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)
Estetrol (E4), also known as 15α-hydroxyestriol, is a naturally occurring analogue of estriol with an additional hydroxyl group, at the C15α position. It is closely related to estriol and has similar but non-identical pharmacological properties. Like estriol, estetrol is a relatively weak and atypical estrogen. Estetrol is under development for potential clinical use for a variety of indications, such as menopausal hormone therapy and hormonal birth control.https://adisinsight.springer.com/drugs/800034634