Heparin

Challenges and Opportunities in the Pharmacological Treatment of Acute Venous Thromboembolism in Children

Venous thromboembolism (VTE) is an important but historically under-recognized problem in pediatrics, with an incidence concentrated in hospitalized children. A number of specific VTE diseases with discrete triggers have been described, but the most common pediatric trigger is the presence of central venous access devices. VTE diseases, though heterogenous in etiology, are linked by the common therapeutic strategies shared by their management. Historically, the most commonly used drug therapies have been unfractionated heparin, low-molecular-weight heparins, and vitamin K antagonists, based on extrapolation from adult data rather than any specific pediatric trials. Although these widely used drugs appear safe and effective in expert hands, the historical lack of pediatric data is problematic in view of the recognized significant differences between children and adults with regards to hemostatic physiology, VTE etiology, and drug pharmacokinetics. The increasing adult usage of novel VTE pharmacotherapies such as direct oral anticoagulants (DOACs) has led to considerable interest in exploring the pediatric applications of these newer drugs. This review summarizes the advantages and disadvantages of existing VTE pharmacotherapies and outlines emerging novel pediatric VTE therapies, particularly DOACs, within the context of the current pediatric trial landscape.

Using anti-Xa level for adjusting intravenous unfractionated heparin infusion in peripartum thromboembolic disease

BACKGROUND

Intravenous unfractionated heparin infusion is often used to minimize the duration of time without anticoagulation around delivery in pregnant patients with high thrombotic risk. Activated partial thromboplastin time is commonly used to monitor and adjust heparin dose. However, using activated partial thromboplastin time is problematic in pregnancy because activated partial thromboplastin time response to unfractionated heparin is attenuated due to elevated Factor VIII levels and may lead to incorrect dosing.

CASE

We report a case of deep venous thrombosis occurring in a term pregnancy managed by intravenous unfractionated heparin adjusted using anti-Xa level around the time of delivery. We modified the intravenous unfractionated heparin nomogram by using anti-Xa levels instead of activated partial thromboplastin time and observed lower dosing of unfractionated heparin than otherwise required to achieve and maintain target levels.

CONCLUSION

This report demonstrates the feasibility and effectiveness of using anti-Xa level to monitor and adjust intravenous unfractionated heparin infusion in pregnancy.

The blood compatibility challenge. Part 1: Blood-contacting medical devices: The scope of the problem

Blood-contacting medical devices are an integral part of modern medicine. Such devices may be used for only a few hours or may be implanted for life. Despite advances in biomaterial science, clotting on medical devices remains a common problem. Systemic administration of antiplatelet drugs or anticoagulants is often needed to reduce the risk of clotting. Although effective, such therapy increases the risk of bleeding, which can be fatal. This chapter (a) describes some of the commonly used blood-contacting devices and their potential complications, (b) provides an overview of the mechanisms that drive device-associated clotting, and (c) reviews the strategies employed to attenuate clotting on blood-contacting medical devices. STATEMENT OF SIGNIFICANCE: This paper is part 1 of a series of 4 reviews discussing the problem of biomaterial associated thrombogenicity. The objective was to highlight features of broad agreement and provide commentary on those aspects of the problem that were subject to dispute. We hope that future investigators will update these reviews as new scholarship resolves the uncertainties of today.

Evaluation of the Activity of Heparin Injected into the Fully Implantable Catheter for Chemotherapy (Portocath) between Two Moments of Use

BACKGROUND

The aim of this study is to analyze whether heparin, used as a lock in fully implantable catheter for chemotherapy (portocath), maintains its activity even if it remains in the catheter for a long period of time.

METHODS

According to the institutional protocol, all catheters routinely use the lock solution with 3 mL of heparinized solution after chemotherapy and the time interval between each change as lock in the catheters studied ranged from 7 to 30 days. A total of 25 blood samples from 22 patients with 6 types of neoplasia on chemotherapy or not were collected according to routine, and the 10 mL of liquid contained in the first aspirated reservoir/catheter (corresponding to the lock of the last section), were sent for laboratory analysis for prospectively studied with the following tests: anti-Xa, partially activated thromboplastin time (APTT), thrombin time (TT), reptilase, and thromboelastogram.

RESULTS

Heparin activity was found in 96% of the anti-Xa and APTT tests. In relation to TT, 92% presented activity. The reptilase test was performed on 24 samples with significant time reduction in all of them. In the INTEM stage, the thromboelastometry test showed activity in 92% of samples and in the HEPTEM phase there was reduction in time in all samples. In all samples, the heparin activity was found to be independent of the time of use.

CONCLUSIONS

We can conclude that lock of heparinized solution used in our service in fully implantable central venous catheters for chemotherapy was maintained with active heparin even after a long period of time (up to 30 days), demonstrating that the half-life of the substance within the catheter is greater than its plasma half-life.

Salvaging Digital Replantation and Revascularisation: Efficiency of Heparin Solution Subcutaneous Injection

BACKGROUND

Distal digital replantation and revascularisation remains one of the demanding microsurgical procedures due to the difficulty of vascular anastomosis. Venous congestion is the most commonly encountered problem after replantation due to the difficulty of venous anastomosis in traumatic injuries. Heparin, among other drugs, is commonly used to facilitate venous drainage and prevent thrombosis. However, systemic heparin can be contraindicated in some patients. The senior author has experience of subcutaneous heparin injection for venous congestion in thirteen patients.

METHODS

An amount of 1 ml of calcium heparin (25,000 U) was mixed in 2.4 ml of normal saline making a solution that has 1000 U per 0.1 ml. 1000 U (0.1 ml) of the solution was injected directly into the congested replanted digits. This was repeated twice daily until venous congestion improved.

RESULTS

All the congested replanted digits survived without systemic side effects. There were no local side effects of the treatment. The PT and APTT have shown slight increase but they remained within the normal range. Haemoglobin levels have dropped slightly but no patients were at any risk of developing anaemia or needed blood transfusion.

CONCLUSIONS

Subcutaneous heparin injections can salvage the replanted digits when venous congestion is a warning flag for replantation failure. It is safe and very efficient in patients where systemic heparin cannot be administered. However, this article shows the results in only thirteen patients which is a small number to show the efficacy, safety, and side effects.

