Zanamivir

Zanamivir

Clinical data
Pronunciation	/zəˈnæmᵻvɪər/
Trade names	Relenza
AHFS/Drugs.com	Monograph
Pregnancy category	AU: B1 US: C (Risk not ruled out)
Routes of administration	Inhalation, IV
ATC code	J05AH01 (WHO)
Legal status
Legal status	AU: S4 (Prescription only) UK: POM (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	2% (oral)
Protein binding	<10%
Metabolism	Negligible
Biological half-life	2.5–5.1 hours
Excretion	Renal
Identifiers
IUPAC name (2R,3R,4S)-4-guanidino-3-(prop-1-en-2-ylamino)-2-((1R,2R)-1,2,3-trihydroxypropyl)-3,4-dihydro-2H-pyran-6-carboxylic acid
Synonyms	5-acetamido- 4-guanidino- 6-(1,2,3-trihydroxypropyl)- 5,6-dihydro- 4H-pyran- 2-carboxylic acid
CAS Number	139110-80-8 Y
PubChem CID	60855
DrugBank	DB00558 Y
ChemSpider	54842 Y
UNII	L6O3XI777I
KEGG	D00902 Y
ChEBI	CHEBI:50663 Y
ChEMBL	CHEMBL222813 Y
PDB ligand	ZMR (PDBe, RCSB PDB)
ECHA InfoCard	100.218.632
Chemical and physical data
Formula	C12H20N4O7
Molar mass	332.31 g/mol
3D model (Jmol)	Interactive image
SMILES O=C(O)C=1O[C@@H]([C@H](O)[C@H](O)CO)[C@H](NC(=O)C)[C@@H](/N=C(\N)N)C=1
InChI InChI=1S/C12H20N4O7/c1-4(18)15-8-5(16-12(13)14)2-7(11(21)22)23-10(8)9(20)6(19)3-17/h2,5-6,8-10,17,19-20H,3H2,1H3,(H,15,18)(H,21,22)(H4,13,14,16)/t5-,6+,8+,9+,10+/m0/s1 Y Key:ARAIBEBZBOPLMB-UFGQHTETSA-N Y

Zanamivir is a medication used to treat and prevent influenza caused by influenza A and B viruses. It is a neuraminidase inhibitor and was developed by the Australian biotech firm Biota Holdings. It was licensed to Glaxo in 1990 and approved in the US in 1999, only for use as a treatment for influenza. In 2006, it was approved for prevention of influenza A and B. Zanamivir was the first neuraminidase inhibitor commercially developed. It is currently marketed by GlaxoSmithKline under the trade name Relenza as a powder for oral inhalation.

Zanamivir is used for the treatment of infections caused by influenza A and influenza B viruses, but in otherwise-healthy individuals, benefits overall appear to be small. It decreases the risk of one's getting symptomatic, but not asymptomatic influenza. The combination of diagnostic uncertainty, the risk for virus strain resistance, possible side effects and financial cost outweigh the small benefits of zanamivir for the prophylaxis and treatment of healthy individuals. As of 2009, no influenza has shown any signs of resistance in the US. Since then, genes expressing resistance to zanamivir were found in Chinese people infected with avian influenza A H7N9 during treatment with zanamivir.

In otherwise-healthy individuals, benefits overall appear to be small. Zanamivir shortens the duration of symptoms of influenza-like illness (unconfirmed influenza or 'the flu') by less than a day. In children with asthma there was no clear effect on the time to first alleviation of symptoms. Whether it affects the risk of one's need to be hospitalized or the risk of death is not clear. There is no proof that zanamivir reduced hospitalizations or pneumonia and other complications of influenza, such as bronchitis, middle ear infection, and sinusitis. Zanamivir did not reduce the risk of self reported investigator mediated pneumonia or radiologically confirmed pneumonia in adults. The effect on pneumonia in children was also not significant.

Low to moderate evidence indicates it decreases the risk of one's getting influenza by 1% to 12% in those exposed. Prophylaxis trials showed that zanamivir reduced the risk of symptomatic influenza in individuals and households, but there was no evidence of an effect on asymptomatic influenza or on other, influenza-like illnesses. Also there was no evidence of reduction of risk of person-to-person spread of the influenza virus. The evidence for a benefit in preventing influenza is weak in children, with concerns of publication bias in the literature.