Estradiol sulfate
As the sodium salt, sodium estradiol sulfate, E2S is present as a minor constituent (0.9%) of conjugated equine estrogens (CEEs), or Premarin. It effectively functions as a prodrug to estradiol in this preparation, similarly to E1S. E2S is also formed as a metabolite of estradiol, as well as of estrone and E1S. Aside from its presence in CEEs, E2S is not available as a commercial pharmaceutical drug.
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.