Cyclodiol

Cyclodiol
Clinical data
Other names	ZK-115194; Cycloestradiol; 14α,17α-Ethano-17β-estradiol; 14α,17α-Ethanoestra-1,3,5(10)-triene-3,17β-diol; 14,21-Cyclo-19-norpregna-1,3,5(10)-triene-3,17α-diol
Routes of; administration	By mouth
Drug class	Estrogen
Pharmacokinetic data
Bioavailability	33 ± 19%
Elimination half-life	28.7 hours
Identifiers
	IUPAC name (8R,9S,13S)-13-Methyl-7,8,9,11,12,13,15,16-octahydro-14,17-ethanocyclopenta[a]phenanthrene-3,17(6H)-diol;
CAS Number	116229-13-1;
PubChem CID	146627;
ChemSpider	18788501;
UNII	GH2S6QPT38;
CompTox Dashboard (EPA)	DTXSID50921978 ;
Chemical and physical data
Formula	C20H26O2
Molar mass	298.426 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES C[C@]12CC[C@H]3[C@H](C14CCC2(CC4)O)CCC5=C3C=CC(=C5)O;
	InChI InChI=1S/C20H26O2/c1-18-7-6-16-15-4-3-14(21)12-13(15)2-5-17(16)19(18)8-10-20(18,22)11-9-19/h3-4,12,16-17,21-22H,2,5-11H2,1H3/t16-,17-,18+,19?,20?/m1/s1; Key:YGXXZMDWSWSCSI-UYUJGIFYSA-N;

Cyclodiol (developmental code name ZK-115194; also known as 14α,17α-ethano-17β-estradiol) is a synthetic estrogen which was studied in the 1990s and was never marketed. It is a derivative of estradiol with a bridge between the C14α and C17α positions. Cyclodiol has 100% of the relative binding affinity of estradiol for the human ERα and similar transactivational capacity as estradiol at the receptor. It has comparable potency to estradiol when administered by subcutaneous injection. The drug shows genotoxicity similarly to estradiol. Cyclodiol showed an absolute bioavailability of 33 ± 19% and an elimination half-life of 28.7 hours in pharmacokinetic studies in women.