Relenza is used as an anti flu drug. Relenza was the first neuraminidase inhibitor commercially developed and works in the treatment of both Influenzavirus A and Influenzavirus B. Zanamivir was discovered in 1989 by scientists at the Australian biotechnology company Biota Holdings, in 1990, zanamivir was licensed to GlaxoSmithKline (GSK) for exclusive worldwide development and marketing. In 1999, the product was approved for marketing in the US under the name of Relenza.

Zanamivir was discovered by the use of computational drug discovery and screening. The X-ray structure of the influzena enzyme neuraminidase was known and also a small molecule (2-deoxy-2,3-didehydro-N-acetylneuraminic acid ) was known inhibit the chemistry of neuraminidase. So Biota Holdings searched for similiar small molecules which intreracted with the active site of neuraminidase better, the structure of Zanamivir was the best match at the time.

Unfortunately, Relenza is not suitable to be taken orally, so GSK devised its administration using a complex inhalation system. The discovery of Tamiflu (taken orally) led to the rapid decline of use of Relenza and GSK stopped marketing the drug, so though still available its market share is small.

Formal Chemical Name (IUPAC)
(4S,5R,6R)-5-acetamido-4-guanidino-6-((1R,2R)-1,2,3-trihydroxypropyl)-5,6-dihydro-4H-pyran-2-carboxylic acid

References

http://en.wikipedia.org/wiki/Relenza