Favipravir
This viral polymerase inhibitor is approved, in Japan, for the treatment of novel strains of the influenza virus unresponsive to current antivirals. Its activity spectrum spreads across A, B and C strains of the virus. Favipravir becomes active after ribosylation and phosphorylation. This triphosphorylated favipravir competitively inhibit the viral RNA-dependent RNA polymerase (RdRp) of influenza virus known as polymerase basic 1 transcriptase thereby interfering with the viral replication (Hayden & Shindo, 2019; Beigel et al., 2019; Principi et al., 2019; Furuta et al., 2013; Madelain et al., 2016).
Favipravir is well tolerated clinically but the adverse effects that can be associated with its use include diarrhoea, teratogenicity, increased serum uric acid levels, elevated levels of transaminases, reduced neutrophil counts (Hayden & Shindo, 2019; Principi et al., 2019; Madelain et al., 2016).