The long history of
influenza drug development has both contributed practical advances in
antiviral chemotherapy and improved the understanding of
influenza pathogenesis and epidemiology. The role played by these
antivirals continues to grow with the dual threats of seasonal and pandemic
influenza. The
neuraminidase inhibitors are proven effective for the
chemoprophylaxis and treatment of
influenza A and B, although
early therapy is essential for disease mitigation. Studies of topically applied
zanamivir have demonstrated the importance of viral replication in the lower respiratory tract, even in uncomplicated
influenza.
Antiviral resistance, especially to the M2
ion channel inhibitors, sometimes limits clinical utility.
Oseltamivir-resistant variants may emerge during treatment but have not yet circulated widely and are usually less fit than wild-type virus; most retain susceptibility to
zanamivir. The transmission fitness cost of these resistant variants is
drug-,
neuraminidase subtype-, and mutation-specific. Continued vigilance in drug resistance surveillance is imperative, as is research into the development of new agents that will provide the potential for alternative and combination
antiviral therapy.