Public Citizen, which lobbied against the approval of Crestor, claims it has new evidence about the risks of taking the drug.
The claims, to be published in a letter in Friday’s edition of The Lancet, the medical journal, come two weeks after European regulators tightened the rules on prescribing Crestor.
Crestor, part of a group of drugs known as statins, is tipped by analysts to achieve peak sales of around $4bn (Â£2.2bn) a year and is central to the Anglo-Swedish group’s plans to overcome generic competition on other drugs.
In the letter, Sidney Wolfe, director of Public Citizen, said the reports of adverse events to regulators showed that the level of rhabdomyolosis [a breakdown of muscle tissue that can lead to kidney damage] caused by Crestor “is probably higher than the highest of any other currently marketed statin”.
AstraZeneca responded that the letter made “misleading claims based on inappropriate interpretation of data”. It added that there was “a large volume of data supporting our view, that of the European regulatory authorities and the FDA, that Crestor has a favourable benefit risk profile”.
Analysts believe there is little chance of the drug being withdrawn, but said sales growth could be slowed by safety concerns.
Timothy Anderson, at Prudential Financial, said the argument adds to growing noise about Crestor’s safety and could help its competitors, particularly Merck and Schering-Plough.
The letter in The Lancet is not the first time the magazine has clashed with AstraZeneca over Crestor. An editorial published last October accused AstraZeneca of using “blatant marketing dressed up as research” and said the evidence to support Crestor’s safety was “inferior” to that of rivals.
Sir Tom McKilop, chief executive of the drugs group, replied that the article was “flawed and incorrect”.
“I deplore the fact that a respected scientific journal like The Lancet should make such an outrageous critique of a serious, well-studied and important medicine,” he wrote in a letter.