δ⁴-Tibolone

Δ4-Tibolone
Clinical data
Other names	ORG-OM-38; Delta-4-Tibolone; 7α-Methylnorethisterone; 7α-Methyl-17α-ethynyl-19-nortestosterone; 17α-Ethynyl-17β-hydroxy-7α-methyl-4-estren-3-one
Identifiers
	IUPAC name (7R,8R,9S,10R,13S,14S,17R)-17-Ethynyl-17-hydroxy-7,13-dimethyl-1,2,6,7,8,9,10,11,12,14,15,16-dodecahydrocyclopenta[a]phenanthren-3-one;
CAS Number	1162-60-3 ;
PubChem CID	22814761;
ChemSpider	18532860;
UNII	LHZ8R2OW0M;
Chemical and physical data
Formula	C21H28O2
Molar mass	312.453 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES C[C@@H]1CC2=CC(=O)CC[C@@H]2[C@@H]3[C@@H]1[C@@H]4CC[C@]([C@]4(CC3)C)(C#C)O;
	InChI InChI=1S/C21H28O2/c1-4-21(23)10-8-18-19-13(2)11-14-12-15(22)5-6-16(14)17(19)7-9-20(18,21)3/h1,12-13,16-19,23H,5-11H2,2-3H3/t13-,16+,17-,18+,19-,20+,21+/m1/s1; Key:WAOKMNBZWBGYIK-KIURNNQRSA-N;

δ⁴-Tibolone (developmental code name ORG-OM-38), also known as 7α-methylnorethisterone or as 7α-methyl-17α-ethynyl-19-nortestosterone, is a synthetic androgen and progestin which was never marketed.^[1]^[2] The compound is a major active metabolite of tibolone, which itself is a prodrug of δ⁴-tibolone along with 3α-hydroxytibolone and 3β-hydroxytibolone (which, in contrast to δ⁴-tibolone, are estrogens).^[1] Tibolone and δ⁴-tibolone are thought to be responsible for the androgenic and progestogenic activity of tibolone, while 3α-hydroxytibolone and 3β-hydroxytibolone are thought to be responsible for its estrogenic activity.^[1]