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.
Estriol (medication)
Estriol is available in oral tablet, vaginal cream, and vaginal suppository forms. It is also available over-the-counter or from compounding pharmacies in the form of topical creams. The medication is available both as estriol and in the form of estriol ester prodrugs such as estriol succinate, estriol acetate benzoate, and estriol tripropionate.