Baloxavir marboxil is a prodrug form of the antiviral and influenza virus cap-dependent endonuclease (CEN) inhibitor baloxavir acid.1,2 It inhibits influenza CEN and CEN/RNA-dependent RNA polymerase (CEN/RdRp) activity in cell-free assays (IC50s = 530 and 340 nM, respectively).2 Baloxavir marboxil prevents mortality in a mouse model of influenza A and B viral infection when administered at a dose of 5 or 50 mg/kg twice in a single day.1 It also reduces lung viral titers, body weight loss, and mortality in a mouse model of influenza A and B viral infection when administered 72 hours post-infection at 50 mg/kg. Formulations containing baloxavir marboxil have been used in the early treatment of uncomplicated influenza.
1.Fukao, K., Ando, Y., Noshi, T., et al.Baloxavir marboxil, a novel cap-dependent endonuclease inhibitor potently suppresses influenza virus replication and represents therapeutic effects in both immunocompetent and immunocompromised mouse modelsPLoS One14(5)e0217307(2019) 2.Noshi, T., Kitano, M., Taniguchi, K., et al.In vitro characterization of baloxavir acid, a first-in-class cap-dependent endonuclease inhibitor of the influenza virus polymerase PA subunitAntiviral Res.160109-117(2017)