Aspirin Might Counter Side Effects of Cox-2 Painkillers

But researchers add new drugs may need to be developed to achieve same effect

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By Randy Dotinga
HealthDay Reporter

TUESDAY, Sept. 13, 2005 (HealthDay News) -- Few prescription drugs have as tarnished a reputation as Vioxx, the painkiller that was removed from the market last September amid reports that it caused heart attacks.

Now, however, researchers are reporting that an old, inexpensive standby -- aspirin -- may actually reduce the nasty cardiovascular effects of Vioxx and its sister medications.

The research was only done in mice, and tests in humans appear to be out of the question. Still, the findings show promise that aspirin could come to the rescue of painkillers known as cox-2 inhibitors, said study senior author Dr. Thomas Coffman, chief of division of nephrology at Duke University in Durham, N.C. "It's at least an idea that we think has some merit."

Last September, Merck & Co. withdrew its billion-dollar blockbuster drug Vioxx from the market. Two similar drugs -- Celebrex and Bextra -- have also come under fire, and the FDA pulled Bextra from the market last spring. Celebrex is still available, but carries heightened label warnings about cardiovascular side effects.

Cox-2 inhibitors are heavy-duty painkillers designed to provide relief without triggering gastrointestinal problems -- unlike aspirin, which can cause stomach bleeding. Similar to aspirin, cox-2s interfere with chemical pathways that contribute to pain in the body.

But like an rescue force that can cause destruction even as it brings relief to a community, some of these drugs seem to also make the body more prone to high blood pressure and other cardiovascular problems.

Essentially, the drugs inhibit a "good guy" hormone, which widens blood vessels and thins blood, and does nothing to a "bad guy" hormone, which constricts blood vessels and makes blood form dangerous clots, Coffman explained.

In the new study, Coffman and his colleagues genetically engineered mice to see what would happen if they tinkered with the hormones. They report their findings in the September issue of Cell Metabolism.

The researchers found that inhibiting both hormones -- the good and the bad -- is safer for the heart, Coffman said. Low doses of aspirin could make that happen by thinning the blood, he said.

But where can researchers go from here? To test the theory behind the study, researchers would need to recruit cox-2 inhibitor users and assign some to take low-dose aspirin and some to take a placebo, said Dr. Scott Solomon, director of noninvasive cardiology at Brigham and Women's Hospital in Boston. In addition to gauging whether the approach reduces cardiovascular problems, it would also reveal if the aspirin boosts stomach bleeding, he said.

But such a study may be unlikely given the reputation of the cox-2 inhibitors.

Instead, study co-author Coffman said it makes the most sense to use the new knowledge to develop new drugs.

The study was funded by the National Institutes of Health and the medical arm of the Veterans Administration.

More information

To learn more about cox-2 drugs, visit the U.S. Food and Drug Administration.

SOURCES: Thomas Coffman, M.D., chief, division of nephrology, and professor, medicine, Duke University, Durham, N.C.; Scott Solomon, M.D., director, noninvasive cardiology, Brigham and Women's Hospital, and associate professor, medicine, Harvard Medical School, Boston; September 2005 Cell Metabolism

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