Pain Killer Ibuprofen Blocks Heart-Protecting Action Of Aspirin

The popular pain killer ibuprofen can cripple aspirin’s ability to protect against a heart attack, researchers report in the New England Journal of Medicine.

The results, if confirmed, would have major implications for millions of people who take a small dose of aspirin every day to thin the blood, but who also take ibuprofen, to cope with conditions such as arthritis.

With both sold over-the-counter, researchers urged heart patients on aspirin to consult their doctors before popping ibuprofen for arthritis or other chronic pain.

“It would not do you a lot of good to take one medication only to have another wipe out its effects,” said Dr. Muredach Reilly, a University of Pennsylvania cardiologist who took part in the study.

Ibuprofen, which is found in Motrin and Advil, belongs to a widely used class of pain relievers known as nonsteroidal anti-inflammatory drugs. Some others in the group showed no interference with aspirin’s cardiac benefit, according to the 30-patient study reported in Thursday’s New England Journal of Medicine.

In the study, when a single dose of ibuprofen was taken beforehand, aspirin lost 98 percent of its blood-thinning power. Even when aspirin was taken first, the anti-arthritis regimen of three daily doses of ibuprofen sapped 90 percent of aspirin’s benefit.

The researchers believe that ibuprofen clogs a channel inside a clotting enzyme known as cyclooxygenase-1. Aspirin gets stuck at the bottleneck and can’t reach its own active site inside the enzyme.

“The odds are very heavily stacked against this being a judicious combination for people to take,” said Dr. Garret FitzGerald, at the University of Pennsylvania, the study’s chief researcher.

The findings show no conflict between aspirin and three other arthritis drugs: rofecoxib, diclofenac and the acetaminophen in Tylenol. But the researchers suggest that other drugs with structures like ibuprofen, such as indomethacin, will similarly block aspirin.

“This isn’t an indictment of all nonsteroidals, but it does give one pause,” said Dr. Leslie Crofford, an arthritis specialist at the University of Michigan. She wrote an accompanying editorial.

She said researchers should now study humans to verify if these blood test findings – known as in-vitro results – translate into a real danger of heart attacks, as expected. However, aspirin researcher Dr. Gerald Roth, at the University of Washington, said “the in-vitro data are reasonably convincing.”

However, Fran Sullivan, a spokesman for Advil maker Whitehall-Robins Healthcare, of Madison, N.J., said if the study is right, “it’s more a matter of timing.”

He suggested that regular aspirin be taken two hours before ibuprofen. He said enteric-coated aspirin, which is released more slowly into the blood, could be taken at bedtime without a conflict. He said people should consult their doctors, though.

Dr. Anthony R. Temple, a vice president for Tylenol and Motrin maker Mcneil Consumer & Specialty Pharmaceucials, in Fort Washington, Pa., said the study is small and should be duplicated by other researchers.

“It does suggest that some further research ought to be done,” he said.

The study, which was funded partly by the National Institutes of Health and aspirin seller Bayer, considered aspirin only as a heart drug, although it is often taken for pain.

Earlier studies have suggested another possible conflict: aspirin may combine with some nonsteroidal anti-inflammatories to magnify their separate tendencies to irritate the stomach lining, Crofford said.

On Thursday, the New England Journal of Medicine also published a separate study on unintended effects of aspirin and acetaminophen. The study supervised at the Karolinska Institute in Stockholm, Sweden, shows a two-and-a-half times greater risk of chronic kidney failure in patients who regularly take either drug.

Earlier research suggested similar side effects, but shortcomings in the studies left the question fuzzy.

© MMI, CBS Worldwide Inc. All Rights Reserved. The Associated Press and Reuters Limited contributed to this report.

Published on DrKelley.info, December 21, 2001. Embedded links (if any) may no longer be active. (Ed. 01.11.11)

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