The "patent cliff" is the chief challenge facing the industry, although some companies will be affected more than others. Patents can sometimes be extended by making slight changes to the chemical composition, for example – a process called "evergreening".
However, some analysts argue that the search for new blockbuster drugs is not good value for money.
PricewaterhouseCoopers (PwC), in its report Pharma 2020: The Vision, says that industry leaders' revenues "have come at a very high price". It notes that between 1985 and 2000 the industry's market value increased 85-fold, outpacing the stock market as a whole. But in the six years to 30 March 2007 the FTSE global pharmaceuticals index rose just 1.3 per cent, while the Dow Jones World Index rose by 34.9 per cent. Additionally, it says that only five of the top companies worldwide generate more than 10 per cent of their revenues from products launched since 2001. "Even allowing for inflation, the industry is investing twice as much in R&D as it was a decade ago to produce two-fifths of the new medicines it then produced," it says.