Ensitrelvir (S-217622) fumarate is the first orally active non-covalent, non-peptidic, SARS-CoV-2 3CL protease inhibitor ( IC 50 =13 nM). In Vitro In a cytopathic effect (cpe)-inhibition assay of SARS-CoV-2 infected VeroE6/TMPRSS2 cells, Ensitrelvir fumarate shows the EC 50 values are approximately 0.4 μM for both wild-type virus and Alpha, Beta, Gamma and Delta variants. EC 50 values for SARS-CoV and MERS-CoV were 0.21 and 1.4 μM respectively. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo Ensitrelvir fumarate dose-dependently inhibits intrapulmonary replication of SARS-CoV-2 in mice. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid