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Sreedharan R, Gandhi T. Masters of Mediation: MN(SiMe 3) 2 in Functionalization of C(sp 3)-H Latent Nucleophiles. Chemistry 2024; 30:e202400435. [PMID: 38497321 DOI: 10.1002/chem.202400435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/16/2024] [Accepted: 03/18/2024] [Indexed: 03/19/2024]
Abstract
Organoalkali compounds have undergone a far-reaching transformation being a coupling partner to a mediator in unusual organic conversions which finds its spot in the field of sustainable synthesis. Transition-metal catalysis has always been the priority in C(sp3)-H bond functionalization, however alternatively, in recent times this has been seriously challenged by earth-abundant alkali metals and their complexes arriving at new sustainable organometallic reagents. In this line, the importance of MN(SiMe3)2 (M=Li, Na, K & Cs) reagent revived in C(sp3)-H bond functionalization over recent years in organic synthesis is showcased in this minireview. MN(SiMe3)2 reagent with higher reactivity, enhanced stability, and bespoke cation-π interaction have shown eye-opening mediated processes such as C(sp3)-C(sp3) cross-coupling, radical-radical cross-coupling, aminobenzylation, annulation, aroylation, and other transformations to utilize readily available petrochemical feedstocks. This article also emphasizes the unusual reactivity of MN(SiMe3)2 reagent in unreactive and robust C-X (X=O, N, F, C) bond cleavage reactions that occurred alongside the C(sp3)-H bond functionalization. Overall, this review encourages the community to exploit the untapped potential of MN(SiMe3)2 reagent and also inspires them to take up this subject to even greater heights.
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Affiliation(s)
- Ramdas Sreedharan
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India
| | - Thirumanavelan Gandhi
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India
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Douketis JD, Spyropoulos AC, Murad MH, Arcelus JI, Dager WE, Dunn AS, Fargo RA, Levy JH, Samama CM, Shah SH, Sherwood MW, Tafur AJ, Tang LV, Moores LK. Perioperative Management of Antithrombotic Therapy: An American College of Chest Physicians Clinical Practice Guideline. Chest 2022; 162:e207-e243. [PMID: 35964704 DOI: 10.1016/j.chest.2022.07.025] [Citation(s) in RCA: 93] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/10/2022] [Accepted: 07/11/2022] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND The American College of Chest Physicians Clinical Practice Guideline on the Perioperative Management of Antithrombotic Therapy addresses 43 Patients-Interventions-Comparators-Outcomes (PICO) questions related to the perioperative management of patients who are receiving long-term oral anticoagulant or antiplatelet therapy and require an elective surgery/procedure. This guideline is separated into four broad categories, encompassing the management of patients who are receiving: (1) a vitamin K antagonist (VKA), mainly warfarin; (2) if receiving a VKA, the use of perioperative heparin bridging, typically with a low-molecular-weight heparin; (3) a direct oral anticoagulant (DOAC); and (4) an antiplatelet drug. METHODS Strong or conditional practice recommendations are generated based on high, moderate, low, and very low certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology for clinical practice guidelines. RESULTS A multidisciplinary panel generated 44 guideline recommendations for the perioperative management of VKAs, heparin bridging, DOACs, and antiplatelet drugs, of which two are strong recommendations: (1) against the use of heparin bridging in patients with atrial fibrillation; and (2) continuation of VKA therapy in patients having a pacemaker or internal cardiac defibrillator implantation. There are separate recommendations on the perioperative management of patients who are undergoing minor procedures, comprising dental, dermatologic, ophthalmologic, pacemaker/internal cardiac defibrillator implantation, and GI (endoscopic) procedures. CONCLUSIONS Substantial new evidence has emerged since the 2012 iteration of these guidelines, especially to inform best practices for the perioperative management of patients who are receiving a VKA and may require heparin bridging, for the perioperative management of patients who are receiving a DOAC, and for patients who are receiving one or more antiplatelet drugs. Despite this new knowledge, uncertainty remains as to best practices for the majority of perioperative management questions.
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Affiliation(s)
- James D Douketis
- Department of Medicine, St. Joseph's Healthcare Hamilton and McMaster University, Hamilton, ON, Canada.
| | - Alex C Spyropoulos
- Department of Medicine, Northwell Health at Lenox Hill Hospital, New York, NY; Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY; Institute of Health Systems Science at The Feinstein Institutes for Medical Research, Manhasset, NY
| | - M Hassan Murad
- Mayo Clinic Evidence-Based Practice Center, Rochester, MN
| | - Juan I Arcelus
- Department of Surgery, Facultad de Medicina, University of Granada, Granada, Spain
| | - William E Dager
- Department of Pharmacy, University of California-Davis, Sacramento, CA
| | - Andrew S Dunn
- Division of Hospital Medicine, Department of Medicine, Mt. Sinai Health System, New York, NY
| | - Ramiz A Fargo
- Department of Internal Medicine, Loma Linda University Medical Center, Loma Linda, CA; Department of Internal Medicine, Riverside University Health System Medical Center, Moreno Valley, CA
| | - Jerrold H Levy
- Department of Anesthesiology, Critical Care, and Surgery (Cardiothoracic), Duke University School of Medicine, Durham, NC
| | - C Marc Samama
- Department of Anaesthesia, Intensive Care and Perioperative Medicine, GHU AP-HP, Centre-Université Paris-Cité-Cochin Hospital, Paris, France
| | - Sahrish H Shah
- Mayo Clinic Evidence-Based Practice Center, Rochester, MN
| | | | - Alfonso J Tafur
- Department of Medicine, Cardiovascular, NorthShore University HealthSystem, Evanston, IL
| | - Liang V Tang
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong, University of Science and Technology, Wuhan, China
| | - Lisa K Moores
- F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD
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Laine M, Panagides V, Frère C, Cuisset T, Gouarne C, Jouve B, Lemesle G, Paganelli F, Alessi MC, Mancini J, Bonello L. On-Ticagrelor Platelet Reactivity and Clinical Outcome in Patients Undergoing Percutaneous Coronary Intervention for Acute Coronary Syndrome. Thromb Haemost 2020; 121:923-930. [PMID: 33260230 DOI: 10.1055/a-1326-5110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND A strong association between on-thienopyridine platelet reactivity (PR) and the risk of both thrombotic and bleeding events in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI) has been demonstrated. However, no study has analyzed the relationship between on-ticagrelor PR and clinical outcome in this clinical setting. OBJECTIVES We aimed to investigate the relationship between on-ticagrelor PR, assessed by the vasodilator-stimulated phosphoprotein (VASP) index, and clinical outcome in patients with ACS undergoing PCI. METHODS We performed a prospective, multicenter, observational study of patients undergoing PCI for ACS. PR was measured using the VASP index following ticagrelor loading dose. The primary study endpoint was the rate of Bleeding Academic Research Consortium (BARC) type ≥2 at 1 year. The key secondary endpoint was the rate of major adverse cardiovascular events (MACE) defined as the composite of cardiovascular death, myocardial infarction, stroke, and urgent revascularization. RESULTS We included 570 ACS patients, among whom 33.9% had ST-elevation myocardial infarction. BARC type ≥2 bleeding occurred in 10.9% and MACE in 13.8%. PR was not associated with BARC ≥2 or with MACE (p = 0.12 and p = 0.56, respectively). No relationship between PR and outcomes was observed, neither when PR was analyzed quantitatively nor when it was analyzed qualitatively (low on-treatment PR [LTPR] vs. no LTPR). CONCLUSION On-ticagrelor PR measured by the VASP was not associated with bleeding or thrombotic events in ACS patients undergoing PCI. PR measured by the VASP should not be used as a surrogate endpoint in studies on ticagrelor.
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Affiliation(s)
- Marc Laine
- Intensive care Unit, Department of Cardiology, Assistance publique des hopitaux de Marseille, Hôpital Nord, Aix Marseille University, Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
| | - Vassili Panagides
- Intensive care Unit, Department of Cardiology, Assistance publique des hopitaux de Marseille, Hôpital Nord, Aix Marseille University, Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
| | - Corinne Frère
- Institute of Cardiometabolism And Nutrition, INSERM UMRS_1166, GRC 27 GRECO, Sorbonne Université, Paris, France.,Department of Haematology, Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France
| | | | - Caroline Gouarne
- Intensive care Unit, Department of Cardiology, Assistance publique des hopitaux de Marseille, Hôpital Nord, Aix Marseille University, Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France.,Department of Haematology, Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France
| | - Bernard Jouve
- Department of Cardiology, Hospital of Aix-en-Provence, F-13100 Aix-en-Provence, France
| | - Gilles Lemesle
- USIC et Centre Hémodynamique, Institut Cœur Poumon, Centre Hospitalier Universitaire de Lille, Lille, France.,Faculté de Médecine de l'Université de Lille, Lille, France.,INSERM UMR 1011, Institut Pasteur de Lille, Lille, France.,FACT (French Alliance for Cardiovascular Trials), Paris, France
| | - Franck Paganelli
- Intensive care Unit, Department of Cardiology, Assistance publique des hopitaux de Marseille, Hôpital Nord, Aix Marseille University, Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
| | - Marie-Christine Alessi
- Centre for CardioVascular and Nutrition Research (C2VN), INSERM 1263, INRA 1260, Marseille, France
| | - Julien Mancini
- Assistance Publique-Hôpitaux de Marseille, INSERM, IRD, SESSTIM, CHU Timone, Department of Public Health (BIOSTIC), Aix Marseille Université, Marseille, France
| | - Laurent Bonello
- Intensive care Unit, Department of Cardiology, Assistance publique des hopitaux de Marseille, Hôpital Nord, Aix Marseille University, Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
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Alvitigala BY, Gooneratne LV, Constantine GR, Wijesinghe RANK, Arawwawala LDAM. Pharmacokinetic, pharmacodynamic, and pharmacogenetic assays to monitor clopidogrel therapy. Pharmacol Res Perspect 2020; 8:e00686. [PMID: 33200888 PMCID: PMC7670852 DOI: 10.1002/prp2.686] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 12/11/2022] Open
Abstract
Clopidogrel is the most common and widely used antiplatelet agent for patients with coronary artery disease following confirmation by electrocardiographic studies. The nonresponsiveness of patients to clopidogrel and the possibility of testing for clopidogrel resistance by platelet function assays (PFA) are contentious issues. Light transmission aggregometry (LTA) is considered as the gold standard test among all PFA. In this review, the most commonly used PFA used for monitoring the effect of clopidogrel, LTA, vasodilator-stimulated phosphoprotein assay phosphorylation, rotational thromboelastometry (ROTEM) delta and ROTEM platelet, thromboelastography, PFA-100, VerifyNow P2Y12 assay, Multiplate analyzer, Plateletworks assay and pharmacogenetic studies, are comparatively discussed including their principles of action, advantages, and disadvantages. VerifyNow P2Y12 assay can be accepted as the ideal point of care test out of the discussed assays. However, modified assays are required which could overcome the limitations associated with currently available assays.
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Affiliation(s)
- Bhawani Yasassri Alvitigala
- Department of Medical Laboratory ScienceFaculty of Health SciencesThe Open University of Sri LankaNugegodaSri Lanka
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Koessler J, Klingler P, Niklaus M, Weber K, Koessler A, Boeck M, Kobsar A. The Impact of Cold Storage on Adenosine Diphosphate-Mediated Platelet Responsiveness. TH OPEN 2020; 4:e163-e172. [PMID: 32803122 PMCID: PMC7426185 DOI: 10.1055/s-0040-1714254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/09/2020] [Indexed: 11/28/2022] Open
Abstract
Introduction
Cold storage of platelets is considered to contribute to lower risk of bacterial growth and to more efficient hemostatic capacity. For the optimization of storage strategies, it is required to further elucidate the influence of refrigeration on platelet integrity. This study focused on adenosine diphosphate (ADP)-related platelet responsiveness.
Materials and Methods
Platelets were prepared from apheresis-derived platelet concentrates or from peripheral whole blood, stored either at room temperature or at 4°C. ADP-induced aggregation was tested with light transmission. Activation markers, purinergic receptor expression, and P2Y12 receptor function were determined by flow cytometry. P2Y1 and P2X1 function was assessed by fluorescence assays, cyclic nucleotide concentrations by immunoassays, and vasodilator-stimulated phosphoprotein (VASP)-phosphorylation levels by Western blot analysis.
Results
In contrast to room temperature, ADP-induced aggregation was maintained under cold storage for 6 days, associated with elevated activation markers like fibrinogen binding or CD62P expression. Purinergic receptor expression was not essentially different, whereas P2Y1 function deteriorated rapidly at cold storage, but not P2Y12 activity. Inhibitory pathways of cold-stored platelets were characterized by reduced responses to nitric oxide and prostaglandin E1. Refrigeration of citrated whole blood also led to the attenuation of induced inhibition of platelet aggregation, detectable within 24 hours.
Conclusion
ADP responsiveness is preserved under cold storage for 6 days due to stable P2Y12 activity and concomitant disintegration of inhibitory pathways enabling a higher reactivity of stored platelets. The ideal storage time at cold temperature for the highest hemostatic effect of platelets should be evaluated in further studies.
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Affiliation(s)
- Juergen Koessler
- Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Germany
| | - Philipp Klingler
- Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Germany
| | - Marius Niklaus
- Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Germany
| | - Katja Weber
- Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Germany
| | - Angela Koessler
- Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Germany
| | - Markus Boeck
- Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Germany
| | - Anna Kobsar
- Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Germany
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Platelet Reactivity in Patients on Aspirin and Clopidogrel Therapy Measured by a New Bedside Whole-Blood Assay. J Cardiovasc Pharmacol 2020; 73:40-47. [PMID: 30383606 DOI: 10.1097/fjc.0000000000000631] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Various tests are available for measuring on-treatment platelet reactivity. The pharmacologically most specific assays are time-consuming and elaborate. A highly specific and convenient assay would be desirable for clinical routine. In this pilot study, we aimed to examine the ability of a novel bedside whole-blood assay-ROTEM platelet-to evaluate platelet inhibition compared with established assays. Platelet reactivity was investigated in 93 patients. Forty-Seven patients were on permanent aspirin therapy and 46 on dual antiplatelet therapy (DAPT) with aspirin and clopidogrel. We used ROTEM platelet impedance aggregometry (ROTEM-PTL), light transmission aggregometry (LTA), Multiplate electrode aggregometry (MEA) and vasodilator-stimulated phosphoprotein flow cytometry. Receiver operating characteristic (ROC) analyses showed ROTEM-PTL differentiates well between patients on medication and healthy individuals: aspirin: ROCAUC 0.99 (95% confidence interval, 0.97-1.01); P < 0.0001; DAPT treatment: ROCAUC 0.80 (95% confidence interval, 0.69-0.91); P < 0.001. Pearson regression analyses showed moderate correlations between assays. Aspirin: MEA versus ROTEM-PTL r = 0.435, P ≤ 0.001; LTA versus ROTEM-PTL r = 0.048, P = 0.180. DAPT: MEA versus ROTEM-PTL r = 0.398, P = 0.001; LTA versus ROTEM-PTL r = 0.409, P = 0.001; vasodilator-stimulated phosphoprotein versus ROTEM-PTL r = 0.164, P = 0.055. ROTEM platelet distinguished well between treated and healthy individuals but correlated moderately with other assays. Clinical trials are needed to investigate the ability of this new assay to identify patients at risk of adverse events.
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Laine M, Panagides V, Frère C, Cuisset T, Gouarne C, Jouve B, Thuny F, Paganelli F, Alessi MC, Mancini J, Bonello L. Platelet reactivity inhibition following ticagrelor loading dose in patients undergoing percutaneous coronary intervention for acute coronary syndrome. J Thromb Haemost 2019; 17:2188-2195. [PMID: 31351022 DOI: 10.1111/jth.14592] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 07/23/2019] [Indexed: 01/20/2023]
Abstract
BACKGROUND Ticagrelor induces more potent platelet reactivity (PR) inhibition with reduced interindividual variability compared to clopidogrel. Although on-clopidogrel PR was shown to correlate with ischemia and bleeding events, no study has investigated the relationship between on-ticagrelor PR and outcome. OBJECTIVES We aimed to evaluate the relationship between on-ticagrelor PR, assessed by the vasodilator-stimulated phosphoprotein index (VASP), and thrombotic and bleeding events in patients with acute coronary syndrome (ACS) treated by percutaneous coronary intervention (PCI). METHODS We performed a prospective, multicenter observational study on patients treated with PCI for ACS. The VASP index was used to assess PR after ticagrelor loading dose (LD). The primary endpoint was the link between major adverse cardiovascular events (MACE) and PR. RESULTS Among the 530 patients with ACS included, 183 (34.5%) were admitted for ST elevation myocardial infarction. We observed high potency and limited interindividual variability after the ticagrelor LD (VASP 19.1% ± 16.6%). At 1 month, 21 (3.8%) MACE and 29 (5.5%) bleedings ≥ 2 according to the Bleedings Academic Research Consortium (BARC) scale were recorded. Neither MACE nor bleeding was associated with PR (P = .34 and P = .78, respectively). However, there was a strong association between PR and the occurrence of definite acute stent thrombosis (P = .03). Platelet reactivity was the only factor associated with acute definite stent thrombosis. CONCLUSION In patients receiving a ticagrelor LD while undergoing PCI for ACS, PR using the VASP did not predict MACE or bleeding, but it was significantly associated with the occurrence of definite acute stent thrombosis.
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Affiliation(s)
- Marc Laine
- Intensive Care Unit, Department of Cardiology, Assistance Publique-Hôpitaux de Marseille, Hôpital Nord, Aix-Marseille University, Marseille, France
- Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
| | - Vassili Panagides
- Intensive Care Unit, Department of Cardiology, Assistance Publique-Hôpitaux de Marseille, Hôpital Nord, Aix-Marseille University, Marseille, France
- Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
| | - Corinne Frère
- Department of Haematology, Assistance Publique Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France
| | | | - Caroline Gouarne
- Intensive Care Unit, Department of Cardiology, Assistance Publique-Hôpitaux de Marseille, Hôpital Nord, Aix-Marseille University, Marseille, France
- Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
| | - Bernard Jouve
- Department of Cardiology, Hospital of Aix-en-Provence, Aix-en-Provence, France
| | - Franck Thuny
- Intensive Care Unit, Department of Cardiology, Assistance Publique-Hôpitaux de Marseille, Hôpital Nord, Aix-Marseille University, Marseille, France
- Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
| | - Franck Paganelli
- Intensive Care Unit, Department of Cardiology, Assistance Publique-Hôpitaux de Marseille, Hôpital Nord, Aix-Marseille University, Marseille, France
- Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
| | - Marie-Christine Alessi
- Centre for CardioVascular and Nutrition Research (C2VN), INSERM 1263, INRA 1260, Marseille, France
| | - Julien Mancini
- Department of Public Health (BIOSTIC), Aix-Marseille University, Hôpital de la Timone, Marseille, France
| | - Laurent Bonello
- Intensive Care Unit, Department of Cardiology, Assistance Publique-Hôpitaux de Marseille, Hôpital Nord, Aix-Marseille University, Marseille, France
- Mediterranean Association for Research and Studies in Cardiology (MARS Cardio), Marseille, France
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McFadyen JD, Fernando H, Peter K. Off-target drug effects on platelet function: Protecting an Achilles heel of drug development. CURRENT OPINION IN TOXICOLOGY 2019. [DOI: 10.1016/j.cotox.2019.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Investigating the Effect of Demographics, Clinical Characteristics, and Polymorphism of MDR-1, CYP1A2, CYP3A4, and CYP3A5 on Clopidogrel Resistance. J Cardiovasc Pharmacol 2019; 72:296-302. [PMID: 30422888 DOI: 10.1097/fjc.0000000000000627] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Clopidogrel is an antiplatelet agent that is indicated for cardiovascular emergencies and procedures. The drug, however, is subject to response variability leading to therapy resistance. In this research, we explored the demographic, clinical, and genetic factors associated with clopidogrel resistance. Data analysis among our 280 subjects receiving clopidogrel showed some risk factors that are significantly associated with clopidogrel resistance compared with responders. Those were: female sex (P = 0.021), advanced age (P = 0.011), obesity (P = 0.002), and higher body mass index (P = 0.008) and higher platelets count (P = 0.002). However, known polymorphisms of MDR-1, CYP1A2, CYP3A4, and CYP3A5 were not associated with treatment resistance when compared to responders to clopidogrel therapy. Knowledge about such risk factors might provide recommendation in the future about starting doses or monitoring recommendations.
