Dasabuvir (formerly known as ABT-333; ABT333; trade name Exviera, Viekira Pak, Viekira XR) is a nonnucleoside inhibitor of the RNA-dependent RNA polymerase encoded by the hepatitis C virus (HCV) NS5B gene. It inhibited recombinant NS5B polymerases derived from HCV genotype 1a and 1b clinical isolates, with IC50 values between 2.2 and 10.7 nM, and was at least 7,000-fold selective for the inhibition of HCV genotype 1 polymerases over human/mammalian polymerases. Dasabuvir is an FDA approved antiviral medication for the treatment of hepatitis C. It is often used together with the combination medication ombitasvir/paritaprevir/ritonavir specifically for hepatitis C virus (HCV) type 1.