hirudin and Venous-Thromboembolism

The efficacy and safety of heparin and low-molecular-weight heparins (LMWHs) are well documented in venous and arterial thromboembolism. Several drawbacks of heparins have inspired the development of newer parenteral anticoagulants for specific indications, including heparin-induced thrombocytopenia (HIT) and percutaneous coronary interventions (PCI). The direct thrombin inhibitors recombinant hirudin and argatroban are now established alternatives for HIT patients, and bivalirudin is one of the most used anticoagulants in PCI. The pentasaccharide fondaparinux is an alternative for LMWH for thromboprophylaxis in various clinical settings and for patients with an acute coronary syndrome (ACS) not scheduled for PCI. In Europe, it was recently approved for treatment of superficial vein thrombosis. Further development of new parenteral anticoagulants is slow and the emphasis has shifted towards development of new oral anticoagulants and antiplatelet drugs. Still, promising new anticoagulants, some targeting less conventional targets in the coagulation system, have been developed and will undergo further clinical evaluation.

Topics: Acute Coronary Syndrome; Antithrombins; Arginine; Fondaparinux; Hirudin Therapy; Hirudins; Humans; Infusions, Parenteral; Peptide Fragments; Percutaneous Coronary Intervention; Pipecolic Acids; Polysaccharides; Randomized Controlled Trials as Topic; Recombinant Proteins; Sulfonamides; Thrombin; Venous Thromboembolism

Heparins and vitamin K antagonists have been the primary agents used for anticoagulation in certain cardiovascular and thromboembolic diseases for over 50 years. However, they can be difficult to administer and are fraught with limitations. In response to the need for new anticoagulants, direct thrombin inhibitors (DTIs) have been developed and investigated for their utility in prophylaxis and treatment of venous thromboembolism (VTE), heparin-induced thrombocytopenia (HIT), acute coronary syndromes (ACS), secondary prevention of coronary events after ACS, and nonvalvular atrial fibrillation. Currently, four parenteral direct inhibitors of thrombin activity are FDA-approved in North America: lepirudin, desirudin, bivalirudin and argatroban. Of the new oral DTIs, dabigatran etexilate is the most studied and promising of these agents. This review discusses the clinical indications and efficacy of these direct thrombin inhibitors as well as future directions in anticoagulant therapy.

Topics: Anticoagulants; Antithrombins; Arginine; Benzimidazoles; Dabigatran; Hirudins; Humans; Peptide Fragments; Pipecolic Acids; Pyridines; Recombinant Proteins; Sulfonamides; Thrombin; Venous Thromboembolism

Venous thrombosis and pulmonary embolism rarely occur in children but are associated with significant morbidity and mortality. Venous thromboembolism (VTE) mostly affects children with severe underlying conditions and multiple risk factors. Newborns and adolescents are at the highest risk. Standard and low molecular weight heparins and vitamin K antagonists are routinely used for the prevention and treatment of VTE. The new anticoagulants, both parenteral such as argatroban, bivalirudin and fondaparinux and oral such as dabigatran and rivaroxaban, have favourable pharmacological properties, all are approved for clinical use in adults and are currently being investigated in children. Argatroban is the only new anticoagulant licensed for use in children so far. The role of these new anticoagulants as alternative anticoagulants for children remains to be defined. This review focuses on the characteristics of VTE in children and reviews current knowledge on the use of the new thrombin and factor Xa inhibitors in this population.

Topics: Adolescent; Anticoagulants; Arginine; Benzimidazoles; beta-Alanine; Child; Child, Preschool; Dabigatran; Drug Approval; Factor Xa Inhibitors; Fondaparinux; Hirudins; Humans; Infant; Infant, Newborn; Morpholines; Peptide Fragments; Pipecolic Acids; Polysaccharides; Recombinant Proteins; Risk Factors; Rivaroxaban; Sulfonamides; Thiophenes; Thrombin; Venous Thromboembolism

Thromboembolic complications are becoming more frequent in children and the use of anticoagulation has increased considerably. The most widely used agents in children, heparin, low molecular weight heparin, and warfarin all have limitations which are exaggerated in children. This has led to the study of newer agents with improved pharmacologic properties such as bivalirudin, argatroban, and fondaparinux. Clinical trials are under way to assess several new oral anticoagulants that are in late phase studies or already licensed in adults. Based on the completed studies in children, several recommendations for the use of currently available agents (bivalirudin, argatroban, and fondaparinux) are suggested for clinical use today. Additional studies need to be conducted for the these agents, so that their use may be expanded in selected indications. New regulatory requirements are leading to a number of studies in the newer anticoagulants that are yet to be licensed in adults for treatment of venous thromboembolism. Pediatric thrombosis is entering a fruitful era of research in anticoagulation management, which is sure to lead to significant changes in how children are treated in the next 10 years.

