AstraZeneca could lose 38 per cent of its revenue because key drug patents will expire in the next five years, according to research by Prudential Equity Group and AXA Framlington.

Britain’s second-biggest drug group, which last year reported annual sales above $25 billion (£12.6 billion), faces losing several top products between now and 2012. They include Arimi-dex, a breast cancer drug with yearly sales of $2.2 billion whose patent ends in 2010; Seroquel, a schizophrenia drug with sales of $4.7 billion and patent expiry in 2011; and Symbicort, an asthma medicine with $3.7 billion sales and a 2012 patent expiry.

Gareth Powell, of AXA Framlington, said that the findings indicated the pressure on AstraZeneca to bolster its pipeline of new drugs. He said: “If Astra wants to replace that level of revenue, then they need to be aggressive about refilling their pipeline.”

AstraZeneca has unveiled several acquisitions recently.

More are expected to be made using its free cashflow, at about $6.8 billion for 2006.

AstraZeneca’s problems are less acute than those of some of its peers. Pfizer, of the US, the world’s largest drugs group, will shed 41 per cent of its revenues by 2012, particularly hit by the 2011 expiry of its patent on the cholesterol-fighter Lipitor, the world’s top-selling drug with sales of $12.1 billion. America’s Forest Laboratories is set to lose 86 per cent of revenues by 2012. Britain’s GlaxoSmithKline is set to lose only 23 per cent of sales.

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