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Miao MZ, Lee JS, Yamada KM, Loeser RF. Integrin signalling in joint development, homeostasis and osteoarthritis. Nat Rev Rheumatol 2024; 20:492-509. [PMID: 39014254 DOI: 10.1038/s41584-024-01130-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2024] [Indexed: 07/18/2024]
Abstract
Integrins are key regulators of cell-matrix interactions during joint development and joint tissue homeostasis, as well as in the development of osteoarthritis (OA). The signalling cascades initiated by the interactions of integrins with a complex network of extracellular matrix (ECM) components and intracellular adaptor proteins orchestrate cellular responses necessary for maintaining joint tissue integrity. Dysregulated integrin signalling, triggered by matrix degradation products such as matrikines, disrupts this delicate balance, tipping the scales towards an environment conducive to OA pathogenesis. The interplay between integrin signalling and growth factor pathways further underscores the multifaceted nature of OA. Moreover, emerging insights into the role of endocytic trafficking in regulating integrin signalling add a new layer of complexity to the understanding of OA development. To harness the therapeutic potential of targeting integrins for mitigation of OA, comprehensive understanding of their molecular mechanisms across joint tissues is imperative. Ultimately, deciphering the complexities of integrin signalling will advance the ability to treat OA and alleviate its global burden.
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Affiliation(s)
- Michael Z Miao
- Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
- Craniofacial Anomalies and Regeneration Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
- Division of Rheumatology, Allergy, and Immunology and the Thurston Arthritis Research Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Janice S Lee
- Craniofacial Anomalies and Regeneration Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
- Office of the Clinical Director, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Kenneth M Yamada
- Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA.
| | - Richard F Loeser
- Division of Rheumatology, Allergy, and Immunology and the Thurston Arthritis Research Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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Role of Vitronectin and Its Receptors in Neuronal Function and Neurodegenerative Diseases. Int J Mol Sci 2022; 23:ijms232012387. [PMID: 36293243 PMCID: PMC9604229 DOI: 10.3390/ijms232012387] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 10/12/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022] Open
Abstract
Vitronectin (VTN), a multifunctional glycoprotein with various physiological functions, exists in plasma and the extracellular matrix. It is known to be involved in the cell attachment, spreading and migration through binding to the integrin receptor, mainly via the RGD sequence. VTN is also widely used in the maintenance and expansion of pluripotent stem cells, but its effects go beyond that. Recent evidence shows more functions of VTN in the nervous system as it participates in neural differentiation, neuronutrition and neurogenesis, as well as in regulating axon size, supporting and guiding neurite extension. Furthermore, VTN was proved to play a key role in protecting the brain as it can reduce the permeability of the blood-brain barrier by interacting with integrin receptors in vascular endothelial cells. Moreover, evidence suggests that VTN is associated with neurodegenerative diseases, such as Alzheimer's disease, but its function has not been fully understood. This review summarizes the functions of VTN and its receptors in neurons and describes the role of VTN in the blood-brain barrier and neurodegenerative diseases.
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Abstract
INTRODUCTION Platelets play a key role in arterial thrombosis and antiplatelet therapy is pivotal in the treatment of cardiovascular disease. Current antiplatelet drugs target different pathways of platelet activation and show specific pharmacodynamic and pharmacokinetic characteristics, implicating clinically relevant drug-drug interactions. AREAS COVERED This article reviews the role of platelets in hemostasis and cardiovascular thrombosis, and discusses the key pharmacodynamics, drug-drug interactions and reversal strategies of clinically used antiplatelet drugs. EXPERT OPINION Antiplatelet therapies target distinct pathways of platelet activation: thromboxane A2 synthesis, adenosine diphosphate-mediated signaling, integrin αIIbβ3 (GPIIb/IIIa), thrombin-mediated platelet activation via the PAR1 receptor and phosphodiesterases. Key clinical drug-drug interactions of antiplatelet agents involve acetylsalicylic acid - ibuprofen, clopidogrel - omeprazole, and morphine - oral P2Y12 inhibitors, all of which lead to an attenuated antiplatelet effect. Platelet function and genetic testing and the use of scores (ARC-HBR, PRECISE-DAPT, ESC ischemic risk definition) may contribute to a more tailored antiplatelet therapy. High on-treatment platelet reactivity presents a key problem in the acute management of ST-elevation myocardial infarction (STEMI). A treatment strategy involving early initiation of an intravenous antiplatelet agent may be able to bridge the gap of insufficient platelet inhibition in high ischemic risk patients with STEMI.
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Affiliation(s)
- Georg Gelbenegger
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Bernd Jilma
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
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Diindolylmethane ameliorates platelet aggregation and thrombosis: In silico, in vitro, and in vivo studies. Eur J Pharmacol 2022; 919:174812. [DOI: 10.1016/j.ejphar.2022.174812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 01/21/2022] [Accepted: 02/08/2022] [Indexed: 01/01/2023]
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Yokosaki Y, Nishimichi N. New Therapeutic Targets for Hepatic Fibrosis in the Integrin Family, α8β1 and α11β1, Induced Specifically on Activated Stellate Cells. Int J Mol Sci 2021; 22:12794. [PMID: 34884600 PMCID: PMC8657911 DOI: 10.3390/ijms222312794] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/24/2022] Open
Abstract
A huge effort has been devoted to developing drugs targeting integrins over 30 years, because of the primary roles of integrins in the cell-matrix milieu. Five αv-containing integrins, in the 24 family members, have been a central target of fibrosis. Currently, a small molecule against αvβ1 is undergoing a clinical trial for NASH-associated fibrosis as a rare agent aiming at fibrogenesis. Latent TGFβ activation, a distinct talent of αv-integrins, has been intriguing as a therapeutic target. None of the αv-integrin inhibitors, however, has been in the clinical market. αv-integrins commonly recognize an Arg-Gly-Asp (RGD) sequence, and thus the pharmacophore of inhibitors for the 5-integrins is based on the same RGD structure. The RGD preference of the integrins, at the same time, dilutes ligand specificity, as the 5-integrins share ligands containing RGD sequence such as fibronectin. With the inherent little specificity in both drugs and targets, "disease specificity" has become less important for the inhibitors than blocking as many αv-integrins. In fact, an almighty inhibitor for αv-integrins, pan-αv, was in a clinical trial. On the contrary, approved integrin inhibitors are all specific to target integrins, which are expressed in a cell-type specific manner: αIIbβ3 on platelets, α4β1, α4β7 and αLβ2 on leukocytes. Herein, "disease specific" integrins would serve as attractive targets. α8β1 and α11β1 are selectively expressed in hepatic stellate cells (HSCs) and distinctively induced upon culture activation. The exceptional specificity to activated HSCs reflects a rather "pathology specific" nature of these new integrins. The monoclonal antibodies against α8β1 and α11β1 in preclinical examinations may illuminate the road to the first medical agents.
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Affiliation(s)
- Yasuyuki Yokosaki
- Integrin-Matrix Biomedical Science, Translational Research Center, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima 734-8551, Japan;
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Nešić D, Zhang Y, Spasic A, Li J, Provasi D, Filizola M, Walz T, Coller BS. Cryo-Electron Microscopy Structure of the αIIbβ3-Abciximab Complex. Arterioscler Thromb Vasc Biol 2020; 40:624-637. [PMID: 31969014 PMCID: PMC7047619 DOI: 10.1161/atvbaha.119.313671] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 12/30/2019] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The αIIbβ3 antagonist antiplatelet drug abciximab is the chimeric antigen-binding fragment comprising the variable regions of murine monoclonal antibody 7E3 and the constant domains of human IgG1 and light chain κ. Previous mutagenesis studies suggested that abciximab binds to the β3 C177-C184 specificity-determining loop (SDL) and Trp129 on the adjacent β1-α1 helix. These studies could not, however, assess whether 7E3 or abciximab prevents fibrinogen binding by steric interference, disruption of either the αIIbβ3-binding pocket for fibrinogen or the β3 SDL (which is not part of the binding pocket but affects fibrinogen binding), or some combination of these effects. To address this gap, we used cryo-electron microscopy to determine the structure of the αIIbβ3-abciximab complex at 2.8 Å resolution. Approach and Results: The interacting surface of abciximab is comprised of residues from all 3 complementarity-determining regions of both the light and heavy chains, with high representation of aromatic residues. Binding is primarily to the β3 SDL and neighboring residues, the β1-α1 helix, and β3 residues Ser211, Val212 and Met335. Unexpectedly, the structure also indicated several interactions with αIIb. As judged by the cryo-electron microscopy model, molecular-dynamics simulations, and mutagenesis, the binding of abciximab does not appear to rely on the interaction with the αIIb residues and does not result in disruption of the fibrinogen-binding pocket; it does, however, compress and reduce the flexibility of the SDL. CONCLUSIONS We deduce that abciximab prevents ligand binding by steric interference, with a potential contribution via displacement of the SDL and limitation of the flexibility of the SDL residues.
