AstraZeneca has withdrawn Exanta, the blood-thinning drug, from the worldwide market following new patient-safety data and a report of serious liver damage.

The drug had once been championed by Sir Tom McKillop, the company's former chief executive, as a potential blockbuster.

AstraZeneca estimated that Exanta was being prescribed for around 400 patients after being blocked by American regulators in late 2004.

Shares in the company were down 1.4 per cent at 2586p in afternoon trade following the announcement. To track the stock click here.

Earlier this month, the company's recently appointed chief executive admitted for the first time that Exanta, once one of its most promising medicines, would never make it on to American pharmacy shelves.

David Brennan told The Times: "We don't see any way forward in the US for Exanta right now, especially given what work we've done in the clinic and what the regulators want to see from us."

Mr Brennan said that the company's research effort into the medicine would not go to waste: "We're still interested in the market but, from a commercial expectation, this isn't something that has tremendous opportunity."

Mr Brennan's comments came after Astra Zeneca posted a 40 per cent increase in quarterly profit and boosted its dividend. However, the City shrugged off the record results, sending the shares lower on fears that the company is not developing enough new drugs.

AstraZeneca offered a flat outlook for 2006 based on a potential hit to its $1.7 billion sales from Toprol-XL, a heart drug used to treat high blood pressure.

On January 17, an American judge invalidated AstraZeneca's patents on Toprol-XL, clearing the way for cheaper generics.

The company now faces a class-action petition demanding it compensate patients for years of charging users too much.

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