Development Of New Anticoagulants Research Articles

A Deep Overview of Anticoagulant Drugs: Recent Synthesis and Their Activity Assay

During the unprecedented COVID-19 pandemic, anticoagulant drugs have emerged as a crucial component of treatment alongside antivirus medications. Patients with severe COVID-19 frequently have critical conditions marked by blood clot development, necessitating the administration of anticoagulants. This review aims to provide a comprehensive overview of various anticoagulant drugs, their synthesis methods, and assays employed to predict their anticoagulant activity. Notable anticoagulant categories frequently utilized include oral anticoagulants heparin, non-vitamin K antagonists, and vitamin K antagonists. In recent years, the development of new anticoagulants has seen a shift towards a multifaceted approach that combines in silico prediction with in vitro and in vivo assays. In silico prediction techniques play a pivotal role in the initial screening process. This integrated approach has yielded promising results, paving the way for the synthesis of novel anticoagulant candidates, as substantiated by a battery of in vitro, in vivo, and ex-vivo tests.

Venous thromboembolism treatment in patients with cancer: reflections on an evolving landscape

Cancer is a leading cause of morbidity and mortality worldwide. It is also one of the strongest risk factors for venous thromboembolism (VTE), reported in approximately 20% of all cases of VTE diagnosed. The thrombotic effect of cancer and its treatments, however, is highly variable among patients and changes over the course of their cancer. Anticoagulant therapy remains the cornerstone of VTE treatment, but it is associated with a substantial rate of VTE recurrence and the potential for serious bleeding. The risk of bleeding in patients with cancer is also dependent on the cancer type and its treatments, often revealing underlying tumor invasion of mucosal or parenchymal tissues, and treatment complications such as thrombocytopenia or coagulopathy. Over the past few decades, efforts to improve the efficacy and safety of anticoagulant therapy for the treatment and prevention of cancer-associated thromboembolism have resulted in changes in the standard of practice. This evolution has been made possible largely through the development of new anticoagulants. This review will reflect on the major advances in the treatment of cancer-associated thrombosis and offer insights on how to address unmet needs in this field.

Novel Substituted Azoloazines with Anticoagulant Activity

Hypercytokinemia, or cytokine storm, often complicates the treatment of viral and bacterial infections, including COVID-19, leading to the risk of thrombosis. However, the use of currently available direct anticoagulants for the treatment of COVID-19 patients is limited due to safety reasons. Therefore, the development of new anticoagulants remains an urgent task for organic and medicinal chemistry. At the same time, new drugs that combine anticoagulant properties with antiviral or antidiabetic activity could be helpfull in the treatment of COVID-19 patients, especially those suffering from such concomitant diseases as arterial hypertension or diabetes. We have synthesized a number of novel substituted azoloazines, some of which have previously been identified as compounds with pronounced antiviral, antibacterial, antidiabetic, antiaggregant, and anticoagulant activity. Two compounds from the family of 1,2,4-triazolo[1,5-a]pyrimidines have demonstrated anticoagulant activity at a level exceeding or at least comparable with that of dabigatran etexilate as the reference compound. 7,5-Di(2-thienyl)-4,5-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine has shown the highest ability to prolong the thrombin time, surpassing this reference drug by 2.2 times. This compound has also exhibited anticoagulant activity associated with the inhibition of thrombin (factor IIa). Moreover, the anticoagulant effect of this substance becomes enhanced under the conditions of a systemic inflammatory reaction.

Novel Antithrombotic Agents in Ischemic Cardiovascular Disease: Progress in the Search for the Optimal Treatment

Ischemic cardiovascular diseases have a high incidence and high mortality worldwide. Therapeutic advances in the last decades have reduced cardiovascular mortality, with antithrombotic therapy being the cornerstone of medical treatment. Yet, currently used antithrombotic agents carry an inherent risk of bleeding associated with adverse cardiovascular outcomes and mortality. Advances in understanding the pathophysiology of thrombus formation have led to the discovery of new targets and the development of new anticoagulants and antiplatelet agents aimed at preventing thrombus stabilization and growth while preserving hemostasis. In the following review, we will comment on the key limitation of the currently used antithrombotic regimes in ischemic heart disease and ischemic stroke and provide an in-depth and state-of-the-art overview of the emerging anticoagulant and antiplatelet agents in the pipeline with the potential to improve clinical outcomes.

