Estradiol valerate
In addition to single-drug formulations, oral estradiol valerate is available in combination with the progestin dienogest as a combined oral contraceptive and intramuscular estradiol valerate is marketed in combination with the progestins hydroxyprogesterone caproate and norethisterone enantate as combined injectable contraceptives. Intramuscular estradiol valerate has also been marketed in combination with testosterone enantate, but this formulation has been discontinued. The availability of estradiol valerate-containing products varies throughout the world.
EC508
EC508, also known as estradiol 17β-(1-(4-(aminosulfonyl)benzoyl)--proline), is an estrogen which is under development by Evestra for use in menopausal hormone therapy and as a hormonal contraceptive for the prevention of pregnancy in women. It is an orally active estrogen ester – specifically, a C17β sulfonamide–proline ester of the natural and bioidentical estrogen estradiol – and acts as a prodrug of estradiol in the body. However, unlike oral estradiol and conventional oral estradiol esters such as estradiol valerate, EC508 undergoes little or no first-pass metabolism, has high oral bioavailability, and does not have disproportionate estrogenic effects in the liver. As such, it has a variety of desirable advantages over oral estradiol, similarly to parenteral estradiol, but with the convenience of oral administration. EC508 is a candidate with the potential to replace not only estradiol in clinical practice, but also ethinylestradiol in oral contraceptives. Evestra intends to seek Investigational New Drug status for EC508 in the second quarter of 2018.