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.
Estradiol acetate
Estradiol acetate, sold under the brand names Femtrace, Femring, and Menoring, is an estrogen medication which is used in hormone therapy for the treatment of menopausal symptoms in women. It is taken by mouth or given as a vaginal ring once every three months.
Side effects of estradiol acetate include breast tenderness, breast enlargement, nausea, headache, and fluid retention. Estradiol acetate is a synthetic estrogen and hence is an agonist of the estrogen receptor (ER), the biological target of estrogens like estradiol. It is an estrogen ester and a prodrug of estradiol in the body. Because of this, it is considered to be a natural and bioidentical form of estrogen.
Estradiol acetate was introduced for medical use in 2001. It is available in the United States and the United Kingdom. The formulation for use by mouth has been discontinued in the United States.