In vitro anticoagulant activity of selected medicinal plants: potential interactions with warfarin and development of new anticoagulants

Warfarin is the most widely used anticoagulant in the world, but it has several limitations including its narrow therapeutic range, need for dose adjustment and high potential for interactions. The simultaneous use of other drugs or even medicinal plants and certain foods could interfere with its therapeutic activity. In this context, this study aims to investigate the in vitro anticoagulant potential and phytochemical constitution of 17 plants selected from a previous clinical cross-sectional study (2014), that investigated the habits of plant utilization among patients taking warfarin. Ethanol extracts and essential oils were evaluated, in vitro, as to their effect in the prothrombin time (PT) and activated partial thromboplastin time (aPTT) tests. Four species that presented aPTT >50s were selected for phytochemical evaluation. Thirteen of the 17 plants selected demonstrated a significant anticoagulant effect in at least one of the evaluated parameters. Citrus sinensis (PT=14.75 and aPTT=53.15), Mentha crispa (aPTT=51.25), Mikania laevigata (PT=14.90 and aPTT=52.10), and Nasturtium officinale (aPTT=50.55) showed greater anticoagulant potential compared to normal plasma pool (PT=12.25 and aPTT=37.73). Chemical profiles of these four species were obtained, and certain compounds were identified: rosmarinic acid from M.crispa and isoorientin from N.officinale. Thus, the results of this study could be a useful indicator for clinical practice towards the possibility of interaction between these plants and anticoagulants, although further clinical research is needed taking into consideration the limitations of in vitro studies. These findings also suggest that further research into the action of these plants could be of real clinical value in identifying potential alternative anticoagulant therapies.

Studies on fragment-based design of allosteric inhibitors of human factor XIa

Human factor XIa (hFXIa) has emerged as an attractive target for development of new anticoagulants that promise higher level of safety. Different strategies have been adopted so far for the design of anti-hFXIa molecules including competitive and non-competitive inhibition. Of these, allosteric dysfunction of hFXIa’s active site is especially promising because of the possibility of controlled reduction in activity that may offer a route to safer anticoagulants. In this work, we assess fragment-based design approach to realize a group of novel allosteric hFXIa inhibitors. Starting with our earlier discovery that sulfated quinazolinone (QAO) bind in the heparin-binding site of hFXIa, we developed a group of two dozen dimeric sulfated QAOs with intervening linkers that displayed a progressive variation in inhibition potency. In direct opposition to the traditional wisdom, increasing linker flexibility led to higher potency, which could be explained by computational studies. Sulfated QAO 19S was identified as the most potent and selective inhibitor of hFXIa. Enzyme inhibition studies revealed that 19S utilizes a non-competitive mechanism of action, which was supported by fluorescence studies showing a classic sigmoidal binding profile. Studies with selected mutants of hFXIa indicated that sulfated QAOs bind in heparin-binding site of the catalytic domain of hFXIa. Overall, the approach of fragment-based design offers considerable promise for designing heparin-binding site-directed allosteric inhibitors of hFXIa.

Low-molecular-weight fucosylated glycosaminoglycan and its oligosaccharides from sea cucumber as novel anticoagulants: A review

Antithrombotic drugs have some side effects, such as risk of serious bleeding. Development of antithrombotic drugs that inhibit components of the intrinsic coagulation pathway and have a low risk of causing bleeding has recently been a focus of research. Fucosylated glycosaminoglycan (FG), also named as fucosylated chondroitin sulfate (FCS), has potent anticoagulant activity and inhibits intrinsic factor tenase (FXase) complex. Low-molecular-weight FG (LFG) and its oligosaccharides show characteristics of anticoagulant and antithrombotic activities with negligible side effects, such as activation of human FXII, induction of platelet aggregation, and especially, the risk of serious bleeding. They are potential new anticoagulant drugs and have been extensively studied in recent years. This review presents recent findings regarding the preparation, structural analysis, pharmacological activity, and structure–activity relationships of LFG and its derived oligosaccharides, so as to provide a reference for the development of new anticoagulants with low side effects.

Advances in the Development of Novel Factor Xa Inhibitors: A Patent Review.

