Taribavirin

Taribavirin
Clinical data
Other names	1-(β-D-Ribofuranosyl)-; 1,2,4-triazole-3-carboximide
Pregnancy; category	X;
Routes of; administration	Oral capsule
ATC code	J05AB04 (WHO) ;
Legal status
Legal status	In Phase III drug trials;
Pharmacokinetic data
Bioavailability	9%
Metabolism	Metabolized to 5'phosphates, de-riboside, and deriboside carboxylic acid
Elimination half-life	12 days - Multiple Dose; 120-170 hours - Single Dose
Excretion	10% fecal, remainder in urine (30% unchanged, remainder metabolites)
Identifiers
	IUPAC name 1-[(2R,3R,4S,5S)- 3,4-dihydroxy-5- (hydroxymethyl)oxolan-2-yl]- 1,2,4-triazole-3-carboximidamide;
CAS Number	119567-79-2;
PubChem CID	451448;
DrugBank	none;
ChemSpider	397669 ;
CompTox Dashboard (EPA)	DTXSID80894181 ;
Chemical and physical data
Formula	C8H13N5O4
Molar mass	243.220 g/mol (279.681 g/mol for HCl salt) g·mol−1
3D model (JSmol)	Interactive image;
	SMILES n1c(nn(c1)[C@@H]2O[C@@H]([C@@H](O)[C@H]2O)CO)C(=[N@H])N;
	InChI InChI=1S/C8H13N5O4/c9-6(10)7-11-2-13(12-7)8-5(16)4(15)3(1-14)17-8/h2-5,8,14-16H,1H2,(H3,9,10)/t3-,4-,5-,8-/m1/s1 ; Key:NHKZSTHOYNWEEZ-AFCXAGJDSA-N ;
	(verify)

Taribavirin (rINN; also known as viramidine, codenamed ICN 3142) is an antiviral drug in Phase III human trials, but not yet approved for pharmaceutical use. It is a prodrug of ribavirin, active against a number of DNA and RNA viruses. Taribavirin has better liver-targeting than ribavirin, and has a shorter life in the body due to less penetration and storage in red blood cells. It is expected eventually to be the drug of choice for viral hepatitis syndromes in which ribavirin is active. These include hepatitis C and perhaps also hepatitis B and yellow fever.

Uses

Taribavirin is as active against influenza as ribavirin in animal models, with slightly less toxicity, so it may also eventually replace ribavirin as an anti-influenza agent.

History

Tarbivirin was first reported in 1973 by J.T.Witkowski et al.,^[1] then working at ICN Pharmaceuticals, in an attempt to find a more active derivative of ribavirin. Taribavirin is presently being developed by Valeant Pharmaceuticals International. Valeant is testing the drug as a treatment for chronic hepatitis C.

Pharmacology

Note on formulas: The carboxamidine group of this molecule is somewhat basic, and therefore this drug is also known and administered as the hydrochloride salt (with a corresponding .HCl chemical formula and different ChemID / PubChem number). At physiologic pH, the positive charge on the molecule from partial protonation of the carboximide group contributes to the relative slowness with which the drug crosses cell membranes (such as in red blood cells) until it has been metabolized into ribavirin. In the liver, however, the transformation from carboxamidine to carboxamide happens on first-pass metabolism and contributes to the higher levels of ribavirin found in liver cells and bile when viramidine is administered.

Notes

^ PMID 4355593

References

Barnard, D (2002). "Viramidine (Ribapharm)". Current Opinion in Investigational Drugs. 3 (11): 1585–9. PMID 12476957. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)
Gish, Robert G. (2006). "Treating HCV with ribavirin analogues and ribavirin-like molecules". Journal of Antimicrobial Chemotherapy. 57 (1): 8–13. doi:10.1093/jac/dki405. PMID 16293677. {{cite journal}}: Unknown parameter |month= ignored (help)
Lin, Chin-Chung (2003). "Pharmacokinetics and Metabolism of 14C Viramidine in Rats and Cynomolgus Monkeys". Antimicrob Agents Chemother. 47 (8): 458–2463. PMC 166067. PMID 12878505. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
Sidwell, RW (2005). "In vitro and in vivo influenza virus-inhibitory effects of viramidine". Antiviral Research. 68 (1): 8–13. doi:10.1016/j.antiviral.2005.06.003. PMID 16087250. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
Witkowski, J. T. (1973). "Synthesis and antiviral activity of 1,2,4-triazole-3-thiocarboxamide and 1,2,4-triazole-3-carboxamidine ribonucleosides". Journal of Medicinal Chemistry. 16 (8): 935–7. doi:10.1021/jm00266a014. PMID 4355593. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[1] PMID 4355593

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