4-[[4-[4-(4-Aminophenyl)-1-piperazinyl]phenoxy]methyl]-2,5-anhydro-1,3,4-trideoxy-2-C-(2,4-difluorophenyl)-1-(1H-1,2,4-triazol-1-yl)-D-threo-pentitol is an impurity of (S)-Citalopram (C505005). (S)-Citalopram is an inhibitor of serotonin (5-HT) uptake. Antidepressant.