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Norris JW, Watson JL, Tablin F, Kozikowski TA, Knych HK. Pharmacokinetics and competitive pharmacodynamics of ADP-induced platelet activation after oral administration of clopidogrel to horses. Am J Vet Res 2019; 80:505-512. [PMID: 31034271 DOI: 10.2460/ajvr.80.5.505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine pharmacokinetics and pharmacodynamics after oral administration of a single dose of clopidogrel to horses. ANIMALS 6 healthy adult horses. PROCEDURES Blood samples were collected before and at various times up to 24 hours after oral administration of clopidogrel (2 mg/kg). Reactivity of platelets from each blood sample was determined by optical aggregometry and phosphorylation of vasodilator-stimulated phosphoprotein (VASP). Concentrations of clopidogrel and the clopidogrel active metabolite derivative (CAMD) were measured in each blood sample by use of liquid chromatography-tandem mass spectrometry, and pharmacokinetic parameters were determined with a noncompartmental model. RESULTS Compared with results for preadministration samples, platelet aggregation in response to 12.5μM ADP decreased significantly within 4 hours after clopidogrel administration for 5 of 6 horses. After 24 hours, platelet aggregation was identical to that measured before administration. Platelet aggregation in response to 25μM ADP was identical between samples obtained before and after administration. Phosphorylation of VASP in response to ADP (20μM) and prostaglandin E1 (3.3μM) was also unchanged by administration of clopidogrel. Time to maximum concentration of clopidogrel and CAMD was 0.54 and 0.71 hours, respectively, and calculated terminal-phase half-life of clopidogrel and CAMD was 1.81 and 0.97 hours, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Clopidogrel or CAMD caused competitive inhibition of ADP-induced platelet aggregation during the first 24 hours after clopidogrel administration. Because CAMD was rapidly eliminated from horses, clopidogrel administration may be needed more frequently than in other species in which clopidogrel causes irreversible platelet inhibition. (Am J Vet Res 2019;80:505-512).
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Karthik S, Sreedharan R, Gandhi T. A Straightforward Metal-Free and Mild Base Promoted Amidation and Transesterification via
Acyl C-O bond Cleavage-An Expedite Synthesis of Aromatic Amides and Esters. ChemistrySelect 2019. [DOI: 10.1002/slct.201803105] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Shanmugam Karthik
- Department of Chemistry, School of Advanced Sciences; VIT University,Vellore; Tamil Nadu - 632014 India
| | - Ramdas Sreedharan
- Department of Chemistry, School of Advanced Sciences; VIT University,Vellore; Tamil Nadu - 632014 India
| | - Thirumanavelan Gandhi
- Department of Chemistry, School of Advanced Sciences; VIT University,Vellore; Tamil Nadu - 632014 India
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12
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Frelinger AL. Platelet Function Testing in Clinical Research Trials. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00037-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Liguori I, Russo G, Curcio F, Bulli G, Aran L, Della-Morte D, Gargiulo G, Testa G, Cacciatore F, Bonaduce D, Abete P. Oxidative stress, aging, and diseases. Clin Interv Aging 2018; 13:757-772. [PMID: 29731617 PMCID: PMC5927356 DOI: 10.2147/cia.s158513] [Citation(s) in RCA: 2062] [Impact Index Per Article: 343.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Reactive oxygen and nitrogen species (RONS) are produced by several endogenous and exogenous processes, and their negative effects are neutralized by antioxidant defenses. Oxidative stress occurs from the imbalance between RONS production and these antioxidant defenses. Aging is a process characterized by the progressive loss of tissue and organ function. The oxidative stress theory of aging is based on the hypothesis that age-associated functional losses are due to the accumulation of RONS-induced damages. At the same time, oxidative stress is involved in several age-related conditions (ie, cardiovascular diseases [CVDs], chronic obstructive pulmonary disease, chronic kidney disease, neurodegenerative diseases, and cancer), including sarcopenia and frailty. Different types of oxidative stress biomarkers have been identified and may provide important information about the efficacy of the treatment, guiding the selection of the most effective drugs/dose regimens for patients and, if particularly relevant from a pathophysiological point of view, acting on a specific therapeutic target. Given the important role of oxidative stress in the pathogenesis of many clinical conditions and aging, antioxidant therapy could positively affect the natural history of several diseases, but further investigation is needed to evaluate the real efficacy of these therapeutic interventions. The purpose of this paper is to provide a review of literature on this complex topic of ever increasing interest.
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Affiliation(s)
- Ilaria Liguori
- Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - Gennaro Russo
- Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - Francesco Curcio
- Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - Giulia Bulli
- Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - Luisa Aran
- Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - David Della-Morte
- Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy.,San Raffaele Roma Open University, Rome, Italy
| | - Gaetano Gargiulo
- Division of Internal Medicine, AOU San Giovanni di Dio e Ruggi di Aragona, Salerno, Italy
| | - Gianluca Testa
- Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy.,Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy
| | - Francesco Cacciatore
- Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy.,Azienda Ospedaliera dei Colli, Monaldi Hospital, Heart Transplantation Unit, Naples, Italy
| | - Domenico Bonaduce
- Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
| | - Pasquale Abete
- Department of Translational Medical Sciences, University of Naples "Federico II", Naples, Italy
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14
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Phosphorylation of vasodilator-stimulated phosphoprotein contributes to myocardial ischemic preconditioning. Basic Res Cardiol 2018; 113:11. [PMID: 29344719 DOI: 10.1007/s00395-018-0667-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 11/15/2017] [Accepted: 01/03/2018] [Indexed: 12/13/2022]
Abstract
Ischemic preconditioning (IP) is a well-known strategy to protect organs against cell death following ischemia. The previous work has shown that vasodilator-stimulated phosphoprotein (VASP) is involved in cytoskeletal reorganization and that it holds significant importance for the extent of myocardial ischemia reperfusion injury. Yet, the role of VASP during myocardial IP is, to date, not known. We report here that VASP phosphorylation at serine157 and serine239 is induced during hypoxia in vitro and during IP in vivo. The preconditioning-induced VASP phosphorylation inactivates the GP IIb/IIIa integrin receptor on platelets, which results in the reduced formation of organ compromising platelet neutrophil complexes. Experiments in chimeric mice confirmed the importance of VASP phosphorylation during myocardial IP. When studying this in VASP-/- animals and in an isolated heart model, we were able to confirm the important role of VASP on myocardial IP. In conclusion, we were able to show that IP-induced VASP phosphorylation in platelets is a protective mechanism against the deleterious effects of ischemia.
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15
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Farhan S, Jarai R, Wojta J, Tentzeris I, Siller-Matula J, Huber K. Platelet function variability and non-genetic causes. Thromb Haemost 2017; 105 Suppl 1:S60-6. [DOI: 10.1160/ths11-01-0025] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 03/25/2011] [Indexed: 12/16/2022]
Abstract
SummaryDual antiplatelet therapy (DAPT) has been established for the treatment of coronary artery disease, especially in and after acute coronary syndromes, and after coronary interventions. Data suggest that a significant percentage of individuals treated with clopidogrel do not receive the expected therapeutic benefit because of a decreased responsiveness of their platelets, which is caused by several extrinsic and intrinsic mechanisms. The clinical consequence of clopidogrel non-responsiveness is severe cardiovascular complications. Besides genetic variability in response to antiplatelet therapy, non-genetic causes such as drug interactions (proton-pump inhibitors, statins, calcium-channel blockers, coumarine derivates, antibiotics, antimycotics) and co-morbidities (diabetes mellitus, renal failure, obesity) are responsible for this phenomenon. Large clinical trials with standardised laboratory methods and hard clinical endpoints are needed to identify these interactions with clopidogrel and predictors for its non-responsiveness.
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16
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Labruyère C, Reny JL, Chapelle C, Piot M, Fontana P, Gris JC, Delavenne X, Mismetti P, Laporte S, Mallouk N. Prevalence of poor biological response to clopidogrel. Thromb Haemost 2017; 107:494-506. [DOI: 10.1160/th11-03-0202] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 12/14/2011] [Indexed: 12/28/2022]
Abstract
SummaryThe existence of poor biological response to clopidogrel has been shown in some patients. Despite the increasing number of studies, this phenomenon remains difficult to quantify. We performed a systematic review to estimate the prevalence of poor biological response to clopidogrel and investigate the factors known to modulate this. An exhaustive search was performed. Altogether 171 publications were identified, providing data for a total of 45,664 subjects. The estimated prevalence of poor biological response to clopidogrel ranged from 15.9% to 49.5% according to the platelet function assay employed. The assays most frequently used were light transmittance aggregometry (LTA), the vasodilator-stimulated phosphoprotein (VASP) assay and the Verify -now® assay. For all these assays, higher cut-off values were associated with a lower prevalence of poor biological response to clopidogrel. However, when choosing a fixed cut-off point for each assay, the prevalence of poor biological response to clopidogrel was highly variable suggesting that other factors could modulate poor biological response to clopidogrel. Finally, none of the studied factors could apparently explain the variability of poor biological response to clopidogrel. This meta-analysis shows that the prevalence of poor biological response depends on the assay employed, the cut-off value and on various unidentified additional factors.
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17
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Cattaneo M. High on-treatment platelet reactivity – definition and measurement. Thromb Haemost 2017; 109:792-8. [DOI: 10.1160/th12-10-0758] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 01/23/2013] [Indexed: 12/31/2022]
Abstract
SummaryIn the last decade, several studies revealed inter-patient response variability to antiplatelet agents: patients who display negligible or no responses to these drugs are considered poor responders, or “resistant” to treatment. In order to identify poor responders to an antiplatelet drug, laboratory tests of platelet function that specifically explore the platelet activation pathway that is targeted by the drug should be utilised. In addition, they should be performed both at baseline and during treatment: however, most studies explored platelet function during antiplatelet treatment, in order to identify those patients with “high on-treatment platelet reactivity” (HPR), which exposes them to increased risk of major adverse cardiovascular events (MACE). Many tests of platelet function have been used, most of which are able to identify patients at risk of MACE. Unfortunately, universal cut-off values for HPR have not been clearly established yet. In addition, the concordance among different tests in the identification of patients at risk is very poor and the most effective and safe treatment for patients at risk is still unknown.
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18
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Bordet JC, Negrier C, Dargaud Y, Quellec SL. Comparison of current platelet functional tests for the assessment of aspirin and clopidogrel response. Thromb Haemost 2017; 116:638-50. [DOI: 10.1160/th15-11-0870] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 06/29/2016] [Indexed: 12/18/2022]
Abstract
SummaryThe two most widely used antiplatelet drugs in the world are aspirin and clopidogrel. However, some patients on aspirin and/or clopidogrel therapy do not respond appropriately to either aspirin or clopidogrel. This phenomenon is usually called “aspirin/clopidogrel resistance”. Several platelet function tests have been used in various studies for the assessment of aspirin and clopidogrel resistance in healthy individuals and patients admitted in cardiology departments. An accurate assessment of platelet response to aspirin/clopidogrel could benefit patients by proposing tailored-antiplatelet therapy based on test results. However, there is a clear lack of standardisation of such techniques and their analytical variability may induce misinterpretation. After a quick report of the mechanisms responsible for aspirin/clopidogrel resistance, we describe the pre-analytical aspects and the analytical performances of current platelet function tests (Light-transmission aggregometry, whole-blood aggregometry, VerifyNow®, Platelet Function Analyzer®, thromboelastography, VASP assay) that are used for the assessment of aspirin/clopidogrel resistance in clinical studies. Considering the different variables that have to be taken into account with each of the platelet function tests, a particular attention should be paid when interpreting results.
