N-Desmethyltamoxifen
N-Desmethyltamoxifen is a major metabolite of tamoxifen, a selective estrogen receptor modulator. N-Desmethyltamoxifen is further metabolized into endoxifen, 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 had relative binding affinities of 2.8%, 181%, and 181%, respectively.