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.
Estetrol (medication)
In addition to a single-drug formulation, estetrol is under development in combination with the progestin drospirenone for use as a birth control pill to prevent pregnancy with the tentative brand name Estelle. Drospirenone is also a potent antimineralocorticoid and antiandrogen in addition to progestogen, and in relation to this, is said to have a progesterone-like medication profile. As of April 2018, estetrol/drospirenone are in phase III clinical trials for pregnancy prevention.