Towards a definition of aspirin resistance: a typological approach

Abstract

'Aspirin resistance' is a poorly defined term to describe the inability of aspirin to protect individuals from thrombotic complications and there are conflicting reports on incidence rates and clinical relevance of this phenomenon. Using collagen (1 microg/ml)-induced platelet aggregation and thromboxane formation (measured as thromboxane B(2)) in citrated platelet-rich plasma, this study demonstrates that aspirin resistance can be classified into three distinct types. In aspirin responders, both, collagen-induced platelet aggregation and thromboxane formation was completely (>95%) inhibited by oral aspirin treatment (100 mg/day). In type I resistance (pharmacokinetic type), oral treatment with aspirin was ineffective but addition of aspirin (100 microM) in vitro resulted in a complete inhibition of collagen-induced platelet aggregation and thromboxane formation. In type II resistance (pharmacodynamic type), neither oral treatment with aspirin nor addition of aspirin in vitro inhibited collagen-induced platelet aggregation and thromboxane formation. In type III resistance (pseudo-resistance), platelet aggregation was induced by a low concentration of collagen (1 microg/ml) despite of a complete inhibition of thromboxane formation by oral aspirin treatment. This typology of aspirin resistance should help to clarify the mechanisms, the actual rate, and the possible clinical consequences of this phenomenon.

Functional and Biochemical Evaluation of Platelet Aspirin Resistance After Coronary Artery Bypass Surgery

“…18 Aspirin resistance involves, besides thromboxane formation, an impaired inhibition of platelet aggregation and an increased expression of P-selectin, a marker of ␣-granule secretion associated with the progression of atherosclerosis. 19 We have previously proposed to classify aspirin resistance into three major categories, 20 of which one (type 1) includes the inhibition of platelet thromboxane formation in vitro but not in vivo (pharmacokinetic type). Type 2 is characterized by the inability of aspirin to inhibit platelet thromboxane formation in vivo and in vitro (pharmacodynamic type).…”

Preparation and characterization of acetylsalicylic acid/chitosan nanoparticles and its antithrombotic effects

“…However, the adverse effects of oral ASA tablets such as gastrointestinal disorders and bleeding often led to treatment discontinuation. Furthermore, many studies found that some patients would get aspirin resistance (AR) or aspirin failure (AF) [5]. All of these limited the application of ASA.…”

Aspirin resistance, an emerging, often overlooked, factor in the management of patients with coronary artery disease

“…Some study the prevalence of aspirin resistance and how to achieve defining its presence, [6][7][8] some study the mechanisms for aspirin resistance, [9][10][11][12] and yet others examine the impact or clin-ical significance of aspirin resistance on the presence or development of cardiovascular disease [13][14][15][16][17][18][19][20][21] (Table I). There is no consensus on the ideal technique for the assessment of the presence of aspirin resistance and therefore no agreement about a standardized definition.…”