A comparison of the antiplatelet effects of prasugrel and high-dose clopidogrel as assessed by VASP-phosphorylation and light transmission aggregometry

2008 ◽  
Vol 99 (01) ◽  
pp. 215-222 ◽  
Author(s):  
Christopher D Payne ◽  
Ying G Li ◽  
Nagy A Farid ◽  
John T Brandt ◽  
David S Small ◽  
...  

SummaryPlatelet inhibition as measured by vasodilator-stimulated phosphoprotein (VASP) and light transmission aggregometry (LTA) have shown concordance following dosing of clopidogrel. No reports have directly compared theVASP assay and LTA at the levels of P2Y12 blockade after loading doses (LDs) of prasugrel or high dose clopidogrel (600 and 900 mg).The aim was to compare theVASP assay and LTA during the loading dose phase of a comparative study of prasugrel and clopidogrel. Prasugrel 60 mg LD/10 mg maintenance dose (MD) and clopidogrel 300 mg/75 mg and 600 mg/75 mg LD/MD regimens were compared in a 3-way crossover study in 41 healthy, aspirin-free subjects. Each LD was followed by seven daily MDs and a 14-day washout period. P2Y12 receptor blockade was estimated using theVASP assay, expressed as platelet reactivity index (VASP-PRI). Platelet aggregation was assessed by light transmission aggregometry (20 and 5 μM ADP).Twenty-four hoursafter prasgurel 60 mg or clopidogrel 300 mg and 600 mg, respectively, VASP-PRI decreased from ∼80% to 8.9%, 54.7%, and 39.0 %, and maximal platelet aggregation (MPA) decreased from ∼79% to 10.8%, 42.7%, and 31.2%, with an overall VASP:MPA correlation of 0.88 (p<0.01). VASP assay responses after the clopidogrel LDs showed a wider range of values (300 mg: 0–93%; 600 mg: 0–80%) than prasugrel (0–13%); MPA responses followed a similar trend. Pearson’s correlation suggested a strong agreement between VASP and LTA (20 μM ADP) for MPA (r=0.86, p<0.0001).VASP and LTA demonstrated concordance across the response range of P2Y12 receptor blockade following thienopyridine LDs.

2006 ◽  
Vol 96 (12) ◽  
pp. 767-773 ◽  
Author(s):  
Agnieszka Pampuch ◽  
Giovanni de Gaetano ◽  
Chiara Cerletti

SummaryThere is need to improve platelet function testing to monitor the response to antiplatelet drugs. We compared flow-cytometric analysis of intraplatelet vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) to light-transmission aggregometry for the detection of drug-induced in-vitro inhibition of the platelet P2Y12 ADP receptor on 22 healthy subjects (10 males, 12 females, 28.5 ± 6.6 years). The platelet reactivity index (PRI) of VASP was calculated both from mean fluorescence intensity (MFI) and percent of fluorescence-positive platelets in the presence of PGE1 with or without ADP (10 µM). Platelet aggregation was induced by ADP (1.25, 2.5 and 5 µM). Cangrelor, a competitive inhibitor of the P2Y12 receptor, preincubated 5 minutes, induced a concentration-dependent inhibition of platelet ADP-receptor function in both tests. Indeed PRI (%) based on either MFI or percent platelets gated were highly correlated with each other (r = 0.97, p<0.0001) and with aggregation in- duced by ADP. The IC50 of cangrelor against each of the three ADP concentrations used in aggregometry increased from 5.8 ± 3.4 nM to 23.1 ± 4.0 nM and to 98 ± 25 nM, respectively. The IC50 of cangrelor based on VASP-P was within the same range (25.5 ± 7.7 nM). No correlation was observed between IC50 values of cangrelor and ADP concentrations giving 50% effect (EC50) in the absence of the drug. However, at 10 nM cangrelor seven subjects could be identified by the VASP-P assay as “low responders” to the drug (PRI> 50%), and six of them also had an aggregation response to 5 µM ADP > 50%. These six subjects showed the lowest ADP EC50 values in the absence of the drug, possibly reflecting high sensitivity of their platelet P2Y12 receptors to ADP. In conclusion, both the VASP-P assay and light-transmission aggregometry detect in a comparable way in-vitro pharmacological inhibition of the platelet P2Y12 ADP receptor and its individual variability.