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Affiliation(s)
- Dragana Nešić
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, Rockefeller University, New York, NY
| | - Yixiao Zhang
- Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, NY
| | - Aleksandar Spasic
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Jihong Li
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, Rockefeller University, New York, NY
| | - Davide Provasi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, NY
| | - Barry S. Coller
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, Rockefeller University, New York, NY
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Buchanan IA, Lee B, Amar AP, Giannotta SL. In situ administration of abciximab for thrombus resolution during intracranial bypass surgery: case report. J Neurosurg 2019; 130:268-272. [PMID: 29350605 DOI: 10.3171/2017.8.jns17430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 08/01/2017] [Indexed: 11/06/2022]
Abstract
Abciximab is a glycoprotein IIb/IIIa receptor antagonist that functions to prevent platelet aggregation, thus reducing thrombus initiation and propagation. It has been widely used during percutaneous endovascular interventions, such as aneurysm coil embolization, angioplasty, atherectomy, and stent placement, as both a preventative and a salvage therapy. The use of abciximab in cardiac and neurosurgical procedures has been associated with a reduced incidence of ischemic complications and a decreased need for repeated intervention. In these settings, abciximab has been delivered transarterially via a microcatheter or infused intravenously for systemic administration. The authors describe novel in situ delivery of abciximab as an agent to dissolve "white clots," which are composed primarily of platelets, during an intracranial superficial temporal artery to middle cerebral artery bypass in a 28-year-old woman with severe intracranial occlusive disease. Abciximab was able to resolve multiple platelet-based clots after unsuccessful attempts with conventional clot dispersal techniques, such as heparinized saline, tissue plasminogen activator, mechanical passage of a wire through the vessel lumen, and multiple takedowns and re-anastomosis. After abciximab was administered, patency was demonstrated intraoperatively using indocyanine green dye and confirmed postoperatively at 1 and 10 months via CT angiography. The in situ use of abciximab as an agent to disperse a thrombus during intracranial bypass surgery is novel and has not previously been described in the literature, and serves as an additional tool during intracranial vessel bypass surgery.
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A Naphthalenic Derivative ND-1 Inhibits Thrombus Formation by Interfering the Binding of Fibrinogen to Integrin αIIb β3. BIOMED RESEARCH INTERNATIONAL 2016; 2016:8587164. [PMID: 28097150 PMCID: PMC5206433 DOI: 10.1155/2016/8587164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/28/2016] [Accepted: 11/10/2016] [Indexed: 12/24/2022]
Abstract
Integrin αIIbβ3 plays a crucial role in the process of platelet aggregation. Three integrin αIIbβ3 antagonists (abciximab, eptifibatide, and tirofiban) have been approved by FDA for clinical use. Unfortunately, they all showed severe side effects such as thrombocytopenia and bleeding risk. Thus, researches on the development of more effective and safer antiplatelet agents are needed. In this manuscript we reported a novel naphthalenic derivative compound ND-1 with potent antithrombotic effect and lower bleeding risk. ND-1 inhibited ADP-, collagen-, thrombin-, and U46619-induced platelet aggregation with IC50 values of 1.29, 14.46, 12.84, and 40.24 μM, respectively. Mechanism studies indicated that ND-1 inhibited the binding of fibrinogen to integrin αIIbβ3 in a dose-dependent manner with an IC50 value of 3.12 μM. ND-1 inhibited P-selectin expression induced by ADP, collagen, thrombin, and U46619 on the surface of platelets. Additionally, this compound reduced platelets spreading to the immobilized fibrinogen. In vivo, ND-1 potently decreased thrombus formation in an arteriovenous shunt thrombosis model in rats and slightly prolonged bleeding time in a tail cutting model in mice. Taken together, our results reveal that ND-1 is a novel antagonist of αIIbβ3 with strong antithrombotic effect and lower bleeding risk.
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Anderson HV, Jordan RE, Weisman HF. Concept and Clinical Application of Platelet Glycoprotein IIb/IIIa Inhibition with Abciximab (c7E3 Fab; ReoPro) for the Prevention of Acute Ischemic Syndromes. Clin Appl Thromb Hemost 2016. [DOI: 10.1177/107602969700300407] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The platelet membrane glycoprotein (GP) IIb/IIIa integrin receptor is the final common pathway leading to platelet aggregation. Local aggregation commonly occurs following atherosclerotic plaque rupture or other injury to the vascular wall. When GP IIb/IIIa is activated, fibrinogen and von Willebrand factor bind to the receptor with high affinity, crosslinking platelets and locking them to the vessel surface and to each other. This process is central to arterial thrombus formation and consequent acute coronary syndromes, such as myocardial infarction (MI), unstable angina, and abrupt closure following revascularization procedures. Abciximab (c7E3 Fab; ReoPro) is a chimeric monoclonal antibody fragment developed specifically to inhibit GP IIb/IIIa receptor activity and thus prevent platelet aggregation and thrombosis. Abciximab has been evaluated in several clinical studies, the largest of which was the Evaluation of Abciximab for the Prevention of Ischemic Complications (EPIC) trial. This randomized, multicenter, placebo-controlled trial enrolled 2,099 patients at high risk for ischemic complications following coronary revascularization. The patients were randomized into three treatment groups: placebo, abciximab bolus (0.25 mg/kg), or abciximab bolus plus 12-h infusion (10 μg/min). Patients in the abciximab bolus plus infusion group had significant reductions, compared with placebo, in a composite end point of death, nonfatal MI, and urgent coronary intervention within 30 days. These positive, short-term findings were maintained at 6 months of follow-up. Bleeding complications and transfusions were significantly increased in abciximab patients, although there was no increase in bleeding-related death, stroke, or surgery. Retrospective secondary analyses suggested that many of the bleeding events observed in the EPIC trial may have been associated with concomitant high-dose heparin therapy, particularly in lighter weight patients. Subsequent clinical trials have shown that bleeding events can be reduced in patients treated with abciximab by using weight-adjusted heparin dosing without affecting the efficacy of the abciximab bolus plus infusion regimen. Examination of health economic data from the EPIC trial showed that abciximab bolus plus infusion is cost effective as well as clinically beneficial. These results confirm the importance of platelet GP IIb/IIIa receptor blockade in the treatment of acute thrombotic syndromes. Key Words: Platelet aggregation—GP IIb/IIIa receptor—Coronary revascularization— Ischemia.
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Abstract
This review covers the recent advances in the development of small RGD (Arg-Gly-Asp sequence) containing peptides and their mimetics as potential antithrombotic agents. Glycoprotein IIb/IIIa (GPIIb/IIIa) antagonists include monoclonal antibodies, RGD peptides, peptide hybrids and nonpeptide mimetics. The current trend in the development of nonpeptide mimetics is clearly directed toward orally active and safe antithrombotic drug candidates. But several nonpeptide mimetics, being evaluated for their oral activity in human clinical trials, are currently not approved for clinical use due to poor safety profile. It is expected that newer and more effective nonpeptide mimetics will be developed in the near future.
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Coller BS. Translating from the rivers of Babylon to the coronary bloodstream. J Clin Invest 2012; 122:4293-9. [PMID: 23114610 DOI: 10.1172/jci66867] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Barry S Coller
- Laboratory of Blood and Vascular Biology, Rockefeller University, 1230 York Avenue, New York, New York 10065, USA.
