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Chen LY, Khan N, Lindenbauer A, Nguyen TH. When Will Fondaparinux Induce Thrombocytopenia? Bioconjug Chem 2022; 33:1574-1583. [PMID: 35878320 PMCID: PMC9390334 DOI: 10.1021/acs.bioconjchem.2c00316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pentasaccharide Fondaparinux, a synthetic selective factor Xa inhibitor, is one of the safest anticoagulants in the heparin family that is recommended as an alternative drug for patients with hypersensitivity to other drugs such as heparin-induced thrombocytopenia (HIT). However, some observations of Fondaparinux-induced thrombocytopenia (FIT) have been reported while others claimed that FIT does not occur in patients with fondaparinux therapy, indicating that the mechanism of FIT remains controversial. Here, we utilized different methodologies including dynamic light scattering, immunosorbent and platelet aggregation assays, confocal laser scanning microscopy, and flow cytometry to gain insights into FIT. We found that at a certain concentration, Fondaparinux formed sufficient large and stable complexes with PF4 that facilitated binding of the HIT-like monoclonal KKO antibody and enhanced platelet aggregation and activation. We proposed a model to describe the role of Fondaparinux concentration in the formation of complexes with platelet factor 4 and how it promotes the binding of KKO. Our results clarify controversial observations of FIT in patients as each contains a dissimilar PF4:Fondaparinux concentration ratio.
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Affiliation(s)
- Li-Yu Chen
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany.,Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, 07745 Jena, Germany
| | - Nida Khan
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany.,Faculty of Mathematics and Natural Sciences, Technische Universität Ilmenau, 98694 Ilmenau, Germany
| | - Annerose Lindenbauer
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany
| | - Thi-Huong Nguyen
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany.,Faculty of Mathematics and Natural Sciences, Technische Universität Ilmenau, 98694 Ilmenau, Germany
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2
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Schindewolf M, Steindl J, Beyer-Westendorf J, Schellong S, Dohmen PM, Brachmann J, Madlener K, Pötzsch B, Klamroth R, Hankowitz J, Banik N, Eberle S, Müller MM, Kropff S, Lindhoff-Last E. Use of Fondaparinux Off-Label or Approved Anticoagulants for Management of Heparin-Induced Thrombocytopenia. J Am Coll Cardiol 2017; 70:2636-2648. [DOI: 10.1016/j.jacc.2017.09.1099] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 09/15/2017] [Accepted: 09/18/2017] [Indexed: 01/18/2023]
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3
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Abstract
Heparin's anticoagulation effect makes it the principal component in the immediate treatment of all thrombotic diseases. After hemorrhage, the most important complication of heparin is thrombocytopenia, the decrease in the number of blood platelets. Ten cases of "heparin-induced thrombocytopenia" are described, and guidelines for diagnosing heparin-induced thrombocytopenia in patients who present for cardiac and vascular surgery are given. Methods of treating patients with heparin-induced thrombocytopenia, including use of arachidonic acid derivatives, antiplatelet agents, other anticoagulants, heparinoids, natural and synthetic thrombin inhibitors, hirudin, and defibrinogenation with ancrod, are discussed.
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Affiliation(s)
- David Cummins
- Departments of Haematology and Anaesthesia, Harefield Hospital, Harefield, Middlesex, United Kingdom
| | - Elaine Hill
- Departments of Haematology and Anaesthesia, Harefield Hospital, Harefield, Middlesex, United Kingdom
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4
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Tran AH, Lee G. Fondaparinux for Prevention of Venous Thromboembolism in Major Orthopedic Surgery. Ann Pharmacother 2016; 37:1632-43. [PMID: 14565815 DOI: 10.1345/aph.1c104] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE: To review clinical information related to fondaparinux, a synthetic pentasaccharide recently approved for the prevention of deep-vein thrombosis (DVT) in patients undergoing major orthopedic surgeries and for extended DVT prophylaxis after hip fracture surgery. DATA SOURCES: Primary and review articles were identified by MEDLINE (1983–June 2003) using the key words pentasaccharide, Org31540, SR90107A, DVT prophylaxis, and fondaparinux. Additional sources were found listed in articles, abstracts, and unpublished data on file from the manufacturer. Articles selected were based on their coverage of the pharmacology, pharmacokinetics, safety, and efficacy of fondaparinux. STUDY SELECTION AND DATA EXTRACTION: All of the articles identified were evaluated and all information deemed relevant was included. DATA SYNTHESIS: Fondaparinux is a selective antithrombin-dependent, indirect inhibitor of activated factor Xa. It has a favorable and predictable pharmacokinetic profile when administered subcutaneously, and has a long half-life, allowing once-daily dosing. Fondaparinux lacks in vitro cross-reactivity with heparin-induced antibodies. Major Phase III studies have demonstrated that subcutaneous fondaparinux sodium 2.5 mg given at least 6 hours postoperatively resulted in a 55% reduction in the risk of venous thromboembolism (VTE) in patients undergoing hip fracture surgery, total hip replacement surgery, or knee replacement surgery compared with standard enoxaparin therapy. It has a safety profile similar to that of enoxaparin with respect to clinically relevant major bleeding, including fatal bleeding, nonfatal bleeding, and bleeding requiring repeat surgery. The use of fondaparinux for prolonged prophylaxis after hip fracture has demonstrated further reduction in VTE events without increasing the risk of bleeding. CONCLUSIONS: Fondaparinux is the first of a new class of synthetic factor Xa inhibitors that demonstrated greater efficacy compared with enoxaparin for the prevention of VTE in major orthopedic surgery without an increase in clinically relevant bleeding. Given the favorable cost-effectiveness analysis and improved efficacy profile, fondaparinux should be considered for formulary addition for DVT prophylaxis in patients undergoing hip and knee replacement surgery. In patients undergoing hip fracture surgery, fondaparinux should be considered the DVT prophylaxis of choice. Extended thromboprophylaxis up to 28 days resulted in additional reduction in VTE (both symptomatic and venography-proven DVT) in patients with hip fracture surgery.
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Affiliation(s)
- Alison H Tran
- Cardiology, Harper University Hospital, Detroit Medical Center, Detroit, MI, USA
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5
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Abstract
Thromboembolic disorders continue to be a major cause of morbidity and mortality, resulting in an increased need for anticoagulant therapy. In recent years, new anticoagulant drugs have been developed at a rapid pace, prompted by the recognition of many undesirable properties of currently used agents, and by a greater knowledge of the active enzymatic sites of clotting factors. Furthermore, the structure of a thrombus is better understood, so that newer drugs can inhibit thrombin or Factor Xa not only on the surface of a thrombus, as in the case of heparin, but also the fibrin-bound thrombin or Factor Xa within the thrombus. These agents are usually small molecules synthesized on the basis of their inhibition of specific active sites in the respective coagulation factors. They possess many improved characteristics, such as greater efficacy and safety, oral administration, reliable pharmacokinetics, less need for laboratory monitoring and minimal interactions with other drugs and diet. Prominent among these are lepuridin (Refludan, Pfizer), fondaparinux (Arixtra, Sanofi-Synthelabo) and ximelagatran (Exanta, Astra Zeneca). However, these new drugs are still far from fulfilling the desired objectives. Most of them possess some but not all of the needed properties. Furthermore, many do not have specific antidotes for immediate reversal of their pharmacologic actions, and all are much more costly than conventional agents. Development of newer agents with properties closer to that of the ideal drug remains a challenge.
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Affiliation(s)
- Hau C Kwaan
- Division of Hematology/Oncology, Northwestern University, Feinberg School of Medicine, 333 East Huron Street, Chicago, IL 60011-3008, USA.
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6
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Fondaparinux - data on efficacy and safety in special situations. Thromb Res 2011; 129:407-17. [PMID: 22133273 DOI: 10.1016/j.thromres.2011.10.037] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/27/2011] [Accepted: 10/28/2011] [Indexed: 12/20/2022]
Abstract
New anticoagulants promise to have better efficacy, more safety and/or a better manageability than traditional anticoagulants. However, knowledge is limited regarding special situations such as renal insufficiency, obesity, pregnancy, long-term therapy, heparin-induced thrombocytopenia, treatment in patients with mechanical heart valves, use for children, and in patients with a high risk of thromboembolic complications. These situations have rarely or even never been the objective of randomised controlled trials. The purpose of the present article is to summarize and discuss available data on efficacy and safety in these special situations for one of the first new anticoagulants, the indirect factor-Xa inhibitor fondaparinux. Furthermore, we discuss safety in licensed indications and management of bleeding complications and comment on measuring of drug concentration in plasma.
