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.
Estetrol/drospirenone
Estetrol/drospirenone (E4/DRSP; tentative brand name Estelle; developmental code name FSN-013) is a combination of estetrol, an estrogen, and drospirenone, a progestin, which is under development by Estetra S.A. as a combined oral contraceptive for the prevention of pregnancy in women. It contains 15 mg estetrol and 3 mg drospirenone. As of 2018, it is in phase III clinical trials for this indication.