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Abstract
Platelets are a remarkable mammalian adaptation that are required for human survival by virtue of their ability to prevent and arrest bleeding. Ironically, however, in the past century, the platelets' hemostatic activity became maladaptive for the increasingly large percentage of individuals who develop age-dependent progressive atherosclerosis. As a result, platelets also make a major contribution to ischemic thrombotic vascular disease, the leading cause of death worldwide. In this brief review, I provide historical descriptions of a highly selected group of topics to provide a framework for understanding our current knowledge and the trends that are likely to continue into the future of platelet research. For convenience, I separate the eras of platelet research into the "Descriptive Period" extending from ~1880-1960 and the "Mechanistic Period" encompassing the past ~50 years since 1960. We currently are reaching yet another inflection point, as there is a major shift from a focus on traditional biochemistry and cell and molecular biology to an era of single molecule biophysics, single cell biology, single cell molecular biology, structural biology, computational simulations, and the high-throughput, data-dense techniques collectively named with the "omics postfix". Given the progress made in understanding, diagnosing, and treating many rare and common platelet disorders during the past 50 years, I think it appropriate to consider it a Golden Age of Platelet Research and to recognize all of the investigators who have made important contributions to this remarkable achievement..
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Affiliation(s)
- Barry S. Coller
- Laboratory of Blood and Vascular Biology, Rockefeller University, 1230 York Avenue, New York, NY 10065, Tel: 212-327-7490, Fax: 212-327-7493
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Weber AA, Schrör K. The significance of platelet-derived growth factors for proliferation of vascular smooth muscle cells. Platelets 2010. [DOI: 10.1080/09537109909169169] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Rocca B, Cristofaro RD, Ventura MD, Bizzi B, Landolfi R. Kinetics of Free Platelet Decrease After ADP: Effect of Fibrinogen Binding Inhibitors. Platelets 2009; 6:152-9. [DOI: 10.3109/09537109509013268] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Knight DM, Jordan RE, Kruszynski M, Tam SH, Giles-Komar J, Treacy G, Heavner GA. Pharmacodynamic enhancement of the anti-platelet antibody Fab abciximab by site-specific pegylation. Platelets 2009; 15:409-18. [PMID: 15745312 DOI: 10.1080/09537100410001723135] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Monoclonal antibodies have been firmly established as human therapeutics. Their high affinity and specificity for target antigens minimize adverse reactions and their molecular size results in extended circulation times relative to small molecule pharmaceuticals. The ability to customize the pharmacokinetics in a rational manner can enhance the potential for these and other classes of biologicals. We have systematically studied the effect of site-specific pegylation of the Fab' fragment of the anti-GPIIb/IIIa, alphavbeta3 antibody c7E3. Regardless of the molecular weight of the PEG molecules, the intrinsic affinity of the resulting constructs remained unchanged. However, in functional assays measuring inhibition of platelet aggregation, the calculated IC50 values of the conjugates decreased with increasing molecular weight of the conjugated PEG. It was determined that the molecular size of the conjugates affects antigen accessibility and whereas high levels of binding to antigen molecules on cells with high antigen density can be demonstrated with the Fab fragment, comparable levels are not achievable with large molecular weight conjugates. In spite of the inability of the larger PEG constructs to achieve saturation binding, functional inhibition of platelet aggregation consistent with saturation binding was demonstrated and the increased molecular size of the conjugates led to predictably prolonged inhibition of platelet aggregation.
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Affiliation(s)
- David M Knight
- Pharmaceutical Research, Centocor, Inc., 200 Great Valley Parkway, Malvern, PA 19355, USA
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Coller BS, Shattil SJ. The GPIIb/IIIa (integrin alphaIIbbeta3) odyssey: a technology-driven saga of a receptor with twists, turns, and even a bend. Blood 2008; 112:3011-25. [PMID: 18840725 PMCID: PMC2569161 DOI: 10.1182/blood-2008-06-077891] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Accepted: 07/21/2008] [Indexed: 01/24/2023] Open
Abstract
Starting 90 years ago with a clinical description by Glanzmann of a bleeding disorder associated with a defect in platelet function, technologic advances helped investigators identify the defect as a mutation(s) in the integrin family receptor, alphaIIbbeta3, which has the capacity to bind fibrinogen (and other ligands) and support platelet-platelet interactions (aggregation). The receptor's activation state was found to be under exquisite control, with activators, inhibitors, and elaborate inside-out signaling mechanisms controlling its conformation. Structural biology has produced high-resolution images defining the ligand binding site at the atomic level. Research on alphaIIbbeta3 has been bidirectional, with basic insights resulting in improved Glanzmann thrombasthenia carrier detection and prenatal diagnosis, assays to identify single nucleotide polymorphisms responsible for alloimmune neonatal thrombocytopenia, and the development of alphaIIbbeta3 antagonists, the first rationally designed antiplatelet agents, to prevent and treat thrombotic cardiovascular disease. The future looks equally bright, with the potential for improved drugs and the application of gene therapy and stem cell biology to address the genetic abnormalities. The alphaIIbbeta3 saga serves as a paradigm of rigorous science growing out of careful clinical observations of a rare disorder yielding both important new scientific information and improved diagnosis, therapy, and prevention of other disorders.
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Affiliation(s)
- Barry S Coller
- Laboratory of Blood and Vascular Biology, The Rockefeller University, New York, NY, USA.
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Nagarakanti R, Sodhi S, Lee R, Ezekowitz M. Chronic antithrombotic therapy in post-myocardial infarction patients. Cardiol Clin 2008; 26:277-88, vii. [PMID: 18407000 DOI: 10.1016/j.ccl.2007.12.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Because 1.1 million myocardial infarctions occur in the United States alone each year, and 450,000 of them are recurrent infarctions, which carry an inherently greater risk of death and disability than first events, the importance of secondary prevention strategies that can be implemented widely is unparalleled in health care. Antithrombotic therapies, both antiplatelet and anticoagulant, have become the mainstays of these strategies. This article covers the use of chronic antiplatelet and anticoagulation agents after myocardial infarction. It does not include the management of these patients in the acute phase.
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Affiliation(s)
- Rangadham Nagarakanti
- Lankenau Institute for Medical Research, Clinical Research Center, Suite G-36, 100 Lancaster Avenue, Wynnewood, PA 19096-3425, USA
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Crenshaw BS, Harrington RA, Tcheng JE. Section Review: Cardiovascular & Renal: Novel antiplatelet agents: The glycoprotein IIb/IIIa inhibitors. Expert Opin Investig Drugs 2008. [DOI: 10.1517/13543784.4.11.1033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Wityak J, Sielecki TM. Section Review: Cardiovascular & Renal: Glycoprotein IIb/IIIa antagonists. Expert Opin Ther Pat 2008. [DOI: 10.1517/13543776.6.11.1175] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abrams J, Schroeder J, Frishman WH, Freedman J. Pharmacologic Options for Treatment of Ischemic Disease. Cardiovasc Ther 2007. [DOI: 10.1016/b978-1-4160-3358-5.50011-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Velat GJ, Burry MV, Eskioglu E, Dettorre RR, Firment CS, Mericle RA. The use of abciximab in the treatment of acute cerebral thromboembolic events during neuroendovascular procedures. ACTA ACUST UNITED AC 2006; 65:352-8, discussion 358-9. [PMID: 16531192 DOI: 10.1016/j.surneu.2005.08.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Accepted: 08/19/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND Recently, a great interest has emerged regarding the use of abciximab for treatment of stroke. Thromboembolic events that occur during neuroendovascular procedures represent a unique subset of stroke patients because definitive angiographic diagnosis and treatment can be performed immediately. The existing literature on this situation suggests excellent results; however, most publications are case reports, and the largest series is 13 cases. We report our experience using abciximab in the treatment of acute thromboembolic events that occur during neuroendovascular procedures. METHODS We reviewed the last 1373 consecutive patients who underwent neuroendovascular procedures at the University of Florida from our prospectively maintained clinical database. Of these patients, 29 (2.11%) endovascular cases were complicated by acute cerebral thromboembolic events that were treated with abciximab. Abciximab was administered in less than 1 hour after the onset of the occlusion in every patient. The Thrombolysis In Myocardial Infarction (TIMI) scale was used to measure immediate angiographic outcome, and the Modified Rankin Scale (MRS) was used to measure clinical outcome at the time of follow-up. Independent outcome was defined as an MRS of 3 or less at follow-up. RESULTS Angiographic improvement in the TIMI grade was achieved in 29 (81%) of 36 arteries. Three intracerebral hemorrhages occurred with abciximab when administered with concurrent mechanical clot disruption; in two of these hemorrhages, recombinant tissue plasminogen activator (r-tPA) was also administered. The mean follow-up time for the living cohort was 7.54 months. Twenty-four (83%) patients were independent at follow-up, 3 (10%) were dependent at follow-up, and 2 (7%) died. CONCLUSION Abciximab appears to be safe and effective in the treatment of acute cerebral thromboembolic complications during neuroendovascular procedures.
