NHC-triphosphate tetraammonium is an active phosphorylated intracellular metabolite of beta-d-N4-Hydroxycytidine (NHC) (HY-125033) as a triphosphate form[1]. NHC-triphosphate tetraammonium is a weak alternative substrate for the viral polymerase and can be incorporated into HCV replicon RNA[1][2].