Topics: Anticoagulants; Arginine; Fondaparinux; Heparin, Low-Molecular-Weight; Hirudins; Humans; Infant; Infant, Newborn; Peptide Fragments; Pipecolic Acids; Polysaccharides; Recombinant Proteins; Sulfonamides; Venous Thromboembolism; Warfarin

Heparin-induced thrombocytopenia (HIT) is an immune-mediated disorder caused by the development of antibodies to platelet factor 4 (PF4) and heparin. The thrombocytopenia is typically moderate, with a median platelet count nadir of approximately 50 to 60 x 10(9) platelets/L. Severe thrombocytopenia has been described in patients with HIT, and in these patients antibody levels are high and severe clinical outcomes have been reported (eg, disseminated intravascular coagulation with microvascular thrombosis). The timing of the thrombocytopenia in relation to the initiation of heparin therapy is critically important, with the platelet count beginning to drop within 5 to 10 days of starting heparin. A more rapid drop in the platelet count can occur in patients who have been recently exposed to heparin (within the preceding 3 months), due to preformed anti-heparin/PF4 antibodies. A delayed form of HIT has also been described that develops within days or weeks after the heparin has been discontinued. In contrast to other drug-induced thrombocytopenias, HIT is characterized by an increased risk for thromboembolic complications, primarily venous thromboembolism. Heparin and all heparin-containing products should be discontinued and an alternative, non-heparin anticoagulant initiated. Alternative agents that have been used effectively in patients with HIT include lepirudin, argatroban, bivalirudin, and danaparoid, although the last agent is not available in North America. Fondaparinux has been used in a small number of patients with HIT and generally appears to be safe. Warfarin therapy should not be initiated until the platelet count has recovered and the patient is systemically anticoagulated, and vitamin K should be administered to patients receiving warfarin at the time of diagnosis of HIT.

Topics: Anticoagulants; Arginine; Autoantibodies; Contraindications; Disseminated Intravascular Coagulation; Fondaparinux; Heparin; Hirudins; Humans; Pipecolic Acids; Platelet Count; Platelet Factor 4; Polysaccharides; Recombinant Proteins; Sulfonamides; Thrombocytopenia; Thrombophilia; Time Factors; Venous Thromboembolism; Vitamin K; Warfarin

Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction mediated by platelet-activating antibodies that target complexes of platelet factor 4 and heparin. Patients are at markedly increased risk of thromboembolism.. These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians, and other health care professionals in their decisions about diagnosis and management of HIT.. ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.. The panel agreed on 33 recommendations. The recommendations address screening of asymptomatic patients for HIT, diagnosis and initial management of patients with suspected HIT, treatment of acute HIT, and special situations in patients with acute HIT or a history of HIT, including cardiovascular surgery, percutaneous cardiovascular intervention, renal replacement therapy, and venous thromboembolism prophylaxis.. Strong recommendations include use of the 4Ts score rather than a gestalt approach for estimating the pretest probability of HIT and avoidance of HIT laboratory testing and empiric treatment of HIT in patients with a low-probability 4Ts score. Conditional recommendations include the choice among non-heparin anticoagulants (argatroban, bivalirudin, danaparoid, fondaparinux, direct oral anticoagulants) for treatment of acute HIT.

