Drug resistance is a debatable phenomenon in many fields of drug therapy. Current definitions of drug resistance are inconsistent and involve various contributing factors. It is our strong belief that electronic compliance monitoring of all solid oral drugs and biomarker measurements form the cornerstones of any study investigating drug resistance.

Successful therapy with inhibitors of blood platelet function is crucial in patients with ischemic vascular disease to prevent fatal or nonfatal clinical events (1996). A proportion of 5.8 – 25% of patients with a prescription for clopidogrel experience therapy failure in terms of inadequately diminished in vitro platelet function (Gladding, Webster et al. 2008), Aspirin resistance in terms of clinical therapy failure have been reported in 10-20% (Angiolillo 2009). A lack of reduction of in vitro platelet aggregation is associated with clinical therapy failure (Angiolillo 2009).

We developped a study design to investigate antiplatelet resistance to aspirin and clopidogrel, which can be seen as a template when investigating drug resistance in general.

Our project aims at:

• discovering the role of noncompliance to the phenomenon of anti-platelet resistance (study A),
• identifying factors associated with nonresponse (study B)
• studying the relationship between compliance and platelet aggregation (study C).

ClinicalTrials.gov Nr. NCT01039480