2020 ◽  
Vol 9 (2) ◽  
pp. 332
Author(s):  
Jean-Christophe Bélanger ◽  
Fabio Luiz Bandeira Ferreira ◽  
Mélanie Welman ◽  
Rahma Boulahya ◽  
Jean-François Tanguay ◽  
...  

The vasodilator-associated stimulated phosphoprotein (VASP) phosphorylation level is a highly specific method to assess P2Y12 receptor inhibition. Traditionally, VASP phosphorylation is analyzed by flow cytometry, which is laborious and restricted to specialized laboratories. Recently, a simple ELISA kit has been commercialized. The primary objective of this study was to compare the performance of VASP assessment by ELISA and flow cytometry in relation to functional platelet aggregation testing by Multiplate® whole-blood aggregometry. Blood from 24 healthy volunteers was incubated with increasing concentration of a P2Y12 receptor inhibitor (AR-C 66096). Platelet function testing was carried out simultaneously by Multiplate® aggregometry and by VASP assessment through ELISA and flow cytometry. As expected, increasing concentrations of the P2Y12 receptor inhibitor induced a proportional inhibition of platelet aggregation and P2Y12 receptor activation across the modalities. Platelet reactivity index values of both ELISA- and flow cytometry-based VASP assessment methods correlated strongly (r = 0.87, p < 0.0001) and showed minimal bias (1.05%). Correlation with Multiplate® was slightly higher for the flow cytometry-based VASP assay (r = 0.79, p < 0.0001) than for the ELISA-based assay (r = 0.69, p < 0.0001). Intraclass correlation (ICC) was moderate for all the assays tested (ICC between 0.62 and 0.84). However, categorization into low, optimal, or high platelet reactivity based on these assays was strongly concordant (κ between 0.86 and 0.92). In conclusion, the consensus-recommended assays with their standardized cut-offs should not be used interchangeably in multi-center clinical studies but, rather, they should be standardized throughout sites.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1245-1245
Author(s):  
Alexander O Spiel ◽  
Ulla Derhaschnig ◽  
Petra Jilma-Stohlawetz ◽  
Bernd Jilma

Abstract Abstract 1245 Background: P2Y12 receptor antagonists have become a mainstay for the treatment of cardiovascular diseases. Yet, they have rarely been evaluated under pathophysiological conditions apart from arterial diseases. Objectives: We hypothesized interactions between prasugrel and enhanced von Willebrand Factor (VWF) release in a model of systemic inflammation, and compared the pharmacodynamic effects of prasugrel versus placebo on agonist-induced platelet aggregation and shear-induced platelet plug formation. Subjects/Methods: Twenty healthy male volunteers were enrolled in a double-blind, placebo-controlled two-way cross-over trial. Each volunteer received either placebo or a 60 mg-loading dose of prasugrel two hours before endotoxin infusion. Platelet inhibition was measured with Multiple Electrode Aggregometry (MEA), the Platelet Function Analyzer-100 (PFA-100) and the Vasodilator Stimulated Phosphoprotein (VASP) phosphorylation assay, respectively. Results: Prasugrel reduced the platelet reactivity index in the VASP assay from 79% to 5–7%, and unequivocally prolonged the closure times of the Innovance cartridge to >300s, but also the CADP-CT to >300s in the majority of subjects. Prasugrel not only blunted platelet aggregation induced by ADP (−81%), but also other pathways including arachidonic acid (−60%), ristocetin (−75%; p<0.001 for all), and to a lesser degree collagen or thrombin receptor activating peptide (TRAP). Prasugrel decreased shear-induced platelet plug formation but VWF release during endotoxemia partly antagonized the inhibitory effect of prasugrel as measured with the PFA-100. Endotoxemia acutely decreased ristocetin and TRAP induced platelet aggregation, and enhanced ristocetin induced aggregation after 24h. Conclusions: These data for the first time demonstrate that strong in vivo blockade of P2Y12 by prasugrel inhibits a broad spectrum of platelet aggregation pathways. However, VWF release may reduce prasugrel's effects under high shear conditions. Disclosures: No relevant conflicts of interest to declare.