Venous Thromboembolism Prophylaxis: A Narrative Review With a Focus on the High-Risk Critically Ill Patient

Venous thromboembolism (VTE) is a major health concern associated with significant morbidity and mortality. Critically ill patients are at an increased risk of VTE compared to general medical patients due to unique risk factors: prolonged immobilization, invasive lines and devices, certain medications, and acquired thrombophilia. Furthermore, VTE in the critically ill is associated with increased duration of mechanical ventilation, increased length of intensive care unit and hospital stay, and a trend toward increased mortality. Clinical practice guidelines therefore recommend VTE prophylaxis with either subcutaneous heparin or low-molecular-weight heparin for all critically ill patients without contraindication. Yet, many patients will develop VTE despite appropriate pharmacologic prophylaxis, which has led to interest in risk-stratifying critically ill patients for more aggressive prophylaxis strategies. Recent research identified patients at highest risk of failure of thromboprophylaxis and provided insight into the pathophysiologic mechanisms. Obesity and the receipt of vasopressors are 2 risk factors consistently identified in observational studies; further clinical data support decreased absorption of anticoagulant administered via the subcutaneous route as the likely mechanism behind thromboprophylaxis failure in these patient populations. Several studies have investigated novel thromboprophylaxis strategies to circumvent pharmacokinetic limitations in patients who are obese or on vasopressors: increased fixed-dose, weight-based subcutaneous, or continuous intravenous infusion of a prophylactic dose of anticoagulant has shown promise in limited studies; however, the results have yet to demonstrate superiority compared to current standard-of-care. This review discusses observational studies identifying patients at risk of thromboprophylaxis failure and critiques clinical studies evaluating novel thromboprophylaxis strategies in high-risk, critically ill patients with a focus on their limitations. Future studies are currently being conducted that will provide further guidance into the appropriate use of individualized thromboprophylaxis.

Heparin-Free DALI LDL-Apheresis in Hyperlipidemic Patients: Efficacy, Safety and Biocompatibility

Background and Aim of Study

In routine DALI apheresis - the first technique for direct adsorption of lipoproteins from whole blood - heparin plus citrate (ACD-A) is used as anticoagulation regimen. However, recently several publications have warned of heparin-induced thrombocytopenia as a rare but potentially life-threatening complication of heparin administration (HIT type 2). The aim of the present study was therefore to test the efficacy and biocompatibility of DALI using a heparin-free anticoagulation regimen consisting exclusively of citrate.

Methods

Four symptomatic hypercholesterolemic patients on regular DALI apheresis were switched to the heparin-free protocol for two sessions each. Two of the patients were on oral anticoagulation using phenprocoumon. In the weekly sessions, 1.3 patient blood volumes were processed at a blood flow rate of 60 ml/min using ACD-A at a ratio of 1:20 (v/v) during adsorber priming and the session.

Results

Clinically, all sessions were essentially uneventful. Uncorrected lipoprotein reductions amounted to 65% for LDL-C, 62% for Lp(a), 53% for VLDL-C, 24% for HDL-C, 17% for triglycerides and 19% for fibrinogen. Cell counts remained virtually constant. No signs of hemolysis or clotting could be detected. Thromboplastin time (Quick) was slightly prolonged and partial thromboplastin time (PTT) moderately elevated in all patients. In constrast, whole blood coagulation time acc. to Lee-White and activated clotting times were increased only in orally anticoagulated patients. Biocompatibility in terms of complement, leukocyte and thrombocyte activation was excellent. Bradykinin activation was moderate peaking at 3038 pg/ml in the efferent line. Systemic thrombin-antithrombin complex (TAT) reflected perfect anticoagulation in orally anticoagulated patients and adequate anticoagulation in the patients without phenprocoumon.

Conclusion

In this pilot study, heparin-free DALI apheresis was safe and effective and may thus be performed in LDL-apheresis dependent patients who suffer from heparin intolerance.

Thromboelastography-based anticoagulation management during extracorporeal membrane oxygenation: a safety and feasibility pilot study

Background

There is no consensus on the management of anticoagulation during extracorporeal membrane oxygenation (ECMO). ECMO is currently burdened by a high rate of hemostatic complications, possibly associated with inadequate monitoring of heparin anticoagulation. This study aims to assess the safety and feasibility of an anticoagulation protocol for patients undergoing ECMO based on thromboelastography (TEG) as opposed to an activated partial thromboplastin time (aPTT)-based protocol.

Methods

We performed a multicenter, randomized, controlled trial in two academic tertiary care centers. Adult patients with acute respiratory failure treated with veno-venous ECMO were randomized to manage heparin anticoagulation using a TEG-based protocol (target 16–24 min of the R parameter, TEG group) or a standard of care aPTT-based protocol (target 1.5–2 of aPTT ratio, aPTT group). Primary outcomes were safety and feasibility of the study protocol.

Results

Forty-two patients were enrolled: 21 were randomized to the TEG group and 21 to the aPTT group. Duration of ECMO was similar in the two groups (9 (7–16) days in the TEG group and 11 (4–17) days in the aPTT group, p = 0.74). Heparin dosing was lower in the TEG group compared to the aPTT group (11.7 (9.5–15.3) IU/kg/h vs. 15.7 (10.9–21.3) IU/kg/h, respectively, p = 0.03). Safety parameters, assessed as number of hemorrhagic or thrombotic events and transfusions given, were not different between the two study groups. As for the feasibility, the TEG-based protocol triggered heparin infusion rate adjustments more frequently (p < 0.01) and results were less frequently in the target range compared to the aPTT-based protocol (p < 0.001). Number of prescribed TEG or aPTT controls (according to study groups) and protocol violations were not different between the study groups.

Conclusions

TEG seems to be safely used to guide anticoagulation management during ECMO. Its use was associated with the administration of lower heparin doses compared to a standard of care aPTT-based protocol.

Trial registration ClinicalTrials.gov, October 22,2014. Identifier: NCT02271126.

Electronic supplementary material

The online version of this article (10.1186/s13613-017-0352-8) contains supplementary material, which is available to authorized users.

Prospective Side by Side Comparison of Outcomes and Complications With a Simple Versus Intensive Anticoagulation Monitoring Strategy in Pediatric Extracorporeal Life Support Patients

OBJECTIVES

A continuous infusion of unfractionated heparin is the most common anticoagulant used for pediatric patients on extracorporeal life support. The objective of this study was to compare extracorporeal life support complications and outcomes between two large-volume pediatric extracorporeal life support centers that use different anticoagulation strategies.

DESIGN

Prospective, observational cohort study.

SETTING

The University of Michigan used simple anticoagulation monitoring, whereas the University of Alberta used an intensive anticoagulation monitoring strategy.

