Estradiol (medication)
Estradiol is available in a variety of different formulations, including oral, intranasal, transdermal/topical, vaginal, injectable, and implantable preparations. An ester may be attached to one or both of the hydroxyl groups of estradiol to improve its oral bioavailability and/or duration of action with injection. Such modifications give rise to forms such as estradiol acetate (oral and vaginal), estradiol valerate (oral and injectable), estradiol cypionate (injectable), estradiol benzoate (injectable), estradiol undecylate (injectable), and polyestradiol phosphate (injectable; a polymerized ester of estradiol), which are all prodrugs of estradiol.
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.