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Affiliation(s)
- Gregory J Velat
- Department of Neurological Surgery, University of Florida College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
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Abstract
Hemostasis is a normal process preventing the sequelae of uncontrolled hemorrhage. In certain settings, these same processes cause adverse clinical events due to thrombotic occlusion of a vessel. The majority of unstable coronary syndromes result from disruption of an atherosclerotic plaque, leading to the exposure of subintimal contents, which triggers coagulation and the formation of a platelet-rich thrombus. The central role of platelet activation in the events that lead to vessel occlusion is well known. However, this process is complex and influenced by a myriad of cellular and plasma-derived mediators that regulate the balance between occlusive and nonocclusive thrombosis.
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Affiliation(s)
- Jane E Freedman
- Boston University School of Medicine, Whitaker Cardiovascular Institute, Boston, MA 02118, USA.
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25
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Sodhi S, Lee R, Ezekowitz M. Chronic Antithrombotic Therapy in Post–Myocardial Infarction Patients. Clin Geriatr Med 2006; 22:167-82, x. [PMID: 16377473 DOI: 10.1016/j.cger.2005.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Recent advances in the acute treatment of myocardial infarction (MI) have allowed more to survive the initial event in coronary artery disease. Increasing importance has been placed on secondary-prevention strategies, with more attention directed toward an optimal therapeutic regimen for post-MI patients. When it comes to the subpopulation of the elderly who have had an MI, however, current practice relies less on population-specific evidence and more on extrapolation of current data. This article reviews the pathogenesis of coronary heart disease and MI, and highlights recent major trials that have explored antiplatelet and anticoagulant medications in the chronic treatment of the post-MI population. Special consideration is given to the geriatric community and its unique challenge regarding chronic antithrombotic therapy.
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Affiliation(s)
- Sandeep Sodhi
- Drexel University College of Medicine, Philadelphia, PA 19102, USA
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26
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Freedman JE, Loscalzo J. Thrombosis. Vasc Med 2006. [DOI: 10.1016/b978-0-7216-0284-4.50014-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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27
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Hanson J, de Leval X, Kolh P, Supuran C, Pirotte B, Dogné JM. Update on GPIIb/IIIa antagonists. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.13.8.1173] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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28
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Iqbal O, Messmore H, Fareed J, Ahmad S, Hoppensteadt D, Hazar S, Tobu M, Aziz S, Wehrmacher W. Antithrombotic agents in the treatment of severe sepsis. Expert Opin Emerg Drugs 2005; 7:111-39. [PMID: 15989540 DOI: 10.1517/14728214.7.1.111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Sepsis, a systemic inflammatory syndrome, is a response to infection and when associated with multiple organ dysfunction is termed severe sepsis. It remains a leading cause of mortality in the critically ill. The response to the invading microorganisms may be considered as a balance between a pro-inflammatory and an anti-inflammatory reaction. While an inadequate pro-inflammatory reaction and a strong anti-inflammatory response could lead to overwhelming infection and the death of the patient, a strong and uncontrolled pro-inflammatory response, manifested by the release of pro-inflammatory mediators may lead to microvascular thrombosis and multiple organ failure. Endotoxin triggers sepsis via the release of various mediators such as tumour necrosis factor-alpha and interleukin-1 (IL-1). These cytokines activate the complement and coagulation systems, release adhesion molecules, prostaglandins, leukotrienes, reactive oxygen species and nitric oxide. Other mediators involved in the sepsis syndrome include IL-1, -6 and -8; arachidonic acid metabolites; platelet activating factor; histamine; bradykinin; angiotensin; complement components and vasoactive intestinal peptide. These pro-inflammatory responses are counteracted by IL-10. Most of the trials targeting the different mediators of the pro-inflammatory response have failed due to a lack of correct definition of sepsis. Understanding the exact pathophysiology of the disease will enable more advanced treatment options. Targeting the coagulation system with various anticoagulant agents including, activated protein C, and tissue factor pathway inhibitor (TFPI) is a rational approach. Many clinical trials have been conducted to evaluate these agents in severe sepsis. While trials on antithrombin and TFPI were not so successful, the double-blind, placebo-controlled, Phase III trial of recombinant human activated Protein C Worldwide Evaluation in Severe Sepsis (PROWESS) was successful, creating a significant decrease in mortality when compared to the placebo group. A better understanding of the pathophysiologic mechanism of severe sepsis will provide better treatment options, and combination antithrombotic treatment may provide a multipronged approach for the treatment of severe sepsis.
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Affiliation(s)
- Omer Iqbal
- Loyola University Medical Center, Maywood, Illinois 60153, USA
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29
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Iqbal O, Aziz S, Hoppensteadt DA, Ahmad S, Walenga JM, Bakhos M, Fareed J. Emerging anticoagulant and thrombolytic drugs. ACTA ACUST UNITED AC 2005; 6:111-35. [PMID: 15989500 DOI: 10.1517/14728214.6.1.111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Since its discovery, heparin has been used intensely as an anticoagulant for several medical and surgical indications. However, efforts are in progress to replace heparin because of its serious complications, such as intraoperative and postoperative bleeding, osteoporosis, alopecia, heparin resistance, heparin rebound, heparin-induced thrombocytopenia (HIT) and thrombosis syndrome (HITTS), and other disadvantages. Significant developments in the field of new anticoagulants have resulted in the evaluation and introduction of low molecular weight heparins (LMWHs) and heparinoids, hirudin, ancrod, synthetic peptides and peptidomimetics. However, despite significant progress in the development of these new anticoagulants, a better or an ideal anticoagulant for cardiovascular patients is not yet available and heparin still continues to amaze both basic scientists and the clinicians. To minimise the adverse effects of heparin, newer approaches to optimise its use in combination with the new anticoagulants may provide better clinical outcome. In our experience, the off-label use of argatroban at a dose of 300 microg/kg iv. bolus followed by 10 microg/kg/minute infusion in combination with aggrastat (a glycoprotein [GP] IIb/IIIa inhibitor) at a dose of 10 microg/kg iv. bolus followed by an infusion of 0.15 microg/kg/minute in patients with HIT undergoing percutaneous coronary interventions resulted in elevation of celite activated clotting time (ACT) to 300 seconds followed by a gradual decline and the ACT remained above 200 seconds even after 200 min of drug administration. A bewildering array of newer anticoagulants now exist, such as LMWHs and heparinoids, indirect or direct thrombin inhibitors, oral thrombin inhibitors, such as melagatran (AstraZeneca) and HC-977 (Mitsubishi Pharmaceuticals), Factor IXa inhibitors, indirect or direct Factor Xa inhibitors, Factor VIIa/tissue factor (TF) pathway inhibitor, newer antiplatelet agents, such as GPIIb/IIIa inhibitors, fibrin specific thrombolytic agent, such as tenecteplase and modulation of the endogenous fibrinolytic activity by thrombin activatable fibrinolytic inhibitor (TAFI), Factor XIIIa inhibitors and PAI-1 inhibitors. The quest for newer anticoagulant, antiplatelet and fibrinolytic agents will continue until ideal agents are found.
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Affiliation(s)
- O Iqbal
- Hemostasis Research Laboratories, Department of Pathology, Loyola University Medical Center, Maywood, IL 60153, USA
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30
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Barkhoudarian G, Ali MJ, Deveikis J, Thompson BG. Intravenously Administered Abciximab in the Management of Early Cerebral Ischemia after Carotid Endarterectomy: Case Report. Neurosurgery 2004; 55:709. [PMID: 16929580 DOI: 10.1227/01.neu.0000134466.55733.3e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
OBJECTIVE AND IMPORTANCE:
Cerebral ischemia is the most worrisome perioperative complication of carotid endarterectomy (CEA). The stroke rate occurring with CEA is estimated to range from 2.3 to 6.3%. Numerous treatment options are available to the neurosurgeon in this scenario, although no “gold standard” exists.
CLINICAL PRESENTATION:
A 61-year-old woman presented with acute left arm weakness 40 minutes after an uneventful CEA for symptomatic carotid stenosis. Emergent angiography demonstrated vascular irregularities in a “moth-eaten” pattern along the arteriotomy closure, suggestive of platelet-fibrin aggregates (“white clot”).
