The widely used cholesterol-lowering drug Crestor has at least twice the incidence of side effects as other drugs in the statin family, although it should still be considered safe for long-term use, according to a study released Monday.
The findings suggest that Crestor, manufactured by AstraZeneca, should probably be reserved for patients who have had a hard time lowering their overall cholesterol levels with other statins, said Dr. Richard H. Karas of the Tufts-New England Medical Center in Boston, who led the study.
The study was based on adverse reactions to statins reported to the Food and Drug Administration by patients and physicians.
Most of those reports involved muscle damage, called rhabdomyolysis, and poor functioning of the kidneys.
Baycol, a statin manufactured by Bayer, was removed from the market in 2001 because it was found to have an unusually high incidence of rhabdomyolysis. The drug was linked to more than 100 deaths.
Comparing the number of reported events with the number of prescriptions written, the team concluded that Crestor, whose generic name is rosuvastatin, was responsible for 2.2 times as many reports as simvastatin, sold by Merck & Co. under the brand name Zocor, and 6.8 times as many as atorvastatin, sold by Pfizer Inc. under the name Lipitor.
The rate of reports for Crestor was about half that of Baycol, Karas said.
The absolute number of problems connected to any of the statins was very low, he emphasized.
In Crestor's first year on the market after being approved in 2003, there were 145 reported muscle or kidney complications out of 5.2 million prescriptions, an absolute risk of one in 35,862.
In virtually all cases, the side effects stopped when drug use was halted.
"The absolute risk [of Crestor] is very low, even though the relative risk is increased," said Dr. Alice K. Jacobs of Boston Medical Center, president of the American Heart Assn. "The overwhelming majority of people who are taking it will have no problem at all."
The study was reported in the online version of the heart association's journal, Circulation.
The American Heart Assn. held a news conference to announce the findings in an effort to reassure people that statins are safe and that patients should not stop using the drugs.
"These are lifesaving drugs and we would not like to see" people stop taking them, said Dr. Elliott Antman of Harvard Medical School, an associate editor of the journal.
An estimated 20 million Americans take statins, one of the latest wonder drugs in physicians' arsenal.
By lowering cholesterol levels, the drugs can significantly reduce the risk of heart attack and stroke.
Recent studies have shown that they also can help prevent certain types of cancer.
The latest study contradicts an FDA study, announced this year, that concluded that Crestor was no more dangerous than other statins.
Experts said the design of the new study made it difficult to draw firm conclusions.
Adverse event reports "are not adequate to make a comparison of different statins," said Dr. Scott Grundy of the University of Texas Southwestern Medical Center at Dallas, who wrote an editorial accompanying the paper.
Events in such reports are random and incompletely reported, he said. There is no indication of how many individuals are taking the drugs, no indication of the type of patient in which the adverse events were observed and no proof that the drugs caused the events.
Critics of Crestor said the findings reaffirmed their belief that the drug was unsafe.
Dr. Sidney Wolfe of the advocacy group Public Citizen said the findings were further evidence that the drug should be removed from the market. The earlier study by the FDA was an outgrowth of a petition filed by Public Citizen calling for the drug's removal.
In light of the new data, the group will resubmit the petition, Wolfe said.