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7
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Fondaparinux cross-reacts with heparin antibodies in vitro in a patient with fondaparinux-related thrombocytopenia. Blood Coagul Fibrinolysis 2011; 22:76-8. [PMID: 21076279 DOI: 10.1097/mbc.0b013e328340ff24] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) related to fondaparinux has been rarely reported, although the ability of fondaparinux to cross-react with heparin antibodies has been often a subject of debate. A patient previously exposed to unfractionated heparin and low-molecular-weight heparin (LMWH) was diagnosed with HIT. During treatment with fondaparinux for 5 consecutive days, his thrombocytopenia significantly deteriorated. A functional platelet activation test in vitro showed clear platelet activation after serum exposure with fondaparinux. After discontinuation of fondaparinux, the platelet count was rapidly reestablished. Fondaparinux cross-reacted with heparin antibodies in this case of HIT, resulting in a deterioration of thrombocytopenia. The implication of this drug in HIT was observed clinically and demonstrated in vitro using a platelet activation test.
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Abstract
Heparin-induced thrombocytopenia (HIT) is an antibody-mediated prothrombotic disorder triggered by PF4-binding polyanions, usually heparin. The pentasaccharide anticoagulant, fondaparinux, despite its negative charge and structural similarity to heparin, does not usually promote antibody binding to PF4 (owing to absent/weak 'cross-reactivity'). Thus, despite its ability to trigger anti-PF4/heparin antibodies ('immunogenicity'), fondaparinux has low - but not zero - risk of inducing HIT de novo, or of exacerbating HIT when antibodies are already present. Indeed, despite rare reports of fondaparinux-induced HIT, this 'dissociation' between immunogenicity and cross-reactivity suggests that fondaparinux should be effective in treating HIT, as supported by several observational studies. An emerging issue: will clinicians accept this favorable experience of fondaparinux for treating HIT when a lack of randomized trials will hinder regulatory approval for this indication?
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Affiliation(s)
- Theodore E Warkentin
- Michael G DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.
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9
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Emerging Anticoagulants and Heparin-Induced Thrombocytopenia: Indirect and Direct Factor Xa Inhibitors and Oral Thrombin Inhibitors. ACTA ACUST UNITED AC 2010. [DOI: 10.3109/9781420045093.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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10
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Aldridge E, Cunningham LL. Current thoughts on treatment of patients receiving anticoagulation therapy. J Oral Maxillofac Surg 2010; 68:2879-87. [PMID: 20727633 DOI: 10.1016/j.joms.2010.04.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 04/06/2010] [Accepted: 04/14/2010] [Indexed: 02/08/2023]
Affiliation(s)
- Eron Aldridge
- Division of Oral and Maxillofacial Surgery, University of Kentucky College of Dentistry, Lexington, KY 40536-0297, USA
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11
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Badger NO. Fondaparinux (Arixtra®), a Safe Alternative for the Treatment of Patients With Heparin-Induced Thrombocytopenia? J Pharm Pract 2010; 23:235-8. [DOI: 10.1177/0897190010362170] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Fondaparinux, a pentasaccharide which selectively binds to antithrombin III, has negligible to no cross-reactivity with heparin-induced thrombocytopenia (HIT) antibodies in in vitro studies. The lack of cross-reactivity suggests a potential role in the management of HIT, and indeed, there are several such case reports and small studies. These published data have used both the prophylactic and weight-based treatment doses. However, due to the small possibility of developing HIT with thromboembolic complications while receiving fondaparinux, it is suggested that the appropriate weight-based treatment dose be used. In all these reports, fondaparinux provided adequate anticoagulation, prevented further thromboembolic events, and platelet counts returned to normal. However, there have been a couple of case reports on possible HIT or HIT-like syndrome secondary to fondaparinux use. Conclusion: Fondaparinux is an attractive anticoagulant therapy in patients with HIT. There is still the need for larger randomized trials evaluating the true efficacy, appropriate dose, safe duration of treatment, and the true incidence of HIT associated with fondaparinux.
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12
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Blackmer AB, Oertel MD, Valgus JM. Fondaparinux and the management of heparin-induced thrombocytopenia: the journey continues. Ann Pharmacother 2009; 43:1636-46. [PMID: 19737996 DOI: 10.1345/aph.1m136] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE To review the available literature addressing the role of fondaparinux in the management of heparin-induced thrombocytopenia (HIT). DATA SOURCES Primary articles were identified by a MEDLINE search (2004-June 2009) of English-language literature using the MeSH headings fondaparinux, heparin, low-molecular-weight heparin, and thrombocytopenia. Relevant consensus guidelines (2006-June 2009) were also identified. STUDY SELECTION AND DATA EXTRACTION All published studies and case reports, as well as relevant consensus guidelines, evaluating the use of fondaparinux for the management of HIT were included. DATA SYNTHESIS The role of fondaparinux in the management of HIT is a therapeutic controversy challenging clinicians today. An open-label, prospective pilot study of 7 patients with acute HIT supports fondaparinux as an alternative anticoagulant. Additionally, a total of 12 patients with HIT from a larger case study and retrospective cohort were successfully treated with fondaparinux. Much of the supporting data exists in the form of case reports, each demonstrating normalization of platelet counts without any evidence of new thrombosis. The differences in clinical scenarios as well as the role and dose of fondaparinux make interpretation of these reports difficult. Three case reports have been published raising concerns regarding fondaparinux causing or failing to manage HIT appropriately. However, common weaknesses such as small sample sizes and nonuniform definitions of HIT limit the usefulness of these findings. The updated American College of Chest Physicians consensus guidelines now recognize fondaparinux as an option in the management of HIT; however, the level of evidence supporting this is of low quality. The use of fondaparinux as a bridging agent between direct thrombin inhibitor and warfarin therapy has been proposed. A recently published case report gives support to this approach. CONCLUSIONS Controlled clinical trials evaluating the use of fondaparinux in the management of HIT need to be completed before this therapy can be routinely recommended.
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Affiliation(s)
- Allison Beck Blackmer
- Department of Pharmacy, The University of North Carolina Hospitals and Clinics, Chapel Hill, NC 27514, USA
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13
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Schenk JF, Stephan B, Kusma M, Groß J, Eichler H. [Orthopedic patients with or without thrombophilia. Diagnostic, therapy and peri-operative strategies]. DER ORTHOPADE 2009; 38:835-42. [PMID: 19730811 DOI: 10.1007/s00132-009-1455-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Venous thrombosis and pulmonary embolisms are currently associated with high mortality rates in Europe as well as in the United States (mortality rate >300,000-500,000/year). The highest risk is attributed to orthopedic surgery. Besides the use of antithrombotic agents, surgical and anesthesiological procedures as well as a multitude of trigger mechanisms, many thrombophilic risk conditions have to be considered. The incidence of thrombotic complications could be continuously reduced by the improvement of different antithrombotic strategies and use of drugs. According to national and international guidelines low molecular weight heparins and fondaparinux (besides aPTT adjusted strategies by using unfractionated heparin) are mainly indicated in high risk patients undergoing hip and knee surgery.The use of newly developed anti-IIa and anti-Xa inhibitors (e.g. dabigatran etexilate, rivaroxaban) is not yet established in guidelines. The discovery of pentasaccharide has further improved the antithrombotic efficiency, but it is still unknown how to manage patients with thrombophilia. Otherwise the knowledge of thrombophilia is not mandatory to know how to manage high risk patients. In contrast information on a history of thrombotic complications as well as indications gained from the family history are of great importance. Whether and to what extent, which patients with or without thrombophilic disposition, under which conditions from which medication within an anti-coagulation prophylaxis profit most over which time period, will be of future interest. Fundamentally, the age of the patient as well as liver and kidney function values and possible interactions between medications must be taken into consideration for selection of individual anti-thrombotic drugs. Even prolongation of medical immobilization prophylaxis can lead to accumulative risks, such as heparin-induced thrombocytopenia, the risk of which grows with increased exposition to the triggering agent.
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Affiliation(s)
- J F Schenk
- Institut für Klinische Hämostaseologie und Transfusionsmedizin, Universitätsklinikum des Saarlandes, Kirrberger Strasse 100, 66421, Homburg-Saar, Deutschland.
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14
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Seldrum S, Lambert M, Hainaut P. Heparin-induced thrombocytopenia successfully treated with fondaparinux. Acta Clin Belg 2009; 64:144-6. [PMID: 19432027 DOI: 10.1179/acb.2009.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We report the successful treatment of a patient with HIT-associated venous thrombosis by fondaparinux, a synthetic pentasaccharide. Although not yet approved for this indication, this new anticoagulant may be a useful alternative in the setting of HIT.