Development of new anticoagulants has been in constant demand throughout the world due to increasing rate of morbidity and mortality caused by thrombotic diseases. Factor Xa (FXa), one of the enzymes and validated target for anticoagulation, regulates the production of thrombin in the coagulation cascade. The importance of oral FXa inhibitors like rivaroxaban, apixaban and edoxaban in thromboembolic conditions is well supported by increasing number of patents and research publications during the recent years. Direct FXa inhibitors as antithrombotic agents offer selective, efficacious and orally active therapy with respect to the other traditional anticoagulants. Newly developed patented molecules are mainly structural bioisosteres of existing drugs and have exhibited better efficacy and safety profile. Development of antidotes for oral direct FXa inhibitors is in pipeline and their expected approval for therapeutic purposes will be further beneficial to anticoagulation therapy. This review is mainly focused on industrial and academic patents on the discovery of direct FXa inhibitors. The review covers patented compounds from December 2011 till date, describing various structural modifications along with biological activity data and advances in the process and formulation technologies of the reported FXa inhibitors.

Получение низкомолекулярных гепаринов методом радиационной деструкции

Низкомолекулярные гепарины (НМГ) широко применяются в медицинский практике. Для получения НМГ существуют различные способы контролируемой деполимеризации нефракционированного гепарина (НФГ). В данной работе представлен метод радиационной деструкции водных растворов гепарина с помощью источника гамма-излучения на основе изотопа 60Co. Установлены оптимальные условия деполимеризации исходного гепарина. Изучена антикоагулянтная активность НМГ в зависимости от дозы облучения. Результаты исследования позволяют рекомендовать данный метод получения НМГ для разработки новых антикоагулянтов.

Interventional Spine and Pain Procedures in Patients on Antiplatelet and Anticoagulant Medications (Second Edition): Guidelines From the American Society of Regional Anesthesia and Pain Medicine, the European Society of Regional Anaesthesia and Pain Therapy, the American Academy of Pain Medicine, the International Neuromodulation Society, the North American Neuromodulation Society, and the World Institute of Pain.

The American Society of Regional Anesthesia and Pain Medicine (ASRA) 2012 survey of meeting attendees showed that existing ASRA anticoagulation guidelines for regional anesthesia were insufficient for their needs. Those surveyed agreed that procedure-specific and patient-specific factors required separate guidelines for pain and spine procedures. In response, a guidelines committee was formed. After preliminary review of published complications reports and studies, the committee stratified interventional spine and pain procedures according to potential bleeding risk: low-, intermediate-, and high-risk procedures. The ASRA regional anesthesia anticoagulation guidelines were largely deemed appropriate for the low- and intermediate-risk categories, but the high-risk category required further investigation. The first guidelines specific to interventional spine and pain procedures were published in 2015. Recent reviews evaluating bleeding complications in patients undergoing specific interventional pain procedures, the development of new regional anesthesia and acute pain guidelines, and the development of new anticoagulants and antiplatelet medications necessitate complementary updated guidelines. The authors desired coordination with the authors of the recently updated regional and acute pain anticoagulation guidelines. The latest evidence was sought through extensive database search strategies and the recommendations were evidence based when available and pharmacology driven otherwise. We could not provide strength and grading of these recommendations because there are not enough well-designed large studies concerning interventional pain procedures to support such grading. Although the guidelines could not always be based on randomized studies or on large numbers of patients from pooled databases, it is hoped that they will provide sound recommendations and the evidentiary basis for such recommendations. This publication is intended as a living document to be updated periodically with consideration of new evidence.

Antithrombotic properties of JJ1, a potent and novel thrombin inhibitor

The development of new anticoagulants is an important goal for the improvement of thrombosis treatment. Recent studies have suggested the importance of thrombin inhibitors in the modulation of thromboembolic disorders. The aim of this study was to discover a new small-molecule thrombin inhibitor. In this study, the compound JJ1, which has a novel scaffold, was selected by structure-based docking simulation to determine its potential inhibitory activity against thrombin. JJ1 was shown to inhibit the catalytic activity of human α-thrombin with a Ki of 0.019 μM by direct binding to the active site and with at least 10,000-fold selectivity relative to that reported for the inhibition of other biologically important serine proteases. JJ1 prolonged clotting times (activated partial thromboplastin time and prothrombin time) and inhibited the activity and production of thrombin. Furthermore, it inhibited thrombin-catalyzed fibrin polymerization and platelet aggregation. Similar to its in vitro antithrombotic activities, JJ1 showed enhanced antithrombotic effects in an in vivo pulmonary embolism and arterial thrombosis model. It also exhibited anticoagulant effects in mice. Collectively, these results demonstrated that JJ1 was a potent, direct, and selective thrombin inhibitor that may be useful in the management of various thrombotic disorders.

