Estradiol, the active form of<unk> . Pharmacodynamics<unk>  is an estradiol ester, or a prodrug of estradiol. As such, it is an estrogen, or an agonist of the estrogen receptors.<unk>  is of about 41% higher molecular weight than estradiol due to the presence of its C17β enantate ester. Because<unk>  is a prodrug of estradiol, it is considered to be a natural and bioidentical form of estrogen. The combination of 10 mg<unk>  and 150 mg DHPA as a once-monthly combined injectable contraceptive (which achieves levels of estradiol of around 350 pg/mL) has been found to have little to no effect on many markers of estrogen-modulated liver protein synthesis, including circulating levels of HDL and LDL cholesterol, copper, ceruloplasmin, total and free cortisol, corticosteroid-binding globulin, and sex hormone-binding globulin. However, it was found to significantly increase levels of triglycerides and to significantly decrease levels of total and free testosterone. In contrast to the<unk> -containing combined injectable contraceptive, low-dose ethinylestradiol-containing birth control pills produce highly significant changes in all of the preceding parameters. Studies in women and female capuchin monkeys have found that injections of<unk>  and DHPA significantly alter levels of coagulation factors. The clinical estrogenic effects of<unk>  and ethinylestradiol have been compared in other studies as well. Pharmacokinetics When<unk>  is administered in an oil solution by intramuscular injection, a depot effect occurs, and this results in it having a long duration of action. The duration of action of<unk>  is considerably longer than that of various other estradiol esters, such as estradiol benzoate, estradiol valerate, and estradiol cypionate, whereas its duration is shorter than that of estradiol undecylate. In general, the longer the fatty acid ester chain, the more lipophilic the estradiol ester, the more slowly it is released from the depot and absorbed into the circulation, and the longer its duration of action. The pharmacokinetics of<unk>  have been assessed in a number of studies. It has usually been studied in combination with DHPA. Following an intramuscular injection of<unk> , levels of estradiol have been found to peak after 3 to 8 days. Maximal levels of estradiol after a 5 mg injection of<unk>  have been found to be about 163 to 209 pg/mL and after a 10 mg injection of<unk>  have been found to be about 283 to 445 pg/mL. However, one outlying study reported peak estradiol levels of 850 pg/mL after an intramuscular injection of 10 mg<unk>  in three postmenopausal women. It used radioimmunoassay for the determinations, with no mention of chromatographic separation. Estradiol levels following an intramuscular injection of 10 mg<unk>  have been found to return to baseline levels of around 50 pg/mL after about 20 to 30 days. However, a metabolic study found that traces of radiolabeled<unk>  remained detectable in blood for at least 30 to 40 days and for as long as 60 days. Studies have reported that the elimination half-life of<unk>  after a single 10 mg intramuscular injection was 5.6 to 7.5 days. The volume of distribution of<unk>  has been reported to be 5.087 L.<unk>  is excreted preferentially in urine. There were concerns about possible accumulation of<unk>  and consequent estrogenic overexposure with once-monthly combined injectable contraceptives containing the medication due its long duration, and this may have limited the use of such combined injectable contraceptives. Subsequent clinical studies have found that there is very limited or no accumulation of<unk>  when it is used in once-a-month injectable contraceptives.
Estradiol enantate
Estradiol undecylate
Estradiol dienantate
Estradiol furoate
Estradiol valerate
Hexestrol diphosphate
Estradiol dipropionate
Estradiol cypionate