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.
Estradiol acetylsalicylate
Estradiol acetylsalicylate, or estradiol 3-acetylsalicylate, is a synthetic estrogen and estrogen ester – specifically, the C3 acetylsalicylic acid (aspirin) ester of estradiol – which was described in the late 1980s and was never marketed. In dogs, the oral bioavailability of estradiol acetylsalicylate was found to be 17-fold higher than that of unmodified estradiol. However, a subsequent study found that the oral bioavailability of estradiol and estradiol acetylsalicylate did not differ in rats (4.3% and 4.2%, respectively), suggestive of a major species difference.