Shares in Elan fell by over 4 per cent today in the wake of reports that a fifth case of the fatal brain disease PML was being linked to its flagship multiple sclerosis drug Tysabri.
The Wall Street Journal said another case of progressive multifocal leukoencephalopathy (PML) was reported on May 16th through the Food and Drug Administration's Adverse Event Reporting System.
An FDA spokeswoman warned the reports did not represent confirmed cases.
Elan and its partner Biogen Idec halted sales of Tysabri in February after it emerged a patient died of PML.
The companies have confirmed three cases of the disease so far. Two of the patients have since died, while a third is said to have improved.
Elan's shares touched a low of €5.50 in morning trade in Dublin today, a €0.31 drop on Friday's close.