Similarly to oral administration of estradiol, but in contrast to the vaginal and transdermal routes, the ratio of estradiol to estrone is decreased with sublingual administration of either estradiol valerate or estradiol. Intramuscular injection
In contrast to oral administration, the bioavailability of estradiol valerate is complete (i.e., 100%) via intramuscular injection. Due to the far greater bioavailability of intramuscular estradiol valerate relative to oral, the former is substantially stronger (in terms of potency) than the latter. As an example, a single 4 mg intramuscular injection is said to be approximately equivalent to 2 mg/day of the medication administered orally over the course of 3 weeks. Estradiol valerate, when given intramuscularly in oil, has a relatively long duration due to the formation of an intramuscular depot from which the medication is slowly released and absorbed. Upon intramuscular injection of estradiol valerate in an oil solution, the solvent (i.e., oil) is absorbed, and a primary microcrystalline depot is formed within the muscle at the site of injection. In addition, a secondary depot may also be formed in adipose tissue. The slow release of estradiol valerate is caused by the increased lipophilicity of the medication, which in turn is due to its long fatty acid valeric acid ester moiety. The elimination half-life of estradiol valerate in oil by intramuscular injection (brand names Estradiol-Depot 10 mg, Progynon Depot-10) is about 3.5 days, with a range of 1.2 days to 7.2 days in different individuals.
Other common esters of estradiol in use include estradiol cypionate, estradiol enantate, and estradiol acetate, the former two of which are C17β esters of estradiol similarly to estradiol valerate and the latter of which is the C3 acetate ester of estradiol.The experimental log octanol/water partition coefficient (log P) of estradiol valerate is 5.6. History
Estradiol valerate was patented by Ciba in 1940 and 1941, with a priority date of 1936. It was synthesized and studied, along with a variety of other estradiol esters, by Karl Junkmann of Schering AG in 1953. The medication was first introduced for medical use via intramuscular injection in 1954 by Schering in Europe under the brand name Progynon Depot and by Squibb in the United States under the brand name Delestrogen. In 1966, oral estradiol valerate was introduced by Schering for medical use in Europe under the brand name Progynova. A report of its metabolism was published in 1967. Esterification of estradiol, as in estradiol valerate, has been claimed to improve its metabolic stability with oral administration. In 1968, micronized preparations of oral estradiol valerate were first introduced under the brand names Progynova 21 and Progynova 21 mite. Along with estradiol benzoate (1933) and estradiol cypionate (1952), estradiol valerate is one of the most widely used esters of estradiol. Society and culture
Generic names
Estradiol valerate is the generic name of the drug and its INN, USAN, BANM, and JAN, while oestradiol valerate was formerly its BANM.