Wednesday, October 26, 2005

Drugs for Flu

I've been interested lately in just how effective anti-flu drugs would be in case of a major flu epidemic. Four drugs are available for treatment of influenza: two of them (amantadine and rimantadine) only work for Influenza A, are pretty toxic, and the virus can rapidly generate resistance to the drugs. The other two drugs are the newer neuraminidase inhibitors. These drugs (zanamivir and oseltamivir) interfere with the release of new virus from infected cells thus preventing the spread of infection and the virus does not generate resistance rapidly (I don't believe this has been proven outside of the laboratory). Unfortunately, replication of influenza virus reaches its peak between 24 and 72 hours after the onset of illness, so the drug has to be given really early. Also, don't expect a cure from taking Tamiflu (oseltamivar). In the best cases, it might shorten your illness by a 1.5-2 days if given within 2 days after you are infected. It can also result in a lower frequency of secondary complications. It is also effective in preventing flu symptoms if taken prior to infection. Again, I'm not sure how well this has been proven in real life pandemic situations. In any case, we would need about 4.2 billion doses of the drug to treat everyone in the USA for 14 days.

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