January 12, 1999
FDA Advises Health Care Professionals of
Important Considerations in Treating Influenza
Washington DC (SafetyAlerts) The Food and Drug
Administration (FDA) today published a Public Health Advisory for health care
practitioners to remind prescribers of important and therapeutic considerations when
treating patients with influenza-like symptoms.
Influenza is now occurring in many areas of the
country, and health care professionals are confronted with therapeutic decisions for large
numbers of patients with flu-like symptoms.
Among other factors, they may consider whether to
use one of the four drugs currently approved for antiviral therapy in uncomplicated
influenza. Two of these, amantadine (Symmetrel and others) and rimantadine (Flumadine),
have been available for some years in the United States for illness due to influenza A.
The recent approval and current promotion of two
additional drugs with activity against influenza A and B, zanamivir (Relenza) and
oseltamivir (Tamiflu), has increased interest in the role of specific antiviral drugs for
While health care professionals and consumers are
becoming familiar with the treatment options, FDA's advisory provides several
considerations for health care professionals treating flu patients.
Vaccination remains the primary method of
preventing and controlling influenza.
Health professionals should use special caution if
they choose to prescribe zanamivir (Relenza) to patients with underlying asthma or chronic
obstructive pulmonary disease.
This product may carry risk, in patients with
severe or decompensated asthma or chronic obstructive pulmonary disease. Bronchospasm was
documented in some patients with mild or moderate asthma following administration of
zanamivir. Any patient who develops bronchospasm should stop the drug and call their
health care provider.
Patients with underlying respiratory disease
should be instructed to have a fast-acting inhaled bronchodilator available when they are
being treated with zanamivir. The Relenza package insert contains important precautionary
information regarding risk of bronchospasm in patients with respiratory disease.
If a decision is made to use Relenza in patients
with airway disease, this should be done only under careful supervision and with
adjunctive care including short-acting bronchodilators available.
Prescribers should also be aware that antiviral
drugs have not been proven to prevent or effectively treat viral complications of
influenza such as viral pneumonia. Antiviral drugs for treatment of influenza have only
been shown to be effective if started in the first two days of symptoms, and the
demonstrated treatment benefit has been limited to a modest increase in the rate of
Prescribers should also consider that patients
with severe influenza-like illness, especially those who have chronic medical conditions,
may have significant bacterial infections (either instead of influenza, or in combination
with influenza). Anti-viral products such as those approved for flu have no activity
against bacterial infections and patients should be treated with appropriate antibacterial
therapy whenever bacterial infection is suspected. FDA has received reports of patients
with serious bacterial infections who initially had influenza-like symptoms and who had
progression of bacterial infection during treatment with antiviral drugs alone.
FDA encourages patients to ask questions and to
make themselves familiar with the complete prescribing information when considering flu
drugs. The labeling for all four flu drugs includes summaries of adverse events observed
during clinical trials, as well as post-marketing experience for the two drugs with a
longer marketing history.
As with all drugs, FDA encourages all health care
professionals to report any serious adverse event associated with the use of antiviral
drugs for influenza to the FDA's MedWatch program at 1-800-FDA-1088 (fax 1-800-FDA-0178),
or to the pharmaceutical manufacturers:
- Relenza (zanamivir), GlaxoWellcome, 1-800-825-5249
- Tamiflu (oseltamivir), Roche, 1-800-526-6367
- Symmetrel (amantadine; also available in generic
forms), Endo, 1-800-462-3636
- Flumadine (rimantadine), Forest, 1-800-678-1605
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and timely product warning notification visit: www.safetyalerts.com.
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