Topics: Administration, Oral; Anticoagulants; Arginine; Cardiovascular Surgical Procedures; Chondroitin Sulfates; Dermatan Sulfate; Evidence-Based Medicine; Fondaparinux; Heparin; Heparitin Sulfate; Hirudins; Humans; Peptide Fragments; Pipecolic Acids; Platelet Count; Recombinant Proteins; Renal Replacement Therapy; Sulfonamides; Thrombocytopenia; Venous Thromboembolism

Thrombotic complications are increasing at a steady and significant rate in children resulting in the more widespread use of anticoagulation in this population. Anticoagulant drugs in children can be divided into the standard agents (heparin, low molecular weight heparin, and vitamin K antagonists) and alternative agents (argatroban, bivalirudin, and fondaparinux). This review will compare and contrast the standard and alternative anticoagulants and suggest situations in which it may be appropriate to use argatroban, bivalirudin, and fondaparinux. Clearly, the standard anticoagulants all have significant shortcomings including variable pharmacokinetics, issues with therapeutic drug monitoring, frequency of administration, efficacy, and adverse effects. The alternative anticoagulants have properties which overcome these shortcomings and prospective clinical trial data are presented supporting the current and future use of these agents in place of the standard anticoagulants.

Topics: Anticoagulants; Arginine; Blood Coagulation; Child; Drug Monitoring; Fondaparinux; Heparin; Hirudins; Humans; Peptide Fragments; Pipecolic Acids; Polysaccharides; Recombinant Proteins; Sulfonamides; Thrombosis; Venous Thromboembolism; Warfarin

Recombinant hirudins (desirudin, lepirudin) are direct thrombin inhibitors administered as anticoagulants for heparin-induced thrombocytopenia (HIT) and venous thromboembolism (VTE) prophylaxis. Although these small polypeptides are widely used, concern exists over reports of antigenicity. In the largest study of r-hirudin immunogenicity to-date, we evaluated the prevalence, quantity and specificity of IgG immune responses to desirudin (15 mg SC q12h for as long as clinically required) in 245 surgical and medically-ill subjects enrolled in DESIRABLE, a multicenter, open-label, clinical trial of hospitalized patients requiring VTE prophylaxis. Sera obtained before and 30 days after desirudin administration were analyzed for IgG anti-desirudin by immunoenzymetric assay using immobilized desirudin to bind desirudin-reactive antibody and peroxidase conjugated monoclonal-anti-human IgG Fc to detect bound IgG antibody. Of 245 study subjects, 19 (7.7%) were antibody "responders" (>2-fold increase in IgG antibody levels with >50% inhibition by desirudin 30 days post-treatment). There were no differences between responders and non-responders in incidence of clinical outcomes or bleeding-related adverse events. Forty-six patients had detectable desirudin-reactive IgG antibody prior to treatment, with no significant increase in antibody levels after exposure and no increase in clinical events. The origin of pre-existing hirudin-reactive IgG antibody requires further investigation involving suspected anti-thrombin-thrombin interactions. These results indicate a low potential for immunogenicity, with <8% of patients developing IgG antibodies after desirudin administration for VTE prophylaxis. In contrast to reports on lepirudin, production of anti-hirudin antibodies to desirudin has no apparent effect on clinical events.

Topics: Aged; Antibodies; Antibodies, Monoclonal; Antibody Specificity; Antithrombins; Female; Heparin; Hirudin Therapy; Hirudins; Humans; Immunoenzyme Techniques; Immunoglobulin G; Male; Middle Aged; Recombinant Proteins; Reproducibility of Results; Thrombin; Thrombocytopenia; Time Factors; Venous Thromboembolism

Patients with central nervous system (CNS) malignancies have a substantial risk for developing both thrombotic and bleeding disorders. The risk of venous thromboembolism (VTE) is substantially higher in these patients, both in the perioperative period and throughout their disease course. Patients with CNS malignancy harbor a latent hypercoagulability, which predisposes to VTE, as do postoperative immobility, hemiparesis, and other factors. The management of VTE in these patients is complex, given the significant morbidity and mortality associated with intratumoral hemorrhage. In the past, the perceived risk of intracranial hemorrhage limited the use of anticoagulation for the management of VTE with many favoring nonpharmacologic methods for prophylaxis and treatment. Inferior vena cava (IVC) filters have since lost favor at many centers given significant complications, which appear to be more frequent in patients with CNS malignancy. Recent studies have demonstrated safe and efficacious use of anticoagulation in these patients with a low incidence of intracranial hemorrhage. Treatment of established VTE is now recommended in this population with many centers favoring low-molecular-weight heparin (LMWH) versus oral warfarin for short- or long-term treatment. We advocate a multimodality approach utilizing compression stockings, intermittent compression devices, and heparin in the perioperative setting as the best proven method to reduce the risk of VTE. In the absence of a strict contraindication to systemic anticoagulation, such as previous intracranial hemorrhage or profound thrombocytopenia, we recommend LMWH in patients with newly diagnosed VTE and a CNS malignancy.

