Conditions: Coronary Artery Disease
Keywords: aspirin aspirin resistance aspirin nonresponse cyclooxygenase thromboxane oxidative stress
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 92
Healthy volunteers: no

Brief summary:
The purpose of this study is to evaluate possible mechanisms of aspirin resistance at a molecular level in aspirin-treated patients with coronary artery disease. We hypothesize that certain patient characteristics associate with aspirin resistance. In addition, we will compare the effects of enteric-coated aspirin and chewable aspirin.

Detailed description:
Aspirin is commonly used for its antithrombotic effects in patients at risk for cardiovascular events. Its primary mechanism of action is the irreversible acetylation of platelet cyclooxygenase-1, thereby inhibiting platelet production of thromboxane A2, a potent vasoconstrictor and activator of platelets. Thromboxane A2, the major product of cyclooxygenase cytochrome oxidase (COX-1) in platelets, induces platelet aggregation. Thromboxane B2 is an inactive metabolite/product of thromboxane A2. This primary outcome measures the extent of inhibition of platelet COX-1 by measuring the amount of the metabolite thromboxane B2 in serum.

Previous studies have demonstrated that many patients have recurrent events despite treatment with aspirin, which has been termed "aspirin resistance" or "aspirin nonresponse." This study addresses some of the possible mechanisms for aspirin nonresponse; specifically, we will test the hypothesis that aspirin nonresponse results from states that produce high peroxide concentrations ("oxidative stress") in platelets. In addition, we will evaluate the effect of enteric coating on the pharmacologic efficacy of aspirin in patients with coronary artery disease.

Arms:
arm 1: patients received enteric-coated aspirin 81 mg qd for 2 weeks arm 2: Patients received chewable aspirin 81 mg qd for 2 weeks

Interventions: intervention 1: enteric-coated aspirin intervention 2: Chewable aspirin
Intervention descriptions: intervention 1: enteric-coated aspirin 81mg daily for 2 weeks intervention 2: chewable aspirin 81mg daily for 2 weeks

Protocol document: