Effects of clopidogrel on "aspirin specific" pathways of platelet inhibition
Effects of clopidogrel on "aspirin specific" pathways of platelet inhibition
The most widely accepted methods of assessing response to clopidogrel involve isolated ADP-induced platelet aggregation. Whilst poor response determined by these assays correlates with adverse clinical events, the number of “poor responders” is far higher than the number of events attributed to treatment failure. Clopidogrel may have effects that cannot be assessed using isolated ADP-induced aggregation.
We have investigated the effect of clopidogrel on Arachidonic Acid (AA) induced platelet activation-an “aspirin specific” pathway using a novel near patient assay. Thirty four volunteers on no medication and 36 patients, on maintenance therapy with aspirin 75 mg daily, were recruited. Blood tests for Thrombelastogram PlateletMapping were taken immediately prior to and 6 hours after administration of a 600 mg clopidogrel loading dose. Changes in the area under the response curve at 15 minutes (AUC15) with both ADP- and AA-stimulation were calculated as were the corresponding percentage platelet and percentage clotting inhibition (%PIn and %CIn). There were predictable and significant changes in the AUC15 of the ADP channel in response to clopidogrel and the corresponding %PIn and %CIn in both volunteers and patients.
There were also significant reductions in the AUC15 of the AA channel (presented as Mean +/- 95%CI), by 27.2 +/- 11.8%, p = 0.005 in volunteers and 35.0 +/- 8.2%, p < 0.001 in patients) and increases in the %PIn and %CIn calculated using the AA channel in volunteers (by 20.0 +/- 11.4%, p + 0.02 and 32.3 +/- 12.8%, p < 0.001 respectively) and patients (by 24.2 +/- 8.6%, p < 0.001 and by 18.0 +/- 8.6, p < 0.001 respectively). Clopidogrel has both independent and aspirin-synergistic effects on AA-induced platelet activation suggesting potentiation of the antiplatelet activity of aspirin. This effect may be clinically important and is not detected by current “gold standard” methods of assessing response to clopidogrel.
platelets, aspirin, angioplasty, stents, clopidogrel
386-390
Hobson, Alex R.
fb159129-d057-45ea-9351-19920a77993e
Qureshi, Zeshan
5742ca8f-1ea4-4b17-9f48-e99249a595d5
Banks, Phil
41d5666b-582d-4bfc-9f0a-78c84ffda976
Curzen, Nick P.
70f3ea49-51b1-418f-8e56-8210aef1abf4
September 2009
Hobson, Alex R.
fb159129-d057-45ea-9351-19920a77993e
Qureshi, Zeshan
5742ca8f-1ea4-4b17-9f48-e99249a595d5
Banks, Phil
41d5666b-582d-4bfc-9f0a-78c84ffda976
Curzen, Nick P.
70f3ea49-51b1-418f-8e56-8210aef1abf4
Hobson, Alex R., Qureshi, Zeshan, Banks, Phil and Curzen, Nick P.
(2009)
Effects of clopidogrel on "aspirin specific" pathways of platelet inhibition.
Platelets, 20 (6), .
(doi:10.1080/09537100903003227).
Abstract
The most widely accepted methods of assessing response to clopidogrel involve isolated ADP-induced platelet aggregation. Whilst poor response determined by these assays correlates with adverse clinical events, the number of “poor responders” is far higher than the number of events attributed to treatment failure. Clopidogrel may have effects that cannot be assessed using isolated ADP-induced aggregation.
We have investigated the effect of clopidogrel on Arachidonic Acid (AA) induced platelet activation-an “aspirin specific” pathway using a novel near patient assay. Thirty four volunteers on no medication and 36 patients, on maintenance therapy with aspirin 75 mg daily, were recruited. Blood tests for Thrombelastogram PlateletMapping were taken immediately prior to and 6 hours after administration of a 600 mg clopidogrel loading dose. Changes in the area under the response curve at 15 minutes (AUC15) with both ADP- and AA-stimulation were calculated as were the corresponding percentage platelet and percentage clotting inhibition (%PIn and %CIn). There were predictable and significant changes in the AUC15 of the ADP channel in response to clopidogrel and the corresponding %PIn and %CIn in both volunteers and patients.
There were also significant reductions in the AUC15 of the AA channel (presented as Mean +/- 95%CI), by 27.2 +/- 11.8%, p = 0.005 in volunteers and 35.0 +/- 8.2%, p < 0.001 in patients) and increases in the %PIn and %CIn calculated using the AA channel in volunteers (by 20.0 +/- 11.4%, p + 0.02 and 32.3 +/- 12.8%, p < 0.001 respectively) and patients (by 24.2 +/- 8.6%, p < 0.001 and by 18.0 +/- 8.6, p < 0.001 respectively). Clopidogrel has both independent and aspirin-synergistic effects on AA-induced platelet activation suggesting potentiation of the antiplatelet activity of aspirin. This effect may be clinically important and is not detected by current “gold standard” methods of assessing response to clopidogrel.
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Published date: September 2009
Keywords:
platelets, aspirin, angioplasty, stents, clopidogrel
Organisations:
Dev Origins of Health & Disease
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Local EPrints ID: 152537
URI: http://eprints.soton.ac.uk/id/eprint/152537
ISSN: 0953-7104
PURE UUID: b8985bba-d7d6-40d5-be58-bf779e993af2
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Date deposited: 14 May 2010 15:01
Last modified: 14 Mar 2024 02:50
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Author:
Alex R. Hobson
Author:
Zeshan Qureshi
Author:
Phil Banks
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