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).
Estriol (medication)
A variety of analogues of estriol are known, including both naturally occurring isomers and synthetic substituted derivatives and esters. 16β-Epiestriol (epiestriol), 17α-epiestriol, and 16β,17α-epiestriol are isomers of estriol that are endogenous weak estrogens. Mytatrienediol (16α-methyl-16β-epiestriol 3-methyl ether) is a synthetic derivative of 16β-epiestriol that was never marketed. Estriol acetate benzoate, estriol succinate, and estriol tripropionate are synthetic estriol esters that have been marketed for medical use, whereas estriol dihexanoate, estriol dipropionate, and estriol triacetate have not been introduced. Quinestradol is the 3-cyclopentyl ether of estriol and has also been marketed. Polyestriol phosphate, an ester of estriol in the form of a polymer, has been marketed previously as well. These esters, ethers, and polymers are prodrugs of estriol. Ethinylestriol and nilestriol are synthetic C17α ethynylated derivatives of estriol. Ethinylestriol has not been marketed, but nilestriol, which is the 3-cyclopentyl ether of ethinylestriol and a prodrug of it, has been.