– ARN 23746 (ARN-23746) is a potent, selective inhibitor of Na+-K+-Cl- importer NKCC1, shows NKCC1 inhibition 31.8% at 10 uM, and 95.2% at 100 uM in the Cl? influx assay on NKCC1-transfected HEK293 cells.ARN23746 did not show significant NKCC2 inhibition and KCC2 inhibition at 10 uM.ARN23746 selectively blocks NKCC1 in a human cell line and restore the physiological [Cl?]i in murine DS neurons in culture, has excellent solubility and metabolic stability, and displays no issues with off-target activity in vitro.ARN23746 demonstrated in vivo efficacy in rescuing cognitive impairment in a DS mouse model and social deficits and repetitive behaviors in an autism mouse model.