PATIENTS

Pediatric patients on extracorporeal life support.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome measure was major bleeding per extracorporeal life support run defined as bleeding that was retroperitoneal, pulmonary, or involved the CNS; bleeding greater than 20 mL/kg over 24 hours; or bleeding that required surgical intervention. Secondary outcomes measured were patient thrombosis per run, circuit thrombosis per run, and survival to hospital discharge per patient. Eighty-eight patients (95 runs) less than 18 years old were enrolled at the two centers over 2 years. The two centers enrolled different extracorporeal life support populations; University of Alberta enrolled more postcardiac surgical patients (74% vs 47%; p = 0.005). The indication for extracorporeal life support support also varied by center (p = 0.04). The two centers used similar proportions of VA extracorporeal life support (p = 0.3). Median (interquartile range) unfractionated heparin doses were similar between University of Michigan and University of Alberta, 30 (21-34) U/kg/hr and 26 (22-31) U/kg/hr, p value equals to 0.3, respectively. Median (interquartile range) antifactor Xa was lower in the University of Michigan cohort (0.23 [0.19-0.28] vs 0.41 [0.36-0.46] U/mL; p < 0.001). There was no significant difference in major bleeding (15% University of Michigan vs 21% University of Alberta; p = 0.6) or in patient thromboses (18% University of Michigan vs 13% University of Alberta; p = 0.5). There was no significant difference in survival to hospital discharge (University of Michigan 63% vs University of Alberta 73%; p = 0.1).

CONCLUSIONS

Although this prospective cohort study compared different pediatric extracorporeal life support populations, the results did not identify a significant difference in outcomes between simple and intensive anticoagulation monitoring strategies.

Therapeutic monitoring of unfractionated heparin - trials and tribulations

INTRODUCTION

Heparin is one of the oldest biological medicines with an established role in prevention and treatment of arterial and venous thromboembolism. Published therapeutic ranges for unfractionated heparin (UFH) mostly precede the large increase in the number of activated partial thromboplastin time (APTT) reagent/instrument combinations that now show wide variability. Areas covered: This paper explores the use of UFH, the development of heparin therapeutic ranges (HTRs), and the strengths and limitations of the methods used to monitor heparin's anticoagulant effect. Expert commentary: Despite longstanding use of UFH for management of thromboembolic conditions, the optimal test for monitoring UFH remains undetermined. Although used extensively for monitoring UFH, routine APTT-derived HTRs are based on limited science that may have little relevance to current laboratory practice. Anti-FXa levels may provide better and more reliable HTRs; however, even these levels show considerable inter-laboratory variation, and there are insufficient clinical studies proving improved clinical efficacy. Alternative tests for monitoring UFH reported over time have not been proven effective nor feasible, secondary to technical or cost issues, or lack of general adoption. Thus, despite limited evidence of clinical utility, an uncomfortable marriage of convenience represented by heparin laboratory monitoring is unlikely to be terminated in the immediate future.

New Anticoagulants for the Prevention and Treatment of Venous Thromboembolism

Anticoagulant drugs, like vitamin K antagonists and heparin, have been the mainstay for the treatment and prevention of venous thromboembolic disease for many years. Although effective if appropriately used, traditional anticoagulants have several limitations such as unpredictable pharmacologic and pharmacokinetic responses and various adverse effects including serious bleeding complications. New oral anticoagulants have recently emerged as an alternative because of their rapid onset/offset of action, predictable linear dose-response relationships and fewer drug interactions. However, they are still associated with problems such as bleeding, lack of reversal agents and standard laboratory monitoring. In an attempt to overcome these drawbacks, key steps of the hemostatic pathway are investigated as targets for anticoagulation. Here we reviewed the traditional and new anticoagulants with respect to their targets in the coagulation cascade, along with their therapeutic advantages and disadvantages. In addition, investigational anticoagulant drugs currently in the development stages were introduced.

Synthesis and Thrombin, Factor Xa and U46619 Inhibitory Effects of Non-Amidino and Amidino N²-Thiophenecarbonyl- and N²-Tosylanthranilamides

Thrombin (factor IIa) and factor Xa (FXa) are key enzymes at the junction of the intrinsic and extrinsic coagulation pathways and are the most attractive pharmacological targets for the development of novel anticoagulants. Twenty non-amidino N²-thiophencarbonyl- and N²-tosyl anthranilamides 1–20 and six amidino N²-thiophencarbonyl- and N²-tosylanthranilamides 21–26 were synthesized to evaluate their activated partial thromboplastin time (aPTT) and prothrombin time (PT) using human plasma at a concentration of 30 µg/mL in vitro. As a result, compounds 5, 9, and 21–23 were selected to study the further antithrombotic activity. The anticoagulant properties of 5, 9, and 21–23 significantly exhibited a concentration-dependent prolongation of in vitro PT and aPTT, in vivo bleeding time, and ex vivo clotting time. These compounds concentration-dependently inhibited the activities of thrombin and FXa and inhibited the generation of thrombin and FXa in human endothelial cells. In addition, data showed that 5, 9, and 21–23 significantly inhibited thrombin catalyzed fibrin polymerization and mouse platelet aggregation and inhibited platelet aggregation induced by U46619 in vitro and ex vivo. Among the derivatives evaluated, N-(3′-amidinophenyl)-2-((thiophen-2′′-yl)carbonylamino)benzamide (21) was the most active compound.

Mitral valve repair in dogs using an ePTFE chordal implantation device: a pilot study

OBJECTIVE

Mitral valve (MV) regurgitation due to degenerative MV disease is the leading cause of cardiac death in dogs. We carried out preliminary experiments to determine the feasibility and short-term effects of beating-heart MV repair using an expanded polytetrafluorethylene (ePTFE) chordal implantation device (Harpoon TSD-5) in dogs.

ANIMALS

This study involved six healthy purpose-bred Beagles (weight range 8.9-11.4 kg).

MATERIAL AND METHODS

Following a mini-thoracotomy performed under general anesthesia, the TSD-5 was used to place 1 or 2 artificial ePTFE cords on the anterior MV leaflet or the posterior MV leaflet via a left-ventricular transapical approach. The procedure was guided and monitored by transesophageal echocardiography. Postoperative antithrombotic treatment consisted of clopidogrel or a combination of clopidogrel and apixaban. Dogs were serially evaluated by transthoracic echocardiography at day 1, 7, 14, 21, and 30. The hearts were then examined for evaluation of tissues reactions and to detect signs of endothelialization.

RESULTS

One or two chords were successfully implanted in five dogs. Four dogs completed the 30 days follow-up. One dog died intra-operatively because of aortic perforation. One dog died early post-operatively from a hemorrhagic pleural effusion attributed to overly aggressive antithrombotic treatment. One dog developed a thrombus surrounding both the knot and the synthetic cord. Postmortem exam confirmed secure placement of ePTFE knots in the mitral leaflets in all dogs and the presence of endothelialization of the knots and chords.

CONCLUSIONS

These preliminary results demonstrate the feasibility of artificial chordal placement using an ePTFE cordal implantation device in dogs.