INTERVENTION:
Abciximab was immediately administered intravenously in the angiography suite, with subsequent improvement of the visualized vascular irregularities on a second angiogram performed 12 minutes after infusion and complete resolution of the presumed platelet-fibrin aggregates on a third angiogram performed the next day. The patient had no further episodes of cerebral ischemia. She was discharged home on the fifth postoperative day with improving left arm weakness, which had completely resolved by her 2-month follow-up visit.
CONCLUSION:
To our knowledge, this is the first reported case of abciximab administered intravenously in the setting of acute thromboembolic brain ischemia after CEA. For the unique situation in which an acute thrombus, or white clot, is thought to be the cause of cerebral ischemia, we believe that abciximab may offer an effective and potentially safer alternative than fibrinolytics and may be a more appropriate drug to use from a physiological perspective.
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31
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Gibson CM, Jennings LK, Murphy SA, Lorenz DP, Giugliano RP, Harrington RA, Cholera S, Krishnan R, Califf RM, Braunwald E. Association Between Platelet Receptor Occupancy After Eptifibatide (Integrilin) Therapy and Patency, Myocardial Perfusion, and ST-Segment Resolution Among Patients With ST-Segment–Elevation Myocardial Infarction. Circulation 2004; 110:679-84. [PMID: 15262838 DOI: 10.1161/01.cir.0000137912.11655.f6] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Paradoxically, fibrinolytic agents may systemically activate platelets, which in turn secrete plasminogen activator inhibitor (PAI-1), an antagonist of the fibrinolytic process in proportion to total body platelet mass. We hypothesized that improved epicardial patency, myocardial perfusion, and ST-segment resolution would be associated with higher levels of platelet receptor occupancy (RO) by a glycoprotein IIb/IIIa antagonist in ST-elevation MI (STEMI).
Methods and Results—
Patients were drawn from the low-dose tenecteplase plus eptifibatide arm of the INTEGRITI study. Angiographic and platelet RO data were analyzed at 2 independent core laboratories. To take into account the absolute platelet count and receptors available for cross-linking, absolute platelet count was multiplied by percent of available receptors to obtain the index of the absolute number of receptors available (IANRA). Percent RO was higher among patients with a patent artery (TIMI flow grade 2/3; 78.2±9.2, n=63 versus 63.9±29.7, n=7;
P
=0.005), those with TIMI myocardial perfusion grade 2/3 (79.6±9.5, n=40 versus 73.0±16.2, n=30;
P
=0.036), and those with complete (≥70%) ST-segment resolution at 60 minutes (81.3±8.3%, n=27 versus 73.1±17.4%, n=24;
P
=0.034). The absolute number of glycoprotein IIb/IIIa receptors available for cross-linking was reduced (ie, the IANRA was lower) among patients with a patent artery (
P
=0.0015), patients with TIMI myocardial perfusion grade 2/3 (
P
=0.026), and patients with ≥70% ST-segment resolution (
P
=0.029).
Conclusions—
This study links restoration of epicardial flow, normal myocardial perfusion, and complete ST-segment resolution with higher levels of platelet glycoprotein IIb/IIIa receptor occupancy after therapy with eptifibatide administered with tenecteplase.
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Affiliation(s)
- C Michael Gibson
- TIMI Study Group and the Department of Medicine, Brigham & Women's Hospital, Harvard Medical School, Boston, Mass, USA
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32
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Zimarino M, De Caterina R. Glycoprotein IIb-IIIa antagonists in non-ST elevation acute coronary syndromes and percutaneous interventions: from pharmacology to individual patient's therapy: part 1: the evidence of benefit. J Cardiovasc Pharmacol 2004; 43:325-32. [PMID: 15076214 DOI: 10.1097/00005344-200403000-00001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Antagonists of platelet glycoprotein IIb/IIIa (abciximab, tirofiban, eptifibatide) have now an approved role in reducing the extent of thrombotic complications leading to myocardial damage during percutaneous coronary interventions (PCI). This effect likely here translates into a long-term survival benefit. However, the question of their usefulness in different clinical scenarios (stable or unstable coronary disease, without PCI) has not been fully answered on the basis of considerations of dosing and cost-effectiveness. These agents seem most useful in high-risk patients with unstable coronary syndromes especially in the presence of co-morbidities such as diabetes or renal insufficiency. This article summarizes reasons for the ongoing debate on their efficacy and highlights areas of uncertainty.
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Affiliation(s)
- Marco Zimarino
- Institute of Cardiology and Center of Excellence on Aging, G. d'Annunzio University, Chieti, Italy.
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33
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Abstract
Our understanding of the pathophysiology of acute coronary syndromes (ACS), including acute ST elevation myocardial infarction, unstable angina and non-ST-segment elevation (NSTE) myocardial infarction, has evolved considerably over the years, with atherothrombosis playing a pivotal role. This review will discuss the recent advances/recommendations for drug therapy based on this enhanced understanding of the pathophysiology of thrombosis. More recently developed agents, such as low-molecular-weight heparins (LMWHs), glycoprotein (GP) IIb-IIIa inhibitors, direct thrombin inhibitors, Factor Xa inhibitors and thienopyridines, offer several potential advantages, either as an alternative to unfractionated heparin (i.e., LMWHs) or as an add-on therapy to aspirin and unfractionated heparin (or LMWHs; e.g., GP IIb-IIIa inhibitors, thienopyridines). The purpose of this review is to describe recent studies with novel antithrombotic agents (e.g., LMWHs, thienopyridines, GP IIb-IIIa inhibitors, bivalirudin) in patients with NSTE ACS, as well as to highlight recommendations for management of patients with NSTE ACS in the recently updated American College of Cardiology (ACC)/American Heart Association (AHA) guidelines, including the appropriate use of antithrombotic therapies.
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34
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Miyamoto M, Yamada N, Ikezawa S, Ohno M, Otake A, Umemura K, Matsushita T. Effects of TRA-418, a novel TP-receptor antagonist, and IP-receptor agonist, on human platelet activation and aggregation. Br J Pharmacol 2003; 140:889-94. [PMID: 14504133 PMCID: PMC1574093 DOI: 10.1038/sj.bjp.0705499] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2003] [Accepted: 08/07/2003] [Indexed: 11/08/2022] Open
Abstract
[4-[2-(1,1-Diphenylethylsulfanyl)-ethyl]-3,4-dihydro-2H-benzo[1,4]oxazin-8-yloxy]-acetic acid N-Methyl-d-glucamine salt (TRA-418) has both thromboxane A2 (TP)-receptor antagonist and prostacyclin (IP)-receptor agonist properties. The present study examined the advantageous effects of TRA-418 based on the dual activities, over an agent having either activity alone and also the difference in the effects of TRA-418 and a glycoprotein alphaIIb/beta3 integrin (GPIIb/IIIa) inhibitor. TRA-418 inhibited platelet GPIIb/IIIa activation as well as P-selectin expression induced by adenosine 5'-diphosphate, thrombin receptor agonist peptide 1-6 (Ser-Phe-Leu-Leu-Arg-Asn-NH2), and U-46619 in the presence of epinephrine (U-46619+ epinephrine). TRA-418 also inhibited platelet aggregation induced by those platelet-stimulants in Ca2+ chelating anticoagulant, citrate and in nonchelating anticoagulant, d-phenylalanyl-l-prolyl-l-arginyl-chloromethyl ketone (PPACK). The TP-receptor antagonist SQ-29548 inhibited only U-46619+epinephrine-induced GPIIb/IIIa activation, P-selectin expression, and platelet aggregation. The IP-receptor agonist beraprost sodium inhibited platelet activation. Beraprost also inhibited platelet aggregation induced by platelet stimulants we tested in citrate and in PPACK. The GPIIb/IIIa inhibitor abciximab blocked GPIIb/IIIa activation and platelet aggregation. However, abciximab showed slight inhibitory effects on P-selectin expression. TRA-418 is more advantageous as an antiplatelet agent than TP-receptor antagonists or IP-receptor agonists separately used. TRA-418 showed a different inhibitory profile from abciximab in the effects on P-selectin expression.
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Affiliation(s)
- Mitsuko Miyamoto
- Pharmaceutical Research Laboratories, Toray Industries, Inc., 1111 Tebiro, Kamakura 248-8555, Japan.
