Food and Drug Administration
U.S. Department of Health and Human Services
Public Health Service 5600 Fishers Lane Rockville, MD 20857
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January 12, 2000
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FDA has 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 this disease.
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.
First, vaccination remains the primary method of preventing and controlling influenza.
Second, prescribers should be aware 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.
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 symptom improvement.
Third, health professionals should use special caution if they choose to prescribe zanamivir (Relenza) to patients with underlying asthma or chronic obstructive pulmonary disease. FDA has received reports of respiratory problems following inhalation of Relenza. 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.
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:
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