| Research Targets Cardiac-Patient Aspirin Tolerance Tuesday, February 20, 2001 BY NORMA WAGNER - THE SALT LAKE TRIBUNE Aspirin, the so-called wonder drug, is known as a pill for whatever ails you. But for some, the tablet works no wonders, and LDS Hospital cardiologists are trying to figure out why. The cardiac unit over the past month enrolled 190 out of an optimal 300 patients in a clinical trial designed to determine if aspirin as a blood thinner simply does not work on some people, and if regular users eventually develop a resistance to the drug. The trial follows preliminary findings from a recent study at the Cleveland Clinic Foundation that showed nearly 6 percent of cardiac patients who were taking a full 325-milligram aspirin daily were completely resistant to the drug's effects. Almost one-quarter of the patients were "semi-responders," meaning they exhibited problems in benefiting from its use. The LDS Hospital study involves collecting blood samples from cardiac patients who take an aspirin daily to prevent blood clots that can lead to stroke or heart attacks. Researchers will test the blood to learn the body's response to aspirin. Aspirin normally blocks the production of platelets, the blood's protective mechanism that stops bleeding. Once activated, platelets become sticky and clump together to seal broken blood vessels and release substances that help promote clotting. In heart patients, by preventing platelet production, the aspirin helps prevent blockages that can cause heart attacks. Blood samples from the cardiac patients will be compared with samples from a control group of patients who do not take aspirin on a regular basis. "We don't know if people are developing a resistance to aspirin, or whether there are some people who are naturally resistant to aspirin from the start. That's what we're hoping to figure out," said J. Brent Muhlestein, director of cardiac research at LDS Hospital. "We'd like to determine the prevalence of these scenarios and then use future studies and analysis to see whether aspirin resistance is present or predictive of future complications." If resistance is occurring due to chronic aspirin use, and if it's happening in high-risk cardiac or stroke patients, physicians may be forced to look at a new generation of alternative drugs to provide a protective benefit for sufferers of heart disease. One such drug is Plavix, generically known as clopidogrel, which works like aspirin in that it locks the body's activation of platelets in the bloodstream. But Plavix is expensive, costing $169.23 for a two-month supply compared with $2.49 for 100 aspirin. There are two other categories of patients where aspirin poses a problem -- those who are allergic to the drug, which is made from the bark of willow trees, and those who simply need multiple doses of aspirin to reap its desired effects. If it turns out that, for whatever reason, there is a population of cardiac patients that is aspirin-resistant, Muhlestein said the next step will be determining whether they are completely immune to its blood-thinning benefits and therefore more prone to suffer a heart-attack than their nonresistant counterparts. "If so, then aspirin resistance does create a larger problem and would indicate another direction we should head in," he said. "If there are certain people who are not getting the benefits of aspirin, it would be nice if they had an alternative in the future." |
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