Estradiol enantate
Estradiol enantate, sold under the brand names Perlutal and Topasel among others, is an estrogen medication which is used in hormonal birth control. It is formulated in combination with dihydroxyprogesterone acetophenide (DHPA; algestone acetophenide), a progestin, and is used as a combined injectable contraceptive. Estradiol enantate is not available alone. The medication is given by injection into muscle once a month.
Side effects of estradiol enantate include breast tenderness, breast enlargement, nausea, headache, and fluid retention. The drug is a synthetic estrogen and hence is an agonist of the estrogen receptor (ER), the biological target of estrogens like estradiol. Estradiol enantate is an estrogen ester and a long-lasting prodrug of estradiol in the body. Because of this, it is considered to be a natural and bioidentical form of estrogen.
Estradiol enantate was first described by 1954, and was first studied in combination with DHPA as a combined injectable contraceptive in 1964. The combination was introduced for clinical use by the mid-1970s. Estradiol enantate is not available as a standalone medication (i.e., by itself without DHPA). The combination is available in Latin America and Hong Kong, and was also previously marketed in Spain and Portugal.
Estradiol phosphate
Estradiol phosphate, or estradiol 17β-phosphate, also known as estra-1,3,5(10)-triene-3,17β-diol 17β-(dihydrogen phosphate), is an estrogen which was never marketed. It is an estrogen ester, specifically an ester of estradiol with phosphoric acid, and acts as a prodrug of estradiol in the body. It is rapidly cleaved by phosphatase enzymes into estradiol upon administration. Estradiol phosphate is contained within the chemical structures of two other estradiol esters, polyestradiol phosphate (a polymer of estradiol phosphate) and estramustine phosphate (estradiol 3-normustine 17β-phosphate), both of which have been marketed for the treatment of prostate cancer.