Favipiravir, also known as T-705 or Avigan, is an experimental antiviral drug being developed by Toyama Chemical of Japan with activity against many RNA viruses. Like some other experimental antiviral drugs (T-1105 and T-1106), it is a pyrazinecarboxamide derivative. Favipiravir is active against influenza viruses, West Nile virus, yellow fever virus, foot-and-mouth disease virus as well as other flaviviruses, arenaviruses, bunyaviruses and alphaviruses. Activity against enteroviruses and Rift Valley fever virus has also been demonstrated.
The mechanism of its actions is thought to be related to the selective inhibition of viral RNA-dependent RNA polymerase. Other research suggests that favipiravir induces lethal RNA transversion mutations, producing a nonviable viral phenotype. Favipiravir is a prodrug and is metabolized to its active form, favirpiravir-RTP, following digestion. Human hypoxanthine guanine phosphoribosyltransferase (HGPRT) is believed to play a key role in this activation process. Favipiravir does not inhibit RNA or DNA synthesis in mammalian cells and is not toxic to them.
In 2014, favipiravir was approved in Japan for stockpiling against influenza pandemics.

Chemical Name	5-fluoro-2-oxo-1H-pyrazine-3-carboxamide
Synonyms	6-fluoro-3-hydroxypyrazine-2-carboxaMide;6-fluoro-3-oxo-3,4-dihydropyrazine-2-carboxamide;2-Pyrazinecarboxamide,6-fluoro-3-hydroxy;Favipiravir;T-705;6-fluoro-3-hydroxy-2-pyrazinecarboxamide;UNII-EW5GL2X7E0;Collapse
CAS No.	259793-96-9
Molecular Formula	C5H4FN3O2
Molecular Weight	157.10300
PSA	88.84000
LogP	-0.29180

Density	1.78 g/cm3
Boiling Point	552.6ºC at 760 mmHg

HS Code	2934999090