FDA Warns Of Tysabri Side Effects; Tells Biogen and Elan Pharmaceuticals To Update Drug's Label

The U.S. Food & Drug Administration (FDA) issued a warning to healthcare professionals and patients about the risk of developing progressive multifocal leukoencephalopathy (PML) when using Tysabri (Natalizumab) – a drug prescribed to treat multiple sclerosis (MS) and Chrone's Disease, an incurable disease that affects the bowels . This is the latest in a string of FDA warnings about the drug that have led to numerous personal injury and product liability lawsuits against the manufacturers, Biogen Idec, Inc. and Elan Pharmaceuticals, Inc.

February 2010: The latest in a string of FDA Tysabri warnings

The FDA has warned healthcare professionals and patients about Tysabri's dangers, including liver damage, liver failure and brain injuries, several times in the past two years. It's September 2009 and August 2008 warnings each detailed increasing reports of injuries. These warnings came after the drug was pulled from the market in 2005 and then reintroduced in 2006 with the FDA's approval.

The FDA's latest warning was sent to healthcare professionals and Tysabri patients on February 5, 2010. According to the FDA's website, the warning notifies them that:

[T]he risk of developing progressive multifocal leukoencephalopathy (PML) increases with the number of Tysabri infusions received. This new safety information, based on reports of 31 confirmed cases of PML received by the FDA as of January 21, 2010, will now be included in the Tysabri drug label and patient Medication Guide. Information about the occurrence of Immune Reconstitution Inflammatory Syndrome (IRIS) in patients who have developed PML and subsequently discontinued Tysabri has also been added to the drug label.

For additional information, go to the FDA's website (link to www.fda.gov/).

What are PML and IRIS?

• PML. PML, or progressive multifocal leukoencephalopathy, is a serious brain infection which can cause severe injury or death in people with damaged immune systems – such as those with HIV. If left untreated, PML can be fatal in a very short time frame – often within a few months. Symptoms include:
  • subtle weakness in the hands or legs
  • difficulty thinking or concentrating
  • memory loss
  • a lack of coordination
  • headaches
  • speech and vision changes
  • seizures

  PML can be diagnosed by undergoing an MRI (magnetic resonance imaging) or by a spinal tap.

• IRIS. IRIS, or Immune Reconstitution Inflammatory Syndrome, is a rare condition characterized by a severe inflammatory response that can occur during or following immune system recovery, causing an unexpected decline in a patient’s condition after return of immune function. IRIS is normally diagnosed by a differential diagnosis – when the diagnosis is narrowed down from a list of possibilities.

Tysabri injury lawyers report that numerous personal injury and product liability lawsuits have been filed against the manufacturers and predict that many more will be filed in the future as the FDA continues to warn about Tysabri's dangerous side effects.