Fig. 4.

Differential surface plot of the synergistic anti-HCV effect of boceprevir with either clemizole (top) or the M1 metabolite of clemizole (bottom). The 3-dimensional plot represents the differences between the actual antiviral effects and the theoretical additive effects at the indicated concentrations for the two compounds tested. Only statistically significant (95% confidence interval) differences between the two compounds were considered at any given concentration. Peaks above the theoretical additive plane indicate synergy, whereas depressions below it indicate antagonism. The colors indicate the level of synergy or antagonism. Both clemizole and the M1 metabolite exhibit a substantial synergistic antiviral effect with boceprevir.