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19
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Akhlaghi F, Khaheshi I, Amirhassani S, Tabrizi R. Do antiplatelet drugs increase the risk of bleeding after tooth extraction? A case-crossover study. Int J Oral Maxillofac Surg 2017; 46:1475-1478. [PMID: 28663019 DOI: 10.1016/j.ijom.2017.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 04/25/2017] [Accepted: 06/05/2017] [Indexed: 10/19/2022]
Abstract
The aim of this study was to assess the risk of bleeding after tooth extraction in patients taking aspirin or clopidogrel. This case-crossover study evaluated patients taking aspirin (80mg/day) or clopidogrel (75mg/day) and undergoing tooth extraction. In the first session, extraction was performed without discontinuing aspirin (group 1) or clopidogrel (group 2). In the second session, patients ceased using antiplatelet drugs 5days prior to tooth extraction. Bleeding was evaluated using a visual analogue scale (VAS) for 72h after tooth extraction. The platelet function assay (PFA) was performed for group 1 and flow cytometry assessment of vasodilator-stimulated phosphoprotein (VASP) was performed for group 2, in both sessions. Thirty-eight patients were studied: 20 in group 1 and 18 in group 2. Analysis of the data did not demonstrate any difference in bleeding severity between sessions 1 and 2 in either group (P>0.05). There was a significant difference between sessions 1 and 2 in group 1 for the mean collagen/epinephrine membrane closure time (PFA) (P=0.001). A significant difference in platelet reactivity index (flow cytometry for VASP) was noted between sessions 1 and 2 in group 2 (P=0.001). According to this case-crossover study, dental extraction can be performed safely without withdrawal of aspirin or clopidogrel.
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Affiliation(s)
- F Akhlaghi
- Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - I Khaheshi
- Cardiovascular Research Centre, Modarres Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - S Amirhassani
- Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - R Tabrizi
- Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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20
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Liu S, Shi X, Tian X, Zhang X, Sun Z, Miao L. Effect of CYP3A4∗1G and CYP3A5∗3 Polymorphisms on Pharmacokinetics and Pharmacodynamics of Ticagrelor in Healthy Chinese Subjects. Front Pharmacol 2017; 8:176. [PMID: 28408884 PMCID: PMC5374142 DOI: 10.3389/fphar.2017.00176] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/16/2017] [Indexed: 01/01/2023] Open
Abstract
Ticagrelor is the first reversible, direct-acting, potent P2Y12 receptor antagonist in management of acute coronary syndromes. It is rapidly absorbed and extensively metabolized. AR-C124910XX, the major active metabolite, antagonizes the P2Y12 receptor at approximately equal potency. The metabolism of ticagrelor to AR-C124910XX involves CYP3A4 and CYP3A5. CYP3A polymorphisms have been well documented, and CYP3A4∗1G (g.20230G>A, rs2242480) and CYP3A5∗3 (g.6986A>G, rs776746) are the most important single nucleotide polymorphisms in Chinese. Genetic differences in CYP3A4 and CYP3A5 expression in human volunteers and patients might affect the clearance of ticagrelor or AR-C124910XX in vivo resulting in subsequent variable patient response. Thus, this study is designed to explore the effects of CYP3A4∗1G and CYP3A5∗3 polymorphisms on the pharmacokinetics and pharmcodynamics of ticagrelor in healthy Chinese subjects. The results indicated that the CYP3A4∗1G polymorphism significantly influenced the pharmacokinetics of AR-C124910XX, and it may be more important than CYP3A5∗3 with respect to influencing ticagrelor pharmacokinetics by increasing CYP3A4 activity. However, the significant effect of CYP3A4∗1G polymorphism on AR-C124910XX plasma levels did not translate into detectable effect on inhibition of platelet aggregation. Therefore, it seems not necessary to adjust the dosage of ticagrelor according to the CYP3A4 or 3A5 genotype.
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Affiliation(s)
- Shuaibing Liu
- Department of Pharmacy, The first affiliated Hospital of Zhengzhou UniversityZhengzhou, China
| | - Xiangfen Shi
- Department of Pharmacy, The first affiliated Hospital of Zhengzhou UniversityZhengzhou, China
| | - Xin Tian
- Department of Pharmacy, The first affiliated Hospital of Zhengzhou UniversityZhengzhou, China
| | - Xiaojian Zhang
- Department of Pharmacy, The first affiliated Hospital of Zhengzhou UniversityZhengzhou, China
| | - Zhiyong Sun
- Department of Pharmacy, The first affiliated Hospital of Zhengzhou UniversityZhengzhou, China
| | - Liyan Miao
- Department of Clinical Pharmacology Research Lab, The first affiliated Hospital of Soochow UniversitySuzhou, China
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21
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Ding P, Wei Y, Chen N, Liu H. Validation of a New ELISA-Based Vasodilator-Associated Stimulated Phosphoprotein Phosphorylation Assay to Assess Platelet Reactivity Index in a Chinese Population. Clin Appl Thromb Hemost 2017; 24:452-461. [PMID: 28110541 DOI: 10.1177/1076029616689300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The level of platelet reactivity during P2Y12-adenosine diphosphate receptor antagonist is associated with ischemic and bleeding risks following percutaneous coronary intervention in acute coronary syndrome. Determining platelet reactivity inhibition may be valuable for confirming effective platelet inhibition for individual patients and identifying patients at risk of bleeding. The enzyme-linked immunosorbent assay (ELISA)-based vasodilator-stimulated phosphoprotein (VASP) assay offers unique advantages over other methods and has not been used in the Chinese population. We enrolled 10 healthy volunteers and 54 patients with acute coronary syndrome. The volunteers received no treatment, and patients were administered a loading dose of clopidogrel or ticagrelor. The platelet reactivity index (PRI) was measured using flow cytometry (FC)-VASP and ELISA-VASP at baseline and 8-hour postloading dose. Blood samples of healthy volunteers and clopidogrel- or ticagrelor-treated patients were frozen and stored for 1, 2, and 4 weeks after initial activation. All frozen samples were tested using ELISA-VASP. The PRI assessed by FC-VASP and ELISA-VASP correlated well showing a high degree of consistency in identifying high or low on-treatment platelet reactivity. No significant time-dependent changes in PRI results were observed in frozen samples stored up to 4 weeks compared to nonfrozen samples. The PRI of ticagrelor-treated patients was lower than that of clopidogrel-treated patients. The ELISA-VASP effectively assesses the PRI, and results obtained from frozen specimens are unaffected by storage and shipment prior to assay. Ticagrelor was superior to clopidogrel in decreasing the PRI.
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Affiliation(s)
- Peng Ding
- 1 Chinese People's Liberation Army General Hospital, Beijing, China.,2 Department of Cardiology, General Hospital of Chinese Armed Police Force, Beijing, China
| | - Yujie Wei
- 2 Department of Cardiology, General Hospital of Chinese Armed Police Force, Beijing, China
| | - Nana Chen
- 2 Department of Cardiology, General Hospital of Chinese Armed Police Force, Beijing, China
| | - Huiliang Liu
- 1 Chinese People's Liberation Army General Hospital, Beijing, China
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22
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Amour J, Garnier M, Szymezak J, Le Manach Y, Helley D, Bertil S, Ouattara A, Riou B, Gaussem P. Prospective observational study of the effect of dual antiplatelet therapy with tranexamic acid treatment on platelet function and bleeding after cardiac surgery. Br J Anaesth 2016; 117:749-757. [DOI: 10.1093/bja/aew357] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2016] [Indexed: 12/20/2022] Open
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23
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den Toom ML, van Leeuwen MW, Szatmári V, Teske E. Effects of clopidogrel therapy on whole blood platelet aggregation, the Plateletworks® assay and coagulation parameters in cats with asymptomatic hypertrophic cardiomyopathy: a pilot study. Vet Q 2016; 37:8-15. [PMID: 27786603 DOI: 10.1080/01652176.2016.1244618] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND Although scientific evidence is limited, clopidogrel is frequently used as prophylaxis for arterial thromboembolism in cats with hypertrophic cardiomyopathy (HCM). OBJECTIVES Evaluating effects of clopidogrel therapy in asymptomatic cats with HCM on (1) conventional whole blood aggregation (WBA), (2) alternative platelet aggregation assessed with tubes of the Plateletworks® assay and (3) standard coagulation parameters. ANIMALS AND METHODS Prospective, randomized, double-blind, placebo-controlled pilot study. Fourteen asymptomatic HCM cats were randomly allocated to receive placebo (n = 5) or clopidogrel (18.75 mg/cat q24h, n = 9) as part of a larger study. Aggregation responses (to 20 µM adenosine diphosphate (ADP) and 10 µg/ml collagen) in WBA and the Plateletworks® assay and standard coagulation parameters were evaluated at baseline and after seven days of therapy. RESULTS Clopidogrel therapy significantly reduced aggregation responses to ADP and collagen in the Plateletworks® agonists tubes (ADP and collagen: P < 0.001), but did not significantly reduce aggregation responses to ADP and collagen in the WBA technique (ADP: P = 0.07, collagen: P = 0.30). Clopidogrel therapy did not show a significant effect on prothrombin time, activated partial thromboplastin time, antithrombin, D-dimers and fibrinogen concentrations. CONCLUSION AND CLINICAL IMPORTANCE Clopidogrel therapy at a dose of 18.75 mg/cat q24h for seven days causes a significant decrease in in vitro platelet aggregation evaluated with the Plateletworks® assay, without affecting standard coagulation parameters in cats with asymptomatic HCM.
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Affiliation(s)
- M L den Toom
- a Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine , Utrecht University , Utrecht , The Netherlands
| | - M W van Leeuwen
- a Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine , Utrecht University , Utrecht , The Netherlands
| | - V Szatmári
- a Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine , Utrecht University , Utrecht , The Netherlands
| | - E Teske
- a Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine , Utrecht University , Utrecht , The Netherlands
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24
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Yin Q, Tai T, Ji JZ, Mi QY, Zhang MR, Huang WJ, Cao CC, Xie HG. Interleukin-10 does not modulate clopidogrel platelet response in mice. J Thromb Haemost 2016; 14:596-605. [PMID: 26712119 DOI: 10.1111/jth.13238] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 12/06/2015] [Indexed: 02/04/2023]
Abstract
UNLABELLED ESSENTIALS: It is unclear whether interleukin-10 (IL-10) could affect clopidogrel metabolism and response. The bioactivation of and response to clopidogrel were determined between mice with or without IL-10. Maximum clopidogrel active metabolite levels were the major driver of platelet response to clopidogrel. IL-10 did not modulate maximum levels of clopidogrel active metabolite and its antiplatelet effects. SUMMARY BACKGROUND Elevated plasma interleukin-10 (IL-10) levels were observed in patients who responded less to clopidogrel (a prodrug that is required for further metabolic bioactivation in the liver). However, no data are currently available suggesting whether there is such an association. OBJECTIVE To systematically explore possible differences in the formation of and response to clopidogrel active metabolite (CAM) in mice with or without IL-10 gene expression. METHODS A single oral dose of clopidogrel (10 mg kg(-1)) was given to IL-10 knockout (KO) mice and wild-type (WT) control mice, respectively, and pharmacokinetic parameters of clopidogrel and CAM were calculated. Moreover, adenosine diphosphate-induced whole-blood platelet aggregation was measured in mice receiving 0, 5, 10, or 20 mg kg(-1) of clopidogrel, respectively. RESULTS Compared with IL-10 KO mice, WT mice had significantly lower area under the plasma concentration-time curve (AUC) of CAM as a result of a shorter mean elimination half-life but had significantly higher AUC of clopidogrel due to slower systemic clearance and smaller volume of distribution. Although AUC of CAM was significantly lower in WT mice than in KO mice, antiplatelet effects of clopidogrel did not differ significantly between the two mouse groups, as their maximum plasma concentrations (Cmax ) of CAM were not significantly different. CONCLUSIONS IL-10 expression level affects AUC rather than Cmax of CAM, but the Cmax of CAM is the major driver of antiplatelet effects of clopidogrel in mice.
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Affiliation(s)
- Q Yin
- General Clinical Research Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - T Tai
- General Clinical Research Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - J-Z Ji
- General Clinical Research Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Q-Y Mi
- General Clinical Research Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - M-R Zhang
- General Clinical Research Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - W-J Huang
- Division of Nephrology, Department of Medicine, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - C-C Cao
- Division of Nephrology, Department of Medicine, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - H-G Xie
- General Clinical Research Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Pharmacology, Nanjing Medical University School of Pharmacy, Nanjing, Jiangsu, China
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25
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Koessler J, Hermann S, Weber K, Koessler A, Kuhn S, Boeck M, Kobsar A. Role of Purinergic Receptor Expression and Function for Reduced Responsiveness to Adenosine Diphosphate in Washed Human Platelets. PLoS One 2016; 11:e0147370. [PMID: 26808867 PMCID: PMC4725951 DOI: 10.1371/journal.pone.0147370] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/04/2016] [Indexed: 01/09/2023] Open
Abstract
Background Washing of platelets is an important procedure commonly used for experimental studies, e.g. in cardiovascular research. As a known phenomenon, responsiveness to adenosine diphosphate (ADP) is reduced in washed platelets, although underlying molecular mechanisms—potentially interfering with experimental results—have not been thoroughly studied. Objectives Since ADP mediates its effects via three purinergic receptors P2Y1, P2X1 and P2Y12, their surface expression and function were investigated in washed platelets and, for comparison, in platelet-rich-plasma (PRP) at different time points for up to 2 hours after preparation. Results In contrast to PRP, flow cytometric analysis of surface expression in washed platelets revealed an increase of all receptors during the first 60 minutes after preparation followed by a significant reduction, which points to an initial preactivation of platelets and consecutive degeneration. The activity of the P2X1 receptor (measured by selectively induced calcium flux) was substantially maintained in both PRP and washed platelets. P2Y12 function (determined by flow cytometry as platelet reactivity index) was partially reduced after platelet washing compared to PRP, but remained stable in course of ongoing storage. However, the function of the P2Y1 receptor (measured by selectively induced calcium flux) continuously declined after preparation of washed platelets. Conclusion In conclusion, decreasing ADP responsiveness in washed platelets is particularly caused by impaired activity of the P2Y1 receptor associated with disturbed calcium regulation, which has to be considered in the design of experimental studies addressing ADP mediated platelet function.
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Affiliation(s)
- Juergen Koessler
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
- * E-mail:
| | - Stephanie Hermann
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
| | - Katja Weber
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
| | - Angela Koessler
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
| | - Sabine Kuhn
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
| | - Markus Boeck
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
| | - Anna Kobsar
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
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26
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Expression and function of purinergic receptors in platelets from apheresis-derived platelet concentrates. BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2015; 14:545-551. [PMID: 26674810 DOI: 10.2450/2015.0073-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 07/17/2015] [Indexed: 01/11/2023]
Abstract
BACKGROUND The storage of platelets affects platelet integrity and functionality, a process named platelet storage lesion (PSL). Reduced adenosine diphosphate (ADP)-induced platelet aggregation is a typical manifestation of PSL. However, the role of ADP receptors in this context has not been evaluated yet. The aim of this study was, therefore, to investigate surface expression and function of the purinergic receptors P2Y1, P2Y12 and P2X1 in stored platelet concentrates. MATERIAL AND METHODS Platelets were obtained from venous whole blood and from apheresis-derived platelet concentrates stored for 0, 2 and 5 days. Purinergic receptor expression was measured by flow cytometry and western blot analysis. Receptor function was determined by calcium-induced fluorescence (P2Y1 and P2X1) or by flow cytometric measurement of the platelet reactivity index (P2Y12). RESULTS The basal surface expression and total content of purinergic receptors remained unchanged throughout storage. After an initial reduction during apheresis, P2X1-mediated calcium flux was maintained, whereas the P2Y1-mediated increase of calcium flux gradually decreased during the course of storage. In contrast, the platelet reactivity index was comparable in freshly obtained and stored platelets. DISCUSSION The function of the P2Y12 receptor is maintained during storage of apheresis-derived platelet concentrates. However, the impairment of P2X1 and especially of P2Y1 receptor function indicated by decreased receptor-mediated calcium flux is an important mechanism contributing to reduced ADP responsiveness of stored platelets.
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27
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Frijhoff J, Winyard PG, Zarkovic N, Davies SS, Stocker R, Cheng D, Knight AR, Taylor EL, Oettrich J, Ruskovska T, Gasparovic AC, Cuadrado A, Weber D, Poulsen HE, Grune T, Schmidt HHHW, Ghezzi P. Clinical Relevance of Biomarkers of Oxidative Stress. Antioxid Redox Signal 2015; 23:1144-70. [PMID: 26415143 PMCID: PMC4657513 DOI: 10.1089/ars.2015.6317] [Citation(s) in RCA: 541] [Impact Index Per Article: 60.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
SIGNIFICANCE Oxidative stress is considered to be an important component of various diseases. A vast number of methods have been developed and used in virtually all diseases to measure the extent and nature of oxidative stress, ranging from oxidation of DNA to proteins, lipids, and free amino acids. RECENT ADVANCES An increased understanding of the biology behind diseases and redox biology has led to more specific and sensitive tools to measure oxidative stress markers, which are very diverse and sometimes very low in abundance. CRITICAL ISSUES The literature is very heterogeneous. It is often difficult to draw general conclusions on the significance of oxidative stress biomarkers, as only in a limited proportion of diseases have a range of different biomarkers been used, and different biomarkers have been used to study different diseases. In addition, biomarkers are often measured using nonspecific methods, while specific methodologies are often too sophisticated or laborious for routine clinical use. FUTURE DIRECTIONS Several markers of oxidative stress still represent a viable biomarker opportunity for clinical use. However, positive findings with currently used biomarkers still need to be validated in larger sample sizes and compared with current clinical standards to establish them as clinical diagnostics. It is important to realize that oxidative stress is a nuanced phenomenon that is difficult to characterize, and one biomarker is not necessarily better than others. The vast diversity in oxidative stress between diseases and conditions has to be taken into account when selecting the most appropriate biomarker.
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Affiliation(s)
- Jeroen Frijhoff
- 1 Faculty of Health, Medicine and Life Sciences, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University , Maastricht, the Netherlands
| | - Paul G Winyard
- 2 University of Exeter Medical School , Exeter, United Kingdom
| | | | - Sean S Davies
- 4 Department of Medicine, Vanderbilt University , Nashville, Tennessee.,5 Division of Clinical Pharmacology, Department of Pharmacology, Vanderbilt University , Nashville, Tennessee
| | - Roland Stocker
- 6 Vascular Biology Division, Victor Chang Cardiac Research Institute , Darlinghurst, New South Wales, Australia .,7 School of Medical Sciences, University of New South Wales , Sydney, New South Wales, Australia
| | - David Cheng
- 6 Vascular Biology Division, Victor Chang Cardiac Research Institute , Darlinghurst, New South Wales, Australia
| | - Annie R Knight
- 2 University of Exeter Medical School , Exeter, United Kingdom
| | | | - Jeannette Oettrich
- 1 Faculty of Health, Medicine and Life Sciences, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University , Maastricht, the Netherlands
| | - Tatjana Ruskovska
- 8 Faculty of Medical Sciences, Goce Delcev University , Stip, Macedonia
| | | | - Antonio Cuadrado
- 9 Centro de Investigación Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) , ISCIII, Madrid, Spain .,10 Instituto de Investigaciones Biomedicas "Alberto Sols" UAM-CSIC , Madrid, Spain .,11 Instituto de Investigacion Sanitaria La Paz (IdiPaz) , Madrid, Spain .,12 Department of Biochemistry, Faculty of Medicine, Autonomous University of Madrid , Madrid, Spain
| | - Daniela Weber
- 13 Department of Molecular Toxicology, German Institute of Human Nutrition (DIfE) , Nuthetal, Germany
| | - Henrik Enghusen Poulsen
- 14 Faculty of Health Science, University of Copenhagen , Copenhagen, Denmark .,15 Bispebjerg-Frederiksberg Hospital , Copenhagen, Denmark
| | - Tilman Grune
- 13 Department of Molecular Toxicology, German Institute of Human Nutrition (DIfE) , Nuthetal, Germany
| | - Harald H H W Schmidt
- 1 Faculty of Health, Medicine and Life Sciences, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University , Maastricht, the Netherlands
| | - Pietro Ghezzi
- 16 Brighton and Sussex Medical School , Brighton, United Kingdom
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Kobayashi M, Kajiwara M, Hasegawa S. A Randomized Study of the Safety, Tolerability, Pharmacodynamics, and Pharmacokinetics of Clopidogrel in Three Different CYP2C19 Genotype Groups of Healthy Japanese Subjects. J Atheroscler Thromb 2015; 22:1186-96. [PMID: 26063503 DOI: 10.5551/jat.28639] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIM We investigated the safety of 600/150 mg regimen of clopidogrel and the pharmacodynamics and pharmacokinetics of both 300/75 mg regimen and 600/150 mg regimen of clopidogrel in 72 Japanese subjects. METHODS A randomized study was conducted in healthy Japanese male subjects. Eligible subjects were stratified by dose regimen (300 mg loading dose of clopidogrel on day 1 followed by a 75 mg maintenance dose from days 2 to 7 or a 600 mg loading dose of clopidogrel on day 1 followed by a 150 mg maintenance dose from days 2 to 7) and CYP2C19 metabolizer group [extensive metabolizers (EMs), intermediate metabolizers (IMs), and poor metabolizers (PMs)]. Platelet aggregation and platelet reactivity were evaluated by measuring the maximum platelet aggregation intensity (MAI) induced by 5 and 20 μM ADP, phosphorylation of vasodilator-stimulated phosphoprotein (VASP), and P2Y12 reaction units (PRU) using the VerifyNow system, respectively. We also measured the plasma concentrations of clopidogrel and its active metabolite H4. RESULTS No treatment emergent adverse events in the 300/75 mg and 600/150 mg regimen were observed in EMs, IMs, and PMs. All CYP metabolizer groups exhibited a lower MAI (%) induced by ADP in the 300/75 mg and 600/150 mg clopidogrel regimens, and MAI (%) in IM group was equipotent to EM irrespective of the clopidogrel dosage. The double dose regimen decreased MAI in the PM group as equipotent to the IM group receiving the standard dose regimen without the extension of bleeding time. No clear relationship of exposure to clopidogrel and CYP2C19 function was observed, whereas active metabolite H4 exposure was likely to be related to CYP2C19 function. CONCLUSION Clopidogrel in the 600/150 mg regimen was well tolerated. All CYP metabolizer groups exhibited a lower MAI (%) induced by ADP and anti-platelet activities analyzed by VASP and VerifyNow test in the 300/75 mg and 600/150 mg regimens in healthy Japanese subjects.
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Joo SJ, Choi JH, Kim SY, Kim KS, Kim YR, Kang SH. An Assay of Measuring Platelet Reactivity Using Monoclonal Antibody against Activated Platelet Glycoprotein IIb/IIIa in Patients Taking Clopidogrel. Korean Circ J 2015; 45:378-85. [PMID: 26413105 PMCID: PMC4580696 DOI: 10.4070/kcj.2015.45.5.378] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 04/10/2015] [Accepted: 04/28/2015] [Indexed: 12/19/2022] Open
Abstract
Background and Objectives Residual platelet reactivity in patients who are taking clopidogrel is commonly measured with VerifyNow assay, which is based on the principle of light transmission aggregometry. However, to evaluate the residual platelet reactivity, it would be more accurate if the reactivity of platelet glycoprotein (GP) IIb/IIIa is directly monitored. In this study, PAC1, a monoclonal antibody against activated platelet GP IIb/IIIa, was used to measure the residual platelet reactivity. Subjects and Methods Twenty seven patients with coronary artery disease taking clopidogrel were enrolled. Platelets in whole blood were stained with fluorescein isothiocyanate (FITC)-conjugated PAC1. Mean fluorescence intensity (MFI) and % positive platelets (PP) were measured with flow cytometry, and the binding index (BI; MFI × %PP/100) was calculated. P2Y12 reaction unit (PRU) and % inhibition of VerifyNow assay were also measured in the usual manner. Results PRU of VerifyNow assay correlated significantly with MFI, %PP, and BI at 10 µM (r=0.59, 0.73, and 0.60, respectively, all p<0.005) and 20 µM of adenosine diphosphate (ADP; r=0.61, 0.75, and 0.63, respectively, all p<0.005). The % inhibition also correlated significantly with MFI, %PP, and BI at 10 µM (r=-0.60, -0.69, and -0.59, respectively, all p<0.005) and 20 µM of ADP (r=-0.63, -0.71, and -0.62, respectively, all p<0.005). Conclusion Direct measurements of the reactivity of platelet GP IIb/IIIa were feasible using PAC1 and flow cytometry in patients taking clopidogrel. Further clinical studies are required to determine the cut-off values which would define high residual platelet reactivity in patients on this treatment protocol.
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Affiliation(s)
- Seung-Jae Joo
- Department of Cardiology, Jeju National University Hospital, Jeju, Korea
| | - Joon-Hyouk Choi
- Department of Cardiology, Jeju National University Hospital, Jeju, Korea
| | - Song-Yi Kim
- Department of Cardiology, Jeju National University Hospital, Jeju, Korea
| | - Ki-Seok Kim
- Department of Cardiology, Jeju National University Hospital, Jeju, Korea
| | - Young Ree Kim
- Department of Laboratory Medicine, Jeju National University Hospital, Jeju, Korea
| | - Sung Ha Kang
- Department of Laboratory Medicine, Jeju National University Hospital, Jeju, Korea
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Mendolicchio GL, Zavalloni D, Bacci M, Roveda M, Quagliuolo V, Anselmi CV, Rota LL, Ruggeri ZM. Tailored antiplatelet therapy in a patient with ITP and clopidogrel resistance. Thromb Haemost 2014; 113:664-7. [PMID: 25428265 DOI: 10.1160/th14-09-0751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 09/25/2014] [Indexed: 11/05/2022]
Affiliation(s)
- Grazia Loredana Mendolicchio
- Grazia Loredana Mendolicchio, MD, PhD, Laboratori di Ricerca Emostasi e Trombosi, Humanitas Clinical and Research Center, via Manzoni 56, 20089 Rozzano (Milano), Italy, Tel.: +39 02 8224 4630, Fax: +39 02 8224 4691, E-mail:
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Spiliopoulos S, Pastromas G, Diamantopoulos A, Katsanos K. Efficacy of clopidogrel treatment and platelet responsiveness in peripheral arterial procedures. Expert Opin Pharmacother 2014; 15:2205-17. [PMID: 25162471 DOI: 10.1517/14656566.2014.953054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
INTRODUCTION Long-term antiplatelet therapy with clopidogrel has been recommended in patients undergoing peripheral arterial procedures. Poor antiplatelet effect of clopidogrel or high on-clopidogrel platelet reactivity (HCPR) has been recently identified in patients with peripheral arterial disease (PAD). AREAS COVERED This review focuses on the use of clopidogrel and the phenomenon of HCPR in PAD patients treated for intermittent claudication or critical limb ischaemia (CLI). The authors summarize current guidelines and recommendations for use of clopidogrel following peripheral arterial procedures and explore the prevalence and clinical impact of HCPR in the PAD population. Underlying mechanisms of HCPR and relevant clinical and genetic factors are analyzed with particular attention to the potential utility of point-of-care platelet function testing (PFT). EXPERT OPINION Clopidogrel is a safe, effective and well-tolerated antiplatelet agent in PAD patients following peripheral arterial revascularization. Dual-antiplatelet therapy could also be considered after complex endovascular procedures. HCPR has been identified in more than 50% of PAD patients on clopidogrel and has been related with significantly increased re-intervention rates. Incidence of HCPR is significantly higher in patients with CLI, diabetes mellitus and chronic renal disease. Personalized antiplatelet therapy on the basis of PFT is an elegant emerging concept for optimization of platelet inhibition and potential identification of patients at increased risk of bleeding and warrants investigation in future large-scale trials.
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Hubertus K, Mischnik M, Timmer J, Herterich S, Mark R, Moulard M, Walter U, Geiger J. Reciprocal regulation of human platelet function by endogenous prostanoids and through multiple prostanoid receptors. Eur J Pharmacol 2014; 740:15-27. [PMID: 25003953 DOI: 10.1016/j.ejphar.2014.06.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 11/18/2022]
Abstract
Platelets are permanently exposed to a variety of prostanoids formed by blood cells or the vessel wall. The two major prostanoids, prostacyclin and thromboxane act through well established pathways mediated by their respective G-protein coupled receptors inhibiting or promoting platelet aggregation accordingly. Yet the role of other prostanoids and prostanoid receptors for platelet function regulation has not been thoroughly investigated. We aimed at a comprehensive analysis of prostanoid effects on platelets, the receptors and pathways involved and functional consequences. We analyzed cAMP formation and phosphorylation of proteins pivotal to platelet function as well as functional platelet responses such as secretion, aggregation and phosphorylation. The types of prostanoid receptors contributing and their individual share in signaling pathways were analyzed and indicated a major role for prostanoid IP1 and DP1 receptors followed by prostanoid EP4 and EP3 receptors while prostanoid EP2 receptors appear less relevant. We could show for the first time the reciprocal action of the endogenous prostaglandin PGE2 on platelets by functional responses and phosphorylation events. PGE2 evokes stimulatory as well as inhibitory effects in a concentration dependent manner in platelets via prostanoid EP3 or EP4 and prostanoid DP1 receptors. A mathematical model integrating the pathway components was established which successfully reproduces the observed platelet responses. Additionally we could show that human platelets themselves produce sufficient PGE2 to act in an autocrine or paracrine fashion. These mechanisms may provide a fine tuning of platelet responses in the circulating blood by either promoting or limiting endogenous platelet activation.
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Affiliation(s)
- Katharina Hubertus
- Institute for Clinical Biochemistry and Pathobiochemistry, University of Wuerzburg, Wuerzburg, Germany
| | - Marcel Mischnik
- Institut für Physik, University of Freiburg, Freiburg, Germany
| | - Jens Timmer
- Institut für Physik, University of Freiburg, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Sabine Herterich
- Institute for Clinical Biochemistry and Pathobiochemistry, University of Wuerzburg, Wuerzburg, Germany
| | - Regina Mark
- Institute for Clinical Biochemistry and Pathobiochemistry, University of Wuerzburg, Wuerzburg, Germany
| | | | - Ulrich Walter
- Center for Thrombosis & Haemostasis, Universitätsklinikum der Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Joerg Geiger
- Institute for Clinical Biochemistry and Pathobiochemistry, University of Wuerzburg, Wuerzburg, Germany; Interdisciplinary Bank of Biomaterials and Data Wuerzburg, Straubmuehlweg 2a, 97078 Wuerzburg, Germany.
