4-ene-3,17-dione, 4-OHA, CGP-32349, lentaron
  • Carbon Isotope Delta Value (d13CVPDB / per thousand): Formestane (-30.71 +/- 0.48)* (for WADA labs, only)"
  • (10R,13S)-4,10,13-trimethyl-2,6,7,8,9,11,12,14,15,16-decahydro-1H-cyclopenta[a]phenanthrene-3,17-dione

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

No measured properties are recorded for this substance yet. Ask suppliers for a technical data sheet.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
302.41 g/molcalc.
Exact mass
302.1882 Dacalc.
LogP (octanol/water)
3.97calc.
Topological polar surface area
54.37 Ųcalc.
Hydrogen bond donors
1calc.
Hydrogen bond acceptors
3calc.
Rotatable bonds
0calc.
Heavy atoms
22calc.
Rings
4calc.
Aromatic rings
0calc.
Fraction sp3 carbons
0.79calc.
Formal charge
0calc.
Stereocentres
5calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Murcko scaffold

The ring system that remains when every side chain is removed

Murcko scaffold of this chemical, O=C1C=C2CCC3C4CCC(=O)C4CCC3C2CC1

O=C1C=C2CCC3C4CCC(=O)C4CCC3C2CC1

4 rings, 19 atoms.

92 other chemicals share this scaffold

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS08: Serious health hazard
Serious health hazard

Hazard statements

  • H360May damage fertility or the unborn child.
Precautionary statements (5)
  • P203Obtain, read and follow all safety instructions before use.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P318If exposed or concerned, get medical advice.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Formestane suppliers

Sponsored listings first, then the documented ranking: membership, verification, replies, completeness, freshness and ratings

All 15 suppliers
15 of 15 offers

Suppliers marked Unclaimed profile have not claimed their profile yet. They are not verified by CompoundList, their offers are price on request and details may have changed, so please confirm them with the supplier. Company representatives can claim a profile with a business email on the company's own website domain. Our team verifies each claim and sends the result by email.

Where suppliers are based

15 suppliers in 3 countries

Send one request to many suppliers

Choose up to 10 suppliers or let us match your request. Compare quotes side by side, free.

Choose suppliersPost a request

Formestane price

Indicative price range per kg from live supplier offers

No published prices right now

Suppliers quote this chemical on request. Send one free request and compare quotes side by side.

Get latest price

Uses and applications

What the substance is used for, by industry and function

Use classes: Pharmaceuticals.

Pharmacological actions

  • Antineoplastic Agents
  • Aromatase Inhibitors

Roles

  • agonist
  • androgen
  • antineoplastic agent
  • enzyme inhibitor
  • hormone
  • molecular messenger
  • pharmaceutical
  • sex hormone

Functional uses

  • Pharmaceutical

Pharmacology

Formestane is a synthetic steroidal substance with antineoplastic activity. Formestane binds irreversibly to and inhibits the enzyme aromatase, thereby blocking the conversion of cholesterol to pregnenolone and the peripheral aromatization of androgenic precursors into estrogens. (NCI04)

Regulatory status

Inventories, regulations and trade controls that list this substance

Controls

  • US DEA controlled substance or listed chemical

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Formestane is traded under.

HS 2937.29Indicative HS code

Steroidal hormones, their derivatives and structural analogues, other

World exports in 2024
$2.32B
+5.7% vs 2023, imports $2.41B
2019 to 2024
Top exporters
  1. Belgium25.3%
  2. United States24.9%
  3. China13.0%
Top importers
  1. Italy18.0%
  2. Canada13.0%
  3. Belgium12.2%
Reported customs values in USD, not prices.Full trade data

The HS code shown for Formestane is indicative (it is known at chapter level only). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Formestane, based on the data on this page

What is Formestane?

Formestane is a 17-oxo steroid that is androst-4-ene-3,17-dione in which the hydrogen at position 4 is replaced by a hydroxy group. Formestane was the first selective, type I steroidal aromatase inhibitor, suppressing oestrogen production from anabolic steroids or prohormones.

What is the CAS number of Formestane?

The CAS registry number of Formestane is 566-48-3.

What is the molecular formula and weight of Formestane?

The molecular formula of Formestane is C19H26O3 and its molar mass is 302.41 g/mol.

What is Formestane used for?

Use classes: Pharmaceuticals.

Is Formestane hazardous?

Formestane carries the GHS signal word "Danger". Main hazards: may damage fertility or the unborn child. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Formestane?

Formestane is usually classified under HS code 293729 (Steroidal hormones, their derivatives and structural analogues, other). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Formestane?

CompoundList lists 15 suppliers of Formestane in United States, China and India. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy Formestane in India?

1 supplier in India list Formestane on CompoundList. Filter the suppliers list by country and send a request to compare prices, grades and delivery times.

What is the price of Formestane?

Suppliers quote Formestane on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Formestane

Get quotes for Formestane

Post one free request with your grade, quantity and destination. Matching suppliers send quotes you can compare side by side.
Post a request Sell Formestane
Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
Embed this structure on your websiteShow code

Paste this code into your page to show the 2D structure of Formestane with a 3D view, its CAS number and a link back to this page. Free to use with the link kept.

<iframe src="https://www.compoundlist.com/embed/structure/formestane-566-48-3" title="Formestane structure on CompoundList" width="360" height="420" style="border:1px solid #E7E2DA;border-radius:12px;max-width:100%" loading="lazy" referrerpolicy="strict-origin-when-cross-origin"></iframe>
Preview the embed

Explore more in Oncology and immunology drugs or HS code 293729

15 suppliers
Free quotes, contact stays private
Get quotes