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35
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Lahav J, Wijnen EM, Hess O, Hamaia SW, Griffiths D, Makris M, Knight CG, Essex DW, Farndale RW. Enzymatically catalyzed disulfide exchange is required for platelet adhesion to collagen via integrin alpha2beta1. Blood 2003; 102:2085-92. [PMID: 12791669 DOI: 10.1182/blood-2002-06-1646] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Integrin alpha2beta1 is the principal adhesive receptor for collagen but platelets also adhere through glycoprotein VI (GPVI). Integrin alphaIIbbeta3 may augment platelet adhesion. We have shown that disulfide exchange is necessary for platelet adhesion to fibrinogen, fibronectin, and collagen. However 2 questions remained: (1) Can activated alphaIIbbeta3 explain the observed role of disulfide exchange in adhesion to collagen, or is this role common to other integrins? (2) Is disulfide dependence specific to the integrin receptors or shared with GPVI? To discriminate adhesive functions of alpha2beta1 from those of alphaIIbbeta3 we used Glanzmann platelets and alphaIIbbeta3-specific antibodies applied to normal platelets. To resolve adhesive events mediated by alpha2beta1 from those of GPVI we used synthetic peptides specific to each receptor. We addressed direct integrin ligation using purified alpha2beta1 and recombinant I domain. We observed the following: adhesion to the alpha2beta1-specific peptide was disulfide-exchange dependent and protein disulfide isomerase (PDI) mediated; membrane-impermeant thiol blockers inhibited alpha2beta1, but not GPVI mediated, adhesion; direct blockade of PDI revealed that it is involved in adhesion through alpha2beta1 but not GPVI; and purified alpha2beta1, but not recombinant I domain, depended on free thiols for ligation. These data suggest that the enzymatically catalyzed adhesion-associated reorganization of disulfide bonds is common to members of the integrin family and specific to this family.
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Affiliation(s)
- Judith Lahav
- The Coagulation Laboratory, Rabin Medical Center-Beilinson Campus, Zabotinski St, Petah-Tiqva 49100, Israel.
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36
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37
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Affiliation(s)
- Steven R Steinhubl
- Department of Medicine, University of North Carolina, Chapel Hill, 27599-7075, USA.
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38
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Manso MA, Escudero C, Alijo M, López-Fandiño R. Platelet aggregation inhibitory activity of bovine, ovine, and caprine kappa-casein macropeptides and their tryptic hydrolysates. J Food Prot 2002; 65:1992-6. [PMID: 12495023 DOI: 10.4315/0362-028x-65.12.1992] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Kappa-casein macropeptide (CMP) is one of the components of whey and is obtained as a by-product in cheesemaking. There has been increasing interest in research to find new uses of cheese industry by-products in order to improve their value and promote their use. Human platelet aggregation inhibitory activities of bovine, ovine, and caprine CMPs and their tryptic hydrolysates were studied. CMPs from the three species exhibited in vitro antithrombotic properties similar to the activity of the gamma-fibrinogen 400-411 peptide. Inhibitory activities increased following hydrolysis with trypsin. Active sequences were identified among the tryptic peptides by reversed-phase high-performance liquid chromatography with on-line mass spectrometry.
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Affiliation(s)
- M A Manso
- Instituto de Fermentaciones Industriales, Consejo Superior de Investigaciones Científicas, Juan de la Cierva 3, 28006 Madrid, Spain
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39
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Pang JTW, Fort S, Della Siega A, Cohen EA. Emergency coronary artery bypass surgery in the era of glycoprotein IIb/IIIa receptor antagonist use. J Card Surg 2002; 17:425-31. [PMID: 12630543 DOI: 10.1111/j.1540-8191.2001.tb01172.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The use of intravenous glycoprotein (GP) IIb/IIIa platelet receptor antagonists in the management of patients with acute coronary syndrome or those undergoing percutaneous coronary intervention (PCI) has become increasingly common in recent years. There are three GP IIb/IIIa receptor antagonists currently available for clinical use. Patients on GP IIb/IIIa receptor antagonists who require emergency surgical revascularization may be at increased risk for excessive peri- and postoperative bleeding. The duration of action of eptifibatide and tirofiban are short because they bind reversibly to the GP IIb/IIIa receptor and have a short half-life. Therefore, within a relatively short time after discontinuation of these agents, surgery can be performed with little or no increased risk of bleeding and without the need for additional hemostatic measures. Abciximab has a short plasma half-life but a long duration of action due to its high-affinity binding of GP IIb/IIIa receptors. Early retrospective studies demonstrated a higher incidence of major bleeding and requirement for blood transfusion, especially in those undergoing surgery within 12 hours of the discontinuation of abciximab. However, platelet transfusion has been shown to successfully reduce the incidence of these complications. The current evidence therefore indicates that, with appropriate measures, urgent surgical revascularization can be safely performed in patients who have received a GP IIb/IIIa receptor antagonist with little added risk. The benefits of these agents in the treatment of patients with an acute coronary syndrome or undergoing PCI are not obviated by the need for emergency bypass surgery.
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Affiliation(s)
- Jeffrey T W Pang
- Schulich Heart Center, Division of Cardiology, Sunnybrook and Women's College Health Sciences Center University of Toronto, Toronto, Ontario, Canada
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40
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Qureshi AI, Suri MFK, Ali Z, Kim SH, Lanzino G, Fessler RD, Ringer AJ, Guterman LR, Hopkins LN. Carotid angioplasty and stent placement: a prospective analysis of perioperative complications and impact of intravenously administered abciximab. Neurosurgery 2002; 50:466-73; discussion 473-5. [PMID: 11841713 DOI: 10.1097/00006123-200203000-00006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
OBJECTIVE To determine the frequency of perioperative complications since the introduction of abciximab, we prospectively evaluated our experience in a consecutive series of patients undergoing carotid angioplasty and stent placement (CAS). CAS has been introduced recently for treatment of carotid artery stenosis. A major limitation to this modality is the risk of perioperative thromboembolic and ischemic events. To reduce the risk of ischemic complications, abciximab, a platelet glycoprotein IIb/IIIa receptor inhibitor, has been introduced as adjunctive treatment for high-risk patients. METHODS Each patient was evaluated by a neurologist before, immediately after, and 24 hours after CAS for identification and classification of new neurological deficits. Bleeding events or other complications during hospitalization were recorded. Bleeding complications were classified as major (hemoglobin decrease,g5 g/dl), minor (hemoglobin decrease, 3-5 g/dl), or insignificant. Abciximab was administered intravenously as a single bolus (0.25 mg/kg) and then via infusion (10 microg/min) for 12 hours as an adjunct to CAS in patients considered to be at high risk for thromboembolic events owing to recent ischemic symptoms and/or complex lesion morphology. RESULTS Intravenously administered abciximab was used in 37 patients (mean age, 70 yr; 21 patients were men) as an adjunct to high-risk CAS. Thirty-three other patients underwent CAS performed with standard intraprocedural heparinization (mean age, 69 yr; 17 patients were men). Minor ischemic strokes were observed in 1 of 37 abciximab-treated patients and in 4 of 33 heparin-treated patients. No major ischemic strokes were observed in either group. Transient neurological deficits were observed in nine patients in the abciximab-treated group and in one patient in the heparin-treated group. Transient neurological deficits in abciximab-treated patients were mainly related to hemodynamic factors (associated with balloon inflation in two patients and with hypotension in another two patients) or occurred after completion of infusion (in three patients). Minor bleeding complications were observed in three patients who received abciximab and in four patients who received standard heparinization. Major bleeding complications were observed in four patients from each group. Two patients who received abciximab developed intracerebral hemorrhages; one hemorrhage was fatal. CONCLUSION The frequency of ischemic stroke in high-risk patients (3%) with the use of intravenously administered abciximab was lower, but not significantly so, than rates observed in lower-risk patients (12%), although the benefit was lost because of the high rate of intracranial hemorrhages (5%). Further efforts are required to determine appropriate selection criteria for use of intravenously administered abciximab and the effect of other strategies that involve distal protection devices.
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Affiliation(s)
- Adnan I Qureshi
- Department of Neurosurgery and Toshiba Stroke Research Center, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York 14209-1194, USA.
