FDA wants Biogen, Elan drug warning revised

WASHINGTON (Reuters) - Prescribing instructions for Biogen Idec and Elan Corp's drug Tysabri should be revised to note cases of a serious brain disorder in patients who were using it as their sole treatment for multiple sclerosis, U.S. health regulators said on Monday.

The Food and Drug Administration said it was working to amend the Tysabri label after two cases of the brain disorder, progressive multifocal leukoencephalopathy (PML), were reported in Europe.

"While the two patients who developed PML were on monotherapy, the FDA still believes that Tysabri monotherapy may confer a lower risk of PML than when Tysabri is used together with other immunomodulatory medications," the FDA said in a statement on its website.

(Reporting by Lisa Richwine; Editing by Braden Reddall)