The evolution of anticoagulant therapy

Understanding Antithrombotic Agents for Rehabilitation Therapy: A Comprehensive Narrative Review

In rehabilitation medicine, attention must be paid to the medication. Among them, antithrombotic drugs are used for the initial treatment and secondary prevention of stroke, so as a basic knowledge, the pharmacological actions, characteristics, indications, and precautions for the use of antithrombotic drugs should be known. Antithrombotic agents are divided into antiplatelet agents and anticoagulants, and the appropriate antithrombotic agent is selected according to the main disease or condition. Antiplatelet agents include aspirin, clopidogrel, ticlopidine, prasugrel, ticagrelor, and cilostazol. Each antiplatelet agent has a different mechanism of action, characteristics, and indications, and should be prescribed with due consideration. Anticoagulants include heparin, synthetic Xa inhibitors, direct oral anticoagulants (DOACs), synthetic antithrombin agents, and warfarin. Knowledge of the mechanism of action, characteristics, and indications of each anticoagulant is necessary, as well as monitoring and dose adjustment. With regard to ischemic cerebrovascular disease (ICD) and antithrombotic agents, the first step is to classify cerebral infarction and to determine whether antiplatelet agents or anticoagulants should be used. Bleeding and recurrence prevention are important considerations in the selection of appropriate antithrombotic agents for the pathophysiology of ICD.

Anticoagulant drugs for patients with atrial fibrillation on dialysis: a systematic analysis and network meta-analysis

Objective: A lack of clarity persists regarding the efficacy and risks associated with direct oral anticoagulants (DOACs) in end-stage renal disease (ESRD) patients with atrial fibrillation (AF) undergoing dialysis, primarily due to limited retrospective studies. Therefore, the objective of this study was to evaluate the existing data and propose a practical protocol for the clinical utilization of DOACs in ESRD patients with AF undergoing dialysis. Methods: PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for clinical studies evaluating DOACs in ESRD patients with AF on dialysis published up to 2 February 2023. DOACs included warfarin, dabigatran, apixaban, edoxaban, and rivaroxaban. The outcomes were mortality, ischemic stroke, hemorrhagic stroke, any stroke, gastrointestinal bleeding, major bleeding, intracranial bleeding, and minor bleeding. Results: Compared with placebo, apixaban (HR = 0.97, 95% CI: 0.88-1.07), rivaroxaban (HR = 0.91, 95% CI: 0.76-1.10), and warfarin (HR = 0.96, 95% CI: 0.90-1.01) did not reduce mortality. Regarding direct comparisons of mortality, the comparisons of warfarin vs. apixaban (HR = 0.99, 95% CI: 0.92-1.06), placebo vs. warfarin (HR = 1.04, 95% CI: 0.99-1.11), and rivaroxaban vs. warfarin (HR = 0.96, 95% CI: 0.80-1.14) did not significantly reduce mortality. Based on the surface under the cumulative ranking curve, rivaroxaban (75.53%), warfarin (62.14%), and apixaban (45.6%) were the most effective interventions for managing mortality, and placebo (16.74%) was the worst. Conclusion: In conclusion, rivaroxaban demonstrated efficacy in reducing mortality and the incidence of ischemic stroke, gastrointestinal bleeding, and intracranial hemorrhage. Dabigatran is recommended for the prevention of hemorrhagic stroke. However, caution should be exercised due to the risk of major bleeding. Warfarin can effectively reduce minor bleeding but does not offer significant protection against gastrointestinal or intracranial bleeding. Apixaban was not recommended for mortality reduction or for preventing ischemic or hemorrhagic strokes. Further research will be necessary to establish specific clinical protocols.

Fluorescent Activity-Based Probe To Image and Inhibit Factor XIa Activity in Human Plasma

Anticoagulation therapy is a mainstay of the treatment of thrombotic disorders; however, conventional anticoagulants trade antithrombotic benefits for bleeding risk. Factor (f) XI deficiency, known as hemophilia C, rarely causes spontaneous bleeding, suggesting that fXI plays a limited role in hemostasis. In contrast, individuals with congenital fXI deficiency display a reduced incidence of ischemic stroke and venous thromboembolism, indicating that fXI plays a role in thrombosis. For these reasons, there is intense interest in pursuing fXI/factor XIa (fXIa) as targets for achieving antithrombotic benefit with reduced bleeding risk. To obtain selective inhibitors of fXIa, we employed libraries of natural and unnatural amino acids to profile fXIa substrate preferences. We developed chemical tools for investigating fXIa activity, such as substrates, inhibitors, and activity-based probes (ABPs). Finally, we demonstrated that our ABP selectively labels fXIa in the human plasma, making this tool suitable for further studies on the role of fXIa in biological samples.