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Ambient hemolysis and activation of coagulation is different between HeartMate II and HeartWare left ventricular assist devices. J Heart Lung Transplant 2013; 33:80-7. [PMID: 24418734 DOI: 10.1016/j.healun.2013.11.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 11/13/2013] [Accepted: 11/26/2013] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Thromboembolic and bleeding events in patients with a left ventricular assist device (LVAD) are still a major cause of complications. Therefore, the balance between anti-coagulant and pro-coagulant factors needs to be tightly controlled. The principle hypothesis of this study is that different pump designs may have an effect on hemolysis and activation of the coagulation system. Referring to this, the HeartMate II (HMII; Thoratec Corp, Pleasanton, CA) and the HeartWare HVAD (HeartWare International Inc, Framingham, MA) were investigated. METHODS For 20 patients with LVAD support (n = 10 each), plasma coagulation, full blood count, and clinical chemistry parameters were measured. Platelet function was monitored using platelet aggregometry, platelet function analyzer-100 system ( Siemens, Marburg, Germany), vasodilator-stimulated phosphoprotein phosphorylation assay, immature platelet fraction, platelet-derived microparticles, and von Willebrand diagnostic. RESULTS Acquired von Willebrand syndrome could be detected in all patients. Signs of hemolysis, as measured by lactate dehydrogenase levels (mean, 470 U/liter HMII, 250 U/liter HVAD; p < 0.001), were more pronounced in the HMII patients. In contrast, D-dimer analysis indicated a significantly higher activation of the coagulation system in HVAD patients (mean, 0.94 mg/liter HMII, 2.01 mg/liter HVAD; p < 0.01). The efficacy of anti-platelet therapy using clopidogrel was not sufficient in more than 50% of the patients. CONCLUSIONS Our results support the finding that all patients with rotary blood pumps suffered from von Willebrand syndrome. In addition, a distinct footprint of effects on hemolysis and the coagulation system can be attributed to different devices. As a consequence, the individual status of the coagulation system needs to be controlled in long-term patients.
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Hurst N, Nooney V, Raman B, Chirkov Y, De Caterina R, Horowitz J. Clopidogrel “resistance”: Pre- vs post-receptor determinants. Vascul Pharmacol 2013; 59:152-61. [DOI: 10.1016/j.vph.2013.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 01/01/2023]
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Current diagnostic trends in coagulation disorders among dogs and cats. Vet Clin North Am Small Anim Pract 2013; 43:1349-72, vii. [PMID: 24144095 DOI: 10.1016/j.cvsm.2013.07.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The diagnostic workup to differentiate hemorrhage caused by vascular injury from a systemic hemostatic imbalance typically involves a combination of broad screening tests and specific assays. The characterization of 3 overlapping phases of primary hemostasis, secondary hemostasis, and fibrinolysis provides a simple diagnostic framework for evaluating patients with clinical signs of hemorrhage. New techniques such as flow cytometry, thrombin-generation assays, thrombelastography, and anticoagulant drug monitoring are under investigation for veterinary patients; however, their ability to improve diagnosis or treatment requires further study in clinical trials.
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Brooks MB, Divers TJ, Watts AE, Ness SL, Frye AH, Stokol T, Fubini SL. Effects of clopidogrel on the platelet activation response in horses. Am J Vet Res 2013; 74:1212-22. [DOI: 10.2460/ajvr.74.9.1212] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Platelet Function Testing and Tailored Antiplatelet Therapy. J Cardiovasc Transl Res 2013; 6:316-28. [DOI: 10.1007/s12265-013-9458-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 03/05/2013] [Indexed: 10/27/2022]
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von Papen M, Gambaryan S, Schütz C, Geiger J. Determination of ATP and ADP Secretion from Human and Mouse Platelets by an HPLC Assay. ACTA ACUST UNITED AC 2013; 40:109-16. [PMID: 23652982 DOI: 10.1159/000350294] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 02/26/2013] [Indexed: 12/25/2022]
Abstract
BACKGROUND Secretion of ADP and ATP is an essential prerequisite for platelet aggregation. Impaired nucleotide secretion can cause aggregation defects and increased bleeding risk. Quantitative determination of platelet nucleotide content and exocytosis is thus of importance for the characterization and diagnosis of bleeding phenotypes. For transgenic animal models with hemostatic defects analysis of potential secretion defects is as well imperative. METHODS Supernatants of washed platelets and platelet-rich plasma were analyzed by HPLC for ADP and ATP concentration. Calibration of the HPLC data was accomplished with an internal standard compensating for loss of analyte, detection sensitivity, and interference of the biomatrix. RESULTS HPLC analysis of nucleotide secretion was carried out with human and mouse platelets. Detection limits were determined for washed platelet and platelet-rich plasma samples. In the physiological concentration range linearity with respect to the peak area is maintained. CONCLUSION The method combines reasonable sensitivity with robustness. The internal standard ensures reliable quantification of nucleotide concentrations even in presence of otherwise interfering substances. The low sample consumption renders possible the application to analysis of small samples like in mouse experiments.
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Affiliation(s)
- Michael von Papen
- Institute for Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Germany
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Ikeda Y, Sudo T, Kimura Y. Cilostazol. Platelets 2013. [DOI: 10.1016/b978-0-12-387837-3.00057-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Towards personalized medicine based on platelet function testing for stent thrombosis patients. THROMBOSIS 2012; 2012:617098. [PMID: 23320159 PMCID: PMC3540832 DOI: 10.1155/2012/617098] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 12/02/2012] [Indexed: 02/08/2023]
Abstract
Stent thrombosis (ST) is a severe and feared complication of coronary stenting. Patients who have suffered from ST are usually treated according to the “one-size-fits-all” dosing regimen of aspirin and clopidogrel. Many ST patients show high on-treatment platelet reactivity (HPR) despite this antiplatelet therapy (APT). It has been shown that HPR is a risk factor for major adverse cardiac events. Therefore, ST patients with HPR are at a high risk for recurrent atherothrombotic events. New insights into the variable response to clopidogrel and the advent of stronger P2Y12 inhibitors prasugrel and ticagrelor have changed the attention from a fixed APT treatment strategy towards “personalized APT strategies.” Strategies can be based on platelet function testing, which gives insight into the overall response of a patient to APT. At our outpatient ST clinic, we practice personalized APT based on platelet function testing to guide the cardiologist to a presumed optimal antiplatelet treatment of ST patients. Beside results of platelet function testing, comedication, clinical characteristics, and genetics have to be considered to decide on personalized APT. Ongoing studies have yet to reveal the optimal personalized APT strategy for cardiologists to prevent their patients from atherothrombotic and bleeding events.
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2012 Update to The Society of Thoracic Surgeons Guideline on Use of Antiplatelet Drugs in Patients Having Cardiac and Noncardiac Operations. Ann Thorac Surg 2012; 94:1761-81. [DOI: 10.1016/j.athoracsur.2012.07.086] [Citation(s) in RCA: 228] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 06/19/2012] [Accepted: 07/10/2012] [Indexed: 12/31/2022]
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Moheimani F, Jackson DE. P2Y12 receptor: platelet thrombus formation and medical interventions. Int J Hematol 2012; 96:572-87. [PMID: 23054651 DOI: 10.1007/s12185-012-1188-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 09/20/2012] [Accepted: 09/20/2012] [Indexed: 12/14/2022]
Abstract
Platelets express a wide range of receptors and proteins that play essential roles in thrombus formation. Among these, the P2Y(12) receptor, a member of the G protein-coupled receptor family, has attracted a significant amount of attention. Stimulation of the P2Y(12) receptor by ADP results in activation of various signaling pathways involved in amplification of platelet activation and aggregation. There have been extensive attempts to design an ideal antithrombotic agent to block P2Y(12), which shows selective expression, as an intervention for cardiovascular disease. Current inhibitors of the P2Y(12) receptor include indirect inhibitor members of the thienopyridine family (ticlopidine, clopidogrel, and prasugrel), and direct P2Y(12) inhibitors (ticagrelor, cangrelor and elinogrel). Of these, clopidogrel is the most commonly prescribed P2Y(12) blocker; however, this product does not fulfill the ideal therapeutic requirements. The main limitations of clopidogrel administration include slow onset, prevention of recovery of platelet functions, and interindividual variability. Hence, advanced studies have been carried out to achieve more efficient and safer P2Y(12) blockade. In this review, we provide a brief but comprehensive report on P2Y(12), its role on platelet thrombus formation, and the targeting of this receptor as an intervention for cardiovascular disease, for the benefit of basic science and clinical researchers.
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Affiliation(s)
- Fatemeh Moheimani
- Thrombosis and Vascular Diseases Laboratory, Health Innovations Research Institute, School of Medical Sciences, RMIT University, PO Box 71, Bundoora, Melbourne, VIC 3083, Australia.
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Macaione F, Montaina C, Evola S, Novo G, Novo S. Impact of dual antiplatelet therapy with proton pump inhibitors on the outcome of patients with acute coronary syndrome undergoing drug-eluting stent implantation. ISRN CARDIOLOGY 2012; 2012:692761. [PMID: 22792485 PMCID: PMC3391936 DOI: 10.5402/2012/692761] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 05/07/2012] [Indexed: 12/29/2022]
Abstract
This study aimed to assess if proton pump inhibitors (PPIs) may reduce the effectiveness of clopidogrel, than H2 antagonist (anti-H2) in order to determine rehospitalization for acute coronary syndrome (re-ACS), target vessel revascularization (TVR) and cardiac death. This case-control study included 176 patients with ACS undergoing angioplasty (PCI) with drug-eluting stent implantation. The population was divided into two groups: PPI group (n = 121) consisting of patients receiving at discharge dual antiplatelet therapy (DAT) plus PPI and anti-H2 group (n = 55), consisting of patients receiving at discharge DAT + H2 receptor antagonist (H2RA). In a followup of 36 months the prevalence of ACS event (P = 0.014), TVR (P = 0.031) was higher in the PPI group than in the anti-H2 group; instead there was no statistically significant difference between groups for death. The variables independently associated with ACS were the diabetes, omeprazole, and esomeprazole; instead the variables independently associated with TVR were only omeprazole. Our data shows that the use of omeprazole and esomeprazole, with clopidogrel, is associated with increased risk of adverse outcomes after PCI with drug-eluting stent implantation.
