The FDA has updated its warning on Biogen Idec's multiple sclerosis drug Tysabri. According to the agency, the risk of a potentially fatal brain infection appears to be greatest during the third year of treatment.
Since Tysabri was reintroduced in 2006, Biogen and the FDA have been keeping close tabs on cases of progressive multifocal leukoencephalopathy, or PML. Biogen regularly updates case counts, and the FDA has been estimating the cumulative risk posed by the drug. This is the first time the agency has calculated PML risk according to specific time intervals. The newly sliced data is designed to help doctors "better assess risk based on duration of treatment," the agency said....Read More - http://www.msrc.co.uk/index.cfm/fuseact ... ageid/1905