nafoxidine nafoxidine nafoxidine (inn; developmental code names u-11,000a) or nafoxidine hydrochloride (usan) is a nonsteroidal selective estrogen receptor modulator (serm) or partial antiestrogen of the triphenylethylene group that was developed for the treatment of advanced breast cancer by upjohn in the 1970s but was never marketed. it was developed at around the same time as tamoxifen and clomifene, which are also triphenylethylene derivatives. the drug was originally synthesized by the fertility control program at upjohn as a postcoital contraceptive, but was subsequently repurposed for the treatment of breast cancer. nafoxidine was assessed in clinical trials in the treatment of breast cancer and was found to be effective. however, it produced side effects including ichthyosis, partial hair loss, and phototoxicity of the skin in almost all patients, and this resulted in the discontinuation of its development. nafoxidineclinical dataother namesu-11,000a; nsc-70735routes ofadministrationby mouthatc codenoneidentifiers iupac name 1-ethyl]pyrrolidine cas number1845-11-0pubchem cid4416iuphar/bps4263chemspider4263unii4riy10wm82keggc14212chebichebi:34881chemblchembl28211comptox dashboard (epa)dtxsid7022386 echa infocard100.222.756 chemical and physical dataformulac29h31no2molar mass425.572 g·mol−13d model (jsmol)interactive image smiles coc1=cc2=c(c=c1)c(=c(cc2)c3=cc=cc=c3)c4=cc=c(c=c4)occn5cccc5 inchi inchi=1s/c29h31no2/c1-31-26-14-16-28-24(21-26)11-15-27(22-7-3-2-4-8-22)29(28)23-9-12-25(13-10-23)32-20-19-30-17-5-6-18-30/h2-4,7-10,12-14,16,21h,5-6,11,15,17-20h2,1h3key:jeywnnazdlfbff-uhfffaoysa-n nafoxidine is a long-acting estrogen receptor ligand, with a nuclear retention in the range of 24 to 48 hours or more. comparison of early clinical experience with antiestrogens for advanced breast cancer antiestrogen dosage year(s) response rate toxicity ethamoxytriphetol 500–4,500 mg/day 1960 25% acute psychotic episodes clomifene 100–300 mg/day 1964–1974 34% fears of cataracts nafoxidine 180–240 mg/day 1976 31% cataracts, ichthyosis, photophobia tamoxifen 20–40 mg/day 1971–1973 31% transient thrombocytopeniaa footnotes: a = "the particular advantage of this drug is the low incidence of troublesome side effects (25)." "side effects were usually trivial (26)." sources: