Estradiol stearate
Estradiol stearate (brand name Depofollan), or estradiol octadecanoate, is a naturally occurring steroidal estrogen and an estrogen ester – specifically, the C17β stearate ester of estradiol. It occurs in the body as a very long-lasting metabolite and prohormone of estradiol. In addition, estradiol stearate is or has been available as a pharmaceutical drug for use via depot intramuscular injection. The drug was introduced in 1941 as Depofollan and was the first long-acting estrogen, although it has never been widely used. It has been reported in at least one source to have a duration of at least one month.
Estriol (medication)
Estriol is an estrogen, or an agonist of the estrogen receptors, ERα and ERβ. It has been found to possess 11–14% and 18–21% of the relative binding affinities of estradiol for the human ERα and ERβ, respectively, while its relative transactivational capacities at these receptors were 11% and 17%, respectively. In addition to being a ligand of the classical nuclear ERs, estriol is an antagonist of the GPER, a membrane estrogen receptor, at high concentrations. This is in contrast to estradiol, which is an agonist of this receptor. Like other estrogens, estriol does not importantly interact with other steroid hormone receptors.