Estradiol (medication)
Estradiol is also widely available in combination with progestogens. It is available in combination with norethisterone acetate under the major brand names Activelle, Cliane, Estalis, Eviana, Evorel Conti, Evorel Sequi, Kliogest, Novofem, Sequidot, and Trisequens; with drospirenone as Angeliq; with dydrogesterone as Femoston, Femoston Conti; and with nomegestrol acetate as Zoely. Estradiol valerate is available with cyproterone acetate as Climen; with dienogest as Climodien and Qlaira; with norgestrel as Cyclo-Progynova and Progyluton; with levonorgestrel as Klimonorm; with medroxyprogesterone acetate as Divina and Indivina; and with norethisterone enantate as Mesigyna and Mesygest. Estradiol cypionate is available with medroxyprogesterone acetate as Cyclo-Provera, Cyclofem, Feminena, Lunelle, and Novafem; estradiol enantate with algestone acetophenide as Deladroxate and Topasel; and estradiol benzoate is marketed with progesterone as Mestrolar and Nomestrol.
Cyclodiol
Cyclodiol (developmental code name ZK-115194; also known as 14α,17α-ethano-17β-estradiol) is a synthetic estrogen which was studied in the 1990s and was never marketed. It is a derivative of estradiol with a bridge between the C14α and C17α positions. Cyclodiol has 100% of the relative binding affinity of estradiol for the human ERα and similar transactivational capacity as estradiol at the receptor. It has comparable potency to estradiol when administered by subcutaneous injection. The drug shows genotoxicity similarly to estradiol. Cyclodiol showed an absolute bioavailability of 33 ± 19% and a terminal half-life of 28.7 hours in pharmacokinetic studies in women.