Mechanisms of Action of Acetaminophen
Public ClinicalTrials.gov record NCT00646906. Field values are reproduced from the official study page; the official ClinicalTrials.gov record remains the source of truth for eligibility, enrollment, and contact information.
Data is sourced from official ClinicalTrials.gov public API records. Always review the official ClinicalTrials.gov record for the latest information.
Official title
A Randomized, Double-Blind, Crossover Study to Evaluate the Mechanism of Action of Acetaminophen
Brief summary
Reproduced verbatim from the official ClinicalTrials.gov record. Not medical advice.
This research study investigates whether the ability of aspirin to reduce the risk of heart attacks may be diminished by the administration of acetaminophen. Patients who have heart disease are often prescribed aspirin because of its unique ability to permanently prevent platelets from aggregating and forming a blood clot. Such blood clots cause heart attacks when they form in a blood vessel that supplies the heart with oxygen rich blood. Some of these same patients also take acetaminophen everyday for relief from arthritis pain. Higher doses of acetaminophen may also have the ability to prevent the platelets from clotting, however only temporarily. Therefore, this study evaluates whether the timing of the administration of acetaminophen (before or after aspirin) interferes with the permanent blood clotting effects of aspirin. The primary hypothesis is that acetaminophen given two hours before aspirin will antagonize the effects of aspirin, while reversing the order of administration will not.
Study identification
- NCT ID
- NCT00646906
- Recruitment status
- Completed
- Study type
- Interventional
- Phase
- Not applicable
- Enrollment
- 55 participants
Conditions and interventions
Conditions
Interventions
- Aspirin First Drug
- Aspirin Last Drug
- Acetaminophen 1000 mg/d Drug
- Acetaminophen 4000 mg/d Drug
- Ibuprofen 800 mg/d Drug
Drug
Eligibility (public fields only)
- Age range
- 18 Years to 55 Years
- Sex
- All
- Healthy volunteers
- Accepts healthy volunteers
This page does not interpret eligibility. Detailed inclusion and exclusion criteria are on the official ClinicalTrials.gov record.
Study timeline
- Start date
- Jun 1, 2004
- Primary completion
- Jan 23, 2012
- Completion
- Jan 23, 2012
- Last update posted
- Feb 11, 2026
2004 – 2012
United States locations
- U.S. sites
- 1
- U.S. states
- 1
- U.S. cities
- 1
| Facility | City | State | ZIP | Site status |
|---|---|---|---|---|
| Hospital of The University of Pennsylvania | Philadelphia | Pennsylvania | 19104 | — |
Site contact phone numbers, emails, and investigator names are intentionally not displayed here. Open the official ClinicalTrials.gov record for site contact information.
About this trial record page
- What this page shows
- Public field values for ClinicalTrials.gov record NCT00646906, including study identification, conditions, interventions, eligibility (age, sex, healthy volunteer), timeline, and U.S. site list.
- What this page does not do
- No medical advice, eligibility judgments, treatment recommendations, study quality scoring, or AI-generated medical summaries. No site contact phone numbers, emails, or investigator names.
- Where the data comes from
- Sourced from the official ClinicalTrials.gov public API. The official record is the source of truth.
- Last refresh
- Last update posted Feb 11, 2026 · Synced Sep 10, 2026
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Open the official record
The complete protocol, eligibility criteria, and contact information for NCT00646906 live on ClinicalTrials.gov.