Estrogen (medication)
Estradiol, estrone, and estriol have all been approved as pharmaceutical drugs and are used medically. Estetrol is currently under development for medical indications, but has not yet been approved in any country. A variety of synthetic estrogen esters, such as estradiol valerate, estradiol cypionate, estradiol acetate, estradiol benzoate, estradiol undecylate, and polyestradiol phosphate, are used clinically. The aforementioned compounds behave as prodrugs to estradiol, and are much longer-lasting in comparison when administered by intramuscular or subcutaneous injection. Esters of estrone and estriol also exist and are or have been used in clinical medicine, for example estrone sulfate (e.g., as estropipate), estriol succinate, and estriol glucuronide (as Emmenin and Progynon).
Pharmacokinetics of progesterone
Progesterone does not appear to be available pharmaceutically in the form of subcutaneous pellet implants. This is in contrast to estradiol and testosterone. Progesterone may be available in the form of subcutaneous pellet implants from some compounding pharmacies however. Such products are not regulated for quality or effectiveness however. Subcutaneous implantation of progesterone has been studied in animals. Although progesterone is not available for subcutaneous implantation as a pharmaceutical product, subcutaneous implants of progestins, such as etonogestrel (Implanon/Nexplanon) and levonorgestrel (Jadelle/Norplant), are available as pharmaceutical preparations. They are used specifically as a form of long-lasting hormonal birth control.