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Affiliation(s)
- S Seldrum
- Service de Médecine Interne Générale, Cliniques Universitaires Saint-Luc, Bruxelles, Belgium
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15
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Warkentin TE, Greinacher A, Koster A, Lincoff AM. Treatment and prevention of heparin-induced thrombocytopenia: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; 133:340S-380S. [PMID: 18574270 DOI: 10.1378/chest.08-0677] [Citation(s) in RCA: 533] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
This chapter about the recognition, treatment, and prevention of heparin-induced thrombocytopenia (HIT) is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patient values may lead to different choices. Among the key recommendations in this chapter are the following: For patients receiving heparin in whom the clinician considers the risk of HIT to be > 1.0%, we recommend platelet count monitoring over no platelet count monitoring (Grade 1C). For patients who are receiving heparin or have received heparin within the previous 2 weeks, we recommend investigating for a diagnosis of HIT if the platelet count falls by >/= 50%, and/or a thrombotic event occurs, between days 5 and 14 (inclusive) following initiation of heparin, even if the patient is no longer receiving heparin therapy when thrombosis or thrombocytopenia has occurred (Grade 1C). For patients with strongly suspected (or confirmed) HIT, whether or not complicated by thrombosis, we recommend use of an alternative, nonheparin anticoagulant (danaparoid [Grade 1B], lepirudin [Grade 1C], argatroban [Grade 1C], fondaparinux [Grade 2C], or bivalirudin [Grade 2C]) over the further use of unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) therapy or initiation/continuation of vitamin K antagonists (VKAs) [Grade 1B]. The guidelines include specific recommendations for nonheparin anticoagulant dosing that differ from the package inserts. For patients with strongly suspected or confirmed HIT, we recommend against the use of vitamin K antagonist (VKA) [coumarin] therapy until after the platelet count has substantially recovered (usually, to at least 150 x 10(9)/L) over starting VKA therapy at a lower platelet count (Grade 1B); that VKA therapy be started only with low maintenance doses (maximum, 5 mg of warfarin or 6 mg of phenprocoumon) over higher initial doses (Grade 1B); and that the nonheparin anticoagulant (eg, lepirudin, argatroban, danaparoid) be continued until the platelet count has reached a stable plateau, the international normalized ratio (INR) has reached the intended target range, and after a minimum overlap of at least 5 days between nonheparin anticoagulation and VKA therapy rather than a shorter overlap (Grade 1B). For patients receiving VKAs at the time of diagnosis of HIT, we recommend use of vitamin K (10 mg po or 5 to 10 mg IV) [Grade 1C].
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Affiliation(s)
| | - Andreas Greinacher
- Institute for Immunology and Transfusion Medicine, Ernst-Moritz-Arndt University Greifswald, Greifswald, Germany
| | | | - A Michael Lincoff
- Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, The Cleveland Clinic Foundation, Cleveland, OH
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16
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Garcia Hejl C, Garcia C, Thefenne-Astier H, Servonnet A, Samson T, Foissaud V. [Fondaparinux: the present and the future]. PATHOLOGIE-BIOLOGIE 2008; 56:97-103. [PMID: 18178332 DOI: 10.1016/j.patbio.2007.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2007] [Accepted: 09/28/2007] [Indexed: 05/25/2023]
Abstract
The development of new antithrombotic molecules which induced an inhibition of activated factor X (fondaparinux, Arixtra) shows effectiveness and safety in prevention of thromboembolic disease in surgery, but also in the treatment of the pulmonary embolism and major venous thromboses and acute myocardial infarction. Recent clinical trials show that new anti-Xa inhibitors also have interesting properties in antithrombotic therapy. Fondaparinux could offer new therapeutic possibilities that could simplify the management of patients under anticoagulant treatment.
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Affiliation(s)
- C Garcia Hejl
- Laboratoire de biochimie, HIA Val-de-Grâce, 74, boulevard Port-Royal, 75005 Paris, France.
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17
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Dailiana ZH, Malizos KN, Varitimidis S, Hantes M, Basdekis G, Rigopoulos N. Low-molecular-weight heparin for prevention of thrombosis: inverted role. ACTA ACUST UNITED AC 2008; 63:E111-5. [PMID: 17413518 DOI: 10.1097/01.ta.0000233909.88264.43] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Heparin induced thrombosis (HIT) after low-molecular-weight (LMWH) administration for thrombosis prevention is a limb and life threatening condition. METHODS Two previously healthy individuals, with nonviable forearm amputation and knee osteoarthritis, suffered from multiple arterial thromboses (>2 sites each) after postoperative administration of LMWH. RESULTS Both patients suffered from thrombocytopenia on the first postoperative days (4-7) and had signs of arterial occlusions on the 9th and 10th postoperative days. The patient with the initially successful forearm replantation was finally amputated below the elbow, whereas the lower extremity of the patient with total knee arthroplasty and contralateral femoral artery occlusion was salvaged with foot fingers amputation only. CONCLUSIONS Early recognition of the syndrome by monitoring daily platelet counts during heparin therapy is essential. In case of postheparin (LMWH or unfractionated) platelet decrease, heparin administration should be ceased after emergency testing for heparin induced antibodies. When HIT syndrome is confirmed to have occurred, heparin/LMWH must be replaced with thrombin-specific inhibitors.
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Affiliation(s)
- Zoe H Dailiana
- Department of Orthopaedic Surgery, School of Health Sciences, University of Thessalia, 22 Papakiriazi St, Larissa 41222, Greece.
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18
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Abstract
Unfractionated heparin is widely used for numerous clinical situations. A well-known adverse effect of heparin exposure is thrombocytopenia. Heparin-induced thrombocytopenia is a clinicopathologic syndrome that can be associated with severe complications and significant mortality. The pathophysiology of heparin-induced thrombocytopenia includes an immune-mediated reaction to heparin that activates platelets and results in an acquired hypercoagulability. Diagnosis of heparin-induced thrombocytopenia should incorporate clinical signs and symptoms and laboratory testing for heparin-induced thrombocytopenia antibodies. Therapy should include discontinuation of heparin, initiation of a direct thrombin inhibitor, and eventually therapy with warfarin (only after the platelet count is at least 100 x 10(9)/L).
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Affiliation(s)
- Joseph M Swanson
- Joseph M. Swanson is Assistant Professor, Department of Clinical Pharmacy, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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19
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Papadopoulos S, Flynn JD, Lewis DA. Fondaparinux as a Treatment Option for Heparin-Induced Thrombocytopenia. Pharmacotherapy 2007; 27:921-6. [PMID: 17542773 DOI: 10.1592/phco.27.6.921] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is an immune-mediated complication that can occur after exposure to heparin products. Because patients with HIT are at increased risk for thrombosis, anticoagulation is warranted. The direct thrombin inhibitors lepirudin and argatroban are approved by the United States Food and Drug Administration (FDA) for this indication. Bivalirudin, another direct thrombin inhibitor, is approved for use in patients with HIT who must undergo percutaneous coronary intervention. The synthetic pentasaccharide fondaparinux lacks FDA approval for treating patients with HIT; however, a few published reports describe its use. Furthermore, various small-scale, in vitro studies have demonstrated a lack of cross-reactivity between fondaparinux and HIT antibodies. Large, in vivo comparison trials must be performed before fondaparinux can become a standard treatment option in the setting of HIT.
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20
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Weitz JI, Linkins LA. Beyond heparin and warfarin: the new generation of anticoagulants. Expert Opin Investig Drugs 2007; 16:271-82. [PMID: 17302522 DOI: 10.1517/13543784.16.3.271] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Heparin and warfarin are widely used for the prevention and treatment of venous and arterial thromboembolism. Although effective, both agents have important limitations; for example, both drugs must be monitored, which is inconvenient for patients and for physicians. Heparin requires parenteral administration and can cause heparin-induced thrombocytopenia, an immune-mediated process that can lead to life-threatening thrombosis. Warfarin also has its limitations. Due to its slow onset of action, warfarin must be overlapped with heparin (or another rapidly acting anticoagulant) when treating patients with established thrombosis or who are at high risk for thrombosis. Warfarin dosing is variable because its activity is influenced by dietary intake of vitamin K, genetic polymorphisms in enzymes that are involved in its metabolism and numerous drug-drug interactions that promote or reduce its activity. New anticoagulants have been developed to overcome these problems. Building on a better understanding of coagulation pathways, advances in structure-based drug design and information derived from natural anticoagulants isolated from hematophagous organisms, most of the new anticoagulants target specific coagulation enzymes. Focussing on drugs that have at least completed Phase II evaluation, this article briefly reviews the coagulation pathways and its natural regulators; outlines the limitations of existing anticoagulants and identifies the opportunities for new ones; highlights the properties of selected new anticoagulants; describes the clinical trial results with these agents; and provides a perspective on their potential strengths and weaknesses.
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Affiliation(s)
- Jeffrey I Weitz
- McMaster University and Henderson Research Centre, 711 Concession Street, Hamilton, Ontario, L8V 1C3, Canada.
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Dager WE, Dougherty JA, Nguyen PH, Militello MA, Smythe MA. Heparin-Induced Thrombocytopenia: Treatment Options and Special Considerations. Pharmacotherapy 2007; 27:564-87. [PMID: 17381384 DOI: 10.1592/phco.27.4.564] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse effect that typically manifests several days after the start of heparin therapy, although both rapid- and delayed-onset HIT have been described. Its most serious complication is thrombosis. Although not all patients develop thrombosis, it can be life threatening. The risk of developing HIT is related to many factors, including the type of heparin product administered, route of administration, duration of therapy, patient population, and previous exposure to heparin. The diagnosis of HIT is typically based on clinical presentation, exposure to heparin, and presence of thrombocytopenia with or without thrombosis. Antigen and activation laboratory assays are available to support the diagnosis of HIT. However, because of the limited sensitivity and specificity of these assays, bedside probability scales for HIT were developed. When HIT is suspected, prompt cessation of all heparin therapy is necessary, along with initiation of alternative anticoagulant therapy. Two direct thrombin inhibitors--argatroban and lepirudin--are approved for the management of HIT in the United States, and bivalirudin is approved for use in patients with HIT who are undergoing percutaneous coronary intervention. Other agents, although not approved to manage HIT, have also been used; however, their role in therapy requires further evaluation. A comprehensive HIT management strategy involves the evaluation of numerous factors. Many patients, including those undergoing coronary artery bypass surgery, those with acute coronary syndromes, those with hepatic or renal insufficiency, and children, require special attention. Clinicians must become familiar with the available information on this serious adverse effect and its treatment so that optimum patient management strategies may be formulated.
