NEW YORK - A brain infection linked to Biogen Idec Inc. and Elan Corp.’s Tysabri is more likely to occur the longer patients use the multiple sclerosis drug, new prescribing information says.
The rate of the disease, progressive multifocal leukoencephalopathy, increases after 24 to 36 months of Tysabri therapy, the change in what is known as the label indicates.
The Food and Drug Administration temporarily suspended sales of Tysabri in 2005 after three cases of the infection were reported. Patients successfully pleaded for the product’s return.
The rate is 1 in 1,000 for patients on the drug from 24 to 36 months, and the rate beyond three years isn’t known, according to Biogen Idec spokeswoman Naomi Aoki.