This trial is active, not recruiting.

Condition platelet aggregation
Treatments aspirin, placebo
Phase phase 4
Sponsor Vanderbilt University
Start date June 2004
End date December 2014
Trial size 150 participants
Trial identifier NCT00748371, GM15431-JAO1


Aspirin has shown to be beneficial to some patients with certain diseases such as coronary artery disease or stroke. We are investigating how aspirin works on regulating platelets and thromboxane over time at different doses. We hope to find the best dose of aspirin and/or other medications to help people who are at risk for heart attack or stroke.

United States No locations recruiting
Other countries No locations recruiting

Study Design

Allocation randomized
Endpoint classification pharmacodynamics study
Intervention model parallel assignment
Masking double blind (subject, investigator)
Primary purpose basic science
ASA 40mg daily for 8 weeks followed by 3 weeks of observation
aspirin acetylsalicylic acid
40mg aspirin: one 40-mg aspirin capsule by mouth each morning + one Avicel capsule by mouth each evening
ASA 1300mg daily for 8 weeks followed by 3 weeks of observation
aspirin acetylsalicylic acid
1300mg aspirin: one 650-mg capsule by mouth twice daily
(Placebo Comparator)
Placebo: one Avicel (cellulose) capsule by mouth twice daily
placebo Avicel
Placebo: one Avicel (cellulose) capsule by mouth twice daily

Primary Outcomes

Comparison of platelet aggregation, serum thromboxane B2 (TxB2) levels, urinary thromboxane metabolite (Tx-M) levels, and urinary prostacyclin metabolite (PGI-M) levels over time and across dose ranges.
time frame: 11 weeks

Eligibility Criteria

Male participants at least 18 years old.

Inclusion Criteria: - Males - Age 18-40 years - Non-smokers Exclusion Criteria: - ASA/NSAID use previous 14 days. - Evidence of ASA/NSAID use within previous 14 days at baseline visit based on investigator interpretation of platelet aggregation and platelet secretion studies. - History of chronic NSAID use. - Currently taking NSAIDs, corticosteroids, or anticoagulants. - History of coronary artery disease, myocardial infarction, coronary artery bypass grafting, percutaneous angioplasty, diabetes mellitus or stroke. - History of gastric,duodenal, or esophageal ulcers or serious gastrointestinal bleed. - History of frequent headaches, pain syndrome, or other condition requiring frequent use of analgesics. - History of adverse reaction to ASA. - Initial platelet count <100K/µl or >500K/µl. - Initial hematocrit <35% or >50%. - Weight less than 110 pounds.

Additional Information

Official title Loss of Effect of Aspirin on Platelet Aggregation During Chronic Administration
Principal investigator John A Oates, M.D.
Description he purpose of the study is to better understand the mechanism for failure of daily aspirin administration to prevent cardiovascular events in some at risk individuals. We seek to describe the effect of chronic aspirin administration at varying doses on platelet aggregation. This will help to define mechanisms for aspirin failure and to pursue possible alternative therapies in patients who fail to respond to aspirin therapy. We hypothesize that (1) inhibition by aspirin (ASA) of ex vivo-induced platelet aggregation varies in a predictable time and dose dependent manner, (2) thromboxane and prostacyclin production is inhibited by ASA in a dose-dependent manner and remains relatively constant over time once maximal inhibition has occurred, and (3) granule secretion by platelets during induced aggregation is inhibited by aspirin acutely but this effect does not persist during chronic administration at high doses.
Trial information was received from ClinicalTrials.gov and was last updated in January 2010.
Information provided to ClinicalTrials.gov by Vanderbilt University.