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Affiliation(s)
- William E Dager
- Department of Pharmaceutical Services, University of California-Davis Medical Center, California 95817-2201, USA.
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22
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Smogorzewska A, Brandt JT, Chandler WL, Cunningham MT, Hayes TE, Olson JD, Kottke-Marchant K, Van Cott EM. Effect of fondaparinux on coagulation assays: results of College of American Pathologists proficiency testing. Arch Pathol Lab Med 2006; 130:1605-11. [PMID: 17076521 DOI: 10.5858/2006-130-1605-eofoca] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2006] [Indexed: 11/06/2022]
Abstract
CONTEXT Fondaparinux, a factor Xa inhibitor, is approved for thromboprophylaxis after orthopedic surgery and for treatment of venous thromboembolism. It may also be efficacious, safe, and cost-effective for other patients; thus, more widespread use of fondaparinux is likely. The effect of fondaparinux on coagulation testing needs to be thoroughly examined. OBJECTIVE To report the effects of fondaparinux on coagulation tests (prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin, factor VIII, thrombin time, anti-factor Xa) across diverse methodologies. DESIGN Samples with different concentrations of fondaparinux (0, 0.4, 0.8, and 2.0 microg/mL) were sent to laboratories participating in the College of American Pathologists Comprehensive Coagulation proficiency survey (N = 898). Laboratory-specific methods were used to assay coagulation parameters. RESULTS Prophylactic or therapeutic fondaparinux prolonged the prothrombin time by approximately 1 second and the activated partial thromboplastin time by 4 to 5 seconds, and reduced factor VIII from 119% to 107% and 102%, respectively. Supratherapeutic fondaparinux reduced factor VIII to 85%. The activated partial thromboplastin time was prolonged in 19%, 29%, and 52% of laboratories with prophylactic, therapeutic, and supratherapeutic fondaparinux levels, respectively. Fibrinogen, antithrombin, and thrombin time assays did not show clinically significant changes. When measuring fondaparinux concentration using an anti-factor Xa assay, the most accurate results were obtained when fondaparinux was used as the calibrator. CONCLUSIONS Fondaparinux, even in prophylactic doses, slightly prolongs the prothrombin time and activated partial thromboplastin time and can interfere with factor VIII assays, but it has no clinically relevant effect on fibrinogen, antithrombin, or thrombin time. A fondaparinux standard curve should be used for reporting fondaparinux levels using an anti-factor Xa assay.
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Affiliation(s)
- Agata Smogorzewska
- Department of Pathology and Laboratory Medicine, Harvard Medical School, Massachusetts General Hospital, Boston 02114, USA
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23
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Greinacher A, Gopinadhan M, Günther JU, Omer-Adam MA, Strobel U, Warkentin TE, Papastavrou G, Weitschies W, Helm CA. Close Approximation of Two Platelet Factor 4 Tetramers by Charge Neutralization Forms the Antigens Recognized by HIT Antibodies. Arterioscler Thromb Vasc Biol 2006; 26:2386-93. [PMID: 16873726 DOI: 10.1161/01.atv.0000238350.89477.88] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Heparin-induced thrombocytopenia (HIT) is a prothrombotic drug reaction caused by antibodies that recognize positively charged platelet factor 4 (PF4), bound to the polyanion, heparin. The resulting immune complexes activate platelets. Unfractionated heparin (UFH) causes HIT more frequently than low-molecular-weight heparin (LMWH), whereas the smallest heparin-like molecule (the pentasaccharide, fondaparinux), induces anti-PF4/heparin antibodies as frequently as LMWH, but without exhibiting cross-reactivity with these antibodies. To better understand these findings, we analyzed the molecular structure of the complexes formed between PF4 and UFH, LMWH, or fondaparinux. METHODS AND RESULTS By atomic force microscopy and photon correlation spectroscopy, we show that with any of the 3 polyanions, but in the order, UFH>LMWH>>fondaparinux--PF4 forms clusters in which PF4 tetramers become closely apposed, and to which anti-PF4/heparin antibodies bind. By immunoassay, HIT antibodies bind strongly to PF4/H/PF4 complexes, but only weakly to single PF4/heparin molecules. CONCLUSIONS HIT antigens are formed when charge neutralization by polyanion allows positively charged PF4 tetramers to undergo close approximation. Whereas such a model could explain why all 3 polyanions form antibodies with similar specificities, the striking differences in the relative size and amount of complexes formed likely correspond to the observed differences in immunogenicity (UFH>LMWH approximately fondaparinux) and clinically relevant cross-reactivity (UFH>LMWH>>fondaparinux).
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Affiliation(s)
- Andreas Greinacher
- Institute for Immunology and Transfusion Medicine, Ernst-Moritz-Arndt University, Sauerbruchstrasse, 17489 Greifswald, Germany.
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24
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Chang JJY, Parikh CR. HEMATOLOGY: ISSUES IN THE DIALYSIS PATIENT: When Heparin Causes Thrombosis: Significance, Recognition, and Management of Heparin-Induced Thrombocytopenia in Dialysis Patients. Semin Dial 2006; 19:297-304. [PMID: 16893407 DOI: 10.1111/j.1525-139x.2006.00176.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is characterized by thrombocytopenia and paradoxical hypercoagulability. HIT occurs when an antibody ("HIT antibody") produced against the complex of heparin and platelet factor 4 (PF4) causes systemic platelet consumption and activation. Nephrologists encounter HIT in the care of end-stage renal disease (ESRD) patients because heparin is a routine anticoagulant in hemodialysis. The incidence of HIT in ESRD appears to be lower than in other clinical settings. However, HIT is equally life threatening in ESRD patients and therefore demands the same prompt recognition and aggressive treatment. Diagnosing HIT requires the detection of HIT antibodies. A functional assay (e.g., [(14)C] serotonin release assay) relies on the patient's HIT antibodies to activate donor platelets at pharmacologic heparin concentrations. The more common antigen assay (e.g., enzyme-linked immunosorbent assay [ELISA]) detects the binding of the patient's HIT antibodies to antigens (e.g., heparin-PF4 complex) in a microtiter well and does not involve platelets. The moment HIT is suspected, heparin should be stopped and an alternative anticoagulant initiated immediately, even before the result of a serologic test becomes available. The advent of several new anticoagulants in the last decade, especially argatroban and bivalirudin, has expanded treatment options for HIT in dialysis patients. This review discusses the epidemiology, pathogenesis, clinical features, diagnosis, and treatment of HIT, with special emphasis on concepts relevant to the care of dialysis patients.
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Affiliation(s)
- John Jae Young Chang
- Section of Nephrology, Clinical Epidemiology Research Center, VA Connecticut Health Care System and Yale University, West Haven, Connecticut 06516, USA
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25
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Abstract
Currently available anticoagulants include heparin, low-molecular weight heparin, fondaparinux and warfarin. Despite advances with low-molecular weight heparin and fondaparinux, the currently available agents have limitations that have provided the impetus for the development of new drugs for prevention and treatment of both venous and arterial thromboembolism. Novel anticoagulants targeting specific steps in coagulation are in various stages of development. This paper reviews the pharmacology of these new agents and describes the results of clinical trials with new anticoagulants in more advanced stages of clinical testing.
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26
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Wijesiriwardana A, Lees DAR, Lush C. Fondaparinux as anticoagulant in a pregnant woman with heparin allergy. Blood Coagul Fibrinolysis 2006; 17:147-9. [PMID: 16479197 DOI: 10.1097/01.mbc.0000214710.19116.40] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We report a patient who had a history of deep vein thrombosis in a previous pregnancy. She was treated with heparins without any reactions in the index pregnancy. Subsequently, when the patient became pregnant again, she developed an acute cutaneous reaction to the low molecular heparin enoxaparin 3 weeks after initiation of therapy. She developed a similar reaction to delteparin as well. She was therefore treated with warfarin until 36 weeks of gestation. Then she was treated with fondaparinux (Arixtra, Sanofi-Synthelabo, Paris, France) 2.5 mg daily for the remainder of the pregnancy. Delivery was at term by induction of labour. Fondaparinux was stopped on the day of the induction of labour. It was re-started 6 h post-delivery and the patient was anticoagulated with warfarin in the post-partum period. There were no bleeding tendencies or recurrences of thrombosis during fondaparinux therapy. Both mother and baby were well after delivery.