2017 ◽  
Vol 117 (05) ◽  
pp. 940-947 ◽  
Author(s):  
Mark R. Thomas ◽  
Dominick J. Angiolillo ◽  
Marc P. Bonaca ◽  
Ramzi A. Ajjan ◽  
Heather M. Judge ◽  
...  

SummaryDiabetes increases cardiovascular risk and reduces pharmacodynamic response to some oral antiplatelet drugs. This study aimed to determine whether ticagrelor 60 mg twice daily (bid) provided potent and consistent platelet inhibition in patients with vs without diabetes in the PEGASUS-TIMI 54 platelet function substudy. Out of 180 patients studied, 58 patients were randomised to and had received at least four weeks of ticagrelor 60 mg bid, with 20 (34 %) having diabetes, 58 patients received ticagrelor 90 mg bid, with 12 (21 %) having diabetes, and 64 patients received placebo, with 18 (28 %) having diabetes. Blood was sampled pre- and 2 hours post-maintenance dose. In patients treated with ticagrelor 60 mg bid, on-treatment platelet reactivity to ADP, as determined by light transmission aggregometry (LTA), VerifyNow and VASP, was similar in patients with vs without diabetes (LTA post-dose, ADP 20 ?M: 29 ± 14 vs 34 ± 10 %, respectively; p = 0.19). A consistent inhibitory effect of ticagrelor 60 mg bid was observed pre- and post-dose regardless of diabetes status, even in insulin-treated patients. Patients with diabetes did not have an increased incidence of high platelet reactivity in either ticagrelor group. Platelet reactivity was similar in patients with diabetes treated with ticagrelor 60 mg vs 90 mg bid. Pharmacokinetics of ticagrelor were not affected by diabetes status. In conclusion, ticagrelor 60 mg bid is equally effective at reducing platelet reactivity in patients with and without diabetes, yielding a consistently high level of platelet inhibition regardless of diabetes status.


2013 ◽  
Vol 110 (10) ◽  
pp. 777-784 ◽  
Author(s):  
Antonio Tello-Montoliu ◽  
Estela Thano ◽  
Fabiana Rollini ◽  
Ronakkumar Patel ◽  
Ryan E. Wilson ◽  
...  

SummaryDifferent aspirin dosing regimens have been suggested to impact outcomes when used in combination with adenosine diphosphate (ADP) P2Y12 receptor antagonists. Prior investigations have shown that not only aspirin, but also potent ADP P2Y12 receptor blockade can inhibit thromboxane A2-mediated platelet activation. The impact of aspirin dosing on ADP mediated platelet activities is unknown and represents the aim of this in vitro pilot pharmacodynamic (PD) investigation. Twenty-six patients with stable coronary artery disease on aspirin 81 mg/day and P2Y12 naïve were enrolled. PD assessments were performed at baseline, while patients were on 81 mg/day aspirin and after switching to 325 mg/day for 7 ± 2 days with and without escalating concentrations (vehicle, 1, 3, and 10 μM) of prasugrel’s active metabolite (P-AM). PD assays included flow cytometric assessment of VASP to define the platelet reactivity index (PRI) and the Multiplate Analyzer (MEA) using multiple agonists [ADP, ADP + prostaglandin (PGE1), arachidonic acid (AA), and collagen]. Escalating P-AM concentrations showed incremental platelet P2Y12 inhibition measured by VASP-PRI (p<0.001). However, there were no differences according to aspirin dosing regimen at any P-AM concentration (vehicle: p=0.899; 1 ïM: p=0.888; 3 ïM: p=0.524; 10 ïM: p=0.548). Similar findings were observed in purinergic markers assessed by MEA (ADP and ADP+PGE1). P-AM addition significantly reduced AA and collagen induced platelet aggregation (p<0.001 for all measures), irrespective of aspirin dose. In conclusion, aspirin dosing does not appear to affect PD measures of ADP-mediated platelet reactivity irrespective of the degree of P2Y12 receptor blockade. P2Y12 receptor blockade modulates platelet reactivity mediated by alternative activators.


