Experts have told us for years that coated aspirin is easier on the stomach, but few have questioned whether that coating might, in fact, reduce aspirin's heart benefits.
Now, though, a new study from the University of Pennsylvania - partly funded by Bayer, a major supplier of safety-coated (also called enteric-coated) aspirin - finds that the coating may reduce or delay aspirin's effect in the blood.
The study, published last week in the journal Circulation, had been designed to discover whether some people are resistant to aspirin's blood-thinning effects. The much-debated theory of "aspirin resistance" is important, given that millions of Americans take a daily aspirin to prevent blood clots that could cause heart attack or stroke.
Some doctors have charged that aspirin resistance is a shaky concept used to get patients to take more expensive prescription medication.
In the new research, 400 healthy volunteers were given either a regular or an enteric-coated 325 milligram aspirin. Researchers wrote that they "failed to identify a single case of true drug resistance." Instead, it appeared that the coating was simply reducing the drug's effects.
Among subjects who took the regular, uncoated aspirin, tests showed it had its intended effect in everyone. Among those who took coated aspirin, however, the protective coating slowed down the drug's release into the bloodstream, making it initially appear as if the aspirin wasn't working.
Garret FitzGerald, M.D., chairman of pharmacology at the University of Pennsylvania and one of the study's authors, said in a statement that there is little evidence that coated aspirin protects the stomach better, and taking it could lead to a false diagnosis of aspirin resistance.
Bayer, however, took issue with some of the study's conclusions and methods, pointing out in a statement that previous studies of coated aspirin have shown that it works comparably to uncoated aspirin, according to the New York Times. "When used as directed," the company said, "both enteric and nonenteric coated aspirin provides meaningful benefits, is safe and effective and is infrequently associated with clinically significant side effects."
One of the authors of a 2003 study that found aspirin resistance in a small percentage of patients also disagreed with the new study's conclusions.
Eric Topol, M.D., with the Scripps Research Institute in La Jolla, California, told the Times that the University of Pennsylvania study looked at only healthy volunteers, "which is very different than studying people who actually have heart disease or other chronic illnesses who are taking various medications." Those conditions or medications could affect the way aspirin works in the body, he told the newspaper.
But cardiologist Sanjay Kaul, M.D., with the Cedars-Sinai Heart Institute in Los Angeles, told Forbes.com that aspirin resistance "has been overblown, driven to a large extent by marketing considerations," including the use of more expensive medication, such as the antiplatelet drug clopidogrel (brand name Plavix).
Those patients who do have heart disease or other conditions, or who take other medications or have sensitive stomachs, should talk with their health providers about whether they should take coated aspirin, or perhaps a regular aspirin together with an antacid.
In other health news:
Knee replacement linked to weight gain. Reuters reports that 30 percent of knee-replacement-surgery patients gained 5 percent or more of their body weight in the five years following surgery, possibly because they spent years, prior to surgery, adapting to knee pain by taking it easy, so they don't automatically change their habits when the pain is reduced.
Federal report: Meditation helps with pain, less with stress. The Los Angeles Times reports that a federal panel gave a scientific stamp of approval to meditation as a means of reducing the severity of chronic and acute pain but found the scientific evidence for meditation reducing stress to be weaker and more inconsistent.