It was discovered by chemical modification of a pyrazine analogue, which was first investigated by in vitro anti-influenza virus activity in cells. Favipiravir is a selective and potent inhibitor of flue nadiral RNA polymerase and effective against all subtypes and strains of influenza viruses, including those that are sensitive or resistant to marketed neuraminidase and M2 inhibitors. Favipiravir showed antiviral activity against other RNA viruses.
Since the middle of the 20th century, significant advances in anti-infection therapies have been made with the advent of antibiotics, vaccines and other antimicrobials. The mainstay of antiviral therapy was preventive vaccines and therapeutic antiviral agents, which are however effective for a certain type of virus. There are still emerging or re-emerging viral infections for which effective drug or vaccine therapies are not available. Resistance to existing antiviral drugs has become a serious problem.
Favipiravir 200 mg has been approved for the treatment of influenza in Japan. However, it is only indicated for novel influenza (strains that cause more serious diseases) and not for seasonal influenza. From 2020, the probability of resistance development seems low.
There is evidence that use during pregnancy can cause damage to the baby.