N-Desmethyltamoxifen (developmental code name ICI-55,548) is a major metabolite of tamoxifen, a selective estrogen receptor modulator (SERM).[1][2] 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.[1][2][3] In one study, N-desmethyltamoxifen had an affinity for the estrogen receptor of 2.4% relative to estradiol.[4] For comparison, tamoxifen, endoxifen, and afimoxifene (4-hydroxytamoxifen) had relative binding affinities of 2.8%, 181%, and 181%, respectively.[4]

References

  1. ^ a b Sanchez-Spitman AB, Swen JJ, Dezentje VO, Moes DJ, Gelderblom H, Guchelaar HJ (June 2019). "Clinical pharmacokinetics and pharmacogenetics of tamoxifen and endoxifen". Expert Review of Clinical Pharmacology. 12 (6): 523–536. doi:10.1080/17512433.2019.1610390. PMID 31008668.
  2. ^ a b Klein DJ, Thorn CF, Desta Z, Flockhart DA, Altman RB, Klein TE (November 2013). "PharmGKB summary: tamoxifen pathway, pharmacokinetics". Pharmacogenet Genomics. 23 (11): 643–7. doi:10.1097/FPC.0b013e3283656bc1. PMC 4084801. PMID 23962908.
  3. ^ Binkhorst L, Mathijssen RH, Jager A, van Gelder T (March 2015). "Individualization of tamoxifen therapy: much more than just CYP2D6 genotyping". Cancer Treat Rev. 41 (3): 289–99. doi:10.1016/j.ctrv.2015.01.002. PMID 25618289.
  4. ^ a b Maximov PY, McDaniel RE, Fernandes DJ, Bhatta P, Korostyshevskiy VR, Curpan RF, Jordan VC (October 2014). "Pharmacological relevance of endoxifen in a laboratory simulation of breast cancer in postmenopausal patients". J Natl Cancer Inst. 106 (10). doi:10.1093/jnci/dju283. PMC 4271116. PMID 25258390.