Pfizer Inc. on Monday said the label of its Celebrex arthritis drug has been changed to add a prominent warning of possible cardiovascular risks, such as increased risk of Heart Attacks, in line with new warnings of other arthritis and pain drugs.

New York-based Pfizer said the package insert label of the drug - one of the company’s biggest products, sales of which have recently declined sharply due to safety concerns - recommends it be prescribed “at the lowest effective dose for the shortest duration.”

The company also said U.S. regulators had approved a new use for the drug, treating ankylosing spondylitis, a form of arthritis that affects the spine.

Second-quarter revenue from Celebrex plunged 45 percent to $401 million, one reason the world’s largest drug maker expects a modest decline in company revenue this year.

A federal advisory panel of doctors in February said Celebrex “significantly” raised the risk of heart problems and Strokes. But the advisors to the U.S. Food and Drug Administration recommended it remain on the market because of its benefits to arthritis patients.

Pfizer last month said its sales forces were holding back on fully promoting Celebrex again until it knew the warning language the FDA will require on the drug’s label.

Safety concerns about Celebrex and other painkillers intensified after Merck & Co. Inc. withdrew its Vioxx arthritis treatment in September when it was shown to double the risk of Heart Attack and Stroke after long-term use.

Celebrex and Vioxx are both newer arthritis treatments designed to block pain with far less risk of ulcers and other gastrointestinal problems than conventional non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and naproxen.

But one of the largest and most important trials conducted on Celebrex failed to show the drug reduced such gastrointestinal risk by a statistically significant degree, although favorable trends were seen.

Even so, Pfizer has widely advertised Celebrex and turned the expensive medicine into a blockbuster product.

Pfizer shares were up 16 cents to $26.66 in midday trading on the New York Stock Exchange, in line with slight gains for the drug sector.