FDA allows Tysabri back on market

As expected, the FDA formally agreed to allow the MS drug Tysabri back on the market. Regulators say they still don't understand the link between Tysabri and the three patients who contracted a rare brain disease, but that patients were clearly willing to run the risks in order to gain the benefits of the drug. However, the FDA suggested that patients try another MS drug first and be sure to avoid any drug combo while taking Tysabri. With regulators suggesting Tysabri as a second-line drug, investors sent shares of Elan and Biogen Idec down, worried that the recommendation is likely to erode Tysabri's market share.

It's rare for the FDA to allow a drug back on the market after it had been pulled for safety risks. But the decision also squares with the agency's efforts to do a better job highlighting the risks associated with a drug so that patients and doctors can make a more informed decision.

- read this article from the Los Angeles Times on Tysabri