Celebrex (search) seems not to carry the heart-attack risk of Vioxx (search), a new study suggests.

Like Vioxx -- recently pulled from the market because it increases the risk of heart attacks -- Celebrex is a member of the drug family known as Cox-2 inhibitors (search). The family also includes Bextra and the not-yet-U.S.-approved Prexige (search) and Arcoxia (search). All fight pain and inflammation by blocking an enzyme called Cox-2.

It's not yet clear whether all of these drugs carry some heart risk for some people. But now it looks as though Celebrex is significantly less risky than Vioxx.

Researchers led by Stephen E. Kimmel, MD, director of cardiology epidemiology at the Hospital of the University of Pennsylvania, interviewed more than 1,700 heart attack survivors and 6,800 randomly selected area residents who never had a heart attack.

"We found an almost threefold lower risk of heart attack in Celebrex relative to Vioxx users," Kimmel tells WebMD. "There is a difference between Cox-2 inhibitors."

Kimmel and colleagues report their findings in the Feb. 1, 2005, issue of Annals of Internal Medicine, posted Dec. 6 on the journal's web site in an early online release.

Who Should -- and Shouldn't -- Take Cox-2 Drugs?

Among the 10 million patients who took Vioxx, the drug caused an estimated 160,000 heart attacks before Merck withdrew the drug from the market. Was this heart toxicity specific to Vioxx? Or do all Cox-2 drugs increase a person's risk of heart attack – a so-called class effect?

It's better to be safe than sorry, argues an editorial accompanying the Kimmel study. The editorial's main author is rheumatologist Axel Finckh, MD, a researcher at Boston's Brigham and Women's Hospital.

"At this time we cannot say there is no class effect of Cox-2 inhibitors," Finckh tells WebMD. "We don't really know at this time what is triggering an increased risk of heart problems. We aren't sure whether it is something within this class of drugs ... or something specific to each of the drugs."

So far, the data on Celebrex are reassuring. But this reassurance is not proof of safety, Finckh says.

"I don't think we can yet say that Celebrex is the safest," he notes. "We just have a little more data on it than other Cox-2 drugs still on the market. We feel more confident to say that for Celebrex, at this point, it may be less risky for patients with no heart risk factors."

Kimmel agrees that Cox-2 drugs should not be the first-line treatment for all patients.

"The whole Cox-2 inhibitor saga has pointed out that these drugs are not for everybody," he says.

Cox-2 drugs don't fight pain any better than older anti-inflammatory drugs such as naproxen and ibuprofen – the so-called NSAID drug family. But these older drugs sometimes cause dangerous stomach or intestinal bleeding. This side effect is significantly less common in patients taking Cox-2 inhibitors.

"Cox-2 drugs are for people at high risk of gastrointestinal bleeding who can't tolerate [older] NSAIDs," Kimmel says. "For people with high risk of bleeding and low risk of heart attack, we say use Celebrex."

It's a harder choice for people at high risk of heart attack and high risk for bleeding complications.

"Those patients should be on aspirin for their hearts. This means they already have a bleeding risk," Kimmel says. "So for them, it might be better to use an [older] NSAID – other than ibuprofen – in combination with a stomach-protecting agent such as a proton-pump inhibitor [Prilosec, for example]."

By Daniel J. DeNoon, reviewed by Michael W. Smith, MD

SOURCES: Kimmel, S.E. Annals of Internal Medicine, Feb. 1, 2005; vol 142; early online release Dec. 6, 2004. Finckh, A. and Aronson, M.D. Annals of Internal Medicine, Feb. 1, 2005; vol 142; early online release Dec. 6, 2004. Stephen E. Kimmel, MD, associate professor of medicine and epidemiology, University of Pennsylvania; director of cardiology epidemiology, Hospital of the University of Pennsylvania, Philadelphia. Axel Finckh, MD, visiting researcher, Brigham and Women's Hospital, Boston.