Millions of Americans take low-dose aspirin every day to prevent heart attacks and strokes. But a study published last week challenges some cherished beliefs about the familiar remedy, leaving some consumers to wonder if they should throw out their coated pills and others concerned that they may be taking expensive substitutes unnecessarily.
The study, published in the journal Circulation, by researchers at the University of Pennsylvania, tested 400 healthy people for evidence that aspirin did not work in them, a phenomenon called "aspirin resistance." Aspirin prevents blood platelets from sticking together, which can lead to heart attacks and strokes. Previous studies have estimated that anywhere from five to 40 per cent of the population is resistant to aspirin's effects.
But the study essentially found that the condition doesn't exist: they could not document a single case of true aspirin resistance in their sample. What had appeared to be aspirin resistance, they said, was caused by the coating commonly used on aspirin pills intended to protect the stomach. The coating slowed the drug's absorption into the body.
The study didn't evaluate whether coated aspirin was less likely to prevent heart attacks or strokes, said Dr. Garret FitzGerald, one of the authors. And people who took the coated aspirin in his study eventually showed a response to it.
But people who seek out coated aspirin may be doing so unnecessarily, he said, especially since previous studies have not consistently shown that the coating even prevents gastric problems. "There's no rationale for you to be on coated aspirin," said FitzGerald, who is a cardiologist and chairman of pharmacology at the University of Pennsylvania.
Some cardiologists have begun advising patients to seek out uncoated aspirin because other studies have suggested that the uncoated type may be more effective. But finding it isn't so easy. Even cheaper store brands, like those sold by CVS and Wal-Mart, come with an enteric coating. One of the few uncoated aspirins on the market is St. Joseph's chewable variety – the old orange-flavored baby aspirin.
But other experts, like Dr. Steven E. Nissen, a cardiologist at the Cleveland Clinic, see no real harm in taking coated aspirin, which is cheap and readily available. Many major studies of aspirin have been conducted using the coated variety.
-New York Times Service.