Intravenous heparin dosing strategy in hospitalized patients with atrial dysrhythmias

Patients with non-valvular atrial fibrillation (AF) have an elevated stroke risk that is 2-7 times greater than in those without AF. Intravenous unfractionated heparin (UFH) is commonly used for hospitalized patients with atrial fibrillation and atrial flutter (AFL) to prevent stroke. Dosing strategies exist for intravenous anticoagulation in patients with acute coronary syndromes and venous thromboembolic diseases, but there are no data to guide providers on a dosing strategy for intravenous anticoagulation in patients with AF/AFL. 996 hospitalized patients with AF/AFL on UFH were evaluated. Bolus dosing and initial infusion rates of UFH were recorded along with rates of stroke, thromboemobolic events, and bleeding events as defined by the International Society on Thrombosis and Haemostasis criteria. Among 226 patients included in the analysis, 76 bleeding events occurred. Using linear regression analysis, initial rates of heparin infusion ranging from 9.7 to 11.8 units/kilogram/hour (U/kg/h) resulted in activated partial thromboplastin times that were within therapeutic range. The median initial infusion rate in patients with bleeding was 13.3 U/kg/h, while in those without bleeding it was 11.4 U/kg/h; p = 0.012. An initial infusion rate >11.0 U/kg/h yielded an OR 1.95 (1.06-3.59); p = 0.03 for any bleeding event. Using IV heparin boluses neither increased the probability of attaining a therapeutic aPTT (56.1 vs 56.3 %; p = 0.99) nor did it significantly increase bleeding events in the study (35.7 vs 31.3 %; p = 0.48). The results suggest that higher initial rates of heparin are associated with increased bleeding risk. From this dataset, initial heparin infusion rates of 9.7-11.0 U/kg/h without a bolus can result in therapeutic levels of anticoagulation in hospitalized patients with AF/AFL without increasing the risk of bleeding.

A carboxymethylcellulose-heparin combination for the prevention of surgical adhesions

BACKGROUND

Adhesions are a major clinical problem after abdominal surgery. Despite decades of research, therapies to prevent adhesion formation are suboptimal.

MATERIALS AND METHODS

We have investigated combinations of carboxymethylcellulose (CMC) and heparin at preventing surgical adhesions in two rat models of adhesion formation. The first was the well-established cecal abrasion model, and the second was a model developed in our laboratory, the avascular mesenteric knot model. This model consistently produced adhesions at the knot in 90% of experiments and causes little or no tissue injury.

RESULTS

Topical administration of CMC 4% gave optimal results in the avascular knot model, but was less effective in the cecal abrasion model. This concentration of CMC was combined with a range of heparin doses between 0.5 and 160 IU/mL in the cecal abrasion model. These heparin doses, apart from the lowest (0.5 IU/mL), were effective in preventing adhesion formation in combination with CMC, as was the commercially available topical product Lipactin. The optimal dose was 30 IU/mL, that abolished adhesions, but there was little difference at doses between 2 and 160 IU. Heparin was effective in doses as low as 2 IU/mL when in combination with CMC. Heparin 160 IU/mL, but not heparin 30 IU/mL or Lipactin, significantly increased the degree of bleeding post cecal abrasion surgery.

CONCLUSIONS

Topical application of tiny doses of heparin, in combination with CMC 4% gel, significantly reduces adhesion formation in experimental models. We suggest that this cheap and, as far as we know, safe intervention should be evaluated in human clinical trials.

Thrombin-Responsive Transcutaneous Patch for Auto-Anticoagulant Regulation

A thrombin-responsive closed-loop patch is developed for prolonged heparin delivery in a feedback-controlled manner. This microneedle-based patch can sense activated thrombin and subsequently releases heparin to prevent coagulation in the blood flow. This "smart" heparin patch can be transcutaneously inserted into skin without drug leakage and can sustainably regulate blood coagulation in response to thrombin.

Surgical manual of the Korean Gynecologic Oncology Group: ovarian, tubal, and peritoneal cancers

The Surgery Treatment Modality Committee of the Korean Gynecologic Oncology Group has determined to develop a surgical manual to facilitate clinical trials and to improve communication between investigators by standardizing and precisely describing operating procedures. The literature on anatomic terminology, identification of surgical components, and surgical techniques were reviewed and discussed in depth to develop a surgical manual for gynecologic oncology. The surgical procedures provided here represent the minimum requirements for participating in a clinical trial. These procedures should be described in the operation record form, and the pathologic findings obtained from the procedures should be recorded in the pathologic report form. Here, we describe surgical procedure for ovarian, fallopian tubal, and peritoneal cancers.

Comparison of Topical Low-Molecular-Weight Heparin-Taurocholate and Bevacizumab for Treatment and Prevention of Corneal Neovascularization

PURPOSE

To compare the therapeutic and preventive effects of topically administered 7-taurocholic acid-conjugated low-molecular-weight heparin (LHT7) and bevacizumab in experimentally induced corneal neovascularization (CoNV).

METHODS

CoNV was induced using sutures in the right eyes of 24 mice. To investigate the therapeutic effects, CoNV was allowed to develop for 1 week before treatment. To ascertain the preventive effects, the treatments were applied immediately after the suture. In each experiment, 12 eyes were divided into 3 groups and treated topically using bevacizumab (bevacizumab group), LHT7 (LHT7 group), and normal saline (control group). The treatments were instilled 3 times daily for 2 weeks. The CoNV area was measured before instillation and after 1 and 2 weeks after instillation.

RESULTS

In the investigation of therapeutic effects, the CoNV area had decreased significantly 1 week after treatment in the bevacizumab group (1.58-0.75 mm; P = 0.036) and LHT7 group (1.38-0.74 mm; P = 0.018). Two weeks after treatment, the CoNV area was significantly smaller in the bevacizumab groups (0.60 mm; P = 0.005) and LHT7 group (0.64 mm; P = 0.015) than in the control group (1.68 mm), but the bevacizumab group did not differ significantly from the LHT7 group. In the experiment addressing the preventive effects, CoNV was less developed in the bevacizumab group (0.70 mm; P = 0.003) and LHT7 group (0.54 mm; P = 0.003) than in the control group (1.75 mm), and the CoNV area was smaller in the LHT7 group than in the bevacizumab group (P = 0.021).

CONCLUSIONS

The effects of LHT7 on CoNV regression are comparable to those of bevacizumab. Topical administration of LHT7 prevents CoNV more effectively than bevacizumab.

