Effectiveness and role of zanamivir in the treatment of influenza infection.

Influenza is a worldwide public health issue. The virus circulates annually in winter and can cause significant morbidity in the general population and increased mortality rates in those who are more susceptible to complications if infected by the virus, especially the elderly. Although antivirals to treat and prevent influenza have been available in several countries for up to 30 years, annual influenza vaccination strategies remain the primary focus in reducing the burden of illness caused by this viral infection. Zanamivir is the first of a new class of compounds to offer significant advantages over existing influenza treatments. It is a potent and specific competitive inhibitor of both influenza A and B virus neuraminidase. The drug is administered topically by inhalation directly to the site of virus replication in a dose of 10 mg twice daily for 5 days. In both experimental and naturally acquired treatment studies, zanamivir has been shown to have efficacy against both influenza A and B virus and to be well tolerated. Significant treatment benefits resulting in reductions in illness of up to 2.5 days have been demonstrated in both the general population and in patients considered at high risk. In addition, patients receiving zanamivir have been able to return to normal activities significantly faster.