Pfizer Inc. (PFE) on Thursday agreed to suspend sales and marketing of its controversial arthritis drug Bextra at the request of U.S. and European drug regulators, who said the risks outweigh the painkiller's benefits.

Pfizer said it disagrees with the regulatory decision on Bextra (search) and will explore options with the agency under which the company might be permitted to resume sales of the drug.

The Food and Drug Administration (search) also asked that Pfizer include a black box warning — the strongest possible — on the package insert for its painkiller Celebrex.

In addition to the prescription drugs, the FDA asked manufacturers of related over-the-counter painkillers to revise their labels to include information about the risks of cardiovascular incidents and gastrointestinal bleeding.

• Click here to read the FDA's public health advisory.

Shares of Pfizer were down 61 cents, or 2.27 percent, at $26.25 on the New York Stock Exchange.

Celebrex (search) and Bextra, like Merck & Co.'s (MRK) Vioxx, are part of a class of painkillers known as COX-2 inhibitors (search), which are designed to avoid the gastric bleeding associated with older drugs like aspirin. Once blockbuster sellers, the painkillers were particularly popular among arthritis sufferers.

Merck withdrew Vioxx last September after a study showed it doubled the risk of heart attack and stroke compared with a placebo in patients who took it for at least 18 months.

The FDA said it singled out Bextra for suspension because it gives no added advantage as a painkiller and can cause a potentially life-threatening skin condition called Stevens-Johnson syndrome (search), an allergic reaction that usually begins as a blistering of the mouth and lips and can spread to the rest of the body.

The agency also asked the makers of dozens of other prescription and non-prescription painkillers, including Motrin, Advil and Aleve, to strengthen warnings about possible heart risks and potentially life-threatening gastrointestinal bleeding. The new warnings do not apply to aspirin.

Motrin and Aleve are members of a class of drugs known as non-steroidal anti-inflammatory drugs, or NSAIDs (search). Bextra, Celebrex and Vioxx are selective NSAIDs designed to reduce the risk of gastro-intestinal bleeding.

Bextra had sales in 2004 of $1.3 billion, while sales of Celebrex were $3.3 billion. New prescriptions for Celebrex had plunged in December after the company released data showing the drug may increase the risk of heart attacks and strokes.

"For now, patients should stop taking Bextra and contact their physicians about appropriate treatment options," Pfizer (search) said in a statement Thursday.

Pfizer said it planned further discussions with the FDA about the possibility of returning Bextra to the market.

"Pfizer respectfully disagrees with FDA's position regarding the overall risk-benefit profile of Bextra," the company said.

In February, advisers to the FDA had recommended that people who depend on Celebrex, Bextra and Vioxx be allowed to continue to use them despite the health risks.

The panel said Vioxx posed the greatest risk and that Celebrex had the fewest side effects. It recommended that the prescription drugs carry strong warnings and that more study be done to get a better understanding about the drugs.

Reuters and The Associated Press contributed to this report.