2017 ◽  
Vol 24 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Jing Sun ◽  
Guo-Hong Yang ◽  
Jun-Xiang Liu ◽  
Xin-Lin Liu ◽  
Yong-Qiang Ma ◽  
...  

To investigate potential clinical characteristics associated with discordance between platelet vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) flow cytometry (FCM) assay and light transmission aggregometry (LTA) in defining high on-clopidogrel platelet reactivity (HPR) after ST-segment elevation myocardial infarction (STEMI). In this study, platelet responsiveness was measured by the above 2 methods simultaneously on day 1 and on day 6 of STEMI onset in 90 consecutive patients who underwent primary percutaneous coronary intervention. The FCM-derived platelet reactivity index and LTA-derived platelet aggregation rate were both significantly reduced after dual antiplatelet therapy on day 6. Multiple variable-adjusted logistic regression analysis revealed that smoking (odds ratio [OR]: 4.507, 95% confidence interval [CI]: 1.123-18.09, P = .034) and onset-to-admission time (per 1 hour increase, OR: 1.196, 95% CI: 1.023-1.398, P = .025) both were independent predictors for the discordance between the 2 methods. Additionally, improved correlation and concordance was observed in nonsmokers compared with smokers. Our data show that smoking and prolonged onset-to-admission time are associated with discordance between platelet VASP-P and LTA in defining HPR after STEMI, which should be considered when planning personalized antiplatelet therapy.


Author(s):  
Eimear Dunne ◽  
Karl Egan ◽  
Siobhán McFadden ◽  
David Foley ◽  
Dermot Kenny

AbstractP2Y12 inhibitors are indicated in patients following percutaneous coronary intervention. Several studies have demonstrated that high on treatment platelet reactivity is correlated with outcomes yet prospective studies of guided therapy have failed to show benefit. There is a paucity of studies on the platelet aggregation response to ADP before P2Y12 therapy is started. The aim of this study was to characterize platelet responses to 20 μM ADP by light transmission aggregometry (LTA) in a homogenous population.Platelet aggregation was assessed in 201 patients on dual antiplatelet therapy, 98 patients on aspirin alone and 47 normal, healthy volunteers free from anti-platelet medication.Consensus guidelines suggest that a platelet aggregation response in response to the agonist ADP of <57% is an adequate therapeutic response to P2Y12 inhibition. Seven healthy donors and 38 patients taking aspirin only had aggregation responses below 57%.The results of our study demonstrate that 15% of normal donors and 38% of patients taking aspirin only would be classified as having a therapeutic response to P2Y12 inhibition using current guidelines.


2008 ◽  
Vol 100 (07) ◽  
pp. 83-89 ◽  
Author(s):  
Sasidhar Guthikonda ◽  
Kirankumar Mangalpally ◽  
Rajnikant Patel ◽  
Timothy DeLao ◽  
Angela L. Bergeron ◽  
...  

SummaryAspirin ‘resistance’ (AR) is a phenomenon of uncertain etiology describing decreased platelet inhibition by aspirin. We studied whether (i) platelets inAR demonstrate increased basal sensitivity to a lower degree of stimulation and (ii) platelet aggregation with submaximal stimulation could predict responses to aspirin. Serum thromboxane B2 (TxB2) levels and platelet aggregation with light transmission aggregometry (LTA ) were measured at baseline and 24 hours after 325 mg aspirin administration in 58 healthy subjects. AR was defined as the upper sixth of LTA (≥ 12%) to 1.5 mM AA. Baseline platelet aggregation with sub-maximal concentrations of agonists [ADP 2 µM, arachidonic acid (AA) 0.75 mM, collagen 0.375 and 0.5 µg/ml] was greater in AR subjects compared with non-AR subjects, but not with higher concentrations (ADP 5 µM and 20 µM, AA 1.5 mM and collagen 1 µg/ml). Post-aspirin platelet aggregation was elevated in AR subjects with both submaximal and maximal stimulation. Baseline and post-aspirin serumTxB2 were higher inAR subjects and decreased further with ex-vivo COX -1 inhibition, suggesting incompletely suppressed COX -1 activity. Pre-aspirin platelet aggregation to 0.75 AA demonstrated a dichotomous response with 29/58 subjects having aggregation ≤15% and 29/58 subjects having aggregation ≥75%. In the high aggregation group 28% had AR compared to 6% in the non-AR group (p=0.04). In conclusion, platelets in AR subjects demonstrate increased basal sensitivity to submaximal stimulation, which could predict responses to antiplatelet therapy.