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27
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Abstract
Heparin-induced thrombocytopenia (HIT) is a clinicopathologic condition and adverse drug reaction caused by immunoglobulin G (IgG) antibodies directed against the heparin-platelet factor 4 complex. In most patients, the onset of thrombocytopenia begins while the patient is receiving heparin. In less than 5% of patients, the onset of thrombocytopenia begins several days following heparin discontinuation and has been termed "delayed-onset" HIT. This review summarizes the presentation and clinical course of published reports of delayed-onset HIT occurring in 30 patients. The diagnosis of delayed-onset HIT should be considered in all patients presenting with venous thromboembolism (VTE) and all patients with recent heparin exposure (within the past 14 days) who present with a low platelet count. Most patients with HIT are treated with direct thrombin inhibitors and transitioned to warfarin oral anticoagulation. Administration of direct thrombin inhibitors requires close monitoring for bleeding, dose adjustments based upon coagulation monitoring and is costly. Fondaparinux, a synthetic pentasaccharide and indirect-acting factor-Xa inhibitor, has little to no cross-reactivity with the heparin-platelet factor 4 antibody in in vitro testing. This review summarizes dosing, monitoring and outcomes of preliminary reports of fondaparinux successfully administered to 13 patients with subacute HIT and 22 patients with acute HIT. While several reports have described the treatment and prophylaxis of thrombosis in patients with HIT using fondaparinux, clinical trials should be conducted and reported before fondaparinux becomes a therapy of choice for HIT.
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Affiliation(s)
- Sarah A Spinler
- Philadelphia College of Pharmacy, University of the Sciences in Philadelphia, 600 S. 43rd St., Philadelphia, PA 19104, USA.
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28
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Decousus H, Rivron-Guillot K, Girard G, Moulin N. Clinical efficacy and safety of fondaparinux in the prevention and treatment of venous and arterial thrombosis. Future Cardiol 2005; 1:743-58. [DOI: 10.2217/14796678.1.6.743] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Fondaparinux (Arixtra®) is a synthetic, selective Factor Xa inhibitor. Its pharmacokinetic profile allows once-daily subcutaneous administration of the drug without any laboratory monitoring. The benefit-to-risk ratio of fondaparinux in the prevention of venous thromboembolism has been extensively studied in both surgical and acutely ill medical patients at risk of thrombosis. Its efficacy and safety have also been investigated in the initial treatment of symptomatic deep-vein thrombosis and pulmonary embolism. Finally, a number of Phase II trials investigated the safety and efficacy of fondaparinux in patients with acute coronary syndromes, and a large Phase III program is ongoing in this setting. This review focuses on the use of fondaparinux in the prevention and treatment of thromboembolic disorders.
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Affiliation(s)
- Hervé Decousus
- Inserm, CIE3, 42055 Saint-Etienne, France; Univ Saint-Etienne, Groupe de Recherche sur la Thrombose, (EA3065), Saint-Etienne, F-42023, France; CHU Saint-Etienne, Service de Médecine Interne et Thérapeutique, Saint-Etienne, F-42055 France
| | - Karine Rivron-Guillot
- Inserm, CIE3, 42055 Saint-Etienne, France; Univ Saint-Etienne, Groupe de Recherche sur la Thrombose, (EA3065), Saint-Etienne, F-42023, France; CHU Saint-Etienne, Service de Médecine Interne et Thérapeutique, Saint-Etienne, F-42055 France
| | - Gaelle Girard
- CHU Saint-Etienne, Service de Médecine Interne et Thérapeutique, Saint-Etienne, F-42055 France
| | - Nathalie Moulin
- CHU Saint-Etienne, Service de Médecine Interne et Thérapeutique, Saint-Etienne, F-42055 France
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29
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Warkentin TE, Cook RJ, Marder VJ, Sheppard JAI, Moore JC, Eriksson BI, Greinacher A, Kelton JG. Anti-platelet factor 4/heparin antibodies in orthopedic surgery patients receiving antithrombotic prophylaxis with fondaparinux or enoxaparin. Blood 2005; 106:3791-6. [PMID: 16109780 PMCID: PMC1895104 DOI: 10.1182/blood-2005-05-1938] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is caused by platelet-activating IgG antibodies that recognize platelet factor 4 (PF4) bound to heparin. Immunogenicity of heparins differs in that unfractionated heparin (UFH) induces more anti-PF4/heparin antibodies than low-molecular-weight heparin (LMWH) and UFH also causes more HIT. Fondaparinux, a synthetic anticoagulant modeled after the antithrombin-binding pentasaccharide, is believed to be nonimmunogenic. We tested 2726 patients for anti-PF4/heparin antibodies after they were randomized to receive antithrombotic prophylaxis with fondaparinux or LMWH (enoxaparin) following hip or knee surgery. We also evaluated in vitro cross-reactivity of the IgG antibodies generated against PF4 in the presence of UFH, LMWH, danaparoid, or fondaparinux. We found that anti-PF4/heparin antibodies were generated at similar frequencies in patients treated with fondaparinux or enoxaparin. Although antibodies reacted equally well in vitro against PF4/UFH and PF4/LMWH, and sometimes weakly against PF4/danaparoid, none reacted against PF4/fondaparinux, including even those sera obtained from patients who formed antibodies during fondaparinux treatment. At high concentrations, however, fondaparinux inhibited binding of HIT antibodies to PF4/polysaccharide, indicating that PF4/fondaparinux interactions occur. No patient developed HIT. We conclude that despite similar immunogenicity of fondaparinux and LMWH, PF4/fondaparinux, but not PF4/LMWH, is recognized poorly by the antibodies generated, suggesting that the risk of HIT with fondaparinux likely is very low.
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Affiliation(s)
- Theodore E Warkentin
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
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30
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Spyropoulos AC. Emerging Strategies in the Prevention of Venous Thromboembolism in Hospitalized Medical Patients. Chest 2005; 128:958-69. [PMID: 16100192 DOI: 10.1378/chest.128.2.958] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Venous thromboembolism (VTE) remains a significant cause of morbidity and mortality in hospitalized patients with acute medical illness. The high prevalence of VTE in this patient population, its clinically silent nature, and associated morbidity and mortality indicate that prophylactic therapy is appropriate in those determined to be at increased risk. Unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) have been shown to reduce the incidence of VTE and are the primary therapies used for prophylaxis in these patients. Although both UFH and LMWH have received grade 1A recommendations for the prevention of VTE in at-risk medical patients in the 2004 American College of Chest Physicians consensus conference statements, LMWH has advantages over UFH in its once-daily dosing scheme, reduced incidence of major and minor bleeding events, and reduced incidence of heparin-induced thrombocytopenia. Fondaparinux is a novel antithrombotic agent characterized by specificity for factor Xa and a lack of platelet interaction. A recent clinical trial in hospitalized patients with acute medical illness found that fondaparinux significantly reduced the incidence of both VTE and fatal pulmonary embolism compared with placebo, without increased major bleeding. Despite the availability of effective thromboprophylactic therapies, VTE prophylaxis continues to be underutilized in hospitalized medical patients.
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Affiliation(s)
- Alex C Spyropoulos
- Clinical Thrombosis Center, Lovelace Sandia Health Systems, 5400 Gibson Blvd SE, Albuquerque, NM 87108, USA.
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31
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Abstract
The limitations of heparin and warfarin have prompted the development of new anticoagulant drugs for prevention and treatment of venous and arterial thromboembolism. Novel parenteral agents include synthetic analogs of the pentasaccharide sequence of heparin that mediates its interaction with antithrombin. Fondaparinux, the first synthetic pentasaccharide, is licensed for prevention of venous thromboembolism (VTE) after major orthopedic surgery and for initial treatment of patients with VTE. Idraparinux, a long-acting pentasaccharide that is administered subcutaneously once-weekly, is being compared with warfarin for treatment of VTE and for prevention of cardioembolic events in patients with atrial fibrillation. New oral anticoagulants include direct inhibitors of thrombin, factor Xa and factor IXa. Designed to provide more streamlined anticoagulation than warfarin, these agents can be given without routine coagulation monitoring. Ximelagatran, the first oral direct thrombin inhibitor, is as effective and safe as warfarin for prevention of cardioembolic events in patients with atrial fibrillation. However, ximelagatran produces a three-fold elevation in alanine transaminase levels in 7.9% of patients treated for more than a month, the long-term significance of which is uncertain. Whether other direct thrombin inhibitors or inhibitors of factors Xa or IXa also have this problem is under investigation. After a brief review of coagulation pathways, this paper focuses on new anticoagulants in advanced stages of clinical testing.
