Favipiravir (Avigan) is an antiviral agent that was accidentally discovered at Research Laboratories of Toyama Chemical Co., Ltd.
It is a potent inhibitor of influenza virus RNA polymerase. Although, primarily being investigated for the treatment of viral influenza infection, it has a broad spectrum of activity against many viral pathogens.
The recent outbreak of the deadly virus COVID-19 has compelled scientists to come up with a solution.
While the role of Remdesivir, chloroquine, and Lopinavir/ritonavir in the treatment of the COVID-19 is being evaluated, Favirpiravir is thought to be another potential drug for the treatment and prevention of the outbreak.
In fact, Favipiravir is the first approved drug in the fight against COVID-19 and China has already started manufacturing it on a larger scale.
Recently, the Massachusett General Hospital published guidelines for the treatment of Coronavirus. However, Favipiravir has not been mentioned in these guidelines.
What is Favipiravir?
Favipiravir is a novel broad-spectrum antiviral drug that has potent antiviral activity. It inhibits the viral RNA polymerase.
It is effective against all the subtypes of influenza strains including those sensitive and resistant to the neuraminidase and M2 inhibitors.
It is a prodrug that is activated intracellularly to Favipiravir-RTP.
The spectrum of antiviral activity of Favipiravir:
It is active against the following viral pathogens [Ref]:
|Orthomyxoviridae||Influenza A (seasonal)
Influenza A (H5N1)
Influenza A (H1N1)pdm09
Influenza A (H7N9)
Rift Valley fever
Crimean-Congo hemorrhagic fever
Severe fever thrombocytopenia syndrome
|Arenaviridae||Junin Pichinde Tacaribe Guanarito Machupo Lassa|
Respiratory syncytial virus
|Flaviviridae||West Nile Yellow fever Zika virus|
|Togaviridae||Western equine encephalitis Venezuelan equine encephalitis Eastern equine encephalitis Barmah forest Ross river Mayaro Chikungunya|
|Picornaviridae||Polio Rhino Enterovirus 71|
In animal studies, when administered at a dose of 30 mg/kg/day divided into two or four doses, there was a significant improvement seen in mice who received the drug compared to those who were not given the drug. None of the mice in the control group survived [Ref].
Compared to ribavirin, it was also found to be more potent in the treatment of viruses from the Bunyaviridae group. This group includes the deadly Lassa virus and Crimean Congo Hemorrhagic fever.
Another serious emerging viral infection is the “Severe fever with thrombocytopenia syndrome” (SFTS) that infects individuals residing primarily in Japan, Korea, and China. Cases are seen throughout the year, however, most cases occur in the winters.
Favipiravir was studied and found to be effective against the SFTS virus in vitro.
It has also been found to be effective in infections caused by the Zika virus and Ebola viruses.
Lastly, if administered in the presymptomatic phase of rabies virus infection at a dose of 30 mg/kg/day in divided doses, it was found to inhibit the viral activity and disease progression.
Favipiravir is an attractive antiviral drug for the treatment of the COVID-19 infection that is associated with a high mortality rate.
It may also be used in the treatment of other deadly viral infections such as Ebola, Zika, and Rabies virus infections.