fialuridine fialuridine fialuridine, or 1-(2-deoxy-2-fluoro-1-d-arabinofuranosyl)-5-iodouracil (fiau), is a nucleoside analogue that was investigated as a potential therapy for hepatitis b virus infection. in a 1993 clinical study at the nih, unexpected toxicity led to the death of 5 out of 15 patients from liver failure alongside lactic acidosis; two further participants required liver transplantation. it is suspected that the toxicity of fialuridine was a result of mitochondrial damage caused by the incorporation of fialuridine into mitochondrial dna via its 3'-hydroxyl moiety, leading to impaired dna synthesis. this toxicity was unusual in that it was not predicted by animal studies. fialuridineclinical dataother names2′-fluoro-5-iodouracilatc codenoneidentifiers iupac name 1--5-iodopyrimidine-2,4-dione cas number69123-98-4 npubchem cid50313chemspider45627 nunii53t7in77lckeggd04181 ychemblchembl271475 nniaid chemdb070971chemical and physical dataformulac9h10fin2o5molar mass372.091 g·mol−13d model (jsmol)interactive image smiles c1c(c(=o)c(=o)n12(((o2)co)o)f)i inchi inchi=1s/c9h10fin2o5/c10-5-6(15)4(2-14)18-8(5)13-1-3(11)7(16)12-9(13)17/h1,4-6,8,14-15h,2h2,(h,12,16,17)/t4-,5+,6-,8-/m1/s1 nkey:ipvfgaytkqkgbm-bypjnblxsa-n n ny (what is this?) (verify)