U.S. Food and Drug Administration Center for Drug Evaluation and Research |
Public Health Advisory |
FOOD AND
DRUG ADMINISTRATION PUBLIC HEALTH ADVISORY SUBJECT: SAFE AND APPROPRIATE USE OF INFLUENZA DRUGS 12 January 2000 Dear Health Care Professional: Diagnostic and therapeutic decisions for patients with symptoms of influenza involve many factors, including consideration of whether to prescribe one of the four drugs currently approved for treatment of influenza. Two of these drugs, amantadine (Symmetrel® and others) and rimantadine (Flumadine®), have been available for many years in the United States. The recent approval of, and promotional activities for, two additional drugs, zanamivir (Relenza®) and oseltamivir (Tamiflu®), have increased attention to, and interest in, the role of specific anti-viral therapy in this disease. Given that influenza is now occurring in many areas of the country, FDA is issuing this public health advisory to health care professionals to remind prescribers of important clinical decisions that need to be made when considering use of anti-viral drugs for treatment of patients with signs and symptoms of influenza. The following three considerations are important primarily for two reasons. First, they are important in identifying patients who are appropriate candidates for anti-viral therapy. Secondly, they are important in recognizing patients who may be at risk for serious adverse outcomes from other non-influenza diagnoses or from adverse events potentially related to anti-influenza therapy.
When initiation of anti-viral therapy alone is considered on a presumptive basis, ongoing clinical assessment and diagnostic evaluation of the patient continues to be important. FDA has received several reports of patients with serious bacterial infections who initially had influenza-like symptoms and whose bacterial infections progressed during treatment with antiviral drugs alone. Prescribers should be aware that patients with severe influenza-like illness, especially patients with chronic medical conditions or complicated manifestations of acute illness, might have significant bacterial infections instead of, or in addition to, viral illness. These anti-viral products have no activity against bacterial infections. Appropriate anti-bacterial therapy should be initiated whenever bacterial infection is suspected.
The evidence for use of anti-viral drugs to treat influenza is based principally on studies in patients with uncomplicated influenza. There is not clear evidence for safety and efficacy in persons with underlying respiratory or cardiac diseases, or in persons with complications of an acute influenza episode (for example, viral or bacterial pneumonia). Such patients may require extensive supportive and adjunctive care. Anti-viral therapy has not been shown to reduce the need for such care and monitoring. All health care professionals are encouraged to report any serious adverse event associated with the use of anti-viral drugs for influenza to the FDAs MedWatch program at 1-800-FDA-1088 (fax 1-800-FDA-0178), or to the respective pharmaceutical manufacturers:
Flumadine® (rimantadine), Forest Pharmaceuticals, Inc., 1-800-678-1605 Relenza® (zanamivir), GlaxoWellcome, Inc. 1-800-825-5249 Symmetrel® (amantadine; also available in generic forms), Endo Pharmaceuticals, Inc., 1-800-462-3636 Tamiflu® (oseltamivir), Roche Laboratories, Inc., 1-800-526-6367 Sincerely yours,
FDA/Center for Drug Evaluation and Research |