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Source: Hayden FG, et al. Inhaled zanamivir for the
prevention of influenza in families. N Engl J Med 2000;343: 1282-1289.
Influenza (flu) remains a major source of morbidity and mortality in the United States, despite the widespread availability of vaccine and antiviral pharmacotherapies. Prevention of influenza by antiviral drug therapy has, until quite recently, been limited by the fact that amantadine and rimantadine are only efficacious against influenza A. Two new neuraminidase inhibitors—zanamivir and oseltamivir—are not only effective against both influenza A and influenza B, but in contrast to amantadine and rimantadine, they have not been thus far associated with emergence of drug-resistant influenza strains.
At the time of this writing, only oseltamivir (Tamiflu) is approved for prophylaxis of influenza. This study used zanamivir (Relenza) in an attempt to reduce family member influenza in a large group of subjects (n = 321) who developed an influenza-like illness (ILI) during the 1998-1999 flu season.
Once an index case came down with an ILI, either zanamivir 10 mg qd (by inhalation) or placebo was given to household contacts for 10 days. The index case was treated with the therapeutic FLU dose, 10 mg bid for five days.
There was a striking difference in the frequency with which previously healthy household contacts came down with ILI if they received zanamivir: 4% vs. 19% on placebo. No serious adverse events occurred.
comment by Louis Kuritzky, MD
Zanamivir, in a standard dose administered by inhalation once daily, appears to be an effective and safe intervention for prevention of influenza A and B; its efficacy for treatment of FLU has been previously established. (Dr. Kuritzky is Clinical Assistant Professor, University of Florida, Gainesville, Fla.)