Shares in Elan Corp have leapt on rumours Denmark's Lundbeck is planning a takeover bid for the Irish drugmaker, although the likelihood of such a bid is being questioned by some analysts.

It has been reported that Lundbeck is on the verge of making a bid of around 8 euros per shares. Elan’s stock price grew by as much as 12% yesterday to around the 5.40 euro mark, giving the firm a market capitalisation of around 2.6 billion euros. Indeed the shares have been climbing all week.

This rumour of the Danish firm’s interest has been doing the rounds since January, when Elan hired Citigroup to conduct a strategic review of its business, that could lead to a sale or merger. The findings of that review are expected soon and since that process started Elan has claimed it was close to selling off a 19.25% stake to another pharmaceutical firm.

However, Ian Hunter, an analyst at Dublin-based stockbroker Goodbody, believes that a Lundbeck takeover is unlikely. In the event of such a takeover, Biogen Idec has the right to buy Elan's 50% stake of the joint vernture the firms have for the multiple sclerosis drug Tysabri (natalizumab) and it would probably enact this clause, thus forcing any Elan buyer into losing its biggest earner. Mr Hunter says Elan's stake in Tysabri is valued at around $4 billion.

Lundbeck is in the process of acquiring USA-based Ovation Pharmaceuticals in a deal which is worth up to $900 million but is still in the market for other deals that will help replace the loss of revenues it will suffer when the antidepressant blockbuster Cipralex/Lexapro (escitalopram) goes off-patent in 2012.