“…One major drawback of Arbidol is that a large dose must be administered to achieve peak plasma concentration and therapeutic efficacy. To understand the molecule mechanism for its broad-spectrum inhibition of influenza viruses, various in vitro assays have been reported (14,(22)(23)(24), From the reported K d s with H1, H2, H3, H4, and H5 HA strains, Arbidol binds with higher affinity to group 2 HAs (K d s = 5.6-7.9 μM) than to group 1 HAs (K d s = 18.8-44.3 μM) (23). Mechanistically, Arbidol has been shown to increase influenza virus HA stability and prevent the low pH-induced HA transition to its fusogenic state, thereby blocking infection at one of the two key steps in cell entry, i.e., at viral fusion.…”