Ethinylestradiol (EE), the active form of EES. EES is an estrogen ester and long-acting prodrug of ethinylestradiol (EE) which is taken orally. The molecular weight of EES is about 136% of that of EE due to the presence of its C3 isopropylsulfonate ester, and hence EES contains about 74% of the amount of EE of an equal dose of EE. EES is more lipophilic than EE, and this results in a depot effect in which EES is taken up into fat and then slowly released from it. Following its release from fat, EES is hydrolyzed into EE. As a result of this depot effect, EES has a very long elimination half-life of about 6 days. This allows it to be taken once per week. Both EES and the related medication quinestrol have been described as depot oral estrogens. EES is a powerful antigonadotropin, and is capable of suppressing circulating total testosterone levels in men to concentrations comparable to those seen with castration (less than 1 to 3% of initial values). In addition, EES can strongly increase sex hormone-binding globulin (SHBG) levels, thereby additionally decreasing free testosterone levels. As such, EES is a powerful functional antiandrogen, which makes it useful for treating prostate cancer. The biological half-life of EES in blood has been reported to be 3 hours.
Ethinylestradiol sulfonate
Ethinylestradiol sulfate
Lipoidal estradiol
Desoxymethyltestosterone
Hexestrol diacetate
Hydroxyestrone diacetate
Hexestrol dipropionate
Cloxestradiol acetate