Novel FXa Inhibitor Identification through Integration of Ligand- and Structure-Based Approaches.

Factor Xa (FXa), a vitamin K-dependent serine protease plays a pivotal role in the coagulation cascade, one of the most interesting targets for the development of new anticoagulants. In the present work, we performed a virtual screening campaign based on ligand-based shape and electrostatic similarity search and protein-ligand docking to discover novel FXa-targeted scaffolds for further development of inhibitors. From an initial set of 260,000 compounds from the NCI Open database, 30 potential FXa inhibitors were identified and selected for in vitro biological evaluation. Compound 5 (NSC635393, 4-(3-methyl-4H-1,4-benzothiazin-2-yl)-2,4-dioxo-N-phenylbutanamide) displayed an IC50 value of 2.02 nM against human FXa. The identified compound may serve as starting point for the development of novel FXa inhibitors.

Identification of the blood coagulation factor interacting sequences in staphylococcal superantigen-like protein 10

Staphylococcal superantigen-like proteins (SSLs) are a family of exoproteins of Staphylococcus aureus. We have shown that SSL10 binds to vitamin K-dependent coagulation factors and inhibits blood coagulation induced by recalcification of citrated plasma. SSL10 was revealed to bind to coagulation factors via their γ-carboxyglutamic acid (Gla) domain. In this study we attempted to identify the responsible sequence of SSL10 for the interaction with coagulation factors. We prepared a series of domain swap mutants between SSL10 and its paralog SSL7 that does not interact with coagulation factors, and examined their binding activity to immobilized prothrombin using ELISA-like binding assay. The domain swap mutants that contained SSL10β1-β3 (23MEMKN ISALK HGKNN LRFKF RGIKI QVL60) bound to immobilized prothrombin, and mutants that contained SSL10β10-β12 (174SFYNL DLRSK LKFKY MGEVI ESKQI KDIEV NLK207) also retained the binding activity. On the other hand, mutants that lacked these two regions did not bind to prothrombin. These sequences, each alone, bound to prothrombin as 33 amino acid length polypeptides. These results suggest that SSL10 has two responsible sequences for the binding to prothrombin. These prothrombin-binding peptides would contribute to the development of new anticoagulants.

A systematic review of contemporary trials of anticoagulants in orthopaedic thromboprophylaxis: suggestions for a radical reappraisal.

In the last decade, major advances in venous thromboembolism (VTE) prophylaxis in orthopaedic surgery have included the development of new anticoagulants that are poised to replace low molecular weight heparins (LMWHs) and improvements in operative and perioperative care that have likely led to a decline in the rates of symptomatic VTE and mortality independent of anticoagulant use. A systematic review of the literature was performed to identify phase III randomized controlled trials of VTE prevention that compared new anticoagulants (fondaparinux, rivaroxaban, dabigatran, apixaban) with LMWH (enoxaparin) in major elective orthopaedic surgery. Our aims were to obtain best estimates of the rates of patient important events (symptomatic VTE, mortality, and bleeding) in contemporary trials of VTE prevention, and to consider the implications of these contemporary rates for clinical practice and future research. Fourteen studies, which enrolled 40,285 patients, were included in the analyses. The combined median rates (ranges) for all five anticoagulants for symptomatic VTE and mortality to the end of follow-up were 0.99% (0.15-2.58%) and 0.26% (0-0.92%) respectively, whereas the median rate (range) of clinically important bleeding was 3.44% (2.25-7.74%). In contemporary trials of anticoagulants, the rates of symptomatic VTE and mortality are low, but the rates of clinically important post-operative bleeding remain relatively high. Based on these results, we propose that approaches that minimize bleeding without substantially reducing efficacy merit investigation, particularly if improvement in surgical and perioperative care have also resulted in falling baseline patient important VTE rates independent of anticoagulant use.

