favipiravir   Click here for help

GtoPdb Ligand ID: 11139

Synonyms: T-705 | T705
Approved drug
favipiravir is an approved drug (China and Japan)
Compound class: Synthetic organic
Comment: Favipiravir (T-705) is an orally delivered, guanine (purine) analogue antiviral drug (cf. remdesivir which is administered i.v.). It targets viral RNA-dependent RNA polymerase (RdRP) of RNA viruses and since the catalytic domain of RdRP is well conserved across species, has a broad-spectrum of activity; although Furuta et al. (2002) reported that actvity was weak against non-influenza virus RNA viruses [4]. Favipiravir was originally identified through a chemical library screen against influenza virus RdRP [3]. Chemically, it is a prodrug. In human cells it undergoes phosphoribosylation and phosphorylation to its active form, favipiravir-ribofuranosyl-5′-triphosphate (F-RTP). F-RTP is bound by the RdRP, but it blocks enzyme activity and so terminates chain elongation [5-6].
2D Structure
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Physico-chemical Properties
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Hydrogen bond acceptors 3
Hydrogen bond donors 2
Rotatable bonds 1
Topological polar surface area 88.84
Molecular weight 157.03
XLogP -0.35
No. Lipinski's rules broken 0
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Canonical SMILES Fc1c[nH]c(=O)c(n1)C(=O)N
Isomeric SMILES Fc1c[nH]c(=O)c(n1)C(=O)N
InChI InChI=1S/C5H4FN3O2/c6-2-1-8-5(11)3(9-2)4(7)10/h1H,(H2,7,10)(H,8,11)
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Summary of Clinical Use Click here for help
Oral favipiravir is already approved in China and Japan to treat influenza, and Phase 3 trials for influenza are underway in the US.

SARS-CoV-2 and COVID-19: a number of clinical trials have been launched globally, to evaluate the safety and efficacy of favipiravir in COVID-19 patients. favipiravir is used to treat COVID-19 in Russia and India under emergency use approvals.

With respect to emergent RNA viruses with future epidemic/pandemic potential [2], favipiravir has shown efficacy in the hamster model of Nipah virus infection [1]. It also has some activity against Ebola virus [7], and evidence of activity in a guinea pig Lassa virus infection model [8].

Click here to link to the full list of favipiravir studies at ClinicalTrials.gov.
Clinical Trials
Clinical Trial ID Title Type Source Comment References
NCT04425460 A Multi-center,Randomized,Double-blind,Placebo-controlled,Phase 3 Study Evaluating Favipiravir in Treatment of COVID19 Phase 3 Interventional Zhejiang Hisun Pharmaceutical Co. Ltd.
NCT04358549 Study of the Use of Favipiravir in Hospitalized Subjects With COVID-19 Phase 2 Interventional Fujifilm Pharmaceuticals U.S.A., Inc.
NCT02329054 Efficacy of Favipiravir Against Ebola (JIKI) Phase 2 Interventional Institut National de la Santé Et de la Recherche Médicale, France
NCT04402203 Study on Safety and Efficacy of Favipiravir (Favipira) for COVID-19 Patient in Selected Hospitals of Bangladesh Phase 2/Phase 3 Interventional Bangladesh Medical Research Council (BMRC)
NCT04373733 Early Intervention in COVID-19: Favipiravir Verses Standard Care Phase 3 Interventional Chelsea and Westminster NHS Foundation Trust