Tysabri numbers bounce back higher than expected

DUBLIN, Ireland An Irish drug maker hopes to see 100,000 people using its multiple sclerosis drug within two years.

Elan said Tuesday that 31,800 people around the world were using Tysabri at the end of last month, including 17,800 in the United States, 13,400 elsewhere and 600 in clinical trials. The number was greater than many analysts had anticipated. Elan developed the drug, known generically as natalizumab, with the American company Biogen Idec.

Tysabri had sales of $500 million in 2007, according to Biogen Idec financial data. Sales of the drug were suspended in 2005 when it was linked to a potentially fatal brain disease, but resumed the next year with stronger guidelines for prescriptions for MS. It was also approved in March for treating Crohn’s bowel disorder.