| Influenza Treatment
Four antiviral drugs (amantadine,
rimantadine, zanamavir and oseltamivir) have been approved by the
U.S. Food and Drug Administration (FDA) for treatment of influenza.
These need to be taken within 2 days after becoming sick. If taken
at the appropriate time, these drugs can reduce influenza symptoms
and may shorten the time you are sick by 1 or 2 days and also make
you less contagious. All of these drugs must be prescribed by a
doctor and taken for 3-5 consecutive days (5 days for oseltamivir
and zanamivir). When used for prevention, they are about 70% to
90% effective in preventing illness in healthy adults.
All of the antiviral drugs may be
effective for influenza A viruses. However, only oseltamivir and
zanamivir are effective for influenza B viruses. These drugs, called
neuraminidase inhibitors, block the normal function of the viral
neuraminidase. Both drugs are available only by prescription. One
of the drugs, zanamivir (Relenza®, Glaxo Wellcome Inc.) is inhaled
as a powder twice a day for 5 days. A special device called a disk
haler is supplied with the medication. The other drug, oseltamivir
phosphate (Tamiflu TM, Roche Pharmaceuticals), is a tablet that
is taken by mouth twice a day for 5 days. According to the WHO,
Tamiflu (Oseltamavir) might be useful for influenza prevention and
treatment in the possibility of an H5N1 Pandemic. Oseltamivir, also
called Tamiflu are used for the bird flu and virus H5N1 strain.
The World Health Organization (WHO) has mentioned Tamiflu as the
drug for tackling bird flu if ever a human pandemic breaks out.
Use of Antiviral Drugs
Antiviral drugs are most often used to help control influenza outbreaks
in institutions, like nursing homes or in hospital wards, where
people at high risk for complications from influenza are in close
contact with each other. Antivirals also have been used on cruise
ships or similar settings to help control influenza outbreaks.
In the event of an outbreak, public
health practice is to combine the use of influenza vaccine and antivirals.
For example, nursing home residents and staff are given vaccine
during an outbreak and also are given antivirals to prevent influenza
until the vaccine takes effect (about 2 weeks). This practice continues
as long as influenza is occurring in that setting.
Influenza antivirals are prescribed
in case of outbreaks and the treatment must begin within 2 days
of the onset of symptoms for the drugs to be effective. Although
all antivirals lessen symptoms and shorten the duration of illness,
only one (oseltamivir) has been shown in a study to reduce lower
respiratory tract complications requiring antibiotics. They do not
cure influenza outright.
When considering the use of antivirals
it is important to remember that most healthy people recover from
influenza without complications.
Who Should Get Antiviral Drugs
People who are at high risk of serious complications from influenza
may benefit most from antiviral medications. This includes: people
65 years of age and older, children 12-23 months of age, people
with chronic medical conditions (for example, heart or lung disease,
diabetes), and pregnant women. (Note that none of the antivirals
are approved for use in children less than 1 year of age.). In any
case you must consult your doctor on the choice and use of antiviral
drugs, even though CDC has provided guidelines for health-care professionals
on the use of antiviral drugs
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