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Affiliation(s)
- J I Weitz
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
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32
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Mismetti P, Zufferey P, Pernod G, Estebe JP, Barrelier MT, Pegoix M, Nertl P. Prévention de la maladie thromboembolique en orthopédie et traumatologie. ACTA ACUST UNITED AC 2005; 24:871-89. [PMID: 16145756 DOI: 10.1016/j.annfar.2005.06.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Orthopaedic and trauma surgery are classified according 3 groups of venous thromboembolic risk. Elective total hip replacement (THR) or total knee replacement (TKR), hip fracture surgery or trauma patients are at high risk. Isolated lower extremity injury with fracture is at moderate risk whereas this risk is low without fracture as well as with knee arthroscopy. In THR and TKR, low molecular weight heparin (LMWH), fondaparinux or melagatran-ximelagatran are strongly recommended. The routine use of other anticoagulants, in particular vitamin K antagonist are not recommended. In patients at high risk of venous thromboembolism as for example trauma patients, optimal use of intermittent pneumatic compression is an alternative option in case of contra-indication to anticoagulant prophylaxis. Graduated compression stockings enhance the efficacy of pharmacological methods. In schedule surgery, initiation of prophylaxis with LMWH may be started postoperatively. To reduce the haemorrhagic risk of anticoagulants, timing of first postoperative dose is essential and is proper to each drug. Duration of prophylaxis depends on the surgical and the individual patients' risk. Extended prophylaxis in THR for up to 42 days with LMWH and up to 35 days with fondaparinux in hip fracture surgery is recommended. However extended prophylaxis after 14 days in TKR has not demonstrated a higher efficacy and should only be considered for patients with additional risk factors. In patients with isolated lower extremity injury or undergoing knee arthroscopy, LMWH should not be routinely used according to a low or a moderate risk and/or the duration of prophylaxis required. But LMWH has to be considered for patients with additional risk factors. Prophylaxis in other orthopedic procedures has not been assessed and will be extrapolated from the above recommendations.
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Affiliation(s)
- P Mismetti
- Unité de pharmacologie clinique: EA 3065, CIE 3n, service de médecine interne et thérapeutique, hôpital Bellevue, CHU, Saint-Etienne, France.
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33
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Walenga JM, Jeske WP, Fareed J. Short- and long-acting synthetic pentasaccharides as antithrombotic agents. Expert Opin Investig Drugs 2005; 14:847-58. [PMID: 16022574 DOI: 10.1517/13543784.14.7.847] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Fondaparinux sodium (Arixtra; GlaxoSmithKline) is the first of a new class of antithrombotic agents. It is a chemically synthesised pentasaccharide mimicking the site of heparin that binds to antithrombin. It is purely a factor Xa inhibitor and an inhibitor of thrombin generation that requires binding to antithrombin. Fondaparinux sodium differs from heparin, low-molecular-weight heparin and heparinoids, and cannot be used interchangeably. It has been approved in the US and Europe for the prophylaxis of venous thrombosis after orthopaedic surgery by a fixed dose of 2.5 mg/day without monitoring. Using this pentasaccharide as a backbone, other structures have been synthesised. Idraparinux sodium (Sanofi-Aventis) differs structurally from fondaparinux sodium as it has additional methyl groups, a long half-life, and once-weekly administration. Both drugs are being developed as antithrombotics for venous and arterial thrombosis, acute coronary syndrome, stroke and as adjuncts to thrombolytic therapy.
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Affiliation(s)
- Jeanine M Walenga
- Cardiovascular Institute (110/5226), Loyola University Medical Center, 2160 S. First Avenue, Maywood, IL 60153, USA.
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34
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Turpie AGG. The safety of fondaparinux for the prevention and treatment of venous thromboembolism. Expert Opin Drug Saf 2005; 4:707-21. [PMID: 16011449 DOI: 10.1517/14740338.4.4.707] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Fondaparinux is the first synthetic selective Factor Xa inhibitor. Along with its antithrombotic efficacy, the safety of fondaparinux has been documented in several Phase II and III clinical trials, including the prevention of venous thromboembolism in patients undergoing major orthopaedic surgery or high-risk abdominal surgery, or in acutely ill medical patients with restricted mobility, and the treatment of patients with deep-vein thrombosis and pulmonary embolism. In all these indications, the safety of fondaparinux used according to its registered regimen was similar to that of reference comparators. In conclusion, due to its superior efficacy and satisfactory safety, fondaparinux may substantially improve the prevention and treatment of venous thrombosis.
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Affiliation(s)
- Alexander G G Turpie
- General Division, Hamilton Health Sciences Corporation, 237 Barton Street East, Hamilton, ON, L8L 2X2, Canada.
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35
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Haase M, Bellomo R, Rocktaeschel J, Ziemer S, Kiesewetter H, Morgera S, Neumayer HH. Use of fondaparinux (ARIXTRA) in a dialysis patient with symptomatic heparin-induced thrombocytopaenia type II. Nephrol Dial Transplant 2005; 20:444-6. [PMID: 15673695 DOI: 10.1093/ndt/gfh544] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Michael Haase
- Department of Nephrology, University and Teaching Hospitals, Humboldt Univeristy of Berlin, Germany.
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36
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Bates SM, Weitz JI. New anticoagulants: beyond heparin, low-molecular-weight heparin and warfarin. Br J Pharmacol 2005; 144:1017-28. [PMID: 15711585 PMCID: PMC1576097 DOI: 10.1038/sj.bjp.0706153] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Revised: 11/17/2004] [Accepted: 12/13/2004] [Indexed: 11/09/2022] Open
Abstract
The limitations of traditional anticoagulants, heparin and warfarin, have prompted the development of new anticoagulant drugs for prevention and treatment of both venous and arterial thromboembolism. After a brief review of thrombogenesis and its regulation, this paper focuses on new anticoagulant agents in more advanced stages of clinical testing.
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Affiliation(s)
- Shannon M Bates
- Department of Medicine, McMaster University and Henderson Research Centre, Hamilton, Ontario, Canada
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37
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Warkentin TE, Greinacher A. Heparin-induced thrombocytopenia: recognition, treatment, and prevention: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004; 126:311S-337S. [PMID: 15383477 DOI: 10.1378/chest.126.3_suppl.311s] [Citation(s) in RCA: 619] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This chapter about the recognition, treatment, and prevention of heparin-induced thrombocytopenia (HIT) is part of the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading, see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following: For patients in whom the risk of HIT is considered to be > 0.1%, we recommend platelet count monitoring (Grade 1C). For patients who are receiving therapeutic-dose unfractionated heparin (UFH), we suggest at least every-other-day platelet count monitoring until day 14, or until UFH is stopped, whichever occurs first (Grade 2C). For patients who are receiving postoperative antithrombotic prophylaxis with UFH (HIT risk > 1%), we suggest at least every-other-day platelet count monitoring between postoperative days 4 to 14 (or until UFH is stopped, whichever occurs first) [Grade 2C]. For medical/obstetric patients who are receiving prophylactic-dose UFH, postoperative patients receiving prophylactic-dose low molecular weight heparin (LMWH), postoperative patients receiving intravascular catheter UFH "flushes," or medical/obstetrical patients receiving LMWH after first receiving UFH (risk, 0.1 to 1%), we suggest platelet count monitoring every 2 days or 3 days from day 4 to day 14, or until heparin is stopped, whichever occurs first (Grade 2C). For medical/obstetrical patients who are only receiving LMWH, or medical patients who are receiving only intravascular catheter UFH flushes (risk < 0.1%), we suggest clinicians do not use routine platelet count monitoring (Grade 2C). For patients with strongly suspected (or confirmed) HIT, whether or not complicated by thrombosis, we recommend use of an alternative anticoagulant, such as lepirudin (Grade 1C+), argatroban (Grade 1C), bivalirudin (Grade 2C), or danaparoid (Grade 1B). For patients with strongly suspected (or confirmed) HIT, we recommend routine ultrasonography of the lower-limb veins for investigation of deep venous thrombosis (Grade 1C); against the use of vitamin K antagonist (VKA) [coumarin] therapy until after the platelet count has substantially recovered; that the VKA antagonist be administered only during overlapping alternative anticoagulation (minimum 5-day overlap); and begun with low, maintenance doses (all Grade 2C). For patients receiving VKAs at the time of diagnosis of HIT, we recommend use of vitamin K (Grade 2C) [corrected] For patients with a history of HIT who are HIT antibody negative and require cardiac surgery, we recommend use of UFH (Grade 1C).
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Affiliation(s)
- Theodore E Warkentin
- Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, General Site, 237 Barton St E, Hamilton, Ontario L8L 2X2, Canada.
