Pre-tax losses widened at biotech group Elan in the first quarter despite a 31 per cent rise in sales.

However, the company was upbeat about sales of its multiple sclerosis drug Tysabri and progress in its Alzheimer's programme.

Elan said an exceptional gain of $44.2 million in the corresponding period last year plus costs of $18.8 million associated with restructuring its debt earlier this year were largely responsible for the loss before tax of $93 million compared to $33.3 million.

The company booked revenue of $176 million in the period compared to $134.3 million in the first three months of 2006.

Chief executive Kelly Martin said that, from an operational point of view, the company was very satisfied with its performance in the first quarter. "The market can expect to see continued financial and operational improvement in 2007, which is a very important year for Elan." he said.

Sales of Disbar came in at the lower end of analysts' projections in the period at $48.4 million However, the company noted that it had accelerated the rate at which new patients were signing up for treatment with the drug. Elan said it was now signing up 325 patients a week.

Mr Martin maintains there is no reason why Tysabri, which has market share of around 2.5 per cent just 10 months after its eventual market launch, should not attain market share of somewhere between 20 and 30 per cent - in line with other major drugs in the MS market.

The company expects the Tysabri programme to become profitable in the third quarter, by which time it will have more than 15,000 people on Tysabri. Mr Martin said the company was working with British medical authorities to address an initial decision recently by the National Institute for Health and Clinical Excellence that the cost of Tysabri should not be covered by the NHS.

Mr Martin said the company's Alzheimer's programmes - in conjunction with Wyeth and Toronto-based transition Therapeutics - were progressing with one treatment moving to Phase III trials later this year and a couple of others entering Phase II trials.

Chief financial officer Shane Cooke said Elan remained on course to record losses before interest, tax, depreciation and amortisation (Ebitda) of less than $50 million for 2007 as a whole "based on the strong performance reflected in the first quarter's results". On an Ebitda basis, losses since the first quarter fell to $6.4 million from $17.2 million in the same period last year.