Naproxen shows antiviral activity against flu

French researchers have discovered that the over-the-counter anti-inflammatory drug naproxen may also exhibit antiviral activity against the influenza A virus.

New influenza vaccines must be developed every year because of mutations in the virus' surface proteins. The French research team found a more reliable target for anti-influenza activity, the nucleoprotein that assembles ribonucleoprotein complexes that are necessary for replication.

Once the nucleoprotein's three-dimensional structure was solved in 2006, scientists began searching for biochemicals that could interfere with its action. Screenings eventually identified Naproxen, better known as the pain-reliever Aleve, as capable of binding to the nucleoprotein and impeding RNA binding.

In further testing, the scientists, led by Anny Slama-Schwok, found that Naproxen reduced viral load in cells infected with H1N1 and H3N2 influenza A virus. In mice, Naproxen demonstrated a therapeutic index against influenza A greater than those of other anti-inflammatories.

The research team said naproxen is a lead compound for drug development that could be readily improved to boost its ability to bind to nucleoprotein further.

The researchers said naproxen, as an already approved drug, could become a treatment against influenza relatively quickly. Their findings are a result of a structure-based investigation published in the American Society for Microbiology journal Antimicrobial Agents and Chemotherapy.