Elan has posted a net loss for continuing operations of $72.8 million for the three months to the end of March, compared with a loss of $74.7 milion for the same period last year.

First quarter sales of its blockbuster multiple sclerosis drug Tysabri rose by 14 per cent to €456 million, up from €399 million for the same period of 2012.

Earlier this year, the company transferred full ownership of the drug to its partner Biogen Idec for an upfront payment of $3.25 billion plus future royalties on sales of the drug.

Elan said it now held $2 billion in cash and cash equivalents, which it said provides the company "with substantial capacity to execute on transactions to diversify our business and grow shareholder value".

Chief financial officer Nigel Clerkin said: "The completion of the Tysabri transaction earlier this month, followed by the $1 billion share buyback and the retirement of our bonds, have collectively transformed our capital structure, and provide the platform to transform our business structure."

Earlier this week, Elan unanimously rejected the latest formal bid for the company from Royalty Pharma, saying it “grossly undervalues” the company.

The new offer of $11.25 (€8.62) per share from Royalty Pharma, lower than an earlier $12.00 offer.