Ibuprofen And Low-Dose Aspirin Best Separated

By Elizabth Mechatie

Concomitant use of low-dose aspirin and ibuprofen may interfere with aspirin's antiplatelet effects, possibly attenuating its cardioprotective benefits, according to the Food and Drug Administration.

"Platelet function tests suggest there is a pharmacodynamic interaction between 400 mg of ibuprofen and low-dose aspirin when they are dosed concomitantly," the FDA reported in a paper that was posted on its MedWatch site on September 8.

Although the implications of this pharmacodynamic interaction have yet to be evaluated using clinical end points, the evidence of such an interaction is important, "because the cardioprotective effect of aspirin, when used for secondary prevention of myocardial infarction, could be attenuated," the paper said.

Not enough data are available to address the effect of taking less than 400 mg of ibuprofen on aspirin's cardioprotective benefits. Nor are there "clear data" on the potential antiplatelet effects associated with chronic use of ibuprofen at doses above 400 mg.

The FDA advised health care professionals to counsel those patients taking immediate-release low-dose (81 mg) aspirin (not enteric coated) and also 400 mg of ibuprofen to take the ibuprofen at least 8 hours before or at least 30 minutes after taking the aspirin.

This dosing approach can minimize the pharmacodynamic interaction that occurs between the two drugs.

Other analgesics that do not interfere with aspirin's antiplatelet effects "should be considered" for those patients who are at high risk for cardiovascular events, according to the paper.

However, other nonselective, over-the-counter NSAIDs should also be considered as having the potential to affect the antiplatelet benefits of aspirin "unless proven otherwise."

The recommendation regarding the timing of the ibuprofen dose does not apply to those patients who are taking enteric-coated low-dose aspirin, and, as such, an advisement cannot be made based on the data available.

Only one study has so far shown that when a dose of 400 mg of ibuprofen is administered to patients at 2, 7, and 12 hours after an enteric-coated low-dose aspirin, the antiplatelet effects are attenuated.

The mechanism suspected to be underlying the interatction between aspirin and ibuprofen may be due to a "competitive inhibition of the acetylation site of cyclooxygenase in the platelet," according to the FDA statement.

Occasional use of ibuprofen, the FDA said, is unlikely to have a negative impact on aspirin's cardioprotective effects because of the long-lasting effects of daily aspirin.

The notice on the drug interactions and the timing recommendations can be found on the FDA's Medwatch site at www.fda.gov/medwatch/safety/2006/safety06.htm#aspirin.