WHO Guideline on Pharmacological Management of Pandemic (H1N1) Influenza
Posted Aug 21 2009 10:20pm
WHO had just issued (20th August, 2009) the guideline for the use of antivirals in the management of patients infected with H1N1 pandemic virus.
The emphasis of the guideline was on the use of oseltamivir and zanamivir to prevent severe illness and deaths, reduce the need for hospitalization, and reduce the duration of hospital stays.
The H1N1 virus is currently still susceptible to both oseltamivir and zanamivir (neuraminidase inhibitors), but resistant to the M2 inhibitors (rimantadine and amantadine).
So far, worldwide, most patients infected with the virus experienced typical influenza symptoms and fully recover within a week, even without any form of medical treatment. Healthy patients with uncomplicated illness need not be treated with antivirals.
However, this is just a weak recommendation with low quality evidence. It should be based on clinical assessment and how the virus is spreading throughout the community.
In areas where the virus is circulating widely in the community, doctors seeing patients with influenza-like illness (ILI) should assume the H1N1 is the cause. Treatment decisions should not wait for laboratory confirmation.
'At risk' group defined by WHO included:
For 'at risk' population, WHO recommends treatment with either oseltamivir or zanamivir. They should receive treatment as soon as possible after symptom onset, without waiting for laboratory confirmation.
For patients present with severe illness or whose condition begins to deteriorate, WHO recommends treatment with oseltamivir as soon as possible, preferably within 48 hours after symptom onset. However, even after 48 hours, treatment should also be provided.
This recommendation covers all patients groups. The dose of oseltamivir can be given up to 150mg twice daily and longer than 5 days based on clinical response.
Clinical deterioration is characterized by primary viral pneumonia, which destroys the lung tissue and does not respond to antibiotics (sometimes, with the failure of multiple organs, including the heart, kidneys and liver). This type of patients require management in ICU in addition to antiviral (oseltamivir).
How about children?
They are classified as 'at-risk' group, however, they should be treated if presented with severe or deteriorating illness, or if they are at risk of more severe or complicated illness.
For pregnant women, WHO recommends treatment should be started once the symptom onset. (Although the studies on oseltamivir in pregnant women not yet established)
Below is the table to summarize the recommendations:
Healthcare professionals need to be alert to danger signs that signal progression to more severe disease. The progression can be very rapid, medical attention is needed when any of the following signs appear in a patient with confirmed or suspected H1N1 infection:
Shortness of breath
Difficulty in breathing
Bloody or coloured sputum
Altered mental status
High fever that persists beyond 3 days
Low blood pressure
As zanamivir is the only alternative to oseltamivir, it should be used when the patient show signs of resistant to oseltamivir.
Personal remark is:
Oseltamivir is not without adverse effects.
Common ones are:
Noted that it has effects on central nervous system as well. So, please observe the patient if they are having such symptoms while taking oseltamivir (it might cause fatal outcome like suicide):