[11][medical citation needed] Favipiravir is a prodrug that is metabolized to its active form, favipiravir-ribofuranosyl-5'-triphosphate (favipiravir-RTP), available in both oral and intravenous formulations.

[14] However, favipiravir has not been shown to be effective in primary human airway cells, casting doubt on its efficacy in influenza treatment.

[21] Toyama Chemical initially hoped that favipiravir would become a new influenza medication that could replace oseltamivir (brand name Tamiflu).

[22] Despite limited data on efficacy, as of March 2021 favipiravir is widely prescribed for outpatient treatment of mild to moderate COVID-19 in Egypt,[23] Hungary[24] and Serbia.

[citation needed] Favipiravir is sold under the brand names Avigan (アビガン, Abigan), Avifavir,[1] Avipiravir,[26] Areplivir,[2] FabiFlu,[27] Favipira,[28] Reeqonus,[29][30] and Qifenda.

[33] Favipiravir, as an antiviral drug, has been authorized for treating COVID-19 in several countries including Japan, Russia, Serbia, Turkey, India, and Thailand, under emergency provisions.

[45] A clinical trial investigating the use of favipiravir against Ebola virus disease began in Guéckédou, Guinea, in December 2014.

[50] Nipah virus is a causative agent of outbreaks of encephalitis with pneumonia and has a high case fatality rate.

in Bangladesh outbreaks are often associated with consumption of raw date palm sap contaminated by saliva and urine of fruit bats.

[51] In a study published in the Scientific Reports, Syrian hamster model for Nipah virus infection was used, which closely mirrors most aspects of human disease, such as widespread vasculitis, pneumonia, and encephalitis.

The treated hamsters displayed 100% survival and no obvious morbidity after lethal NiV challenge, whereas all the control cases died of severe disease.

In aqueous solution the keto-like tautomer is substantially stabilized due to the specific interaction with the water molecules.