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41
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Shlansky-Goldberg R. Platelet aggregation inhibitors for use in peripheral vascular interventions: what can we learn from the experience in the coronary arteries? J Vasc Interv Radiol 2002; 13:229-46. [PMID: 11875083 DOI: 10.1016/s1051-0443(07)61716-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
During the last decade, an enormous amount of information has been gathered about the function of the platelet and its impact on percutaneous vascular interventions. With the discovery of the GP IIb/IIIa receptor, which is responsible for platelet aggregation, new drug antagonists have been developed to prevent platelet aggregation that may result in arterial thrombosis or platelet microembolization. These drugs include the three GP IIb/IIIa receptor antagonists approved by the Food and Drug Administration: abciximab (ReoPro), eptifibatide (Integrilin), and tirofiban (Aggrastat). These drugs have been used in several large studies to improve the outcome of coronary interventions and in conjunction with plasminogen activators to accelerate thrombolysis. In addition, because no oral GP IIb/IIIa inhibitor exists, other oral regimens have been developed with use of the thienopyridines, ticlopidine (Ticlid) and clopidogrel (Plavix), in combination with aspirin to prevent platelet aggregation and thrombosis. Because the majority of investigations have been performed in patients undergoing coronary interventions, knowledge of these data is necessary to attempt to translate the use of these antiplatelet drugs to peripheral vascular interventions. The goal of this article is to review the use of these agents in the percutaneous treatment of coronary artery disease and give insight to their potential utility in noncoronary interventions.
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Affiliation(s)
- Richard Shlansky-Goldberg
- Division of Interventional Radiology, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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42
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Qureshi AI, Suri MFK, Ali Z, Kim SH, Lanzino G, Fessler RD, Ringer AJ, Guterman LR, Hopkins LN. Carotid Angioplasty and Stent Placement: A Prospective Analysis of Perioperative Complications and Impact of Intravenously Administered Abciximab. Neurosurgery 2002. [DOI: 10.1227/00006123-200203000-00006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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43
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Shlansky-Goldberg R. Combination therapy in peripheral vascular disease: the rationale of using both thrombolytic and antiplatelet drugs. J Am Coll Surg 2002; 194:S103-13. [PMID: 11800349 DOI: 10.1016/s1072-7515(01)01098-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Richard Shlansky-Goldberg
- Division of Interventional Radiology, Hospital of the University of Pennsylvania, Philadelphia 19104, USA
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44
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Tcheng JE, Talley JD, O'Shea JC, Gilchrist IC, Kleiman NS, Grines CL, Davidson CJ, Lincoff AM, Califf RM, Jennings LK, Kitt MM, Lorenz TJ. Clinical pharmacology of higher dose eptifibatide in percutaneous coronary intervention (the PRIDE study). Am J Cardiol 2001; 88:1097-102. [PMID: 11703951 DOI: 10.1016/s0002-9149(01)02041-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This study describes the dose-exploration phase of the PRIDE trial, an investigation of the clinical pharmacology of higher dose eptifibatide in patients who underwent elective percutaneous coronary intervention (PCI). Outcomes of treatment with the platelet glycoprotein IIb/IIIa inhibitors were dependent upon proper dosing selection. In this multicenter, placebo-controlled clinical study, 127 patients were randomized 1:1:2:2 into 1 of the following treatment groups: placebo; eptifibatide as a 135 microg/kg bolus followed by a 0.75 microg/kg/min infusion; eptifibatide as a 180 microg/kg bolus with a 2.0 microg/kg/min infusion; or eptifibatide as a 250 microg/kg bolus with a 3.0 microg/kg/min infusion. Light transmission aggregometry was used to determine platelet aggregation in response to 20 microM adenosine diphosphate, and platelet receptor occupancy was also determined. Eptifibatide exhibited linear pharmacokinetics over the dose range studied. Inhibition of platelet aggregation was greater in samples collected in sodium citrate compared with those collected in D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone. The 180/2.0 dosing regimen achieved 90% inhibition of platelet aggregation immediately (5 minutes) and at steady state (8 to 24 hours). At 1 hour, mean inhibition of platelet aggregation was 80%. Eptifibatide exhibited dose-dependent pharmacodynamics that were dependent upon choice of anticoagulant. A 180 microg/kg bolus followed by a 2.0 microg/kg/min infusion at steady state achieved >80% inhibition of platelet aggregation. With the single-bolus regimen, however, there was an early loss of the inhibition of platelet aggregation before steady state was reached. Additional dose-exploration studies may further optimize eptifibatide dosing.
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Affiliation(s)
- J E Tcheng
- Duke Clinical Research Institute, Durham, North Carolina, USA.
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45
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Galeote G, López Pastor A, Cárcamo C, Sobrino N, Calvo L, García Muñoz S, Hussein M, Férnandez-Chacón JL, Sobrino JA. [Variable response to the biological inhibition of platelets by abciximab in patients subjected to percutaneous coronary angioplasty]. Rev Esp Cardiol 2001; 54:1256-63. [PMID: 11707234 DOI: 10.1016/s0300-8932(01)76494-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION AND OBJECTIVES Abciximab has been shown to reduce the risk of thrombotic complications during coronary angioplasty, however there are still many aspects to be resolved. The aim of this study was to investigate the various biological effects of abciximab on platelets during coronary angioplasty. METHODS The degree of platelet inhibition (with 5 and 20 mol/l concentrations of ADP), occlusion time (measurement of platelet haemostatic capacity, PFA-100), and the platelet activation markers were determined in 15 patients who underwent basal coronary angioplasty and abciximab treatment. Determinations were obtained before, 15 minutes after procedure initiation, at procedure termination, and 24 hours after procedure termination. RESULTS More than 80% platelet aggregation inhibition was observed in 13 patients during the procedure, but after 24 hours (p < 0.05) was only detected in two. The occlusion time during the procedure was > 300 sec. in 13 patients, 6 of whom evolved to normal values after 24 hours (p < 0.05). A high correlation (p = 0.02) was found between these two parameters during the intervention, but not after 24 hours. No platelet inhibition or occlusion time changes were observed in 2 patients during the study. The expression of p-selectin increased significantly during the procedure (p < 0.05). CONCLUSIONS The variability of platelet function inhibition and existence of circulating activation during coronary angioplasty following the administration of abciximab support the use of early analytical controls with the objective of modifying guidelines for use in order to optimize its effect or to combine it with other antithrombotic agents.
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Affiliation(s)
- G Galeote
- Laboratorio de Cardiología Intervencionista, Hospital Universitario La Paz, Madrid, Spain.
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46
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Kereiakes DJ, Lorenz T, Young JJ, Kukielka G, Mueller MN, Nanniazzi-Alaimo L, Phillips DR. Differential effects of citrate versus PPACK anticoagulation on measured platelet inhibition by abciximab, eptifibatide and tirofiban. J Thromb Thrombolysis 2001; 12:123-7. [PMID: 11729363 DOI: 10.1023/a:1012991303381] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND High levels of glycoprotein (GP) IIb/IIIa receptor inhibition are required to prevent arterial thrombosis following percutaneous coronary intervention. Ex-vivo turbidometric platelet aggregation in citrate anticoagulated blood samples has been the primary method previously utilized to derive dose regimens for administering platelet GP IIb/IIIa inhibitors. Enhanced GP IIb/IIIa binding and inhibition of platelet aggregation for eptifibatide secondary to citrate induced reduction of ionized plasma calcium concentrations has been reported. METHODS/RESULTS We evaluated the differential effects of citrate versus PPACK anticoagulation on turbidometric platelet inhibition in normal volunteers by eptifibatide, tirofiban or abciximab. The decrease in ionized calcium afforded by citrate was associated with enhanced in vitro platelet inhibition for all three GP IIb/IIIa inhibitors, including abciximab. The magnitude of citrate effect was greatest for eptifibatide. Both tirofiban and abciximab have similar citrate calcium chelation associated enhancement of measured platelet inhibition. CONCLUSION Accurate assessment and comparison of platelet inhibition by GP IIb/IIIa inhibitors may require avoidance of calcium chelating anticoagulants.
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Affiliation(s)
- D J Kereiakes
- The Carl and Edyth Lindner Center for Research and Education, 2123 Auburn Avenue, Suite 424, Cincinnati, OH 45219, USA.
