Merck & Co. Inc.‘s withdrawn arthritis drug Vioxx may return to the market after U.S. health advisers narrowly voted it was safe enough to be sold despite an increased risk of heart attack and stroke.

Pfizer Inc.‘s rival pain relievers Celebrex and Bextra, which had also been under a cloud over elevated risks of heart problems, were also safe enough for sale, the Food and Drug Administration advisory panel said.

The 17-15 vote on Vioxx’s safety to go to market electrified Merck shares, which closed up 13 percent at $32.61 on the New York Stock Exchange. Pfizer gained 6.9 percent to close at $26.80.

It was a stunning turnaround for Vioxx, which was withdrawn in September by Merck after a study showed Vioxx doubled heart attack and stroke risk compared to a placebo.

“Merck has appreciated the opportunity to present data at this advisory committee meeting,” the company said in a statement. “We look forward to discussions with the FDA.”

Most of the advisers said Vioxx, Celebrex and Bextra should all have “black box” warnings on their heart risks.

The FDA usually follows advice from its panels. Officials have said the agency will make final decisions on Celebrex and other pain relievers in a matter of weeks. All three drugs are part of a class called COX-2 inhibitors.

COX-2 inhibitors were designed to ease pain as effectively as older, nonprescription drugs known as nonsteroidal anti-inflammatory drugs, or NSAIDs, while being easier on the stomach. NSAIDs include ibuprofen and naproxen.

Merck officials say Vioxx offers a unique benefit because it is the only COX-2 inhibitor shown to cause fewer serious stomach problems than naproxen, Merck officials said.