We are open as normal during COVID-19 pandemic. Order online, same day shipping out.

    WARNING: This product is for research use only, not for human or veterinary use.

MedKoo CAT#: 200330

CAS#: 96301-34-7

Description: Atamestane is a synthetic steroidal substance with antineoplastic activity. Atamestane 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.

Price and Availability

Size Price Shipping out time Quantity
Inquire bulk and customized quantity

Pricing updated 2020-05-29. Prices are subject to change without notice.

Atamestane, purity > 98%, is not in stock, may be available through custom synthesis. For cost-effective reason, minimum 1 gram order is requested. The product will be characterized by NMR, HPLC and MS analysis. Purity (HPLC) is usually >98%. CoA, QC data, MSDS will be provided when product is successfully made. The estimated lead time is 2-3 months. Please send email to to inquire quote.

Chemical Structure


Theoretical Analysis

MedKoo Cat#: 200330
Name: Atamestane
CAS#: 96301-34-7
Chemical Formula: C20H26O2
Exact Mass: 298.19328
Molecular Weight: 298.41924
Elemental Analysis: C, 80.50; H, 8.78; O, 10.72

Synonym: Atamestanum; Atamestano; Biomed777; CCRIS 6528; SH489; SH-489; SH 489

IUPAC/Chemical Name: (8R,9S,10S,13S,14S)-1,10,13-trimethyl-7,8,9,10,11,12,13,14,15,16-decahydro-3H-cyclopenta[a]phenanthrene-3,17(6H)-dione


InChi Code: InChI=1S/C20H26O2/c1-12-10-14(21)11-13-4-5-15-16-6-7-18(22)19(16,2)9-8-17(15)20(12,13)3/h10-11,15-17H,4-9H2,1-3H3/t15-,16-,17-,19-,20-/m0/s1

SMILES Code: O=C(C=C1CC[C@@]2([H])[C@]3([H])CC4)C=C(C)[C@]1(C)[C@@]2([H])CC[C@]3(C)C4=O

Technical Data

Solid powder

>98% (or refer to the Certificate of Analysis)

Shipping Condition:
Shipped under ambient temperature as non-hazardous chemical. This product is stable enough for a few weeks during ordinary shipping and time spent in Customs.

Storage Condition:
Dry, dark and at 0 - 4 C for short term (days to weeks) or -20 C for long term (months to years).

Soluble in DMSO, not in water

Shelf Life:
>2 years if stored properly

Drug Formulation:
This drug may be formulated in DMSO

Stock Solution Storage:
0 - 4 C for short term (days to weeks), or -20 C for long term (months).

HS Tariff Code:

Additional Information



 1: Goss PE, Qi S, Hu H. Comparing the effects of atamestane, toremifene and tamoxifen alone and in combination, on bone, serum lipids and uterus in ovariectomized rats. J Steroid Biochem Mol Biol. 2009 Feb;113(3-5):233-40. doi: 10.1016/j.jsbmb.2009.01.005. Epub 2009 Jan 20. PubMed PMID: 19429427.

2: Goss P, Bondarenko IN, Manikhas GN, Pendergrass KB, Miller WH Jr, Langecker P, Blanchett D. Phase III, double-blind, controlled trial of atamestane plus toremifene compared with letrozole in postmenopausal women with advanced receptor-positive breast cancer. J Clin Oncol. 2007 Nov 1;25(31):4961-6. PubMed PMID: 17971594.

3: Sabnis GJ, Macedo L, Goloubeva O, Schayowitz A, Zhu Y, Brodie A. Toremifene-atamestane; alone or in combination: predictions from the preclinical intratumoral aromatase model. J Steroid Biochem Mol Biol. 2008 Jan;108(1-2):1-7. Epub 2007 Sep 7. PubMed PMID: 17942301; PubMed Central PMCID: PMC3081608.

4: Santen RJ, Demers L, Ohorodnik S, Settlage J, Langecker P, Blanchett D, Goss PE, Wang S. Superiority of gas chromatography/tandem mass spectrometry assay (GC/MS/MS) for estradiol for monitoring of aromatase inhibitor therapy. Steroids. 2007 Jul;72(8):666-71. Epub 2007 May 21. PubMed PMID: 17588628.

5: Goss PE, Qi S, Hu H, Cheung AM. The effects of atamestane and toremifene alone and in combination compared with letrozole on bone, serum lipids and the uterus in an ovariectomized rat model. Breast Cancer Res Treat. 2007 Jul;103(3):293-302. Epub 2006 Oct 25. PubMed PMID: 17063268.

6: Muller M, van den Beld AW, van der Schouw YT, Grobbee DE, Lamberts SW. Effects of dehydroepiandrosterone and atamestane supplementation on frailty in elderly men. J Clin Endocrinol Metab. 2006 Oct;91(10):3988-91. Epub 2006 Jun 27. PubMed PMID: 16804050.

7: Ito K, Fukabori Y, Shibata Y, Suzuki K, Mieda M, Gotanda K, Honma S, Yamanaka H. Effects of a new steroidal aromatase inhibitor, TZA-2237, and/or chlormadinone acetate on hormone-induced and spontaneous canine benign prostatic hyperplasia. Eur J Endocrinol. 2000 Oct;143(4):543-54. PubMed PMID: 11022202.

8: Harada N, Honda SI, Hatano O. Aromatase inhibitors and enzyme stability. Endocr Relat Cancer. 1999 Jun;6(2):211-8. PubMed PMID: 10731111.

9: Steckelbroeck S, Heidrich DD, Stoffel-Wagner B, Hans VH, Schramm J, Bidlingmaier F, Klingmüller D. Characterization of aromatase cytochrome P450 activity in the human temporal lobe. J Clin Endocrinol Metab. 1999 Aug;84(8):2795-801. Erratum in: J Clin Endocrinol Metab 1999 Dec;84(12):4606. PubMed PMID: 10443682.

10: Boehm S, Nirnberger G, Ferrari P. Estrogen suppression as a pharmacotherapeutic strategy in the medical treatment of benign prostatic hyperplasia: evidence for its efficacy from studies with mepartricin. Wien Klin Wochenschr. 1998 Dec 11;110(23):817-23. Review. PubMed PMID: 10025034.