Unfractionated heparin or low-molecular-weight heparin in the elderly

With the ageing of the general population, clinicians are facing with increased frequency the challenge of administering parenteral anti-coagulation therapy in the elderly, the main indications being venous thromboembolism (VTE), acute coronary syndromes (ACS), atrial fibrillation and bridging therapy. Assessing the risk/benefit ratio is always difficult in this category of patients, because of the higher risk for hemorrhagic events, although in most cases the benefit outweighs the risk, especially in the setting of VTE. The development of early invasive strategies for treating ACS has improved outcomes, while reducing the need for prolonged anticoagulation. For ST-segment elevation acute myocardial infarction (STEMI), primary percutaneous coronary intervention (PCI) is the mainstay treatment with well documented benefits in terms of mortality reduction regardless of the patient's age. However, evidence is less strong regarding early invasive treatment for over 75-year old Non-STEMI patients, resulting in a significant percentage being treated conservatively, including parenteral anticoagulation. This review will focus on the use of parenteral anticoagulation (unfractionated or low-molecular weight heparin) in older patients. We will analyze current guidelines-based parenteral anticoagulation indications, while focusing on specific considerations in the elderly, such as: frailty and comorbidities, pharmacokinetics, the hemorrhagic risk and available clinical evidence. The goal is to offer a comprehensive tool for the clinician managing parenteral anticoagulation in older patients.

Aspirin plus tirofiban inhibit the thrombosis induced by Russell's viper venom

Background

Thrombosis and coagulopathy are the commonest hematological manifestations of envenomation of Russell’s viper venom (RVV). Factor X is activated by a factor X-activating enzyme from Russell’s viper venom (RVV-X) to start the coagulation cascade. We established an animal model with local ischemic effects induced by RVV. We tried to treat RVV envenomation with antiplatelets and anticoagulants without recourse to antivenom.

Methods

RVV was injected into the foot pad of mice. We observed the effects at different intervals and compared local changes in ischemia with drug treatment after 30 min.

Results

A combination of aspirin plus tirofiban could prevent the ischemic change induced by RVV. The antithrombotic effects of single-use of aspirin or tirofiban were better than single-use of heparin or clopidogrel.

Conclusion

The aspirin + tirofiban group had a better outcome with respect to prevention of tissue ischemia and gangrene. This indicates that the activation and aggregation of platelets is the major cause of thrombosis induced by RVV.

Attenuation of corneal neovascularization by topical low-molecular-weight heparin-taurocholate 7 without bleeding complication

AIM

To investigate the antiangiogenic effects and safety of topically administered low-molecular-weight heparin-taurocholate 7 (LHT7) on corneal neovascularization (CoNV).

METHODS

Twenty-four Sprague-Dawley rats were randomly distributed into four groups of six rats each. The central corneas were cauterized using a silver/potassium nitrate solution. From 2d after cauterization, 12.5 mg/mL (low LHT7 group) or 25 mg/mL (high LHT7 group) LHT7 was topically administered three times daily; 12.5 mg/mL bevacizumab was topically administered as positive control (bevacizumab) group, with normal saline (NS) administered as negative control (NS group). The corneas were digitally photographed to calculate the CoNV percentage from the neovascularized corneal area at 1 and 2wk.

RESULTS

The 4 study groups did not have different CoNV percentages at 1wk after injury (P>0.05). However, the low LHT, high LHT, and bevacizumab groups had significantly lower CoNV percentages than the NS group at 2wk (all P<0.05). No significant differences in CoNV percentage were found among the low LHT, high LHT, and bevacizumab groups (all P>0.05). All groups except the NS group had lower CoNV percentages at 2wk post-injury than the levels observed at 1wk (all P<0.05).

CONCLUSION

Topically-administered LHT7 inhibited CoNV without complication after chemical cauterization in the rat.

Therapy of unstable angina with the low molecular weight heparins

Unstable angina is in most cases caused by partial or complete coronary artery occlusion due to the disruption of an atherosclerotic plaque and to thrombus formation. An immediate antithrombotic approach is essential to prevent fatal and non-fatal myocardial infarction, and the combination of aspirin and unfractionated heparin has played a pivotal role in the past years. Low molecular weight heparins have improved pharmacokinetic and pharmaco-dynamic properties over unfractionated heparin that have resulted in greater efficacy and safety in the field of venous thromboembolism. Low molecular weight heparins can be administered by once or twice daily subcutaneous injections at fixed, weight-adjusted doses without the need for monitoring. Because of their potential, many recent clinical trials have evaluated their efficacy and safety in the management of patients with unstable angina. Three low molecular weight heparins have so far been tested: nadroparin, dalteparin and enoxaparin. The results of the published trials confirm that the newer compounds are at least as safe and effective as unfractionated heparin, and offer considerable therapeutic advantages. Nevertheless, the different properties of the three compounds and perhaps the different designs of the clinical trials have led to not entirely comparable findings.

Recent advances in thromboresistant and antimicrobial polymers for biomedical applications: just say yes to nitric oxide (NO)

Biomedical devices are essential for patient diagnosis and treatment; however, when blood comes in contact with foreign surfaces or homeostasis is disrupted, complications including thrombus formation and bacterial infections can interrupt device functionality, causing false readings and/or shorten device lifetime. Here, we review some of the current approaches for developing antithrombotic and antibacterial materials for biomedical applications. Special emphasis is given to materials that release or generate low levels of nitric oxide (NO). Nitric oxide is an endogenous gas molecule that can inhibit platelet activation as well as bacterial proliferation and adhesion. Various NO delivery vehicles have been developed to improve NO's therapeutic potential. In this review, we provide a summary of the NO releasing and NO generating polymeric materials developed to date, with a focus on the chemistry of different NO donors, the polymer preparation processes, and in vitro and in vivo applications of the two most promising types of NO donors studied thus far, N-diazeniumdiolates (NONOates) and S-nitrosothiols (RSNOs).

Heparin-Induced Thrombocytopenia

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.

Erratum to: Pharmacology of anticoagulants used in the treatment of venous thromboembolism

Anticoagulant drugs are the foundation of therapy for patients with VTE. While effective therapeutic agents, anticoagulants can also result in hemorrhage and other side effects. Thus, anticoagulant therapy selection should be guided by the risks, benefits and pharmacologic characteristics of each agent for each patient. Safe use of anticoagulants requires not only an in-depth knowledge of their pharmacologic properties but also a comprehensive approach to patient management and education. This paper will summarize the key pharmacologic properties of the anticoagulant agents used in the treatment of patients with VTE.

Optimal Management of Bleeding Complications After Cardiac Surgery

Patients undergoing cardiac surgery with cardiopulmo nary bypass (CPB) are at increased risk for excessive perioperative blood loss requiring transfusion of blood products. Point-of-care evaluation of platelets, coagu lation factors, and fibrinogen can enable physicians to assess bleeding abnormalities rapidly. They also can facilitate the optimal administration of pharmacologic and transfusion-based therapy and allow physicians to identify patients with surgical bleeding. The ability to reduce the unnecessary use of blood products in this setting has important implications for emerging issues in blood inventory and blood costs. The ability to de crease operative time along with re-exploration rates has important consequences for health care costs in an increasingly managed health care environment. Copyright© 2001 by W.B. Saunders Company.

Heparin-appended polycaprolactone core/corona nanoparticles for site specific delivery of 5-fluorouracil

The aim of the present work is to formulate heparin-modified-polycaprolactone (HEP) core shell nanoparticles (NPs) of 5-fluorouracil (5-FU). These NPs were characterized for various in vitro parameters like particle size, zeta potential, etc. HEP NPs were found to maintain comparatively slower drug release pattern (98.9% in 96 h) than PCL NPs. Cytotoxicity studies demonstrated a massive cytotoxic potential of 5-FU-loaded HEP NPs in A549, MDA-MD-435, and SK-OV-3 cancer cell lines. Pharmacokinetic parameters were also determined in blood after IV administration of HEP NPs: AUC, C_max, MRT, and T_max values are 6096.075 ± 5.90 μg h/mL, 144.38 ± 1.52 μg/L, 58.71 ± 0.25 h, 96 ± 0.50 h, respectively and 117.92 ± 1.78, 45.35 ± 3.00, 1.2 ± 0.25, 0.5 ± 0.02 in plain 5-FU solution.

State-of-the-Art Review : Activated Partial Thromboplastin Time in Heparinized Plasma: Influence of Reagent, Acute-Phase Reaction, and Interval Between Sampling and Testing

Plasma samples from 10 healthy persons and 10 patients with acute-phase reaction were heparinized in vitro to obtain up to 0.70 U/ml. Activated partial throm boplastin time (APTT) was then determined using an op tical method (Automated Coagulation Laboratory or ACL Machine) and four different reagents (Actin, Ceph otest, Platelin, and Thrombosil). Heparin sensitivity var ied between individuals, and it was lower in acute-phase plasma than in healthy plasma. There was also a marked difference in heparin sensitivity among the different re agents; Actin was the least sensitive reagent, while Plate lin was the most sensitive reagent in healthy plasma and Thrombosil the most sensitive reagent in acute-phase plasma. Delay in testing prolonged the APTT values both in acute-phase and healthy heparinized plasma. With Ac tin and Cephotest, a delay of 90 min at 22°C resulted in 30-50% prolongation of APTT. A delay of 150 min caused a prolongation of 75-110% with Actin. Cephotest, Plate lin, and Thrombosil were less prolonged. Ex vivo samples from heparinized plasma showed similar degrees of pro longation. Storage at 4°C resulted in less prolongation. Assuming a therapeutic range of 0.35-0.70 U/ml of hep arin, the therapeutic APTT ratios in heparinized acute- phase plasma were 1.5-3.0 for Actin and 2.5-4.5 for Cephotest, Platelin, and Thrombosil. These results un derscore certain limitations in monitoring heparin therapy with the APTT system. Unless the assay is performed within 30 min after sampling, unduly prolonged APTT values will be recorded, which may lead to giving the patient an inappropriately small dose of heparin.

State-of-the-Art Review: The Preclinical and Clinical Pharmacology of Novastan (Argatroban): A Small-Molecule, Direct Thrombin Inhibitor

Because of the unsatisfactory options available for safe and effective antithrombotic therapy, recent, intense research and development efforts have been focused on direct thrombin inhibitors, also known as site-directed thrombin inhibitors. The intravenous agent Novastan (argatroban) is a small-molecule, reversible, direct thrombin inhibitor that is selective for the catalytic site of the thrombin molecule. Argatroban's molecular properties (small molecule; fast, selective, and reversible inhibition of the thrombin catalytic site; and similar in vitro potency for inhibiting both clot-bound and soluble thrombin) offer the potential for significant antithrombotic efficacy with minimal systemic anticoagulant ef fects. Its clinical pharmacologic properties offer the potential for minimal risk of bleeding, very rapid achievement of therapeutic antithrombotic efficacy, predictable dose-response, and rapid restoration of the hemostatic systems to normal upon termination of intravenous infusion. Argatroban is currently approved for clinical use in Japan for the treatment of peripheral arterial occlusive disease. It is in advanced clinical development in North America, South America, and Western Europe for several clinical indications, including (1) adjunctive therapy to thrombolytic agents in the treatment of acute myocardial infarction and (2) antithrombotic therapy for patients with heparin-induced thrombocytopenia and heparin-induced thrombocytopenia and thrombosis syndrome. Key Words: Molecular properties—Novastan (argatroban)—Pharmacology—Thrombin inhibitor.

State-of-the-Art Review: Usefulness of Laboratory Techniques for Evaluating Antithrombotic Efficacy of New Therapeutic Strategies

New drugs and new therapeutic strategies are being introduced for the prevention and the management of cardiovascular and thromboembolic disorders. Extensive clinical studies and large-scale epidemiological investigations are conducted to demonstrate the efficacy of these therapeutic approaches. Laboratory assays are invaluable tools for this exploration. We discuss how the new understanding concerning the regulation of the coagulolytic equilibrium offers novel investigation tools. Parameters reflecting the activities of new drugs targeted to their impact site and presenting few side effects are available. In addition to global clotting methods and chromogenic substrate-based assays, introduction of immunoassays has allowed measurement of most of the molecular markers of hemostatic activation. We recommend use of a panel of markers exploring the endothelial damage, the blood cell involvement, the early coagulant pathways' activation (XIIa and VIIa), the thrombin-formation pathways, the fibrin formation, and the evaluation of the global fibrinolytic capacity. When related to the clinical end points, all these laboratory assays offer useful and reliable monitoring of new drugs. They contribute to the establishment of new therapeutic strategies. Key Words: Hemostasis—Activation—Antithrombotic—Therapy— Laboratory monitoring.

The Treatment of Proximal Vein Thrombosis with Subcutaneous Low-Mole Molecular-Weight Heparin Compared with Continuous Intravenous Heparin

Low-molecular-weight heparin, compared with unfractionated heparin, has a higher bioavailability and a more prolonged half-life. There are limited data comparing the use of low-molecular-weight heparin with unfractionated heparin for the treatment of deep vein thrombosis. We have compared fixed-dose, subcutaneous low-molecular-weight heparin given once daily with adjusted-dose intravenous heparin given by continuous infusion in a multicenter double-blind clinical trial for the initial treatment of patients with proximal vein thrombosis. Clinical outcomes were objectively documented. Six of 213 patients receiving low-molecular-weight heparin (2.8%) and 15 of 219 patients receiving intravenous heparin (6.9%) developed new episodes of venous thromboembolism (p = 0.07; 95% confidence interval for the difference, 0.02%-8.1%). During initial therapy, major bleeding occurred in one patient receiving low-molecular-weight heparin (0.5%) and in 11 patients receiving intravenous heparin (5.0%), a risk reduction of 91% (p = 0.006). This apparent protection against major bleeding was lost during long-term therapy. Minor bleeding complications were rare. During the period of the study, 10 patients receiving low-molecular-weight heparin (4.7%) died, as compared with 21 patients receiving intravenous heparin (9.6%), a risk reduction of 51%(p = 0.049). This study shows that low-molecular-weight heparin is at least as effective as classic intravenous heparin therapy and that there was a reduction in deaths and bleeding complications. Furthermore, low-molecular-weight heparin was more convenient to administer. The simplified therapy with low-molecular-weight heparin given by once-daily subcutaneous injection without monitoring may allow patients with uncomplicated proximal deep vein thrombosis to be cared for as outpatients. Key Words: Low-molecular-weight heparin—Unfractionated heparin—Deep vein thrombosis—Deaths—Bleeding complications.

