US regulatory authorities have approved the resumption of sales of Elan's multiple sclerosis drug Tysabri.
The drug had been withdrawn following the deaths of two patients involved in trials of the drug from a rare brain disease. The decision allows the drug to be sold on a restricted basis.
When Tysabri was removed from the market last year, Elan shares fell by 70% in one day's trading.
In a statement this morning, Elan and its partner Biogen said they expected Tysabri to be available in July.
The conditions attached to the return of the treatment include a change in the labelling accompanying the product to include warnings about the risks, continuing safety assessments and an educational programme designed to inform patients and doctors about the product.
Shares in Elan slumped €2.70 to close at €12.06 in Dublin this evening - a fall of almost 19%.
