What is favipiravir?

The favipiravir, or T-705 or avifavir, or avigan, is a pyrazine carboxamide derivative with activity against RNA viruses. Favipiravir is converted to the ribofuranosyl triphosphate derivative by host enzymes and selectively inhibits viral RNA-dependent RNA polymerase of influenza A and B viruses. These RNA polymerases are required for transcription and replication of viral genomes. Favipiravir has also been investigated for the treatment of avian influenza, Ebola virus, Lassa virus and recently for COVID-19.

The IUPAC systematic name for favipiravir is 6-fluoro-3-hydroxypyrazine-2-carboxamide.

Chemical structure

Favipiravir belongs to the family of nigrogenated heterocycles called pyrazines that have a primary carboxamide group. It has the molecular formula C5H4FN3O2.


favipiravir T-705 avifavir avigan ZCGNOVWYSGBHAU-UHFFFAOYSA-N
3D Structure


It was discovered in Japan by the Toyama Chemical Company.