Drugs maker AstraZeneca has admitted that its premises have been raided by EU competition regulators as part of an investigation into collusion to block the entry of cheaper generic drugs to the market. AstraZeneca is the only company to confirm that it has been raided but there were other companies involved. A spokeswoman for AstraZeneca said that the raid related "to alleged practices regarding Nexium in Europe". Nexium is a heartburn and anti-ulcer drug with annual sales of $5bn. This figure is declining and Nexium is no longer AstraZeneca's biggest selling drug. The patent on Nexium has expired in a number of EU countries but generic competition has been limited. There are generic versions in Germany and Spain.