A Review of Common Approaches to Heparin Dosing

The use of heparin has remained steady for the last 20 years. Significant advances have been made in the understanding of the pathogenesis of clotting disorders and their prevention. Despite these gains, our understanding of the most safe and effective approach to optimizing the dosing of heparin has lagged. With new insight into improvements in outcome related to rapid achievement of the therapeutic range, it has become apparent that the standard approach to heparin dosing is out of date. Individualized heparin dosing based on weight and computer-assisted dosing methods is superior for bringing patients into the desired therapeutic range more quickly, with less cost and better short- and long-term outcomes. Copyright © 1995 by W.B. Saunders Company

Controlled continuous systemic heparinization increases success rate of artery-only anastomosis replantation in single distal digit amputation: A retrospective cohort study

Replantation is a prime indication for distal digital amputation, as it helps restore hand aesthetics and functions; however, venous anastomosis is often not feasible. Previous studies used systemic anticoagulation in distal digital artery only anastomosis replantation surgery to improve replantation success rate, however, which yielded limited level of clinical evidence. This study aimed to compare controlled continuous heparinization (CCH) and intermittent bolus heparinization (IBH) for surgical outcome and clinical variables after single distal digital artery only anastomosis replantation surgery.A single-institution, retrospective cohort study was performed. Out of 324 patients who underwent digital replantation surgery, we focused the study for the Zone I and II single distal digital amputation patients excluding confounding factors. Sixty-one patients were included in this study and underwent artery-only anastomosis replantation surgery with postoperative CCH (34 patients) or IBH (27 patients) protocols. The CCH group targeted activated partial thromboplastin time (aPTT) at 51 to 70 seconds, monitoring aPTT levels every eight hours and administering 100 mg of aspirin per day. The IBH group received 300 mg of aspirin per day and underwent IBH (12,500 U). Both groups received intravenous prostaglandin E1 drips (10 μg). To verify the factors affecting the success rate of the heparin protocol, patient factors, clinical factors, and operative factors were extracted from the medical records. Statistical analysis with inverse probability of treatment weights propensity score methods compared treatment outcomes and clinical variables.The CCH group's replantation success rate was higher (91.17% vs 59.25%), and the transfusion rate was increased (P = 0.032). However, the significant decrease in hemoglobin levels (>15%) did not differ between the groups (P = 0.108). Multivariable logistic regression analysis with potent univariate variables (P < .10) revealed that CCH was a statistically significant variable in replantation success rate (P = 0.004). Neither the major bleeding complications nor the significant decrease in patients' platelet levels were observed in both groups.Our study suggests that CCH after artery-only anastomosis replantation surgery in Zone I and II distal digital replantation is a safe method to improve the replantation success rate and may provide a guideline for use of the anticoagulation method following artery-only anastomosis distal digital replantation surgery.

Development of a population pharmacokinetic-pharmacodynamic model of a single bolus dose of unfractionated heparin in paediatric patients

BACKGROUND

Unfractionated heparin (UFH) is the anticoagulant of choice in paediatric patients undergoing a variety of cardiac procedures. There are currently no population pharmacokinetic-pharmacodynamic (PKPD) models for UFH in paediatrics.

OBJECTIVE

The aim of the present study was to develop and evaluate a PKPD model of UFH in paediatrics.

METHODS

Data from 64 children who received 75-100 IU kg(-1) of UFH during cardiac angiography were analysed. Five blood samples were collected at baseline and at 15, 30, 45 and 120 min postdose. The UFH concentration was quantified using a protamine titration assay. The UFH effect was quantified using activated partial thromboplastin time (aPTT). A PKPD model was fitted using nonlinear mixed-effects modelling. Patient covariates such as gender, weight (WT) and fat-free mass (FFM) were tested. The final model was evaluated using the likelihood ratio test and visual predictive checks (VPCs).

RESULTS

A one-compartment model with linear elimination provided the best fit for the dose-concentration data. FFM was a significant covariate on clearance. A linear model provided the best fit for the concentration-effect data using aPTT as a biomarker for effect. The models performed well using VPCs. However, when used to simulate UFH infusion (at a much lower dose), the model overpredicted target aPTT responses.

CONCLUSIONS

A PKPD model to describe the time course of the UFH effect was developed in a paediatric population. FFM was shown to describe drug disposition well. However, when applied to smaller UFH infusion doses, the model overpredicted target aPTT responses. This unsuccessful extrapolation may be attributed to a possible nonlinear relationship for heparin PKPD.

Point-of-care diagnostics for niche applications

Point-of-care or point-of-use diagnostics are analytical devices that provide clinically relevant information without the need for a core clinical laboratory. In this review we define point-of-care diagnostics as portable versions of assays performed in a traditional clinical chemistry laboratory. This review discusses five areas relevant to human and animal health where increased attention could produce significant impact: veterinary medicine, space travel, sports medicine, emergency medicine, and operating room efficiency. For each of these areas, clinical need, available commercial products, and ongoing research into new devices are highlighted.

