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Clinical data
Other namesZK-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
By mouth[1]
Drug classEstrogen
Pharmacokinetic data
Bioavailability33 ± 19%[1]
Elimination half-life28.7 hours[1]
  • (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
PubChem CID
CompTox Dashboard (EPA)
Chemical and physical data
Molar mass298.426 g·mol−1
3D model (JSmol)
  • C[C@]12CC[C@H]3[C@H](C14CCC2(CC4)O)CCC5=C3C=CC(=C5)O
  • 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

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.[2][1][3] It is a derivative of estradiol with a bridge between the C14α and C17α positions.[2][1][3][4] Cyclodiol has 100% of the relative binding affinity of estradiol for the human ERα and similar transactivational capacity as estradiol at the receptor.[2] It has comparable potency to estradiol when administered by subcutaneous injection.[2] The drug shows genotoxicity similarly to estradiol.[2][4] Cyclodiol showed an absolute bioavailability of 33 ± 19% and an elimination half-life of 28.7 hours in pharmacokinetic studies in women.[1]

See also[edit]


  1. ^ a b c d e f Baumann A, Fuhrmeister A, Brudny-Klöppel M, Draeger C, Bunte T, Kuhnz W (October 1996). "Comparative pharmacokinetics of two new steroidal estrogens and ethinylestradiol in postmenopausal women". Contraception. 54 (4): 235–242. doi:10.1016/S0010-7824(96)00194-1. PMID 8922877.
  2. ^ a b c d e Oettel M, Schillinger E (6 December 2012). Estrogens and Antiestrogens II: Pharmacology and Clinical Application of Estrogens and Antiestrogen. Springer Science & Business Media. pp. 10, 15, 76, 329, 332. ISBN 978-3-642-60107-1.
  3. ^ a b Lang R, Reimann R (1993). "Studies for a genotoxic potential of some endogenous and exogenous sex steroids. I. Communication: examination for the induction of gene mutations using the Ames Salmonella/microsome test and the HGPRT test in V79 cells". Environmental and Molecular Mutagenesis. 21 (3): 272–304. doi:10.1002/em.2850210311. PMID 8462531. S2CID 39049586.
  4. ^ a b Hundal BS, Dhillon VS, Sidhu IS (March 1997). "Genotoxic potential of estrogens". Mutation Research. 389 (2–3): 173–181. doi:10.1016/S1383-5718(96)00144-1. PMID 9093381.