Aspirin is often used to prevent heart attacks and strokes. Patients usually take an 81 mg (baby aspirin) or 325 mg (regular strength) pill. It also comes in plain, enteric coated, or buffered. Enteric coated aspirin is often recommended to decrease the risk of ulcers, the idea being that it doesn't dissolve until it gets past the stomach, though there is limited evidence that it really makes a difference.
Another concern over the past decade is that some patients may be resistant to aspirin, and perhaps needed to be on more expensive medications, such as Plavix (clopidogrel), which recently went generic, though is still pricier than aspirin.
Now a new study from the University of Pennsylvania, published in the journal Circulation, questioned the idea of aspirin resistance, and said that some patients who did not respond to the coated aspirin did respond to plain aspirin. But that does not mean you should conclude that taking coated aspirin may put you at increased risk for a heart attack.
This study looked at 400 health volunteers and gave them a single 325 mg dose of aspirin, either plain or coated, and measured the chemical cyclooxygenase-1 to see if it worked. If they appeared "resistant" then they gave one week each of coated 81 mg aspirin and clopidogrel. Although 49% of the volunteers did not respond to the single aspirin, they all responded to the daily dosing.
So the bottom line is if you take a coated aspirin every day, you probably don't need to be concerned about it not working. If you don't regularly take aspirin, but experience chest pain, after you call 911, take a plain aspirin, and preferably chew it to speed absorption. If you only have coated aspirin, it should work just as well if you chew it. Coated aspirin, made by Bayer and other manufacturers, are a little more expensive than plain aspirin, but are still fairly inexpensive.
Daniel Ginsberg, MD, FACP, is an internal medicine physician who has avidly applied computers to medicine since 1986, when he first wrote medically oriented computer programs. He is in practice in Tacoma, Washington. This post originally appeared on his blog, World's Best Site.