A newspaper advertisement for AstraZeneca Plc’s cholesterol drug Crestor that touts patient safety is misleading and should no longer be published, regulators warned in a letter released on Wednesday.

In the letter dated Dec. 21, the Food and Drug Administration said it was particularly concerned the advertisement downplayed risks associated with Crestor and wrongly suggested the agency has “confidence” in the drug.

The advertisement reads: “The FDA has confidence in the safety and efficacy of Crestor,” but that “misleadingly suggests that the agency does not believe that Crestor poses safety risks,” the FDA wrote.

“In fact, recent public statements made by the agency contradict that conclusion,” the FDA letter said.

AstraZeneca spokesman Steven Lampert said the company maintained that the advertisement was not misleading, adding it was a “one time thing” that was no longer being published.

The company has insisted Crestor, known generically as rosuvastatin, is as safe as other drugs in the family known as statins.

The warning letter cited comments by Steven Galson, acting director of the FDA’s drug division, who told The Washington Post in November the agency was “very concerned about Crestor since the day it was approved.”

The full-page advertisement ran Nov. 23 and Nov. 24 in The Washington Post, The New York Times, USA Today and other papers just days after veteran FDA scientist David Graham told a congressional hearing that Crestor was one of five drugs that could be unsafe.

Immediately after the advertisement ran, consumer watchdog group Public Citizen called the promotion misleading and asked the FDA to prohibit its future publication.

The group has cited reports the drug can cause kidney damage and is calling for Crestor to be pulled from the market. The FDA’s letter “is further reason for the FDA to act on our March 2004 petition and immediately ban Crestor,” said Sidney Wolfe, head of Public Citizen’s Health Research Group.

AstraZeneca has previously said Public Citizen’s concerns about the advertisement were “absurd.”

But the FDA said AstraZeneca, in its advertisement, minimized risks associated with the 40-milligram dose of Crestor. Those risks, which can include acute kidney failure and kidney damage, previously led the company to agree to “special distribution measures” for the 40-mg dose of Crestor “and to three long-term post-marketing clinical trials,” the letter said.

The FDA told the company it must reply to the letter by Jan. 7.

The agency routinely sends dozens of warning letters to companies each year, which can lead to fines, injunctions and other penalties if companies do not correct the problem.

The letter was posted on the FDA Web site at http://www.fda.gov/cder/warn/2004/12779.pdf.