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 benzoate
Estradiol benzoate, sold under the brand name Progynon-B among others, is a medication which is used in hormone therapy for menopausal symptoms and low estrogen levels in women, in hormone therapy for transgender women, and in the treatment of gynecological disorders. It is also used in the treatment of prostate cancer in men. Estradiol benzoate is used in veterinary medicine as well. When used clinically, the medication is given by injection into muscle usually two to three times per week.
Side effects of estradiol benzoate include breast tenderness, breast enlargement, nausea, headache, and fluid retention. Estradiol benzoate 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 benzoate was discovered in 1933 and was introduced for medical use in 1936. It was the first estradiol ester to be discovered or marketed, and was one of the first estrogens to be introduced for medical use. Along with estradiol dipropionate, it was among the most widely used esters of estradiol for many years following its introduction. However, in the 1950s, longer-acting estradiol esters that necessitate less frequent injections, such as estradiol valerate and estradiol cypionate, were developed, and have since mostly superseded estradiol benzoate. Nonetheless, estradiol benzoate remains widely available throughout the world. It is no longer available for medical use in the United States.