Validation of an Assay to Measure Cyclooxygenase-1 Activity

Not Applicable

Completed

• Conditions: Healthy
• Interventions: Other: Chewable aspirin

• Registration Number: NCT00761891
• Lead Sponsor: Vanderbilt University

Brief Summary

The purpose of this study is to obtain a reference range for a newly developed assay of ex vivo platelet COX-1 activity in normal volunteers taking a routine clinical dose of aspirin.

Detailed Description

Aspirin has been shown to reduce cardiovascular events in at-risk individuals, but some aspirin-treated patients fail to exhibit expected changes in bleeding time and platelet aggregation. Recent evidence has correlated aspirin "non-response" to poor cardiovascular outcomes.

In order to study the mechanisms of aspirin resistance, an assay is needed to measure the catalytic activity of platelet cyclooxygenase (which should be inhibited by aspirin). A common assay in general use is the measurement of thromboxane B2 production in clotting whole blood. This measure, however, is influenced by genetic and environmental variations in the glass-activated coagulation pathway, albumin binding capacity, platelet activation pathways, arachidonic acid pools, and phospholipase activity.

Our laboratory has developed a direct assay of platelet cyclooxygenase (COX-1) activity that is not influenced by these variations. This study will generate a reference range in normal volunteers taking a routine clinical dose of aspirin (81mg daily) for this assay.

Basic Information
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Recruitment & Eligibility
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Study & Design
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Trial Locations

Study Timeline

• Study Start: 2007-05
• Primary Completion: 2008-05
• Study First Submitted: 2008-09-26
• Study First Submitted QC: 2008-09-29
• Study First Posted: 2008-09-30
• Study Completion: 2010-01
• Results First Submitted: 2017-04-10
• Status Verified: 2019-04
• Results First Submitted QC: 2019-04-17
• Last Update Submitted: 2019-04-17
• Results First Posted: 2019-04-18
• Last Update Posted: 2019-04-18

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 64

Inclusion Criteria

• Non-smoker
• No chronic medical illness
• No chronic medications

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Exclusion Criteria

• Aspirin/NSAID use in preceding 14 days
• History of chronic NSAID use
• Currently taking NSAIDs, opioid analgesics, corticosteroids, or anticoagulants
• History of coronary artery disease, myocardial infarction, coronary artery bypass grafting, percutaneous angioplasty, diabetes mellitus, or stroke.
• History of hypertension
• Body mass index > 35
• 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 reactions to aspirin
• Screening platelet count < 100,000/ul or > 500,000/ul
• Screening hematocrit < 35% or > 50%
• Weight less than 110 pounds
• Pregnant females

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Chewable aspirin	Chewable aspirin	81 mg daily for 2 weeks

Primary Outcome Measures

Name	Time	Method
A Reference Range in Normal Volunteers Taking a Routine Clinical Dose of Aspirin (81mg Daily) for 2 Weeks	2 weeks	Determine the level of Thromboxane B2 at which patients with a result above are not fully inhibited, and patients with a TxB2 level below are fully inhibited.; The reference range is the level of serum thromboxane at which participants below have fully inhibited COX-1 and participants above do not have fully inhibited COX-1 activity

Secondary Outcome Measures

Name	Time	Method
Serum Thromboxane	Baseline and at 2 weeks	SerumTxB2: They are formed from the prostaglandin endoperoxides and cause platelet aggregation, contraction of arteries, and other biological effects.

Trial Locations

Locations (1)

Vanderbilt University; 🇺🇸 Nashville, Tennessee, United States