2012 ◽  
Vol 107 (02) ◽  
pp. 388-395 ◽  
Author(s):  
Nicolas Bourguet ◽  
Danièle Boulay-Moine ◽  
Atsuhiro Sugidachi ◽  
Shinji Yamaguchi ◽  
Paul Barragan ◽  
...  

SummaryThienopyridines and other agents target the platelet P2Y12 receptor and inhibit several platelet activities mediated by adenosine diphosphate (ADP). The measurement of vasodilator-associated stimulated phosphoprotein (VASP) phosphorylation, expressed as platelet reactivity index (PRI), mirrors the degree of P2Y12 receptor inhibition and can detect the well-known variable response to clopidogrel. The commercially available VASP assay uses flow cytometry (FC) and requires that the test be run within 48 hours of blood collection. A new ELISA VASP assay offers the advantages of using more widely available technology and the potential to freeze and store samples before analysis. The objectives of the present study were to compare the performance of the ELISA and FC methods and to describe the relative flexibility of the ELISA-based assay. Human blood samples encompassing a wide range of levels of P2Y12 blockade achieved in vitro by preincubation with P2Y12 antagonists or in vivo from patients treated with clopidogrel were included, reflecting the wide spread of values reported in clinical studies. The correlation between the PRI measured by ELISA and FC was highly significant (r=0.95, p<0.001), (n=80). After the initial activation, samples were stable for at least four weeks when frozen (−20°C) prior to analysis by ELISA. Frozen samples from patients treated with clopidogrel appeared stable for up to nine weeks. Based on these results, the ELISA-based assay appears to provide a reliable and more flexible alternative to the FC method to determine P2Y12 receptor blockade and may enable more extensive utilisation of the VASP assay in clinical studies.Note: All work done at BioCytex, Marseille, France and Daiichi Sankyo, Tokyo, Japan.


Author(s):  
Feryal Hashim Rada

Objective: Ticagrelor, cyclopentyl triazolopyrimidine drug, and Clopidogrel, second-generation thienopyridine drug are antiplatelet drugs indicated for the prevention of thrombotic events in patients with acute or chronic coronary syndromes. The aim of this study is to assess efficacy and safety outcomes of ticagrelor treatment versus Clopidogrel treatment in patients with stable coronary artery disease (stable angina) using maximal platelet aggregation percent (MPAP) method and platelet reactivity index percent (PRIP) method.Methods: A total of 42 patients (27 male and 15 female), their ages ranging (48±8) years with stable angina enrolled from Ibn Albitar Center for Cardiac Surgery for this crossover study. After satisfying, the properties of inclusion criteria they screened for clopidogrel treatment 75 mg daily for 2 weeks than after 2 weeks periods of wash off they treated with ticagrelor 90 mg twice daily for another 2 weeks. Platelet reactivity was tested at baseline (before treatment), after 2 weeks treatment with clopidogrel and after another 2 weeks treatment with ticagrelor. Platelet reactivity measured by light transmittance aggregometry test and by vasodilator-stimulated phosphoprotein (VASP) phosphorylation test.Results: The results of MPAP after 2 weeks treatment with clopidogrel or ticagrelor showed high significant reduction in platelet aggregation in patients with ticagrelor treatment as compared to clopidogrel treatment (30±6% vs. 44±8%). As well, the results of PRIP using VASP-phosphorylation after 2 weeks treatment with clopidogrel or ticagrelor showed high significant reduction in platelet aggregation in patients with ticagrelor treatment as compared to clopidogrel treatment (22±5% vs. 36±7%).Conclusion: Treatment with ticagrelor produced a reduction in platelet reactivity consistent with the reduction in major adverse cardiovascular events and improved survival without increasing major bleeding.


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