estradiol cyclooctyl acetate estradiol cyclooctyl acetate estradiol cyclooctyl acetate (e2coa), or estradiol 17β-cyclooctylacetate, also known as estra-1,3,5(10)-triene-3,17β-diol 17β-cyclooctylacetate, is an estrogen medication and an estrogen ester – specifically, the 17β-cyclooctylacetate ester of estradiol – which has been studied for use in hormone replacement therapy for ovariectomized women and as a hormonal contraceptive in combination with a progestin but was never marketed. it has greater oral bioavailability than does micronized estradiol due to absorption via the lymphatic system and hence partial bypassing of first-pass metabolism. it is approximately twice as potent as micronized estradiol orally and has a comparatively reduced impact on liver parameters such as changes in sex hormone-binding globulin production. it was investigated in combination with desogestrel as a birth control pill, but resulted in unacceptable menstrual bleeding patterns and was not further developed. estradiol cyclooctyl acetateclinical dataother namese2coa; estradiol cyclooctylacetate; estradiol 17β-cyclooctylacetate; estra-1,3,5(10)-triene-3,17β-diol 17β-cyclooctylacetateroutes ofadministrationby mouthdrug classestrogen; estrogen esteridentifiers iupac name phenanthren-17-yl] 2-cyclooctylacetate cas number66791-46-6pubchem cid67083chemspider60433comptox dashboard (epa)dtxsid10985354 chemical and physical dataformulac28h40o3molar mass424.625 g·mol−13d model (jsmol)interactive image smiles c12cc3(1cc2oc(=o)cc4ccccccc4)ccc5=c3c=cc(=c5)o inchi inchi=1s/c28h40o3/c1-28-16-15-23-22-12-10-21(29)18-20(22)9-11-24(23)25(28)13-14-26(28)31-27(30)17-19-7-5-3-2-4-6-8-19/h10,12,18-19,23-26,29h,2-9,11,13-17h2,1h3/t23-,24-,25+,26+,28+/m1/s1key:czcgbahdfurtgu-vmblqbcysa-n