Formestane

Formestane

Clinical data
Trade names	Lentaron
AHFS/Drugs.com	International Drug Names
ATC code	L02BG02 (WHO)
Identifiers
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
Synonyms	4-Hydroxyandrost-4-ene-3,17-dione
CAS Number	566-48-3 Y
PubChem CID	11273
ChemSpider	10799 Y
UNII	PUB9T8T355
KEGG	D07260 Y
ChEBI	CHEBI:75172 N
ChEMBL	CHEMBL132530 Y
ECHA InfoCard	100.153.838
Chemical and physical data
Formula	C19H26O3
Molar mass	302.408 g/mol
3D model (Jmol)	Interactive image
SMILES O=C4C(/O)=C3/CC[C@@H]2[C@H](CC[C@@]1(C(=O)CC[C@H]12)C)[C@@]3(C)CC4
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 Y Key:OSVMTWJCGUFAOD-KZQROQTASA-N Y
NY (what is this?)

Formestane (trade name Lentaron), also known as 4-hydroxyandrost-4-ene-3,17-dione, is a type I, steroidal, selective aromatase inhibitor. It is used in the treatment of estrogen receptor-positive breast cancer in postmenopausal women. The drug is not active orally, and is instead available only as an intramuscular depot injection. Because of this, it is no longer popular as many orally active aromatase inhibitors have been identified and introduced. Formestane is an analogue of androstenedione.

Formestane is often used to suppress the production of estrogens 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 weak aromatase inhibitor.