Efficacy comparison of 3CL protease inhibitors ensitrelvir and nirmatrelvir against SARS-CoV-2 in vitro and in vivo.

Direct in vitro and in vivo efficacy comparisons of 3CL PIs revealed that ensitrelvir demonstrated comparable in vitro efficacy to that of nirmatrelvir in cell culture and exhibited equal to or greater in vivo efficacy in terms of unbound-drug plasma concentration in both animal models evaluated. The results suggest that ensitrelvir may become an important resource for treating individuals infected with SARS-CoV-2.