The European Commission opened an antitrust investigation today against AstraZeneca.
It has done so on suspicion Europe's second-largest drug maker abused the patent system to extend protection for its money-spinning anti-ulcer drug Losec.
The Commission said in a statement it suspected the Anglo-Swedish group misrepresented facts and dates to national patent offices in a ploy to extend exclusivity beyond the five years permitted and prevent manufacturers of generic drugs from competing.
But AstraZeneca said it "vigorously refutes" the allegation that it abused the patent system to protect Losec.
Losec revolutionised the treatment of stomach ulcers and other acid-related diseases, and by the end of the 1990s had become the world's best selling prescription medicine.
Sales are now declining in the face of generic competition. The Commission said some of the alleged evidence for the investigation came from raids on the company's offices in Sweden and Britain in February 2000.
AstraZenica's share price dropped on the news, down 3 per cent at 2,420 pence by 10 a.m., after being 0.54 per cent down on yesterday's close of 2491 just before the announcement.