Zanamivir and oseltamivir: New options in the management of influenza

Zanamivir and oseltamivir are the first of the novel neuraminidase inhibitors to be introduced for the management of influenza A and B. Both drugs appear to have advantages over the older aminoadamantanes, notably in their efficacy in influenza B. Five-day courses have produced significant reductions in duration of symptoms and severity of illness in clinical trials in otherwise healthy adults. Zanamivir is given by oral inhalation, whereas oseltamivir is presented as a tablet for oral ingestion; any significance of this difference has yet to be determined in the clinical setting. Zanamivir and oseltamivir are also potentially useful in the prophylaxis of influenza. Debate currently centres on the clinical significance relative to cost of improvements conferred by either agent in otherwise healthy adults, and attention is now focused on ensuring that optimal benefit is derived from their use (e.g. by treatment of patients at most risk of secondary complications).