moxestrol moxestrol moxestrol, sold under the brand name surestryl, is an estrogen medication which has been used in europe for the treatment of menopausal symptoms and menstrual disorders. it is taken by mouth. in addition to its use as a medication, moxestrol has been used in scientific research as a radioligand of the estrogen receptor. moxestrolclinical datatrade namessurestrylother namesr-2858, ru-2858, nsc-118191; 11β-methoxy-17α-ethynylestradiol; 11β-meo-ee 11β-methoxy-17α-ethynylestra-1,3,5(10)-triene-3,17β-diolpregnancycategory x (contraindicated) routes ofadministrationby mouthdrug classestrogen; estrogen etheratc codeg03cb04 (who) legal statuslegal status in general: ℞ (prescription only) pharmacokinetic databioavailability33%protein bindingminimalmetabolismliverelimination half-life8.2 hoursidentifiers iupac name (8s,9s,11s,13s,14s,17r)-17-ethynyl-11-methoxy-13-methyl-7,8,9,11,12,14,15,16-octahydro-6h-cyclopentaphenanthrene-3,17-diol cas number34816-55-2pubchem cid11954041chemspider10128336unii6923nt44owkeggc14757chebichebi:34857chemblchembl1628161comptox dashboard (epa)dtxsid8022375 chemical and physical dataformulac21h26o3molar mass326.436 g·mol−13d model (jsmol)interactive image smiles cc12cc(c3c(c1ccc2(c#c)o)ccc4=c3c=cc(=c4)o)oc inchi inchi=1s/c21h26o3/c1-4-21(23)10-9-17-16-7-5-13-11-14(22)6-8-15(13)19(16)18(24-3)12-20(17,21)2/h1,6,8,11,16-19,22-23h,5,7,9-10,12h2,2-3h3/t16-,17-,18-,19+,20-,21-/m0/s1key:mtmzziptqitgcy-olgwugkesa-n medical uses moxestrol is or has been used in the treatment of menopausal symptoms and menstrual disorders. it has been used at dosages of 50 to 150 µg per week for long-term therapy to 25 to 250 µg per day for short-term therapy. pharmacology pharmacodynamics moxestrol 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 moxestrol 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), moxestrol possesses several-fold selectivity for the erα (ki = 0.50 nm) over erβ (ki = 2.6 nm). relative affinities (%) of moxestrol and related steroids compoundprarergrmrshbgcbg estradiol2.67.91000.60.138.7<0.1 ethinylestradiol15–251–31121–3<1 ? ? moxestrol (11β-meo-ee)0.8<0.1123.2<0.1<0.2<0.1 ru-16117 (11α-meo-ee)1–3<113<1<1 ? ? notes: values are percentages (%). reference ligands (100%) were progesterone for the pr, testosterone for the ar, e2 for the er, dexa for the gr, aldosterone for the mr, dht for shbg, and cortisol for cbg. sources: pharmacokinetics the bioavailability of moxestrol is 33%. its plasma protein binding is minimal. the medication is metabolized in the liver. its biological half-life is 8.2 hours. chemistry