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47
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Gilchrist IC, O'Shea JC, Kosoglou T, Jennings LK, Lorenz TJ, Kitt MM, Kleiman NS, Talley D, Aguirre F, Davidson C, Runyon J, Tcheng JE. Pharmacodynamics and pharmacokinetics of higher-dose, double-bolus eptifibatide in percutaneous coronary intervention. Circulation 2001; 104:406-11. [PMID: 11468201 DOI: 10.1161/hc2901.093504] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Pharmacodynamics of eptifibatide, a cyclic heptapeptide antagonist of platelet glycoprotein IIb/IIIa, are substantially altered by anticoagulants that chelate calcium, resulting in overestimation ex vivo of the in vivo effects of this agent. We conducted a dose-ranging study to characterize the pharmacodynamics and pharmacokinetics of eptifibatide under physiological conditions. METHODS AND RESULTS Patients (n=39) undergoing elective percutaneous coronary intervention were randomly assigned to an eptifibatide bolus followed by an infusion (180-microgram/kg bolus followed by 2 microgram/kg per minute or 250-microgram/kg bolus followed by 3 microgram/kg per minute) for 18 to 24 hours. In a 2:1 ratio, these patients received either a second bolus of eptifibatide (90 microgram/kg or 125 microgram/kg for the initial 180-microgram/kg or 250-microgram/kg groups, respectively) or placebo 30 minutes after the initial bolus. Bleeding times, ex vivo platelet aggregation, receptor occupancy, and plasma eptifibatide levels at baseline and at 1, 2, 3, 4, 6, and 8 hours were evaluated. Platelet inhibition was dose dependent and >80% in all groups by steady state. The single-bolus regimens had a transient loss of inhibition at 1 hour, consistent with rapid distribution and drug elimination. Pharmacokinetic modeling suggested that optimal dosing of eptifibatide would be obtained with a 180-microgram/kg bolus and a 2-microgram/kg per minute infusion followed by a second 180-microgram/kg bolus 10 minutes later. CONCLUSIONS A novel higher-dose, double-bolus regimen of eptifibatide in coronary intervention attains and maintains >90% inhibition of platelet aggregation in >90% of patients, providing the pharmacodynamic construct for the design of the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial of adjunctive eptifibatide in coronary stent implantation.
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48
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Graff J, Andries D, Elsner M, Westrup D, Bassus S, Franz N, Klinkhardt U, Harder S. Platelet CD62 expression and PDGFAB secretion in patients undergoing PTCA and treatment with abciximab. Br J Clin Pharmacol 2001; 51:577-82. [PMID: 11422017 PMCID: PMC2014496 DOI: 10.1046/j.1365-2125.2001.01392.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS To investigate a correlation of the platelet activation marker CD62 and secretion of the growth factor PDGF from platelets in coronary patients under therapy with the GPIIb/IIIa-inhibitor abciximab. METHODS Flow cytometric assessment of fibrinogen binding (GPIIb/IIIa-binding site) and CD62 expression, as well as PDGF release of human platelets (immunoassay) and platelet aggregation with 20 microM ADP and 2 microg ml(-1) collagen were evaluated in nine patients with stable coronary artery disease. Patients were undergoing elective balloon angioplasty and were treated with aspirin (100 mg day(-1)), heparin (ACT < 220 s) and abciximab (bolus and infusion over 12 h). Blood samples were obtained before initiation of abciximab therapy (under aspirin and heparin) (I), 3 h after angioplasty under abciximab (II) and 12 h after termination of abciximab infusion (III). RESULTS Compared with sample I before abciximab therapy, fibrinogen binding was reduced to 37% (+/- 34 s.d., P < 0.05) (II) and 55% (+/- 40 s.d., P < 0.05) (III). Reduced fibrinogen binding also led to a significant reduction of the aggregation response to ADP (down to 37% +/- 20) and collagen (down to 0%). Mean fluorescence intensity of CD62-expression was 78 units (+/- 20 s.d.) (I), 72 units (+/- 14 s.d.) (II) and 64 units (+/- 12 s.d., P < 0.05) (III). PDGF release from isolated, washed platelets was 99 (+/- 33 s.d.) ng/10(9) platelets at (I), 82 (+/- 31 s.d.) ng/10(9) platelets and 96 (+/- 30 s.d.) ng/10(9) platelets. CONCLUSIONS The results indicate that despite a strong reduction of GPIIb/IIIa-binding and platelet aggregation, CD62 as a marker of platelet secretion and the secretion product PDGF were only slightly reduced under abciximab treatment. No direct correlation between CD62 expression and PDGF release could be demonstrated.
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Affiliation(s)
- J Graff
- Institute of Clinical Pharmacology, Medical School of the J.W. Goethe University, Frankfurt am Main, Germany.
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Neumann FJ, Hochholzer W, Pogatsa-Murray G, Schömig A, Gawaz M. Antiplatelet effects of abciximab, tirofiban and eptifibatide in patients undergoing coronary stenting. J Am Coll Cardiol 2001; 37:1323-8. [PMID: 11300442 DOI: 10.1016/s0735-1097(01)01165-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES We sought to investigate whether abciximab, tirofiban and eptifibatide achieve comparable antiplatelet effects with coronary stenting. BACKGROUND The glycoprotein (GP) IIb/IIIa antagonists abciximab, tirofiban and eptifibatide differ in chemical structure, binding site and pharmacokinetics. METHODS Sixty patients undergoing coronary stenting were randomly assigned to abciximab (bolus 0.25 mg/kg body weight, infusion 10 microg per min for 12 h), tirofiban (bolus 10 microg/kg, infusion 0.15 microg/kg per min for 72 h) or eptifibatide (bolus 180 microg/kg, infusion 2 microg/kg per min for 72 h). We took serial blood samples to analyze platelet function by using flow cytometry, turbidimetric aggregometry and the rapid platelet-function assay (RPFA). RESULTS As assessed by RPFA, platelet aggregation after 2 h of infusion was reduced to 5.9 +/- 7.8% (mean +/- SD) of baseline by abciximab, to 5.0 +/- 5.4% by tirofiban and to 7.8 +/- 7.1% by eptifibatide (p = 0.42). Turbidimetric aggregometry with adenosine diphosphate stimulation yielded similar results, whereas percent inhibition of platelet aggregation after thrombin receptor stimulation was 45.8 +/- 16.8% with abciximab, 51.3 +/- 17.6% with tirofiban and 52.9 +/- 14.8% with eptifibatide (p = 0.37). Tirofiban and eptifibatide maintained their level of platelet inhibition during infusion. Flow cytometry revealed that the reduction in the monocyte-platelet interaction by abciximab, tirofiban and eptifibatide was not significantly different (20.0 +/- 21.9%, 23.8 +/- 18.2% and 21.0 +/- 19.8%, respectively; p = 0.87). CONCLUSIONS Abciximab, tirofiban and eptifibatide, at currently recommended doses, achieved similar levels of inhibition of platelet aggregation and a similar reduction in the platelet-monocyte interaction.
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Affiliation(s)
- F J Neumann
- Medizinische Klinik and Deutsches Herzzentrum, Technische Universität München, Munich, Germany.
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50
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Chew DP, Bhatt DL, Sapp S, Topol EJ. Increased mortality with oral platelet glycoprotein IIb/IIIa antagonists: a meta-analysis of phase III multicenter randomized trials. Circulation 2001; 103:201-6. [PMID: 11208677 DOI: 10.1161/01.cir.103.2.201] [Citation(s) in RCA: 266] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Numerous clinical trials have established the benefits of intravenous glycoprotein IIb/IIIa inhibition in the management of coronary artery disease. In contrast, the recent large-scale, placebo-controlled, randomized trials of the oral glycoprotein IIb/IIIa antagonists have failed to provide commensurate reductions in late composite ischemic end points despite potent inhibition of platelet aggregation. METHODS AND RESULTS The ORs for death, myocardial infarction, urgent revascularization, and major bleeding from the 4 large-scale, placebo-controlled, randomized trials with oral glycoprotein IIb/IIIa inhibitors were calculated and combined. Stratification by low-dose or high-dose therapy and the use of concurrent aspirin was also undertaken. In 33 326 patients followed for >30 days, a consistent and statistically significant increase in mortality was observed with oral glycoprotein IIb/IIIa therapy (OR, 1.37; 95% CI, 1.13 to 1.66; P:=0.001). This effect was evident regardless of aspirin coadministration and treatment with either low-dose or high-dose therapy. Although a reduction in urgent revascularization was observed with oral glycoprotein IIb/IIIa inhibition, pooled analysis favored an increase in myocardial infarction that did not demonstrate statistical significance. CONCLUSIONS Although we found a highly significant excess in mortality consistent across 4 trials with 3 different oral glycoprotein IIb/IIIa inhibitor agents, this was associated with a reduction in the need for urgent revascularization and no increase in myocardial infarction. These findings suggest the potential for a direct toxic effect with these agents and argue against a prothrombotic mechanism. Further investigation to elucidate the cause of this increased fatality risk is warranted.
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Affiliation(s)
- D P Chew
- Department of Cardiology, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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