A year after the reintroduction of Elan's multiple sclerosis treatment Tysabri to the market, almost 14,000 patients are taking the drug, the Irish company said yesterday.

In a stock exchange announcement released to coincide with the first anniversary of the drug's return to the commercial market, Elan and its US partner Biogen said, as of the middle of July, 1,800 physicians had prescribed the drug to more than 8,600 patients in the US. In the EU more than 4,300 people are on the drug, with a further 1,000 patients involved in global clinical trials using Tysabri.

The drug, designed to treat relapsing forms of multiple sclerosis, was taken off the market in 2005 after being linked with several cases of a potentially deadly brain disease known as progressive multifocal leukoencephalopathy.

It was reintroduced in the US in July 2006, under a restricted distribution programme and in the EU under a special risk-management plan.

Analysts welcomed yesterday's figures, which come less than a week after European regulators advised against the use of Tysabri as a treatment for Crohn's disease and a week before the US Food and Drug Administration meets to discuss such a use of the drug in the US.

Davy analyst Jack Gorman said Tysabri was attracting new users at a rate in line with the broker's expectations, while Orla Hartford at NCB said the 14,000 figure was 8.5 per cent more than the broker had expected.

Mr Gorman said Davy remained comfortable with its long-term projections that, by 2010, Tysabri will be being used by almost 60,000 patients and be generating global revenues of about $1.6 billion (€1.2 billion).

Shares in Elan rallied on the news, ending the day 2 per cent higher at €14.95.