Estrogen (medication)
Estradiol, estrone, and estriol have all been approved as pharmaceutical drugs and are used medically. Estetrol is currently under development for medical indications, but has not yet been approved in any country. A variety of synthetic estrogen esters, such as estradiol valerate, estradiol cypionate, estradiol acetate, estradiol benzoate, estradiol undecylate, and polyestradiol phosphate, are used clinically. The aforementioned compounds behave as prodrugs to estradiol, and are much longer-lasting in comparison when administered by intramuscular or subcutaneous injection. Esters of estrone and estriol also exist and are or have been used in clinical medicine, for example estrone sulfate (e.g., as estropipate), estriol succinate, and estriol glucuronide (as Emmenin and Progynon).
Estradiol cyclooctyl acetate
Estradiol cyclooctyl acetate (ECoA), or estradiol 17β-cyclooctylacetate, also known as estra-1,3,5(10)-triene-3,17β-diol 17β-cyclooctylacetate, is a synthetic, steroidal estrogen 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.