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2D Structure
Also known as: 259793-96-9, 6-fluoro-3-hydroxypyrazine-2-carboxamide, 6-fluoro-3-oxo-3,4-dihydropyrazine-2-carboxamide, T-705, Avigan, 5-fluoro-2-oxo-1h-pyrazine-3-carboxamide
Molecular Formula
C5H4FN3O2
Molecular Weight
157.10  g/mol
InChI Key
ZCGNOVWYSGBHAU-UHFFFAOYSA-N
FDA UNII
EW5GL2X7E0

Favipiravir is a pyrazinecarboxamide derivative with activity against RNA viruses. Favipiravir is converted to the ribofuranosyltriphosphate derivative by host enzymes and selectively inhibits the influenza viral RNA-dependent RNA polymerase.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
5-fluoro-2-oxo-1H-pyrazine-3-carboxamide
2.1.2 InChI
InChI=1S/C5H4FN3O2/c6-2-1-8-5(11)3(9-2)4(7)10/h1H,(H2,7,10)(H,8,11)
2.1.3 InChI Key
ZCGNOVWYSGBHAU-UHFFFAOYSA-N
2.1.4 Canonical SMILES
C1=C(N=C(C(=O)N1)C(=O)N)F
2.2 Other Identifiers
2.2.1 UNII
EW5GL2X7E0
2.3 Synonyms
2.3.1 MeSH Synonyms

1. 6-fluoro-3-hydroxy-2-pyrazinecarboxamide

2. Avigan

3. Fabiflu

4. T-705 Cpd

2.3.2 Depositor-Supplied Synonyms

1. 259793-96-9

2. 6-fluoro-3-hydroxypyrazine-2-carboxamide

3. 6-fluoro-3-oxo-3,4-dihydropyrazine-2-carboxamide

4. T-705

5. Avigan

6. 5-fluoro-2-oxo-1h-pyrazine-3-carboxamide

7. Favipiravir (t-705)

8. 6-fluoro-3-hydroxy-2-pyrazinecarboxamide

9. T 705

10. Pyrazinecarboxamide, 6-fluoro-3,4-dihydro-3-oxo-

11. 6-fluoro-3-hydroxy-pyrazine-2-carboxamide

12. Favipiravir; T-705

13. Ew5gl2x7e0

14. T705

15. Mfcd12032148

16. 2-pyrazinecarboxamide, 6-fluoro-3-hydroxy-

17. 6-fluoro-3,4-dihydro-3-oxo-2-pyrazinecarboxamide

18. Favipiravir [inn]

19. T-705 Cpd

20. Unii-ew5gl2x7e0

21. Fapilavir

22. Favilavir

23. Favipiravir [usan:inn:jan]

24. Avigan (tn)

25. Favipiravir [mi]

26. Favipiravir [jan]

27. Favipiravir [usan]

28. Favipiravir [who-dd]

29. Schembl587913

30. Favipiravir (jan/usan/inn)

31. Ampz0004

32. Chembl221722

33. Schembl15157866

34. Gtpl11139

35. Dtxsid60948878

36. Chebi:134722

37. Bcpp000056

38. Bcp02422

39. Ex-a2285

40. Bbl104098

41. S7975

42. Stl557913

43. Zinc13915654

44. Akos005166863

45. Akos015995178

46. Zinc584639712

47. Zinc584639713

48. Ccg-266269

49. Cs-0612

50. Db12466

51. Pb25591

52. Pb42412

53. Ncgc00373041-03

54. Ncgc00373041-06

55. Ac-28900

56. Da-19682

57. Hy-14768

58. Ms-20791

59. Sy110833

60. 6-fluoro-3-hydroxypyrazine-2-carbo Xamide

61. Am20080851

62. Ft-0686297

63. Ft-0701282

64. A25520

65. D09537

66. 6-fluoro-3,4-dihydro-3-oxo-pyrazinecarboxamide

67. 793p969

68. A902150

69. J-518718

70. T 705,cas;259793-96-9

71. Q16934561

2.4 Create Date
2005-08-01
3 Chemical and Physical Properties
Molecular Weight 157.10 g/mol
Molecular Formula C5H4FN3O2
XLogP3-0.6
Hydrogen Bond Donor Count2
Hydrogen Bond Acceptor Count4
Rotatable Bond Count1
Exact Mass157.02875454 g/mol
Monoisotopic Mass157.02875454 g/mol
Topological Polar Surface Area84.6 Ų
Heavy Atom Count11
Formal Charge0
Complexity282
Isotope Atom Count0
Defined Atom Stereocenter Count0
Undefined Atom Stereocenter Count0
Defined Bond Stereocenter Count0
Undefined Bond Stereocenter Count0
Covalently Bonded Unit Count1
4 Drug and Medication Information
4.1 Drug Indication

In 2014, favipiravir was approved in Japan to treat cases of influenza that were unresponsive to conventional treatment. Given its efficacy at targetting several strains of influenza, it has been investigated in other countries to treat novel viruses including Ebola and most recently, COVID-19.


