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July 2000

RE: Important Revisions to Safety Labeling for RELENZA® (zanamivir for inhalation)

Dear Health Care Professional:

Glaxo Wellcome Inc. is writing to inform you of important revisions to the safety labeling for Relenza (zanamivir for inhalation), which is approved for the treatment of uncomplicated acute illness due to influenza virus.

Since the approval of Relenza in July 1999, the labeling has included a PRECAUTION describing the potential for bronchospasm in patients with underlying respiratory disease, and has stated that safety and efficacy have not been shown in this population, and that the drug should be stopped in any patient who develops bronchospasm or decline in lung function. Subsequently, we have received post-marketing reports of serious respiratory adverse events when Relenza was used in patients with known airways disease. Reports of decline in respiratory function in patients without a history of airways disease have also been received. Some adverse events have required immediate treatment or hospitalization, and some patients with serious adverse events have had fatal outcomes. Although the causality of these adverse events is difficult to determine (given the nature of influenza, its potential complications, and possible concomitant conditions), the labeling for Relenza has been revised to more clearly reflect that serious respiratory adverse events have been reported in patients with or without known underlying respiratory disease, and to incorporate additional updated safety information. Important safety-related labeling changes include the following:

• A WARNING has been added to describe reports of bronchospasm and decline in lung function in some patients receiving Relenza; many, but not all, of these had underlying airways disease such as asthma or chronic obstructive pulmonary disease (COPD).
• The new WARNINGS section includes a statement that Relenza is not generally recommended for treatment of patients with underlying airways disease such as asthma or COPD, because of the risk of serious adverse events and because efficacy has not been demonstrated in this population. Some patients with serious adverse events during treatment with Relenza have had fatal outcomes, although causality was difficult to assess.
• The PRECAUTUIONS section contains expanded information regarding considerations needed if use of Relenza is contemplated in the context of underlying airways disease.
• The PRECAUTIONS section also contains information about allergic-like reactions in patients receiving Relenza, and about the potential for serious bacterial infections to appear with influenza-like symptoms or as complications of influenza.
• New animal toxicity data have led to a change in the Pregnancy Category from B to C.
• The ADVERSE REACTIONS section contains additional information about postmarketing adverse event reports, and about lower respiratory adverse events in pediatric patients with underlying respiratory disease.

In addition to the above changes in the prescribing information, a Patient Information leaflet has been prepared. This Patient Information is also supplied to pharmacies with each carton of Relenza for dispensing to the patient. A copy of the complete package insert, including professional prescribing information and the Patient Information leaflet, is enclosed.

Glaxo Wellcome is committed to providing you with the most current product information for the management of your patients being treated with Relenza. You can assist us in monitoring the safety of Relenza by reporting adverse reactions to the Glaxo Wellcome Product Surveillance Department at 1-888-825-5249 or to the FDA MedWatch program by telephone at 1-800-332-1088, by FAX at 1-800-332-0178, via www.fda.gov/medwatch, or by mail to MedWatch, HF-2, FDA, 5600 Fishers Lane, Rockville, Md. 20857.

Please refer to the enclosed complete prescribing information for Relenza. If you have questions about the new information or want additional medical information about Relenza, please contact the Glaxo Wellcome Customer Response Center at 1-888-TALK-2-GW.

Sincerely,

Richard S. Kent, M.D.
Vice President and Chief Medical Officer

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