Tamiflu Confirmed Effective for Avian Flu

A new study in mice has confirmed that Tamiflu (oseltamivir), used against influenza strains, is effective against the avian flu virus H5N1.

The study was conducted by researchers at St. Jude Children's Hospital (Memphis, TN, USA) who used oseltamivir to treat mice infected with the H5N1 virus. The highest dose used was equivalent to the dose currently recommended for humans sick with the flu. Of 80 mice infected with the virus, 20 received a placebo, 30 were given oseltamivir at one of three dosage levels for five days, and 30 received the drug at one of three dosage levels for eight days. None of the mice receiving placebo survived. Only five of the 10 mice given the highest daily dose for five days survived. Although oseltamivir suppressed the virus in the mice, the virus continued to grow if the drug was stopped after five days.

Mice given the drug for eight days, on the other hand, fared better. Survivors included one of 10 mice given the lowest daily dose, 2 of 10 given the middle-range daily dose, and eight of 10 given the highest daily dose. Oseltamivir decreases the ability of the influenza virus to spread from infected cells to uninfected cells by inhibiting neuraminidase, a protein required for the virus to exit infected cells.

Public health experts fear that this avian flu strain could develop the ability to easily spread from person to person and kill millions in a pandemic. "The H5N1 avian flu viruses are in a process of rapid evolution,” noted Elena A. Goborkova, Ph.D., of St. Jude Children's Hospital. "Our results provide baseline information that will be needed for further studies on preventing and treating avian flu with antiviral drugs.

The St. Jude researchers say further study is needed to see if using higher doses of oseltamivir for a longer period of time can prevent the H5N1 virus in the lungs from gaining a foothold and then spreading to the brain.




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