Surging sales of the multiple sclerosis drug Tysabri helped boost revenue at Elan, although the Irish group is to shelve plans to sell its drug technology unit because of the financial markets turmoil.

Quarterly sales of Tysabri, used to treat MS and Crohn’s disease, have increased from less than $8m in 2006 to $237m (£147m) in the last quarter, with more than 35,000 patients now taking the drug. For every 10,000 patients on Tysabri, Elan makes approximately $100m in additional annual profit.