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Savi P, Chong BH, Greinacher A, Gruel Y, Kelton JG, Warkentin TE, Eichler P, Meuleman D, Petitou M, Herault JP, Cariou R, Herbert JM. Effect of fondaparinux on platelet activation in the presence of heparin-dependent antibodies: a blinded comparative multicenter study with unfractionated heparin. Blood 2004; 105:139-44. [PMID: 15388575 DOI: 10.1182/blood-2004-05-2010] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a complication of heparin therapy caused by antibodies against a complex of platelet factor 4 and heparin. Fondaparinux (Arixtra) is a new synthetic selective factor Xa inhibitor. We performed a serologic study to determine the cross-reactivity of HIT sera with fondaparinux. Using a prospective, blinded study design, 39 clinically and serologically confirmed sera from patients with HIT and 15 control sera were sent to 3 different laboratories, each of which specialized in a particular HIT assay. These include the serotonin release assay, heparin-induced platelet agglutination assay, and platelet aggregation assay. Two of 82 assays (2.4%) performed in the presence of control sera were positive, both with unfractionated heparin. In the presence of HIT sera, 75 of 94 (79.8%) evaluable assays were positive with unfractionated heparin; fondaparinux was significantly (P < .001) less reactive than unfractionated heparin, only 3 of 91 evaluable assays (3.3%) being positive. Using flow cytometry, unlike unfractionated heparin, fondaparinux did not induce the binding of PAC1 and anti-CD62 monoclonal antibodies or of annexin V to platelets with HIT sera. Together, these results suggest that fondaparinux is nonreactive to HIT sera and raise the possibility that the drug may be used for prophylaxis and treatment of thrombosis in patients with a history of HIT.
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Affiliation(s)
- Pierre Savi
- Cardiovascular/Thrombosis Research Department, Sanofi-Synthelabo Recherche, Toulouse, France.
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Jappe U, Juschka U, Kuner N, Hausen BM, Krohn K. Fondaparinux: a suitable alternative in cases of delayed-type allergy to heparins and semisynthetic heparinoids? A study of 7 cases. Contact Dermatitis 2004; 51:67-72. [PMID: 15373846 DOI: 10.1111/j.0105-1873.2004.00399.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hypersensitivity to unfractionated and low-molecular-weight heparins and semisynthetic heparinoids is increasingly common. 7 female patients between 30 and 74 years with delayed-type allergy to heparins and semisynthetic heparinoids were investigated for (cross)-reactivity to fondaparinux, a new pentasaccharide with selective factor Xa inhibition. All patients showed delayed-type reactions to heparins and some additional cross-reaction to a heparinoid on intracutaneous testing. 6/7 tolerated fondaparinux on intradermal testing as well as on subcutaneous challenge testing. However, the 7th patient developed a characteristic delayed-type reaction to both skin tests with fondaparinux. Fondaparinux is a new synthetic pentasaccharide with a molecular weight of 1.728 Da. In some patients with cross-reactivity between various heparins and semisynthetic heparinoids, lepirudin, a recombinant hirudin, may be a safe and effective alternative. However, combined allergy to hirudin and heparins has been reported. Sometimes, intravenous administration of heparins or heparinoids may be tolerated. However, these patients are at risk of developing a systemic reaction. The pathogenesis of heparin hypersensitivity is not fully understood. Heparins may act as haptens by binding to dermal and/or subcutaneous structural proteins. The chemical structures of heparins and fondaparinux are different concerning their alpha- and beta-configuration and the molecular weight. However, some of their functional groups are nearly identical and therefore similar chemical and pharmacological reactivity is to be expected. Fondaparinux seems to be a valuable alternative in most cases of heparin and hirudin hypersensitivity. The clearly rare cross-reaction between fondaparinux and heparins, now confirmed by us, may be due to differences in the response to haptens.
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Affiliation(s)
- U Jappe
- Department of Dermatology and Venereology, University of Heidelberg, Heidelberg, Germany.
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Dager WE, Andersen J, Nutescu E. Special Considerations with Fondaparinux Therapy: Heparin-Induced Thrombocytopenia and Wound Healing. Pharmacotherapy 2004; 24:88S-94S. [PMID: 15317404 DOI: 10.1592/phco.24.10.88s.36122] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Multiple options for anticoagulation therapy are now available, placing an additional responsibility on health care workers for choosing the optimal therapy for each patient. The heparins carry a risk of heparin-induced thrombocytopenia (HIT), an immune-mediated reaction to heparin that may lead to pulmonary embolism and death. Fondaparinux, a new, synthetic pentasaccharide, binds to antithrombin III and potentiates antithrombin III's inhibition of factor Xa. Fondaparinux does not bind to platelet factor 4 and thus is theoretically unable to cause immunoallergic HIT. Unlike low-molecular-weight heparins, fondaparinux does not cross-react in vitro with sera from patients with clinical cases of HIT. These findings suggest that fondaparinux would not lead to formation of HIT antibodies and would not provoke clinical thrombosis in patients who had HIT antibodies because of previous exposure to heparins. To date, no cases of immunoallergic HIT have been associated with fondaparinux use in clinical trials. Anecdotal evidence suggests that fondaparinux eventually may prove to be valuable for preventing and treating thrombosis in patients with HIT. The effect of anticoagulants on wound healing is another consideration when choosing a thromboprophylactic strategy after major surgery. There is evidence that thrombin plays a role in wound healing, but fondaparinux is too small to enable antithrombin III to inhibit thrombin. Thus, fondaparinux may be less likely than a low-molecular-weight heparin to interfere with wound healing.
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Affiliation(s)
- William E Dager
- Department of Pharmacy, University of California-Davis Medical Center, and University of California-Davis School of Medicine, Sacramento, California, USA
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Abstract
Anticoagulants are pivotal agents for prevention and treatment of thromboembolic disorders. Limitations of existing anticoagulants, vitamin K antagonist and heparins, have led to the development of newer anticoagulant therapies. These anticoagulants have been designed to target specific coagulation enzymes or steps in the coagulation pathway. New anticoagulants that are under evaluation in clinical trials include: (1) inhibitors of the factor VIIa/tissue factor pathway; (2) factor Xa inhibitors, both indirect and direct; (3) activated protein C and soluble thrombomodulin; and (4) direct thrombin inhibitors. Although most of these are parenteral agents, several of the direct inhibitors of factor Xa and thrombin are orally active. Clinical development of these therapies often starts with studies in the prevention of venous thrombosis before evaluation for other indications, such as prevention of cardioembolism in patients with atrial fibrillation or prosthetic heart valves. At present, the greatest clinical need is for an oral anticoagulant to replace warfarin for long-term prevention and treatment of patients with venous and arterial thrombosis. Ximelagatran, an oral direct thrombin inhibitor, is the first of a series of promising new agents that might fulfill this need. Large phase 3 trials evaluating ximelagatran for the secondary prevention of venous thromboembolism and prevention of cardioembolic events in patients with atrial fibrillation have been completed.
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Affiliation(s)
- Jack Hirsh
- Henderson Research Center, and McMaster University, Hamilton, Ontario, Canada.
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Abstract
Fondaparinux (Arixtra) is the first synthetic selective Factor Xa inhibitor. Its efficacy and safety in the prevention of venous thromboembolism (VTE) was first studied in patients undergoing major orthopedic surgery, a setting in the highest risk category for postoperative thrombotic complications. Low-molecular-weight heparins are frequently used in this setting, but the rates of VTE still range between 15% and 33%. In large clinical trials, fondaparinux started 6 hours postoperatively was significantly more effective than enoxaparin in preventing VTE in patients undergoing total hip replacement, total knee replacement or hip fracture surgery. The benefit of extended fondaparinux prophylaxis after hip fracture surgery was also investigated. Other trials have demonstrated that fondaparinux is efficacious in the prevention of VTE in other patient populations at risk of thrombosis and in the treatment of symptomatic VTE.
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Affiliation(s)
- Kenneth A Bauer
- Harvard Medical School, Hematology Section, VA Boston Healthcare System, and Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
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Abstract
Fondaparinux is the first of a new class of antithrombotic compounds, the synthetic pentasaccharides. By binding rapidly and strongly to antithrombin, its sole physiologic target in plasma, fondaparinux catalyzes specifically the inhibition of factor Xa, which results in effective and linear dose-dependent inhibition of thrombin generation. Fondaparinux does not bind to platelets. Its antithrombotic effect has been demonstrated in several animal models of arterial and venous thrombosis. At equivalent antithrombotic concentrations, fondaparinux induced less bleeding than unfractionated heparin in experimental bleeding models. Furthermore, it did not cross-react with sera from patients with heparin-induced thrombocytopenia. Administered subcutaneously, the absorption of fondaparinux is complete, rapid, and independent of dose. It has a linear pharmacokinetic profile, and its half-life of approximately 17 h allows for once-daily dosing. Fondaparinux is almost completely excreted by the kidneys. Owing to the limited intrasubject and intersubject variability, routine monitoring and dose adjustments should not be required for most patients. Fondaparinux has been approved for use in thromboprophylaxis after major orthopedic surgery, where it has demonstrated its efficacy compared to a low-molecular-weight heparin. Its clinical development in other indications is ongoing.
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Affiliation(s)
- Kenneth A Bauer
- Department of Medicine, Harvard Medical School, and Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA.
