[Acetylsalicylic acid resistance--clinical diagnosis with unclear mechanism].

A review on the subject of aspirin resistance and its role in vascular diseases is presented. Although the clinical diagnosis of aspirin resistance is frequently made, little is known about its biochemical background. Only a few follow-up studies, with varying design, have dealt with the possible association between an aspirin resistant phenotype and clinical outcome in patients with atherothrombosis. However, it was recently shown that ibuprofen acts as a competitive inhibitor in the blockage of COX-1. This pharmacodynamic interaction results in secondary aspirin resistance, which may have clinical significance in patients taking both medicines. With the complex nature of vascular diseases in mind, it is not surprising that aspirin used as a single preventive strategy fails in many cases. At present, there is no clear evidence that treatment failure is associated with a particular aspirin resistant phenotype.