n-desmethyltamoxifen n-desmethyltamoxifen n-desmethyltamoxifen (developmental code name ici-55,548) is a major metabolite of tamoxifen, a selective estrogen receptor modulator (serm). n-desmethyltamoxifen is further metabolized into endoxifen (4-hydroxy-n-desmethyltamoxifen), which is thought to be the major active form of tamoxifen in the body. in one study, n-desmethyltamoxifen had an affinity for the estrogen receptor of 2.4% relative to estradiol. for comparison, tamoxifen, endoxifen, and afimoxifene (4-hydroxytamoxifen) had relative binding affinities of 2.8%, 181%, and 181%, respectively. n-desmethyltamoxifenclinical dataother namesici-55,548; nortamoxifen; ndmtamdrug classselective estrogen receptor modulatoridentifiers iupac name 2-phenoxy]-n-methylethanamine cas number31750-48-8pubchem cid6378383chemspider2297759uniiooj759o35ckeggc16546chebichebi:80554echa infocard100.170.899 chemical and physical dataformulac25h27nomolar mass357.497 g·mol−13d model (jsmol)interactive image smiles cc/c(=c(\c1=cc=cc=c1)/c2=cc=c(c=c2)occnc)/c3=cc=cc=c3 inchi inchi=1s/c25h27no/c1-3-24(20-10-6-4-7-11-20)25(21-12-8-5-9-13-21)22-14-16-23(17-15-22)27-19-18-26-2/h4-17,26h,3,18-19h2,1-2h3/b25-24-key:nydcdzseeauohn-izhyloqssa-n