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CAS Number
PubChem CID
ECHA InfoCard 100.006.809
Chemical and physical data
Formula C18H20O2
Molar mass 268.355 g/mol
3D model (Jmol)
 NYesY (what is this?)  (verify)

Equilin, also known as 7-dehydroestrone, as well as estra-1,3,5(10),7-tetraen-3-ol-17-one, is an estrogen from horses.[1] Equilin is one of the estrogens present in the mixture of estrogens isolated from horse urine and marketed as Premarin. Premarin became the most commonly used form of estrogen for hormone replacement therapy in the United States of America. Estrone is the major estrogen in Premarin (about 50%) and equilin is present as about 25% of the total. Estrone is a major estrogen that is normally found in women. Equilin is not normally present in women, so there has been interest in the effects of equilin on the human body.[2]

The estrogens in Premarin are present mainly as "conjugates", modified chemical forms in which the active estrogen is coupled to another chemical group such as sulfate. Estrone sulfate is usually the major form of estrogen in women. After being taken into a woman's body, the conjugated estrogens of Premarin are converted to the active unconjugated estrogens or excreted from the woman's body. Estrone can be converted to estradiol, which is thought to be the major active estrogen in women.

See also[edit]


  1. ^ J. Elks (14 November 2014). The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. p. 495. ISBN 978-1-4757-2085-3. 
  2. ^ Sawicki, MW; Erman, M; Puranen, T; Vihko, P; Ghosh, D (1999). "Structure of the ternary complex of human 17β-hydroxysteroid dehydrogenase type 1 with 3-hydroxyestra-1,3,5,7-tetraen-17-one (equilin) and NADP+". Proceedings of the National Academy of Sciences of the United States of America. 96 (3): 840–5. doi:10.1073/pnas.96.3.840. PMC 15312Freely accessible. PMID 9927655.