A report has revealed that the Food and Drug Administration has given green signal to Biogen Idec Inc. and Elan Corp. for their multiple sclerosis drug Tysabri which would now be available in the US market.

Earlier, some issues were raised regarding the safety of the drug but the companies have won the U. S. clearance, which is said to double the sales of the drug worldwide. However, the FDA has asked that the approval would help them to know whether or not the drug is safe.

It has been claimed that the drug causes severe brain infection among the patients taking the drug. But, it somehow was not clear so this led the FDA to provide them clearance. Talking about the approval, George Scangos, the Chief Executive Officer of Weston, Massachusetts-based Biogen, said that they are quite happy to regain the trust of the FDA.

He further affirmed that it would be wrong to say that they were not expecting the clearance as they knew they were never wrong. There was brain infection risk, and this is the reason they have even put up the warning on the drug box informing about the same.

Scangos said that they have even conducted the research which has made them better understand about the drug.

In addition to it, the FDA’s advice would help doctors to assess the level of risk. Scangos said, “The revision of the Tysabri label to include the use of the JCV assay as a risk-stratification tool is important for doctors and patients because it allows Tysabri to be most efficiently used in the safest group of patients”.

Though the company has got the permission, the FDA and the European Commission have made it clear that they would be watching the progress of the drug.