NEW YORK (CNN) - Under pressure from regulators, Pfizer has agreed to limit advertising of Celebrex after a clinical trial showed the painkiller was linked to an increased risk of heart attacks and strokes.

The move by the world's biggest drugmaker came after a request from the Food and Drug Administration. Pfizer said it will pull Celebrex ads from TV, radio, newspapers and magazines, effective immediately.

The drugmaker warned Friday that one colon cancer study had shown that Celebrex might increase the chance of heart attack and stroke in some patients.

New York-based Pfizer (Research) said it was not pulling the blockbuster drug from the market.

But spokeswoman Mariann Caprino told CNN Business News Monday that Pfizer had decided to halt the ads.

According to analysts, Pfizer spent $71 million on advertising on Celebrex in the first nine months of this year -- one of the biggest ad budgets for a prescription drug.

The new findings for Celebrex came 11 weeks after Merck & Co. recalled Vioxx, a similar arthritis drug. A Vioxx study found the drug doubled the incidence of heart attack and stroke among patients taking it to prevent colon polyps that cause cancer.

Pfizer stock tumbled 11.2 percent Friday on the Celebrex news.

Celebrex is approved in the United States for treatment of arthritis pain at doses of 100 milligrams to 200 milligrams a day, or double that for rheumatoid arthritis.

Patients in the cancer study were taking 400 milligrams to 800 milligrams of Celebrex daily. The National Cancer Institute suspended the trial because the people on Celebrex showed two to three times the cardiovascular risk than those taking a placebo.

A second cancer study found no problems with the drug, Pfizer said.

Medical experts advised patients to consult their doctors about Celebrex.

Industry analysts said the development was a blow to Pfizer, a company that's been admired on Wall Street for its drug development and marketing.