Pharmacodynamics<unk>  is an estrogen, or an agonist of the estrogen receptors. It is the 11β-methoxy derivative of ethinylestradiol and is one of the most potent estrogens known, being some 10 to 100 times more potent than estradiol and about 5-fold more potent than ethinylestradiol. The very high potency of<unk>  has been attributed to its high affinity for the estrogen receptor (ER), its negligible plasma binding to sex hormone binding globulin and low binding to serum albumin, and its lower relative rate of metabolism. In contrast to estradiol, which has roughly the same affinity for both ERs (Ki = 0.12 nM and 0.15 nM, respectively),<unk>  possesses several-fold selectivity for the ERα (Ki = 0.50 nM) over ERβ (Ki = 2.6 nM). Relative affinities (%) of<unk>  and related steroids Compound Estradiol 2.6 7.9 100 0.6 0.13 8.7 <0.1 Ethinylestradiol 15–25 1–3 112 1–3 <1 ? ?<unk>  (11β-MeO-) 0.8 <0.1 12 3.2 <0.1 <0.2 <0.1 RU-16117 (11α-MeO-) 1–3 <1 13 <1 <1 ? ? Notes: Values are percentages (%). Reference ligands (100%) were progesterone for the , testosterone for the , for the , for the , aldosterone for the , for , and cortisol for . Sources: Pharmacokinetics The bioavailability of<unk>  is 33%. Its plasma protein binding is minimal. The medication is metabolized in the liver. Its biological half-life is 8.2 hours.
Moxestrol
Hexestrol
Fosfestrol
Gestodene
Benzestrol
Dimestrol
Dienestrol
Allenestrol