A single 4 mg intramusuclar (i.m.) injection ofestradiol cypionateorestradiol valerateresults in maximal plasma levels of estradiol of about 250 pg/mL and 390 pg/mL, respectively, with levels declining to 100 pg/mL (which was baseline for estradiol cypionate) by 12–14 days.[50][51]A single 2.5 mg intramuscular injection ofestradiol benzoatein individuals being treated with aGnRH analogue(and hence having minimal baseline levels of estrogen) was found to result in serum estradiol levels of >400 pg/mL at 24 hours post-administration.[45]The differences in the serum levels of estradiol achieved with these different estradiol esters may be explained by their different rates of absorption, as their durations and levels attained appear to be inversely proportional. For instance, estradiol benzoate, which has the shortest duration (4–5 days with a single i.m. dose of 5 mg), produces the highest levels of estradiol, while estradiol cypionate, which has the longest duration (~11 days with a single i.m. dose of 5 mg), produces the lowest levels of estradiol).[45]Estradiol valerate was found to have a duration of 7–8 days after a single i.m. dose of 5 mg.[45] 這證明為了ev 是最好選擇 要快要美的會用eb 但對健康有害 術為安全就用 ec