Elan shares have fallen another 23 per cent today on news that a rare infection has been confirmed in a second patient receiving their multiple sclerosis drug Tysabri.
Shares in company were trading at €4.30 on the Dublin market this afternoon.
The company suspended sales of Tysabri on Monday after one confirmed case and one suspected case of progressive multifocal leukoencephalopathy (PML) in patients participating in a long-term clinical trial of Tysabri in combination with Avonex, Biogen's older multiple sclerosis drug.
Biogen and Elan said they will work with clinical investigators to evaluate Tysabri-treated patients and will consult with leading experts to better understand the possible risk of PML.
Biogen and Elan said they are co-operating with the US Securities and Exchange Commission in connection with the voluntary suspension in the marketing of Tysabri.
The companies said that to date, they have received no reports of PML in patients receiving Tysabri monotherapy for MS or in patients with Crohn's disease or rheumatoid arthritis.
Biogen has not received any reports of PML in patients treated with Avonex alone, a product on the market since 1996.