Biogen Idec Inc. and Elan Corp. are seeking Food and Drug Administration (FDA) approval for the use of their multiple-sclerosis drug Tysabri in patients with Crohn's Disease. Tysabri, which is already approved to treat multiple sclerosis, now faces a review by outside medical experts on Tuesday who will advise on whether the federal agency should approve the drug.

The use of this drug can lead, in some instances, to the development of a rare and incurable nervous system disease known as progressive multifocal leukoencephalopathy, or PML, that is usually fatal after six months

Health officials report that a multiple sclerosis drug pulled from the market last year because of a rare but life-threatening side effect will return under a restricted distribution program.

The Food and Drug Administration says it will let Biogen Idec Inc. and Elan Corp. PLC continue selling Tysabri under a requirement that doctors, pharmacies and patients register with a program designed to ensure the safe use of the drug

Advisors to the U.S. Food and Drug Administration (FDA) have recommended the return of a drug called, Tysabri, despite concerns about its safety.

After only four months on the market, manufacturers voluntarily recalled the drug after two patients taking Tysabri died from a brain infection called, progressive multifocal leukoencephalopathy (PML)

Federal regulators will debate the potential risks of letting a multiple sclerosis drug back on the shelves. An advisory panel will spend Tuesday and Wednesday deciding whether Tysabri should be back on the market.

Drug makers voluntarily took it off the market in February 2005 after three users developed a rare and often fatal brain disease. Two of them died. The two companies want to begin selling it again, saying its benefits outweigh the risks. They're also proposing a plan to guard against more cases of the brain disease

The Food and Drug Administration has removed the clinical hold on Biogen-IDEC's studies of Tysabri (natalizumab) for patients with multiple sclerosis.

MS Patients who were previously treated with the drug under an investigational study can now resume treatment