Topics: Antibodies, Monoclonal, Humanized; Anticoagulants; Arginine; Bevacizumab; Central Nervous System Neoplasms; Fondaparinux; Glioblastoma; Glioma; Hemorrhage; Heparin, Low-Molecular-Weight; Hirudins; Humans; Pipecolic Acids; Polysaccharides; Postoperative Complications; Pulmonary Embolism; Recombinant Proteins; Sulfonamides; Thrombocytopenia; Vena Cava Filters; Venous Thromboembolism; Venous Thrombosis; Warfarin

The direct thrombin inhibitor lepirudin is mainly applied in heparin-induced thrombocytopenia. We report here the case of a 37-year-old kurdish woman in whom Behcets disease was diagnosed in 1998 when she presented with a Budd Chiari syndrome (BCS) complicated by pulmonary embolism. Recurrent venous thromboembolism (VTE) occurred despite anticoagulant therapy with UFH, LMWH or phenprocoumon and various immunosuppressive therapy regimens. In 2001, when BCS recurred ultimately i.v. lepirudin was administered. When the patient improved and remained clinically stable lepirudin was applied subcutaneously. During long-term treatment with twice-daily 50 mg no further VTE was observed over the following years. Additionally, no bleeding complications occurred. In May 2005 anticoagulant therapy was switched to phenprocoumon. BCS reoccurred when INR values were suboptimal in February 2007, and lepirudin treatment was immediately restarted. After admission the patient received 50 mg b.i.d. lepirudin s.c. with plasma levels in the therapeutic range (0.5-1.0 mg / l). Over the following months, lepirudin levels repeatedly exceeded the upper limit of this range and the dosage was stepwise reduced. Finally, 20 mg b.i.d. were sufficient to obtain therapeutic levels. Renal function was normal, but lepirudin antibodies were present in high titer, as assessed by ELISA. We suppose that these antibodies reduce renal filtration of lepirudin thus leading to increased plasma levels. This case is an example for successful long-term therapeutic-dose anticoagulation with s.c. lepirudin in a patient with Behcets disease and recurrent VTE despite therapeutic anticoagulant therapy with LMWH or vitamin K antagonists. However, frequent measurement of lepirudin plasma levels is needed. If stepwise dose lowering is required over time, the presence of lepirudin antibodies should be considered.

Topics: Adult; Antibodies; Anticoagulants; Behcet Syndrome; Dose-Response Relationship, Drug; Female; Heparin; Hirudins; Humans; Recombinant Proteins; Recurrence; Venous Thromboembolism

To report the use of subcutaneous lepirudin in an obese patient with heparin resistance.. A 34-year-old morbidly obese male (weight 145 kg) presented with hypoxia on postoperative day 1 following a sigmoid colectomy. A continuous unfractionated heparin infusion was started for a suspected pulmonary embolism. Doses were escalated without therapeutic activated partial thromboplastin time (aPTT) response and an antithrombin (AT) level was obtained. The AT level was reported as 78% (reference range 85-120%). Computed tomography angiography ruled out pulmonary embolism and lepirudin 50 mg administered subcutaneously twice daily was started (serum creatinine 1.3 mg/dL) for prevention of venous thromboembolism. The resulting aPTT values were therapeutic (63 and 60 sec, reference range 24-34, therapeutic heparin range 55-85). The dose was adjusted to 25 mg twice daily. aPTT values were 35 and 48 seconds. His serum creatinine increased to 1.6 mg/dL and minor bleeding was noted. The dose was decreased to 25 mg once daily, with resulting aPTT values of 31, 39, and 41 seconds. The patient was discharged to home without development of venous thromboembolism, as confirmed by duplex ultrasonography.. Commonly administered anticoagulants, such as unfractionated heparin, low-molecular-weight heparins, and fondaparinux, exert their effect by complexing with AT and thrombin (Factor IIa), activating AT and preventing thrombin from exerting coagulation effect. Without AT present, these drugs have little effect on inhibiting the coagulation cascade. Lepirudin is a synthetic irreversible direct thrombin inhibitor and does not rely on AT to exert its anticoagulation action. It can be given subcutaneously and is eliminated primarily by the kidneys. Dosage adjustments for both renal function and obesity need to be considered and aPTT should be monitored.. In obese patients or those with heparin resistance, subcutaneous lepirudin can be monitored and the regimen adjusted based on aPTT values. Further studies are warranted to maximize efficacy and define dosing.

