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.
Pharmacokinetics of progesterone
Progesterone does not appear to be available pharmaceutically in the form of subcutaneous pellet implants. This is in contrast to estradiol and testosterone. Progesterone may be available in the form of subcutaneous pellet implants from some compounding pharmacies however. Such products are not regulated for quality or effectiveness however. Subcutaneous implantation of progesterone has been studied in animals. Although progesterone is not available for subcutaneous implantation as a pharmaceutical product, subcutaneous implants of progestins, such as etonogestrel (Implanon/Nexplanon) and levonorgestrel (Jadelle/Norplant), are available as pharmaceutical preparations. They are used specifically as a form of long-lasting hormonal birth control.