5 Pharmacology and Biochemistry
5.1 Pharmacology

Favipiravir functions as a prodrug and undergoes ribosylation and phosphorylation intracellularly to become the active favipiravir-RTP. Favipiravir-RTP binds to and inhibits RNA dependent RNA polymerase (RdRp), which ultimately prevents viral transcription and replication.


5.2 MeSH Pharmacological Classification

Antiviral Agents

Agents used in the prophylaxis or therapy of VIRUS DISEASES. Some of the ways they may act include preventing viral replication by inhibiting viral DNA polymerase; binding to specific cell-surface receptors and inhibiting viral penetration or uncoating; inhibiting viral protein synthesis; or blocking late stages of virus assembly. (See all compounds classified as Antiviral Agents.)


5.3 ATC Code

J - Antiinfectives for systemic use

J05 - Antivirals for systemic use

J05A - Direct acting antivirals

J05AX - Other antivirals

J05AX27 - Favipiravir


5.4 Absorption, Distribution and Excretion

Absorption

The bioavailability of favipiravir is almost complete at 97.6%. The mean Cmax for the recommended dosing schedule of favipiravir is 51.5 ug/mL. Studies comparing the pharmacokinetic effects of multiple doses of favipiravir in healthy American and Japanese subjects are below: Japanese subjects First Dose: Cmax = 36.24 ug/mL tmax = 0.5 hr AUC = 91.40 ugxhr/mL American subjects First Dose: Cmax = 22.01 ug/mL tmax = 0.5 hr AUC = 44.11 ugxhr/mL Japanese Subjects Final Dose: Cmax = 36.23 ug/mL Tmax = 0.5 hr AUC = 215.05 ugxhr/mL American Subjects Final Dose: Cmax = 23.94 ug/mL Tmax = 0.6 hr AUC = 73.27 ugxhr/mL When favipiravir was given as a single dose of 400 mg with food, the Cmax decreased. It appears that when favipiravir is given at a higher dose or in multiple doses, irreversible inhibition of aldehyde oxidase (AO) occurs and the effect of food on the Cmax is lessened.


Route of Elimination

Favipiravir's metabolites are predominantly renally cleared.


Volume of Distribution

The apparent volume of distribution of favipiravir is 15 - 20 L.


Clearance

The recommended oral dosing regimen for favipiravir is as follows: Day 1: 1600 mg twice daily; Days 2-5: 600 mg twice daily. The reported CL/F for favipiravir 1600 mg dosed once daily is 2.98 L/hr 0.30 and the CL/F values for favipiravir 600 mg dosed twice daily on days 1-2 and once daily on days 3-7 were 6.72 L/hr 1.68 on Day 1, and 2.89 L/hr 0.91 on Day 7. There is currently no reported clearance data for favipiravir 1600 mg dosed twice daily.


5.5 Metabolism/Metabolites

Favipiravir is extensively metabolized with metabolites excreted mainly in the urine. The antiviral undergoes hydroxylation primarily by aldehyde oxidase and to a lesser extent by xanthine oxidase to the inactive metabolite, T705M1.


5.6 Biological Half-Life

The elimination half-life of favipiravir is estimated to range from 2 to 5.5 hours.


5.7 Mechanism of Action

The mechanism of action of favipiravir is novel compared to existing influenza antivirals that primarily prevent entry and exit of the virus from cells. The active favipiravir-RTP selectively inhibits RNA polymerase and prevents replication of the viral genome. There are several hypotheses as to how favipiravir-RTP interacts with RNA dependent RNA polymerase (RdRp). Some studies have shown that when favipiravir-RTP is incorporated into a nascent RNA strand, it prevents RNA strand elongation and viral proliferation. Studies have also found that the presence of purine analogs can reduce favipiravirs antiviral activity, suggesting competition between favipiravir-RTP and purine nucleosides for RdRp binding. Although favipiravir was originally developed to treat influenza, the RdRp catalytic domain (favipiravir's primary target), is expected to be similar for other RNA viruses. This conserved RdRp catalytic domain contributes to favipiravir's broad-spectrum coverage.