An estrogen conjugate is a conjugate of an endogenous estrogen. They occur naturally in the body as metabolites of estrogens and can be reconverted back into estrogens. They serve as a circulating reservoir for estrogen, particularly in the case of orally administered pharmaceutical estradiol. Estrogen conjugates include sulfate and/or glucuronide conjugates of estradiol, estrone, and estriol:
Estrogen conjugates are conjugated at the C3, C16α, and/or C17β positions, where hydroxyl groups are available.[1]
Estrogen conjugates have been used as pharmaceutical estrogens, as in estrone sulfate as estropipate (piperazine estrone sulfate) and in conjugated estrogens (Premarin) and conjugated estriol (Progynon, Emmenin).