Antivirals in seasonal and pandemic influenza--future perspectives.

Antiviral drugs continue to be an important option for the treatment of influenza disease and will likely be the only option during the early phases of pandemic. However, the limited number of drug classes licensed for treatment of influenza raises several issues, particularly in the face of drug resistance. Two classes of drugs are presently licensed for treatment of influenza, M2 and neuraminidase inhibitors. M2 inhibitors are currently not recommended for treatment of influenza because of widespread resistance and resistance to neuraminidase inhibitors has been observed during the past influenza seasonal outbreaks. Additional antiviral drugs with novel mechanisms of action are clearly needed for the treatment of influenza. Fortunately, the landscape of drugs in early and advanced development has dramatically increased over the last 5 years. Drugs targeting viral functions such as attachment, entry/fusion, transcription, and polymerase and drugs targeting host factors affecting viral replication are currently in clinical trials. Examples of these novel antiviral drugs and the challenges for influenza antiviral drug development are discussed in this article.