GlaxoSmithKline has informed Healthcare Professionals of a recent update to the Relenza ( Xanamivir ) Inhalation Powder package insert.
The revision to the product label is a result of information about adverse events reported during postmarketing clinical use of Relenza.
The revised Warnings and Precautions section of the Relenza Inhalation Powder package insert now includes the following information and guidance under a new Neuropsychiatric Events subheading:
Influenza can be associated with a variety of neurologic and behavioral symptoms which can include events such as seizures, hallucinations, delirium, and abnormal behavior, in some cases resulting in fatal outcomes.
These events may occur in the setting of encephalitis or encephalopathy but can occur without obvious severe disease.
There have been postmarketing reports ( mostly from Japan )of delirium and abnormal behavior leading to injury in patients with influenza who were receiving neuraminidase inhibitors, including Relenza.
Because these events were reported voluntarily during clinical practice, estimates of frequency cannot be made, but they appear to be uncommon based on usage data for Relenza.
These events were reported primarily among pediatric patients and often had an abrupt onset and rapid resolution.
The contribution of Relenza to these events has not been established.
Patients with influenza should be closely monitored for signs of abnormal behavior.
If neuropsychiatric symptoms occur, the risks and benefits of continuing treatment should be evaluated for each patient.
Relenza is indicated for treatment of uncomplicated acute illness due to influenza A and B virus in adults and pediatric patients 7 years of age and older who have been symptomatic for no more than 2 days.
Source: FDA, 2008
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