The new cholesterol-lowering drug Crestor has more potentially harmful side effects than similar drugs and should be taken off the market, according to a lengthy correspondence published in today's issue of the journal the Lancet.

The letter, written by Sidney Wolfe of Public Citizen's Health Research Group, said that in its first seven months on the market, Crestor was linked to 18 cases of rhabdomyolysis -- a breakdown of muscle fibers that releases proteins that can severely harm the kidney.

The letter said that the drug has greater risk than other statins without providing greater benefit.

"I can't think of another instance where there's better documentation of elevated risk during clinical trials, and it is now being seen post-market," said Wolfe, who heads the health care advocacy organization. "There are many other statins, so I see no reason for this one to be on the market."

The conclusion was vigorously disputed by the drugmaker, AstraZeneca, and the Food and Drug Administration. Both said the risk-to-benefit equation was similar in all statins, including Crestor.

David Orloff, director of the FDA division of endocrinologic and metabolic drugs, said Wolfe's information about Crestor's record is similar to the agency's. But he said that the FDA has come to a very different conclusion about the meaning of the data.

"At this time, we have not concluded that this drug is different with regard to risk-versus-benefit, and see it as no different than other statin drugs on the market," Orloff said. "We are watching, but now we see no unusual signal."

Crestor is a particularly potent statin and has been shown to be effective in lowering LDL cholesterol, the kind associated with heart disease. It was approved by the FDA last August and went on the market soon after, with an aggressive advertising campaign.

Another powerful statin, Baycol, was taken off the market in 2001 after it was linked to the deaths of 31 patients from kidney disease. The drug's manufacturer, Bayer AG, removed the drug after consultations with the FDA.

Orloff said Crestor is not similar to Baycol in the severity of the muscle and kidney problems it appeared to be causing.

Gary Bruell, spokesman for AstraZeneca, said Wolfe's Public Citizen group has "launched a highly public crusade against our drug."

He said both the FDA advisory panel that reviewed the drug and the FDA staff unanimously approved Crestor. "Since that time, Public Citizen has continued to make misleading comments using selective information to attack the product," Bruell said.

European and Canadian regulators have recently issued warnings about Crestor, saying that people using it at higher dosages should be especially careful.