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FDA Approves Emergency Use of Tamiflu, Relenza

Apr 28, 2009 | Parker Waichman Alonso LLP

During the current swine flu outbreak and responding to U.S. Authorizations (EUAs), the U.S. Food and Drug Administration (FDA) is making some diagnostic and treatment tools available, under specific situations, to public health and medical personnel. The FDA issued the EUAs for Relenza (zanamivir) and Tamiflu (oseltamivir phosphate) and the rRT-PCR Swine Flu Panel diagnostic test. The FDA explained the EUA is part of Project BioShield, which became law in July 2004.

The EUA authority permits the FDA to allow use of “unapproved or uncleared medical products or unapproved or uncleared uses of approved or cleared medical products” during an established emergency. Such use ends when either the swine flu emergency is deemed over or the authorization is revoked. Under the EUAs, Tamiflu and Relenza may be given to large population sectors without compliance with label requirements and can be distributed by some public health officials and volunteers based on state and local laws and/or public health emergency responses, explained the FDA.

GlaxoSmithKline’s Relenza can be inhaled to treat influenza in children age seven and older. Roche Laboratories’ Tamiflu is prescribed for children age one and up, and is taken orally within 48 hours of flu symptom onset. Relenza is approved to prevent influenza in adults and children five years of age and older.  In a pandemic outbreak, Tamiflu and Relenza would be used to treat people ill with flu, as well as flu prevention and treatment in children under one year. If no flu vaccine is available, Tamiflu could be taken daily for flu prevention.  EUAs allow alternate dosing for children older than one.

The FDA determined the EUA for the Swine Flu test may be effective in testing samples from individuals diagnosed with influenza A infections, whose virus subtypes cannot be identified by currently available tests. The EUA allows the Centers for Disease Control and Prevention (CDC) to distribute the test to public health and other qualified laboratories with the needed equipment and trained personnel to perform and interpret results.  The test amplifies the viral genetic material from a nasal or nasopharyngeal swab. A positive result indicates presumptive swine flu infection, but not the infections’ stage; a negative result alone does not exclude the possibility of infection.

In November 2007, an FDA advisory panel recommended stronger warnings about psychiatric side effects be added to the labeling of both Tamiflu and Relenza.  The recommendations where based on a review of nearly 600 psychiatric adverse event reports in Tamiflu patients, and another 115 reports among people taking Relenza.  Documents posted online by FDA staffers at the time said that there have been reports of 596 neuropsychiatric events, including 16 neuropsychiatric-related deaths, among children and adults taking Tamiflu. Among those reports, 75% came from Japan. In total, the FDA said, there were 25 deaths from all causes reported among Tamiflu users on a world-wide basis in patients younger than 21.  Japan was also the origin of 81 of the Relenza reports, but no deaths where associated with that drug. Of the 48 million people treated with Tamiflu since its approval in 1999, the majority of users – 35 million – have been in Japan.

In March 2008, the U.S. label of Tamiflu  was updated to include new warnings about delirium and abnormal behavior seen in some patients - mostly children - taking the drug.   A month later, similar warnings were included on Relenza's label.