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.
Estradiol-containing birth control pill
Combined birth control pills that contain natural estradiol or an estradiol ester (e.g., estradiol valerate) include:It is hypothesized that these contraceptives may pose less of a risk of blood clots than contraceptives containing ethinylestradiol, which is the conventional estrogen that is used in oral contraceptives, but this has yet to be proven. However, incidence of irregular vaginal bleeding may be higher with estradiol-containing contraceptives in relation to the fact that estradiol is a weaker estrogen than ethinylestradiol in the endometrium.