Estradiol (medication)
, estradiol is available in the United States in the following forms:Oral estradiol valerate (Progynova) and other esters of estradiol that are used by injection like estradiol benzoate, estradiol enantate, and estradiol undecylate all are not marketed in the U.S. Polyestradiol phosphate (Estradurin) was marketed in the U.S. previously but is no longer available.
Pharmacokinetics of estradiol
Estradiol is well-absorbed regardless of route of administration. However, the bioavailability of estradiol differs substantially with different routes of administration. Oral estradiol has an average bioavailability of around 5%, requiring relatively high dosages of estradiol for effects. Conversely, transdermal estradiol has much higher potency, with a 20-fold lower dosage of transdermal estradiol being equivalent in potency to oral estradiol. Estradiol administered in the form of an ester by intramuscular or subcutaneous injection has complete bioavailability.