What antiviral drugs are available for treatment of seasonal and avian influenza?

Answer

Two drugs (in the neuraminidase inhibitors class), oseltamivir (commercially known as Tamiflu ®) and zanamivir (commercially known as Relenza ®) can reduce the severity and duration of illness caused by seasonal influenza. The effectiveness of the drugs, among other things, depends on their early administration (within 48 hours after symptom onset). For cases of human infection with H5N1, the drugs may improve prospects of survival, if administered early, but clinical data is limited. The H5N1 virus is expected to be susceptible to the neuraminidase inhibitors. Some adverse reactions to Tamiflu have been reported in children. For additional information, please see: http://www.fda.gov/cder/drug/infopage/tamiflu/QA20051117.htm

For the neuraminidase inhibitors, the main constraints – which are substantial – involve limited production capacity and a price that is prohibitively high for many countries. At present manufacturing capacity, which has recently quadrupled, it will take a decade to produce enough oseltamivir to treat 20% of the world’s population. The manufacturing process for oseltamivir is complex and time-consuming, and is not easily transferred to other facilities.

So far, most fatal cases of H5N1 infection have resulted from the effects of the virus, and cannot be treated with antibiotics. Nonetheless, since influenza is often complicated by secondary bacterial infection of the lungs, antibiotics could be life saving in the case of late-onset pneumonia.

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