Emergence of H5N1 avian influenza viruses with reduced sensitivity to neuraminidase inhibitors
and novel reassortants in Lao People's Democratic Republic.
Randomized controlled clinical trials conducted before the emergence of oseltamivir-resistant influenza viruses have demonstrated that neuraminidase inhibitors
such as oseltamivir and zanamivir reduce the duration and severity of illness if started within 48 hours of illness onset (6) and are approximately 80% effective in preventing illness among close contacts of patients with influenza (7).
The addition reflects postmarketing reports of delirium and abnormal behavior in patients with influenza taking neuraminidase inhibitors
, including zanamivir (Relenza, Glaxo-SmithKline).
The neuraminidase inhibitors
zanamivir (Relenza) and oseltamivir (Tamiflu) provide a similar level of protection against illness from influenza A and B, but these drugs are not used in children under 7 years of age, he said.
Pyrosequencing as a tool to detect molecular markers of resistance to neuraminidase inhibitors
in seasonal influenza A viruses.
In a related report that appeared just before the CDC report, a systematic review of 52 randomized, controlled trials of the adamantane drugs and the newer generation neuraminidase inhibitors
oseltamivir (Tamiflu) and zanamivir (Relenza) also raised serious doubts about the wisdom of using the four drugs for routine control of seasonal influenza.
Two classes of antiviral medications are available currently: adamantanes or M2 ion channel inhibitors (i.e., amantadine and rimantadine) and neuraminidase inhibitors
(i.e., oseltamivir and zanamivir).
Studies are still needed to test whether neuraminidase inhibitors
actually reduce mortality, whether they have any therapeutic impact on primary viral pneumonia or other severe influenza virus complications, and how they can be used in hospitalized patients, Dr.
-- Treatment with neuraminidase inhibitors
shortens the course of influenza among children, but physicians should look for more compelling reasons to use this treatment in specific patents, Dr.
The limited effect of oseltamivir on reducing disease duration, usually only shortening the duration by 1 day in healthy persons (4), the possibility of serious side effects (5), the possibility of the virus developing resistance to neuraminidase inhibitors
(6,7), and the cost to health care of unnecessary prescriptions are reasons to strive for better adherence to prescribing guidelines.
A study of children aged 5-12 years old showed that treatment of their influenza with neuraminidase inhibitors
reduced the duration of their illness by an average 1.25 days, and also resulted in a 30% reduction in complications and a 20% reduction in antibiotic use.
* Comment: Tamiflu is one of two available neuraminidase inhibitors
, which work by blocking the influenza enzyme that promotes viral release from infected cells.