Clinical consequences are still unknown

Aspirin is a highly effective antiplatelet agent that is used by millions of people to reduce cardiovascular morbidity and mortality.1 2However, a recent pharmacodynamic study showed that ibuprofen, a non-aspirin, non-steroidal, anti-inflammatory drug, can inhibit the antiplatelet effects of aspirin.3 This effect occurred in people who took daily ibuprofen before taking aspirin or in those taking ibuprofen regularly. Participants who took a single daily ibuprofen after aspirin did not exhibit an inhibitory effect. It is therefore possible that ibuprofen, if taken regularly or before daily aspirin, could reduce or even negate the beneficial effects of aspirin. If this interaction is clinically relevant it could have enormous public health implications because non-aspirin nonsteroidals are among the most commonly used drugs in the world.4

Designing studies to address the clinical relevance of this interaction presents some unique challenges. The ideal study would accurately measure the use of aspirin and ibuprofen, both prescription and non-prescription, and their frequency of use in the period immediately preceding the outcome. Reliance on prescription records or one time assessments of medication use at baseline are likely to be inaccurate for several reasons. …