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Turpie AGG, Eriksson BI, Lassen MR, Bauer KA. Fondaparinux, the first selective factor Xa inhibitor. Curr Opin Hematol 2003; 10:327-32. [PMID: 12913785 DOI: 10.1097/00062752-200309000-00001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Fondaparinux (Arixtra, Sanofi-Synthelabo, Paris, France) is a pentasaccharide that selectively inhibits factor Xa; it is the first of a new class of synthetic antithrombotic agents. Fondaparinux has a linear pharmacokinetic profile allowing once-daily subcutaneous administration. Absence of metabolism, complete bioavailability, and lack of nonspecific binding in plasma contribute to the predictability of its effect. Fondaparinux has been approved for use in the prophylaxis of venous thromboembolism following orthopedic surgery. In this setting, it was found to reduce VTE risk by more than 50% in comparison with the low molecular weight heparin enoxaparin, with an incidence of clinically important bleeding not significantly different from that of standard low molecular weight heparin regimens. Furthermore, 4 weeks of prophylaxis with fondaparinux after hip fracture surgery was shown to reduce the risk of venous thromboembolism by 96% compared with 1-week prophylaxis. Finally, the efficacy and safety of fondaparinux in the treatment of venous thromboembolism and acute coronary syndromes appears promising.
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Abstract
The limitations of traditional anticoagulants, heparin and warfarin, have prompted the development of new anticoagulant drugs for prevention and treatment of both venous and arterial thromboembolism. After a brief review of thrombogenesis and its regulation, this study focuses on new anticoagulant agents in more advanced stages of clinical testing.
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Affiliation(s)
- Shannon M Bates
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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Abstract
Hip fracture surgery carries a high risk of venous thromboembolism and, until recently, was poorly investigated. The efficacy and safety of fondaparinux, a new synthetic antithrombotic, were investigated in two large, thromboprophylaxis studies. Results of the Penthifra study, which was a randomized, double-blind phase III trial, showed that 1 week of fondaparinux, compared with enoxaparin, significantly reduced venous thromboembolic events from 19.1% to 8.3% (relative risk reduction: 56.4%; P<.001) without increasing bleeding risk. Penthifra Plus results showed that extending fondaparinux prophylaxis from 1 to 4 weeks was well tolerated and, compared to placebo, significantly reduced delayed venous thromboembolism events from 35% to 1.4% (relative risk reduction: 95.9%; P<.001). Based on these findings, 4-week fondaparinux treatment may become the standard thromboprophylaxis after hip fracture surgery.
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Affiliation(s)
- Bengt I Eriksson
- Department of Orthopedics, Sahlgrenska University Hospital/OSTRA, S-41685 Göteborg, Sweden
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Comp PC. Selective factor Xa inhibition improves efficacy of venous thromboembolism prophylaxis in orthopedic surgery. Pharmacotherapy 2003; 23:772-87. [PMID: 12820819 DOI: 10.1592/phco.23.6.772.32190] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Venous thromboembolism is a serious, frequent, and potentially fatal complication of major orthopedic surgery. Currently available pharmacologic agents for the prevention of venous thromboembolism in this high-risk population consist of the oral anticoagulants and the heparin family of antithrombotic agents (unfractionated heparin, low-molecular-weight heparin, heparinoids). These classes of agents interfere with the activity of both thrombin and factor Xa (or their respective zymogens) to varying degrees. Newer antithrombotic agents in various stages of development exert their antithrombotic effect through a more targeted mechanism of action. Direct factor Xa inhibitors and the newest class of antithrombotic agents, the indirect factor Xa inhibitors, the prototype of which is the synthetic pentasaccharide fondaparinux sodium, limit fibrin formation through their exclusive inactivation of factor Xa. Clinical data from venous thromboembolism prophylaxis trials in hip and knee replacement and hip fracture surgeries, including the recently completed fondaparinux phase II and phase III trials, indicate that selective antifactor Xa activity may improve the efficacy:safety ratio of antithrombotic therapies for the prevention of venous thromboembolism in high-risk major orthopedic surgery.
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Affiliation(s)
- Philip C Comp
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA.
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O'Shea SI, Ortel TL, Kovalik EC. Alternative methods of anticoagulation for dialysis-dependent patients with heparin-induced thrombocytopenia. Semin Dial 2003; 16:61-7. [PMID: 12535303 DOI: 10.1046/j.1525-139x.2003.03014.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dialysis patients who are continually exposed to heparin are at risk for heparin-induced thrombocytopenia (HIT). Heparin-induced antibodies have been reported to occur in 0-12% of hemodialysis (HD) patients. The diagnosis or suspicion of HIT in this patient population requires careful confirmation of the diagnosis and substitution of heparin with an alternate anticoagulant for dialysis. Alternate agents such as the direct thrombin inhibitors (hirudin and argatroban) are available, but careful dosing and monitoring of the anticoagulant effect are required. Despite careful dosing, hemorrhagic complications have occurred with these agents. Unfortunately there are limited options for treatment of hemorrhagic complications and no specific antidotes are available for the direct thrombin inhibitors. In this report the currently available alternatives to heparin for dialysis, including dosing and monitoring recommendations, are reviewed.
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Affiliation(s)
- Susan I O'Shea
- Divisions of Hematology and Nephrology, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Samama MM, Gerotziafas GT. Evaluation of the pharmacological properties and clinical results of the synthetic pentasaccharide (fondaparinux). Thromb Res 2003; 109:1-11. [PMID: 12679126 DOI: 10.1016/s0049-3848(03)00030-6] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fondaparinux (Arixtra) is the first of a new class of selective indirect antithrombin-dependent factor Xa inhibitors, which inhibits thrombin generation. Fondaparinux is a completely synthetic pentasaccharide. It is a single molecular entity with a well-defined pharmacological target. Fondaparinux has nearly complete bioavailability after subcutaneous injection. The pharmacokinetics of fondaparinux appears predictable and consistent. The peak plasma level is obtained about 2 h after the subcutaneous injection, indicating that a rapid onset of antithrombotic activity is obtained on initiation of treatment. The elimination half-life is about 17 h and it is dose-independent, which allows a convenient once-daily dosing regimen. Fondaparinux is eliminated exclusively by the kidneys. Thus, the estimation of the renal function especially in elderly patients is important for the treatment with fondaparinux, whereas it is contraindicated in patients with severe renal insufficiency. Phase II clinical studies have identified a subcutaneous dose of 2.5 mg once daily for prophylaxis of venous thromboembolism in patients undergoing major orthopaedic surgery. Four phase-III clinical trials using bilateral phlebography for the diagnosis of DVT, demonstrated a combined 50% relative risk reduction of asymptomatic venous thromboembolic events in orthopaedic surgery patients in comparison to the low-molecular-weight heparin (LMWH) enoxaparin. Hemorrhagic complications for fondaparinux were either comparable or higher than those for LMWH but the authors did not judge that the increased bleeding was clinically relevant. A dose ranging study led to the selection of the dose of 7.5 mg at a single daily subcutaneous injection as optimal for the treatment of VTE. In two phase III clinical trials, the dose of 7.5 mg/day is expected to be as efficacious and safe as heparin for the treatment of DVT or PE, respectively. Phase II studies show that the efficacy-to-safety ratio of fondaparinux in the treatment of unstable angina or as an adjunct to thrombolysis in acute myocardial infarction is promising. These results demonstrated that a single anti-Xa agent devoid of antithrombin activity is a potent antithrombotic drug. Fondaparinux has obtained FDA and European health authorities approval. Its use on a large scale will allow the evaluation of its efficacy and tolerance in the daily clinical practice. Chemical modifications of the original synthetic pentasaccharide increase the affinity to AT resulting in a more potent inhibition of FXa and longer half-life. Idraparinux is the first of these new oligosaccharides that we named "meta-pentasaccharides." After subcutaneous injection the half-life of idraparinux is about 80 h allowing a single injection per week. A dose-finding study has established the optimal dose given once a week to be compared with warfarin for the treatment of DVT.
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Affiliation(s)
- Meyer-Michel Samama
- Service d'Hématologie Biologique, Hôpital Hôtel-Dieu, 1, place du Parvis Notre Dame, F-75181 Paris Cedex 04, France.
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Bauer KA, Eriksson BI, Lassen MR, Turpie AGG. Factor Xa inhibition in the prevention of venous thromboembolism and treatment of patients with venous thromboembolism. Curr Opin Pulm Med 2002; 8:398-404. [PMID: 12172443 DOI: 10.1097/00063198-200209000-00010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Venous thromboembolism (VTE) is a life-threatening complication following orthopedic surgery. Selective factor Xa inhibition is a new antithrombotic approach designed to avoid difficulties associated with heparins and other current anticoagulants. Several antifactor Xa compounds are in early investigation, but fondaparinux (Arixtra; NV Organon, Oss, The Netherlands; Sanofi-Synthelabo, Paris, France) is the first and most advanced compound in the development of a new class of synthetic antithrombotic agents--the selective factor Xa inhibitors. Fondaparinux has a highly favorable pharmacokinetic profile; four large phase 3 trials comparing subcutaneous fondaparinux 2.5 mg once daily with the low molecular weight heparin (LMWH) enoxaparin in doses approved by regulatory bodies showed that fondaparinux reduced the overall risk of VTE in major orthopedic surgery by > 50% without increasing clinically relevant bleeding. Fondaparinux also appears to be a very promising candidate for the treatment of patients with existing VTE.
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Affiliation(s)
- Kenneth A Bauer
- VA Boston Healthcare System and Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
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