Otamixaban versus UFH, enoxaparin and fondaparinux in the prevention of cardiac catheter thrombosis in vitro (electron microscopic results from the OPEN-CATH study)

Efficient and safe anticoagulation is crucial in patients requiring percutaneous coronary intervention (PCI), where remaining rates of life-threatening complications trigger the development of new anticoagulants with improved efficacy/safety ratios. This in vitro study compared the efficacy of otamixaban, a new synthetic parenteral direct factor Xa inhibitor, with unfractionated heparin, enoxaparin and fondaparinux with/without combination with eptifibatide in the prevention of cardiac catheter thrombosis. Blood (49 ml each) from 10 healthy male volunteers pretreated with oral 500 mg aspirin was anticoagulated with unfractionated heparin (0.9 UI/ml), enoxaparin (0.6 IE/ml) or fondaparinux (0.5 μg/ml) at PCI-recommended doses, or with otamixaban at concentrations of 250 or 500 ng/ml. Each group was combined with/without 1.7 μg/ml eptifibatide (n=10 groups). The blood-anticoagulant mixtures were circulated continuously through a cardiac catheter for 60 min or until the catheter became blocked by thrombotic debris. Overall thrombus weight, global and specific coagulation parameters, and electron microscopic features such as deposits of platelets, erythrocytes and fibrin on the catheter surface were quantified as endpoints. The otamixaban regimes differed not statistically relevant from UFH and enoxaparin groups regarding the deposition of erythrocytes and demonstrated similar or even significantly reduced platelet deposition, whereas fondaparinux treatment resulted in significant increases of both values (p<0.05). Fibrin deposition was significantly reduced by all UFH and otamixaban regimes compared to the enoxaparin and fondaparinux treatment groups (p<0.05). Moreover, otamixaban, unfractionated heparin and enoxaparin in combination with/without eptifibatide ensured maximum circulation time (60 min), while the fondaparinux regimes caused premature catheter occlusions after 27±1 and 22±2 minutes (+/- eptifibatide), respectively. Regarding the generated thrombus weight, all otamixaban regimes did not differ significantly from the UFH and enoxaparin groups, while thrombus generation was significantly increased by both fondaparinux regimes compared to all other treatment options. In conclusion otamixaban, proved to be as effective as unfractionated heparin and enoxaparin and superior to fondaparinux with/without additional eptifibatide treatment in the prevention of cardiac catheter thrombosis in vitro. These data suggest that otamixaban might be a worthwhile alternative to currently recommended anticoagulants used for an invasive strategy.

In vitro comparison of the novel, dual-acting FIIa/FXa-inhibitor EP217609C101, unfractionated heparin, enoxaparin, and fondaparinux in preventing cardiac catheter thrombosis

Efficient and safe anticoagulation is crucial in patients requiring percutaneous coronary intervention (PCI) or extracorporeal circulation during cardiac surgery. Although new anticoagulant strategies have emerged for PCI as alternatives to the established treatment with heparins, the development of new anticoagulants with an improved efficacy/safety ratio is still necessary. Our study compared the efficacy of the novel, dual-acting, neutralizable FIIa/FXa-inhibitor EP217609C101 (EP) at 2, 1.2, 0.9, and 0.6μg/ml to unfractionated heparin (UFH), enoxaparin, and fondaparinux in preventing cardiac catheter thrombosis under in vitro conditions. Blood drawn by venepunction from healthy male volunteers (n=10) pretreated with 500mg aspirin orally was treated with the anticoagulant to test and continuously circulated through a cardiac catheter for 60min or until the catheter became blocked by thrombotic debris. Anticoagulant efficacy was assessed by thrombus weight, electron microscopic features of the developing thrombi, and laboratory parameters. Whereas UFH, enoxaparin, EP 2, and EP 1.2μg/ml secured maximum circulation times, statistically significant premature catheter occlusions were observed for EP 0.9, EP 0.6μg/ml, and fondaparinux. The UFH group and both high-dose concentrations of EP showed significantly lower thrombus weights than the low-dose concentrations of EP and fondaparinux, (p≤0.05). On electron microscopic analysis of the thrombotic debris no differences were observed in erythrocyte deposition between UFH, enoxaparin, and all EP concentrations tested. A significant reduction in fibrin deposition was achieved by UFH and EP 2μg/ml but no significant differences in platelet deposition were found, except for a significant reduction for EP 0.6μg/ml. Our in vitro study showed that EP217609C101 is a promising new drug that is dose-dependently superior to classical (UFH, enoxaparin) and newer (fondaparinux) drugs in preventing heart catheter thrombosis.