Topics: Adult; Anticoagulants; Critical Care; Dose-Response Relationship, Drug; Drug Resistance; Heparin; Hirudins; Humans; Injections, Subcutaneous; Male; Obesity, Morbid; Partial Thromboplastin Time; Recombinant Proteins; Venous Thromboembolism

This article about hemorrhagic complications of anticoagulant and thrombolytic treatment is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Bleeding is the major complication of anticoagulant and fibrinolytic therapy. The criteria for defining the severity of bleeding vary considerably between studies, accounting in part for the variation in the rates of bleeding reported. The major determinants of vitamin K antagonist (VKA)-induced bleeding are the intensity of the anticoagulant effect, underlying patient characteristics, and the length of therapy. There is good evidence that VKA therapy, targeted international normalized ratio (INR) of 2.5 (range, 2.0-3.0), is associated with a lower risk of bleeding than therapy targeted at an INR > 3.0. The risk of bleeding associated with IV unfractionated heparin (UFH) in patients with acute venous thromboembolism is < 3% in recent trials. This bleeding risk may increase with increasing heparin dosages and age (> 70 years). Low-molecular-weight heparin (LMWH) is associated with less major bleeding compared with UFH in acute venous thromboembolism. Higher doses of UFH and LMWH are associated with important increases in major bleeding in ischemic stroke. In ST-segment elevation myocardial infarction, addition of LMWH, hirudin, or its derivatives to thrombolytic therapy is associated with a small increase in the risk of major bleeding, whereas treatment with fondaparinux or UFH is associated with a lower risk of bleeding. Thrombolytic therapy increases the risk of major bleeding 1.5-fold to threefold in patients with acute venous thromboembolism, ischemic stroke, or ST-elevation myocardial infarction.

Topics: Anticoagulants; Brain Ischemia; Evidence-Based Medicine; Fondaparinux; Hemorrhage; Heparin, Low-Molecular-Weight; Hirudins; Humans; International Normalized Ratio; Myocardial Infarction; Polysaccharides; Risk Factors; Severity of Illness Index; Thrombolytic Therapy; Treatment Outcome; Venous Thromboembolism; Vitamin K

Treatment of patients with heparin-induced thrombocytopenia type II (HIT II) and thrombosis in some cases that represents a clinical challenge, which, if unrecognized, may lead to treatment delay or disease progression with potentially lethal outcome. We present a case of a 19-year-old patient with antiphospholipid syndrome, factor V (FV) Leiden mutation in heterozygous state, and venous thromboembolism. The patient was subjected to intravenous infusions of unfractionated heparin (UFH), and 16 days after the beginning of the treatment, his condition worsened, with thrombocytopenia and extension of thrombosis. Whereas the patient had a high clinical score for HIT II, functional and antigenic assays for the presence of HIT antibodies were negative. After repeated negative functional and antigenic assays, pseudo-HIT was suspected and nadroparin was introduced, which resulted in further worsening of the clinical presentation. Disease remission, along with complete normalization of platelet count, was finally accomplished with the introduction of lepirudin. The presence of multiple comorbid states, such as antiphospholipid syndrome, can potentially make laboratory confirmation of disease more difficult in patients with HIT II. In our opinion, it is of great importance that HIT II diagnosis be primarily clinical and that laboratory test results are carefully interpreted, especially when HIT is indicated by high clinical score values.

Topics: Administration, Oral; Adult; Antibodies; Anticoagulants; Antiphospholipid Syndrome; Diagnosis, Differential; Factor V; Heparin; Hirudins; Humans; Infusions, Intravenous; Male; Mutation; Nadroparin; Platelet Count; Recombinant Proteins; Thrombocytopenia; Venous Thromboembolism