ELAN HAS updated the label on its breakthrough multiple sclerosis (MS) drug Tysabri to reflect the increased risk of patients contracting a serious brain disease if they are on the drug for more than two years.

The company announced last night that, effective immediately, it was updating the label on the drug in the US market following consultation with the US regulator, the Food and Drug Administration (FDA).

The FDA is expected to confirm the move on its own website in the coming days.

The company and its US partner, Biogen Idec, had come under pressure when the European Medicines Agency (EMEA) announced recently that it was opening a review of the risks and benefits of the drug after 24 people had contracted the rare and potentially fatal brain disease progressive multifocal leukoencephalopathy (PML). Four of those patients had died subsequently, the EMEA said.

The news came as a shock. Just a week earlier, the FDA had stated that, as of September 8th, there were just 13 known cases of the disease in Tysabri patients.

Last night Elan and Biogen updated the patient medication guide and the prescriber information guide on the drug’s website www.tysabri.com to reflect the new label.

A spokeswoman for the company said there was no other change in the wording of the label. In particular, the guidance of a one-in-1,000 risk of contracting PML is unchanged.

Both companies have indicated that talks with the FDA are ongoing as more information about the drug emerges.

The EMEA review is continuing separately. Elan said last night it expected a similar change of wording would be approved in talks with the European regulator.