Reversal of the Antiplatelet Effects of Ticagrelor in Combination With Aspirin, Using Normal Platelets (REVSTARTS)

April 5, 2017 updated by: Paul Kruger, Hamilton Health Sciences Corporation
The specific objective of this study is to investigate the potential for normal platelets to reverse the inhibition of platelet aggregation in patients treated with ticagrelor in combination with aspirin.

Study Overview

Status

Unknown

Conditions

Intervention / Treatment

Detailed Description

Ticagrelor is one of three commercially available antiplatelet adenosine diphosphate (ADP) antagonists (the other two are clopidogrel and prasugrel). They exert their antiplatelet effects by binding to P2Y12 receptors on the platelet surface. Ticagrelor is used in combination with aspirin to prevent and treat thrombosis in patients with acute coronary syndrome, particularly after stent implantation. ADP antagonists are combined with aspirin because aspirin blocks platelet aggregation by preventing thromboxane production, and blocking two different pathways leads to greater efficacy than either drug used alone. Recent clinical trials indicate ticagrelor in combination with aspirin is more effective for prevention of thrombotic events in patients with symptomatic coronary artery disease than aspirin in combination with clopidogrel, but causes significantly more bleeding. The improved efficacy and reduced safety occurs because ticagrelor causes greater inhibition of ADP-mediated platelet activation. The latter can be reliably measured in the laboratory.

Management of patients who bleed while taking an ADP antagonist in combination with aspirin is challenging because there is no specific antidote, Platelet transfusion has the potential to reverse the effects of clopidogrel or prasugrel and aspirin, but these findings cannot be extrapolated to ticagrelor in combination with aspirin because the pharmacokinetic and pharmacodynamic effects of ticagrelor differ.

Aspirin, clopidogrel active metabolite, and prasugrel active metabolite have half-lives of 15-20 minutes, 30 minutes, and four hours respectively. They are irreversible platelet inhibitors which bind to and permanently block platelet function. After their drug elimination, new platelets which enter the circulation from megakaryocytes in the bone marrow are unaffected. Therefore, after elimination, newly transfused platelets have the potential to restore haemostasis. In contrast, ticagrelor, a reversible platelet inhibitor, has a longer half-life (7.7 to 14.1 hours). As a result of its longer half-life, newly added platelets (both from the bone marrow and transfused platelets) are inhibited by ticagrelor for at least 24 hours after the last dose. Therefore, reversing platelet inhibition and controlling excessive bleeding associated with ticagrelor by platelet transfusion poses a greater challenge than with clopidogrel and prasugrel. Nevertheless, because of its greater efficacy, ticagrelor is preferred over clopidogrel in high risk patients.

Previous studies of platelet transfusion and ev vivo mixing within 24 hours of drug administration have shown than the inhibition of ADP-mediated platelet activation by clopidogrel and prasugrel, but not ticagrelor can be reversed or modulated by the addition of donor platelets. Although reversing the platelet inhibitory effects of ticagrelor might not be possible within 24 hours of stopping the drug, it should be possible in the days that follow. This has not been examined. Accordingly, we propose to perform a study in which we systematically evaluate inhibition of ADP mediated platelet activation, a reliable measure of ticagrelor's antiplatelet activity, when donor platelets are added to the platelets of subjects treated with ticagrelor at time intervals up to 96 hours after their last dose.

Study Type

Interventional

Enrollment (Anticipated)

10

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Ontario
      • Hamilton, Ontario, Canada, L9L 2X2
        • Recruiting
        • Population Health Research Institute
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Healthy subjects
  • At least 18 years of age
  • No history of cardiovascular disease
  • Not taking antiplatelet therapy prior to participation

Exclusion Criteria:

  • Known thrombocytopenia, other coagulation disorder such as von Willebrand's disease, haemophilia
  • Allergy or intolerance to ticagrelor or aspirin (if known)
  • Consumption of drugs within the preceding fourteen days that potentially can interfere with metabolism of ticagrelor through CYP3A4, CYP3A or P-glycoprotein (eg, ketoconazole, clarithromycin, nefazodone, ritonavir, atazanavir, diltiazem, amprenavir, aprepitant, erythromycin, fluconazole, verapamil, rifampicin, dexamethasone, phenytoin, carbamazepine, phenobarbital, cyclosporine, simvastatin, atorvastatin, tolbutamide, digoxin)21
  • Previous transfusion or pregnancy (because of potential alloimmunisation)
  • Pregnant or trying to conceive, or breastfeeding
  • Unable or unwilling to give written informed consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Antiplatelet Treatment
Subjects will be treated with five days of ticagrelor in combination with acetylsalicylic acid.
Drug: Antiplatelet treatment
Subjects will be treated with ticagrelor in combination with acetylsalicylic acid for five days. Ticagrelor will be administered at a loading dose of 180 mg, followed by 90 mg twice daily maintenance dose. Acetylsalicylic acid will be administered at a dose of 81 mg daily.
Other Names:
  • Ticagrelor and acetylsalicylic acid
No Intervention: Control
Subjects will not receive antiplatelet treatment and their PRP will be used as the source of untreated platelets in laboratory mixing studies.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Reversal of platelet inhibition
Time Frame: 5 days
The primary outcome is to measure the efficacy of untreated platelets in reversing the platelet inhibition due to ticagrelor in combination with aspirin by ex vivo mixing studies. Increase in platelet aggregation will be measured by light transmission aggregometry after stimulation by adenosine diphosphate, arachidonic acid, and collagen.
5 days

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Timing of reversal of platelet inhibition
Time Frame: 5 days
The secondary outcome measure is to determine the time point post cessation at which untreated donor platelets reverse the antiplatelet effect of ticagrelor in combination with aspirin.
5 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hamilton Health Sciences Corporation

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

January 1, 2017

Primary Completion (Anticipated)

December 1, 2017

Study Completion (Anticipated)

January 1, 2018

Study Registration Dates

First Submitted

December 26, 2016

First Submitted That Met QC Criteria

December 26, 2016

First Posted (Estimate)

December 29, 2016

Study Record Updates

Last Update Posted (Actual)

April 6, 2017

Last Update Submitted That Met QC Criteria

April 5, 2017

Last Verified

April 1, 2017

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • PopulationHRI

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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