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Affiliation(s)
- Francesca Macaione
- Division of Cardiology and Post-Graduate School of Cardiology, Center for the Early Diagnosis of Preclinical and Multifocal Atherosclerosis and for the Secondary Prevention, University Hospital “P. Giaccone” of the University of Palermo, 127-90127 Palermo, Italy
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Borsiczky B, Sarszegi Z, Konyi A, Szabados S, Gaszner B. The effect of clopidogrel besylate and clopidogrel hydrogensulfate on platelet aggregation in patients with coronary artery disease: A retrospective study. Thromb Res 2012; 129:700-3. [DOI: 10.1016/j.thromres.2011.08.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 08/02/2011] [Accepted: 08/15/2011] [Indexed: 11/25/2022]
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Stellbaum C, Ayral Y, Morguet A, Schultheiss HP, Rauch U. Doubling the clopidogrel dose in patients with reduced responsiveness to the standard dose is associated with a limited effectiveness as evaluated by impedance aggregometry. CARDIOVASCULAR REVASCULARIZATION MEDICINE 2012; 13:159-66. [PMID: 22503564 DOI: 10.1016/j.carrev.2012.02.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 02/10/2012] [Accepted: 02/27/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND Different methods are available for quantifying platelet function inhibition. Measuring vasodilator-stimulated phosphoprotein (VASP) phosphorylation is currently the most specific method for assessing the clopidogrel effect. The aim of our study was to compare different tests in view of a clinically applicable bedside test. Further, we examined whether doubling the clopidogrel dose to 150mg/d in clopidogrel low-responder would lead to a reduction in platelet reactivity. METHODS AND RESULTS ADP-, ADP Hs-, and TRAP-induced platelet aggregation were measured by impedance aggregometry in 100 patients with CAD and 18 healthy controls. Moreover, platelet aggregation was assessed by flow cytometrical detection of VASP-phosphorylation and surface P-selectin in a subgroup of 34 patients and in healthy controls. Another 10 patients with CAD, identified as low-responder, were treated with a clopidogrel dose of 150mg/d. Thereafter, ADP-induced platelet aggregation was assessed by impedance aggregometry. Significant correlations were observed between ADP-induced platelet aggregation assessed by VASP-phosphorylation and by impedance aggregometry. Doubling the dose of clopidogrel to 150mg/d was associated with a reduction of ADP-induced platelet aggregation in only 60% of the patients. CONCLUSIONS Impedance aggregometry is a valuable bedside test to assess platelet function inhibition. Doubling the clopidogrel dose is not effective to reduce high on-treatment platelet reactivity in almost half of these patients, pointing to the need of a more powerful platelet inhibitor.
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Affiliation(s)
- Caroline Stellbaum
- Department of Internal Medicine/Cardiology, Campus Benjamin Franklin, Charité-Universitätsmedizin Berlin, Berlin, Germany
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Douketis JD, Spyropoulos AC, Spencer FA, Mayr M, Jaffer AK, Eckman MH, Dunn AS, Kunz R. Perioperative management of antithrombotic therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012; 141:e326S-e350S. [PMID: 22315266 DOI: 10.1378/chest.11-2298] [Citation(s) in RCA: 1043] [Impact Index Per Article: 86.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND This guideline addresses the management of patients who are receiving anticoagulant or antiplatelet therapy and require an elective surgery or procedure. METHODS The methods herein follow those discussed in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines. Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines article of this supplement. RESULTS In patients requiring vitamin K antagonist (VKA) interruption before surgery, we recommend stopping VKAs 5 days before surgery instead of a shorter time before surgery (Grade 1B). In patients with a mechanical heart valve, atrial fibrillation, or VTE at high risk for thromboembolism, we suggest bridging anticoagulation instead of no bridging during VKA interruption (Grade 2C); in patients at low risk, we suggest no bridging instead of bridging (Grade 2C). In patients who require a dental procedure, we suggest continuing VKAs with an oral prohemostatic agent or stopping VKAs 2 to 3 days before the procedure instead of alternative strategies (Grade 2C). In moderate- to high-risk patients who are receiving acetylsalicylic acid (ASA) and require noncardiac surgery, we suggest continuing ASA around the time of surgery instead of stopping ASA 7 to 10 days before surgery (Grade 2C). In patients with a coronary stent who require surgery, we recommend deferring surgery > 6 weeks after bare-metal stent placement and > 6 months after drug-eluting stent placement instead of undertaking surgery within these time periods (Grade 1C); in patients requiring surgery within 6 weeks of bare-metal stent placement or within 6 months of drug-eluting stent placement, we suggest continuing antiplatelet therapy perioperatively instead of stopping therapy 7 to 10 days before surgery (Grade 2C). CONCLUSIONS Perioperative antithrombotic management is based on risk assessment for thromboembolism and bleeding, and recommended approaches aim to simplify patient management and minimize adverse clinical outcomes.
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Affiliation(s)
- James D Douketis
- Department of Medicine, McMaster University, Hamilton, ON, Canada
| | | | | | - Michael Mayr
- Medical Outpatient Department, University Hospital Basel, Basel, Switzerland
| | - Amir K Jaffer
- Division of Hospital Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL
| | - Mark H Eckman
- Division of General Internal Medicine and Center for Clinical Effectiveness, University of Cincinnati Medical Center, Cincinnati, OH
| | - Andrew S Dunn
- Department of Medicine, Mount Sinai School of Medicine, New York, NY
| | - Regina Kunz
- Academy of Swiss Insurance Medicine, Department of Medicine, University Hospital Basel, Basel, Switzerland.
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48
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Goggs R, Poole AW. Platelet signaling-a primer. J Vet Emerg Crit Care (San Antonio) 2012; 22:5-29. [PMID: 22316389 DOI: 10.1111/j.1476-4431.2011.00704.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 11/25/2011] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To review the receptors and signal transduction pathways involved in platelet plug formation and to highlight links between platelets, leukocytes, endothelium, and the coagulation system. DATA SOURCES Original studies, review articles, and book chapters in the human and veterinary medical fields. DATA SYNTHESIS Platelets express numerous surface receptors. Critical among these are glycoprotein VI, the glycoprotein Ib-IX-V complex, integrin α(IIb) β(3) , and the G-protein-coupled receptors for thrombin, ADP, and thromboxane. Activation of these receptors leads to various important functional events, in particular activation of the principal adhesion receptor α(IIb) β(3) . Integrin activation allows binding of ligands such as fibrinogen, mediating platelet-platelet interaction in the process of aggregation. Signals activated by these receptors also couple to 3 other important functional events, secretion of granule contents, change in cell shape through cytoskeletal rearrangement, and procoagulant membrane expression. These processes generate a stable thrombus to limit blood loss and promote restoration of endothelial integrity. CONCLUSIONS Improvements in our understanding of how platelets operate through their signaling networks are critical for diagnosis of unusual primary hemostatic disorders and for rational antithrombotic drug design.
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Affiliation(s)
- Robert Goggs
- School of Physiology and Pharmacology, Faculty of Medical and Veterinary Sciences, University of Bristol, UK.
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Sambu N, Curzen N. Monitoring the effectiveness of antiplatelet therapy: opportunities and limitations. Br J Clin Pharmacol 2012; 72:683-96. [PMID: 21366666 DOI: 10.1111/j.1365-2125.2011.03955.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Previous clinical studies have shown heterogeneity in individual patient responses to antiplatelet therapy and high residual platelet reactivity is associated with increased risk of adverse clinical events. Monitoring response to antiplatelet therapy and tailoring treatment accordingly is currently not recommended in routine clinical practice largely due to the lack of a standardized definition of antiplatelet therapy hyporesponse and the need for a widely accepted point-of-care platelet function test that can be reliably utilized in frontline clinical practice. Recent data have shown that titrating the dose of clopidogrel in patients undergoing percutaneous coronary intervention significantly reduces the incidence of major adverse cardiovascular events and large-scale clinical trials are currently underway to investigate whether individually tailored treatment based on results of platelet function testing leads to improved clinical outcome. Furthermore, genetic testing has demonstrated a link between CYP2C19 genetic polymorphisms, altered clopidogrel metabolite concentrations and adverse clinical events. Clinical studies are currently underway to investigate the potential clinical benefit associated with genotype-guided tailoring of antiplatelet therapy. With the advent of newer, more potent antiplatelet agents and their associated increased bleeding risks, it will become imperative in the future to select the most appropriate, safe and effective drug.
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Affiliation(s)
- Nalyaka Sambu
- Wessex Cardiothoracic Unit, Southampton University Hospital School, UK
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50
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Kobsar A, Koessler J, Kehrer L, Gambaryan S, Walter U. The thrombin inhibitors hirudin and Refludan(®) activate the soluble guanylyl cyclase and the cGMP pathway in washed human platelets. Thromb Haemost 2012; 107:521-9. [PMID: 22234363 DOI: 10.1160/th11-07-0461] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 12/01/2011] [Indexed: 11/05/2022]
Abstract
A number of direct thrombin inhibitors are successfully used clinically and experimentally as novel antithrombotics and specific anticoagulants. They are also used as anticoagulants in certain blood collection tubes for the analysis of platelet function. A series of platelet function tests have emerged to measure adequate responses to antiplatelet therapy. For comparative and practical reasons, it would be of advantage to use the same anticoagulant in blood collection tubes for different methods, e.g. thrombin inhibitors. However, there are little data on the effects of thrombin inhibitors on platelet signalling pathways that could influence results. We examined the applicability of thrombin inhibitor containing blood for platelet reactivity index (PRI) measurements of the VASP assay and investigated the effects of two thrombin inhibitors (hirudin and lepirudin) on cAMP- and cGMP-mediated signalling pathways in washed human platelets. We show that induction of VASP phosphorylation by PGE1 is markedly reduced in lepirudin containing blood samples. In consequence, PRI levels were highly variable compared to routinely used citrated blood. Surprisingly, in vitro incubation of platelets with thrombin inhibitors increases platelet cGMP levels and induces NOS independent sGC/PKG-mediated VASP phosphorylation. We conclude that thrombin inhibitors activate sGC/PKG-dependent pathways resulting in an increase of VASP phosphorylation which contributes to deviations in PRI measurements. These effects of thrombin inhibitors on sGC- and cGMP-mediated pathways including increased VASP phosphorylation may indicate the presence of an important additional platelet-based mechanism for the reduction of thrombus formation and thromboembolism by thrombin inhibitors.
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Affiliation(s)
- Anna Kobsar
- Institut fuer Klinische Biochemie und Pathobiochemie-Zentrallabor, Universitaetsklinikum Wuerzburg, Wuerzburg, Germany.
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