Some common painkillers are much riskier than others, two new studies show.

The two studies look at existing clinical trial data for the common kind of painkillers known as NSAIDs (nonsteroidal anti-inflammatory drugs), particularly the NSAIDs known as Cox-2 inhibitors.

The studies add to the wisdom of the 2004 decision to remove the Cox-2 inhibitor Vioxx from market. It carries a remarkably high risk -- not only for potentially fatal heart problems, but also for kidney trouble.

The new data also raise troubling questions about the older NSAID, diclofenac, sold generically and also under the brand names Voltaren and Cataflam.

On the other hand, the studies show that low doses of the Cox-2 inhibitor Celebrex -- under 200 milligrams per day -- appear relatively safer. They seem to suggest that the problems with Vioxx do not automatically implicate all other Cox-2 drugs.

How Safe Are NSAIDs?

Painkillers With Low Heart Risk

The safest painkiller in regards to heart risk in these studies is naproxen, sold under the brand name Aleve and Naprosyn. Also apparently safe in regards to heart risk are ibuprofen (sold as Advil, Motrin, Nupren, and other brand names) and piroxicam (sold as Feldene).

Although caution is certainly warranted, the new findings show no reason why clinical trials of new Cox-2 drugs -- to be called ArCoxia and Prestige -- should not continue.

Because of their relevance to consumers, the studies were released early by The Journal of the American Medical Association. They will appear in the journal's Oct. 4 issue.

In an editorial accompanying the studies, FDA drug safety reviewer David J. Graham, MD, MPH -- writing for himself and not for the FDA -- notes that safety problems with Vioxx were apparent long before the drug was removed from the market. But because the FDA had no definitive proof of this risk, it did not ban the drug.

Graham -- as well as the authors of one of the papers, Harvard researchers Jingjing Zhang, MD, PhD, and colleagues -- call for major changes in the way the FDA evaluates drug safety.

"We clearly still have a lot to learn about the pharmacological effects of Cox-2 inhibitors," Zhang said, in a news release. "Meanwhile, both physicians and patients should exercise careful consideration before using NSAIDs and Cox-2 inhibitors."

WebMD Special Report: Painkillers Under Fire

By Daniel J. DeNoon, reviewed by Louise Chang, MD

SOURCES: Zhang, J. The Journal of the American Medical Association, Oct. 4, 2006; vol 296, early online release. McGettigan, P. and Henry, D. The Journal of the American Medical Association, Oct. 4, 2006; vol 296, early online release. Graham, D.J. The Journal of the American Medical Association, Oct. 4, 2006; vol 296, early online release. News release, Harvard School of Public Health.