¿Qué dicen las guías sobre la anticoagulación en la fibrilación auricular no valvular?

The development of new anticoagulants has modified antithrombotic therapy in nonvalvular atrial fibrillation. As a result, the main clinical practice guidelines have incorporated the new evidence. To reach the most appropriate therapeutic decision, it is essential to accurately identify the risks of stroke and hemorrhage. The most widely recommended scales for risk stratification are CHADS2 and HAS-BLED. The definitive role of the new anticoagulants in thromboembolic prophylaxis remains to be established. Currently, these drugs should be considered as one more option, together with vitamin K antagonists, although some scientific societies consider them to be the drug of choice.

Thrombosis: simplified

The devastating consequences of venous thromboembolism have forever provided the impetus to explore safe and effective treatment strategies. To date, the pathophysiology and mechanism of thrombosis have been extensively studied and details of new thrombophilic conditions are continually being discovered. Although there has been extensive research detailing various predispositions to thrombosis, uncertainties regarding their appropriate management continue. This review aims to highlight the various challenges involved in identifying those at risk; provide appropriate management options; and lastly present the current views on the development of new anticoagulants that are competing to replace the traditional agents.

Functional characterisation of Vizottin, the first factor Xa inhibitor purified from the leech Haementeria vizottoi

The strategic position of factor Xa (FXa) in blood coagulation makes it a compelling target for the development of new anticoagulants. Blood-sucking animals have in their salivary glands mixtures of anticoagulants, which could be used for designing novel antithrombotic compounds. Herein, we describe Vizottin, the first FXa inhibitor from the salivary complex of the leech Haementeria vizottoi . Vizottin was purified by gel filtration and reverse-phase chromatography, and shown to have anticoagulant effects in human plasma, prolonging the recalcification time in a dose-dependent manner (IC50 40 nM). Vizottin induced blood incoagulability in FX-deficient plasma, whereas in normal and reconstituted plasma, Vizottin doubled the prothrombin time at 160 nM. This peptide competitively inhibited human FXa (K(i) 2 nM) like FXa inhibitors from other leeches, albeit via a distinct mechanism of action. At high concentrations, vizottin inhibited the amidolytic activity of factor VIIa/tissue factor (IC50 96.4 nM). Vizottin inhibited FXa in the prothrombinase complex and Gla-domainless FXa. Moreover, vizottin did not interfere with FX activation induced by RVV-X, a known enzyme that requires the Gla-domain of FX for activation. Competition experiments in the presence of FXa and GGACK-FXa (active site blocked) demonstrated that the inhibition of FXa by vizottin is through binding to the active site rather than an exosite. This novel inhibitor appears to exert its inhibitory effects through direct binding to the active site of FXa in a time-dependent manner, but not involving a tight-binding model. In this context, vizottin is a promising model for designing novel anticoagulants for the treatment of thrombotic diseases.

Antikoagulation bei Vorhofflimmern

According to new criteria based on the CHAD(2)DS(2)-VASc score, the threshold for administering anticoagulation therapy for atrial fibrillation patients is being increasingly lowered. With the development of new anticoagulants, more therapy options are available. Currently, vitamin K antagonists are still the standard treatment. However, this therapy is problematic for some patients. Because of the increased bleeding risk and need for continuous blood tests to monitor coagulation, many patients needing anticoagulation therapy are not treated. The new anticoagulants apixaban, rivaroxaban and dabigatran were developed with the goal of avoiding these problems. Dabigatran has already been approved for thromboembolism prophylaxis for patients with atrial fibrillation. All three substances do not require routine control blood tests. Whether the costs saved by this together with the prevention of ischemic and bleeding events justify the higher price of these drugs compared to vitamin K antagonists needs to be examined by socioeconomic studies.