Antivirals for Pandemic Influenza

Amantadine and rimantadine share features that would make them useful agents in responding to pandemic influenza. These include an antiviral spectrum encompassing influenza A viruses, favorable pharmacokinetics, a potential for stockpiling supplies, and documented prophylactic and therapeutic effectiveness in pandemic influenza. However, current production capability is insufficient to provide adequate drug for mass chemoprophylaxis in the event of vaccine unavailability. The risk of adverse drug effects, particularly central nervous system side effects, which occur more often with amantadine than rimantadine, and potential drug interactions are additional concerns. Short-course treatment of ill persons would provide symptom benefit, but convincing evidence that early antiviral treatment reduces bacterial and other influenza complications is currently lacking. Drug-resistant viruses emerge during therapy, appear to be fully pathogenic, and are transmissible to close contacts. Influenza neuraminidase inhibitors are promising investigational agents, but remaining issues include prophylactic efficacy, cost, efficient administration, and resistance emergence.