Experts: Benefits of Aspirin for the Heart Could Be Reduced by the Coating on Pain Pills

For years, aspirin has been seen as a drug that could help prevent heart attacks and strokes due to its blood thinning properties, but a new study is challenging that theory.

The University of Pennsylvania released a study this week, published in the American Heart Association journal "Circulation" that tested whether people were resistant to aspirin's blood thinning effects. The study included 400 healthy volunteers, and was partially funded by the world's largest aspirin manufacturer Bayer, according to the New York Times.

In the study, they found that 49 percent of the patients tested encountered a resistance to absorbing coated aspirin, but not to immediate release aspirin.

"Pseudoresistance, reflecting delayed and reduced drug absorption, complicates enteric coated but not immediate release aspirin administration," the study concluded.

Garret FitzGerald, head of the Institute for Translational Medicine and Therapeutics at the University of Pennsylvania, Philadelphia, and senior author of the report, told Fox News that his team could not find any individuals who were truly resistant to aspirin absorption.

However, the results of the study provide a new look at aspirin, which is usually given to patients with heart problems and blocked arteries as a way to ease circulation. According to Dr. Fitzgerald, roughly 90 percent of aspirin sold for heart protection is coated; manufacturers do this in order to prevent some aspirin-takers from experiencing stomach problems or ulcers as a result of taking the drug.

"When we looked for aspirin resistance using the platelet test, it detected it in about one-third of our volunteers," Dr. Tilo Grosser, a research assistant professor of Pharmacology at UPenn, told Red Orbit.com in a prepared statement. "But, when we looked a second time at the incidence of aspirin resistance in the volunteers, the one-third that we measured who was now resistant was mostly different people. Nobody had a stable pattern of resistance that was specific to coated aspirin."

Some medical experts say that patients taking coated aspirin for heart-related problems should chew on the tablets rather than simply swallowing them whole in order to gain maximum effect.

"Chew the aspirin, don't just swallow it," said ABC News senior health and medical editor Dr. Richard Besser. "You need that anti-clotting effect in your bloodstream as quickly as possible. If you have uncoated aspirin, that's best. If not, take a coated aspirin. But remember: Chew it, don't swallow it."

When asked by ABC News about the results of the study, Bayer representatives questioned the research team's conclusions.

"The authors' suggestion that use of enteric coated aspirin should be questioned, based on these study results, is of concern given the study population and methodology used, neither of which reflect real-world clinical use," spokeswoman Anne Coiley told the news outlet in a statement.