A popular painkiller available without prescription can block the benefits of aspirin taken to reduce the risk of heart attack. The discovery by an Irish researcher working in the US means that patients taking both drugs face a higher risk of stroke and heart attack.
Low doses of aspirin are often advised for patients with heart trouble or previous heart attacks because it helps to thin the blood. Prof Garret FitzGerald and colleagues found, however, that a top pain remedy, ibuprofen, given to reduce the pain of arthritis in these same patients, can stop the aspirin doing any good.
Prof FitzGerald is Robinette professor of cardiovascular medicine and chair of the University of Pennsylvania department of pharmacology. He and colleagues publish their findings this morning in the New England Journal of Medicine.
Ibuprofen is one of the most widely used pain remedies. Sold without prescription under familiar brand names such as Advil and Nurofen and also in generic forms, it is particularly effective in relieving the pain of arthritis in elderly patients. Prescription forms such as Brufen are also in widespread use.
Many of these same patients, particularly those considered at high risk of a heart attack, are also encouraged to take low dose aspirin as a way to reduce cardiovascular risks. "A lot of people are taking low dose aspirin to protect themselves from heart attack and stroke. A lot of people are taking painkillers. Our findings have shown that multiple daily doses of ibuprofen can undermine the cardioprotective effects of a daily aspirin regimen," Prof FitzGerald stated.
Aspirin and ibuprofen are two of the most frequently consumed drugs, Prof FitzGerald said. The research team wanted to know whether these and other popular painkillers could interact.
Both drugs target versions of a particular enzyme, a protein called COX. One version, COX-1, is essential for blood clotting and aspirin acts to block it, thus thinning the blood. The second version, COX-2, is linked to the inflammation typical of arthritis, and ibuprofen inhibits this.
Ibuprofen also attaches to COX-1 however and the researchers found that once there it could prevent aspirin from attaching. This stopped its ability to reduce clotting, so patients hoping to reduce their risk of the clots that cause heart attacks got no benefit at all. Other popular painkillers do not seem to have this effect.
The finding "has very big clinical implications", Prof FitzGerald stated.
"The bottom line is the over-the-counter issue: your choice of pain remedy really matters. This means that a doctor needs to consider carefully when advising for pain medication."
