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.
Segesterone acetate
A combination of SGA and the estrogen estradiol is under development in a transdermal gel formulation for use as a contraceptive in women by the Population Council in conjunction with Antares Pharma in the United States and Europe. As of December 2017, it is in phase III clinical trials for this indication. The medication has the tentative brand name NestraGel. A combination of SGA and the estrogen ethinylestradiol is under development in a vaginal ring formulation for use as a one-year contraceptive by the Population Council in multiple regions including Latin America, Europe, and Australia. It has completed phase III clinical trials and efforts are underway to pursue regulatory approval. It was approved in the United States in August 2018.