The immobilization of a direct thrombin inhibitor to a polyurethane as a nonthrombogenic surface coating for extracorporeal circulation

A biomaterial with both antithrombin and antiplatelet properties is the ideal surface for use in extracorporeal circulation (ECC) as it targets both fibrin generation and platelet adhesion. A hemocompatible surface coating avoids the need for systemic anticoagulation by providing a local anticoagulant effect at the polymer-blood interface. Previous work has demonstrated the potential use of argatroban, a direct thrombin inhibitor, as a nonthrombogenic material for extracorporeal devices. The work reported here focuses on the characterization of argatroban linked to a polyurethane-silicone polymer, CarboSil®. Chemical immobilization, the amount of argatroban, incubation times, and saturation point were evaluated to achieve maximal antithrombin activity at the polymer surface. Cross-linked polymer coatings reacted with 10 and 30 µmole of argatroban were prepared and tested. These coatings resulted in argatroban activity levels of 0.131 µM and 0.446 µM, respectively. After refining the cross-linking process, argatroban activity increased by approximately 3.6 fold. Maintenance of activity and leaching from the polymer surface were also evaluated. Using the refined process for linking argatroban to polymer, the resulting polymer was applied as a surface coating to the inner lumen of poly(vinyl chloride) ECC circuit tubing and its antithrombin effect evaluated using a 4 h rabbit ECC model. Following 4 h of blood exposure, the argatroban circuit demonstrated significantly less thrombus formation compared to the control CarboSil® coating with a 4.1 cm² thrombus average area for the control coating compared to 1.2 cm² for the argatroban coating (n=4). There was no significant change in thrombin time from baseline in plasma from animals in which the argatroban coated circuit was used, with a thrombin time of 16.2 s at t=0 and 14.5 s after 4 h. These results demonstrate the potential efficacy of immobilized argatroban as a hemocompatible biomaterial for extracorporeal life support devices.

Pharmacology of anticoagulants used in the treatment of venous thromboembolism

Anticoagulant drugs are the foundation of therapy for patients with VTE. While effective therapeutic agents, anticoagulants can also result in hemorrhage and other side effects. Thus, anticoagulant therapy selection should be guided by the risks, benefits and pharmacologic characteristics of each agent for each patient. Safe use of anticoagulants requires not only an in-depth knowledge of their pharmacologic properties but also a comprehensive approach to patient management and education. This paper will summarize the key pharmacologic properties of the anticoagulant agents used in the treatment of patients with VTE.

The evolution of anticoagulant therapy

Arterial and venous thromboembolism are leading causes of morbidity and mortality around the world. For almost 70 years, heparins (unfractionated heparin and low molecular weight heparins) and vitamin K antagonists have been the leading therapeutic medical options for the treatment and prevention of thromboembolic disorders. Nevertheless, the many limitations of these traditional anticoagulants have fuelled the search for novel agents over the past 15 years, and a new class of oral anticoagulants that specifically target activated factor X and thrombin has been developed and is now commercially available. In this narrative review, the evolution of anticoagulant therapy is summarised, with a focus on newer oral anticoagulants.

In vitro and in vivo characterization of a reversible synthetic heparin analog

BACKGROUND

The global supply of unfractionated heparin (UFH) and all commercially available low molecular weight heparins (LMWH) remain dependent on animal sources, such as porcine intestine or bovine lung. Recent experience has shown that contamination of the supply chain (with over-sulfated chondroitin sulfates) can result in lethal toxicity. Fondaparinux is currently the only commercially available synthetic analog of heparin. We recently described a new class of chemoenzymatically synthesized heparin analogs. One of these compounds (S12-mer) is a dodecasaccharide consisting of an antithrombin-binding moiety with repeating units of IdoA2S-GlcNS6S and two 3-O-sulfate groups that confer the ability to bind protamine.

OBJECTIVE/METHODS

We sought to further characterize this new compound in vitro using biochemical and global coagulation assays and in vivo using thrombosis and hemostasis assays.

RESULTS

The anticoagulant activities of the Super 12-mer (S12-mer) and Enoxaparin in anti-factor Xa and plasma-based thrombin generation assays were roughly equivalent with a 50% reduction in peak thrombin generation occurring at approximately 325nM. When protamine was titrated against a fixed concentration of S12-mer in plasma or blood, the S12-mer displayed a significant restitution of thrombin generation and clot formation. In vivo, S12-mer inhibited venous thrombosis to a similar extent as Enoxaparin, with similar bleeding profiles.

CONCLUSIONS

These data show that the S12-mer has almost identical efficacy to Enoxaparin in terms of FXa inhibition, while displaying significant reversibility with protamine. Taken together with the ability to ensure purity and homogeneity from batch to batch, the S12-mer is a promising new synthetic heparin analog with a potentially enhanced safety profile.

Heparin in malignant glioma: review of preclinical studies and clinical results

Glioblastoma multiforme (GBM) is the most common primary brain tumor that is invariably lethal. Novel treatments are desperately needed. In various cancers, heparin and its low molecular weight derivatives (LMWHs), commonly used for the prevention and treatment of thrombosis, have shown therapeutic potential. Here we systematically review preclinical and clinical studies of heparin and LMWHs as anti-tumor agents in GBM. Even though the number of studies is limited, there is suggestive evidence that heparin may have various effects on GBM. These effects include the inhibition of tumor growth and angiogenesis in vitro and in vivo, and the blocking of uptake of extracellular vesicles. However, heparin can also block the uptake of (potential) anti-tumor agents. Clinical studies suggest a non-significant trend of prolonged survival of LMWH treated GBM patients, with some evidence of increased major bleedings. Heparin mimetics lacking anticoagulant effect are therefore a potential alternative to heparin/LMWH and are discussed as well.

The Effect of Low Molecular Weight Heparins on Fracture Healing

Venous Thromboembolism is a serious complication in the trauma patient. The most commonly studied and used anticoagulant treatment in prophylaxis of thrombosis is heparin. The prolonged use of unfractionated heparin has been connected with increased incidence of osteoporotic fractures. Low molecular-weight-heparins (LMWHs) have been the golden rule in antithrombotic therapy during the previous two decades as a way to overcome the major drawbacks of unfractioned heparin. However there are few studies reporting the effects of LMWHs on bone repair after fractures. This review presents the studies about the effects of LMWHs on bone biology (bone cells and bone metabolism) and underlying the mechanisms by which LMWHs may impair fracture healing process. The authors' research based on literature concluded that there are no facts and statistics for the role of LMWHs on fracture healing process in humans and the main body of evidence of their role comes from in vitro and animal studies. Further large clinical studies designed to compare different types of LMWHs, in different dosages and in different patient or animal models are needed for exploring the effects of LMWHs on fracture healing process.

Anticoagulation strategies and difficulties in neonatal and paediatric extracorporeal membrane oxygenation (ECMO)

Objective:

The aim of this review is to highlight an emerging problem with anticoagulation-related complications in neonatal and paediatric ECMO, to explore for flaws in the currently recommended anticoagulation management responsible for these problems and to discuss possible strategies mitigating further escalation of the issue.

Data Sources:

Pertinent neonatal and paediatric literature on the topic of interest and international Extracorporeal Life Support Organisation (ELSO) registry data request.

Conclusions:

The international ELSO registry data reveals increasing rates of anticoagulation-related complications during neonatal and paediatric ECMO worldwide. The causes are multifactorial and the proposed solution to the problem is to match anticoagulation management to the pathophysiological complexity of haemostasis on ECMO.