Dasabuvir is a nonnucleoside inhibitor of the RNA-dependent RNA polymerase encoded by the HCV NS5B gene, inhibits recombinant NS5B polymerases derived from HCV genotype 1a and 1b clinical isolates, with IC50 between 2.2 and 10.7 nM.

Dasabuvir is at least 7,000-fold selective for the inhibition of HCV genotype 1 polymerases over human/mammalian polymerases. Dasabuvir inhibits the polymerase enzymatic activity of genotype 1 laboratory strain enzymes (H77, BK, N, and Con1 strains), as well as enzymes produced from polymerase genes from HCV genotype 1-infected subjects, with IC50s between 2.2 and 10.7 nM. Dasabuvir inhibits replication of HCV subgenomic replicons in cell culture assays, with EC50 values of 7.7 and 1.8 nM against genotype 1a (H77) and 1b (Con1), respectively. In the presence of 40% human plasma, there is a 12- to 13-fold decrease in inhibitory potency, yielding EC50s of 99 and 21 nM for HCV genotype 1a (H77) and 1b (Con1) replicons, respectively[1].

References:
[1]. Kati W, et al. In vitro activity and resistance profile of dasabuvir, a nonnucleoside hepatitis C virus polymerase inhibitor. Antimicrob Agents Chemother. 2015 Mar;59(3):1505-11.