Unfractionated heparin or low-molecular-weight heparin for venous thromboembolism prophylaxis after hepatic resection: A meta-analysis

BACKGROUND

Two systematic reviews summarized the efficacy and safety of pharmacological prophylaxis for venous thromboembolism (VTE) after hepatic resection, but both lacked a discussion of the differences in the pharmacological prophylaxis of VTE in different ethnicities. Therefore, we aimed to evaluate the efficacy and safety of low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH) for VTE prophylaxis in Asian and Caucasian patients who have undergone hepatic resection.

METHODS

We searched PubMed, Web of Science, Embase, China National Knowledge Infrastructure, Wanfang Data, and VIP databases for studies reporting the primary outcomes of VTE incidence, bleeding events, and all-cause mortality from January 2000 to July 2022.

RESULTS

Ten studies involving 4318 participants who had undergone hepatic resection were included: 6 in Asians and 4 in Caucasians. A significant difference in VTE incidence was observed between the experimental and control groups (odds ratio [OR] = 0.39, 95% confidence interval [CI]: 0.20, 0.74, P = .004). No significant difference in bleeding events and all-cause mortality was observed (OR = 1.29, 95% CI: 0.80, 2.09, P = .30; OR = 0.71, 95% CI: 0.36, 1.42, P = .33, respectively). Subgroup analyses stratified by ethnicity showed a significant difference in the incidence of VTE in Asians (OR = 0.16, 95% CI: 0.06, 0.39, P < .0001), but not in Caucasians (OR = 0.69, 95% CI: 0.39, 1.23, P = .21). No significant differences in bleeding events were found between Asians (OR = 1.60, 95% CI: 0.48, 5.37, P = .45) and Caucasians (OR = 1.11, 95% CI: 0.58, 2.12, P = .75). The sensitivity analysis showed that Ejaz's study was the main source of heterogeneity, and when Ejaz's study was excluded, a significant difference in VTE incidence was found in Caucasians (OR = 0.58, 95% CI: 0.36, 0.93, P = .02).

CONCLUSION

This study's findings indicate that the application of UFH or LMWH for VTE prophylaxis after hepatic resection is efficacious and safe in Asians and Caucasians. It is necessary for Asians to receive drug prophylaxis for VTE after hepatic resection. This study can provide a reference for the development of guidelines in the future, especially regarding the pharmacological prevention of VTE in different ethnicities.

Marine Biological Macromolecules and Chemically Modified Macromolecules; Potential Anticoagulants

Coagulation is a potential defense mechanism that involves activating a series of zymogens to convert soluble fibrinogen to insoluble fibrin clots to prevent bleeding and hemorrhagic complications. To prevent the extra formation and diffusion of clots, the counterbalance inhibitory mechanism is activated at levels of the coagulation pathway. Contrariwise, this system can evade normal control due to either inherited or acquired defects or aging which leads to unusual clots formation. The abnormal formations and deposition of excess fibrin trigger serious arterial and cardiovascular diseases. Although heparin and heparin-based anticoagulants are a widely prescribed class of anticoagulants, the clinical use of heparin has limitations due to the unpredictable anticoagulation, risk of bleeding, and other complications. Hence, significant interest has been established over the years to investigate alternative therapeutic anticoagulants from natural sources, especially from marine sources with good safety and potency due to their unique chemical structure and biological activity. This review summarizes the coagulation cascade and potential macromolecular anticoagulants derived from marine flora and fauna.

Dry Needling and Antithrombotic Drugs

Many clinicians increasingly use dry needling in clinical practice. However, whether patients' intake of antithrombotic drugs should be considered as a contraindication for dry needling has not been investigated to date. As far as we know, there are no publications in analyzing the intake of antiplatelet or anticoagulant agents in the context of dry needling techniques. A thorough analysis of existing medications and how they may impact various needling approaches may contribute to improved evidence-informed clinical practice. The primary purpose of this paper is to review the current knowledge of antithrombotic therapy in the context of dry needling. In addition, reviewing guidelines of other needling approaches, such as electromyography, acupuncture, botulinum toxin infiltration, and neck ultrasound-guided fine-needle aspiration biopsy, may provide specific insights relevant for dry needling. Based on published data, taking antithrombotic medication should not be considered an absolute contraindication for dry needling techniques. As long as specific dry needling and individual risks are properly considered, it does not change the risk and safety profile of dry needling. Under specific circumstances, the use of ultrasound guidance is recommended when available.

Overexpression of protein disulfide isomerase enhances vitamin K epoxide reductase activity

Vitamin K epoxide reductase (VKOR) activity is catalyzed by the VKORC1 enzyme. It is the target of vitamin K antagonists (VKA). Numerous mutations of VKORC1 have been reported and have been suspected to confer resistance to VKA and/or affect its velocity. Nevertheless, the results between studies have been conflicting, the functional characterization of these mutations in a cell system being complex due to the interweaving of VKOR activity in the vitamin K cycle. In this study, a new cellular approach was implemented to globally evaluate the vitamin K cycle in the HEK293 cells. This global approach was based on the vitamin K quinone/vitamin K epoxide (K/KO) balance. In the presence of VKA or when the VKORC1/VKORC1L1 were knocked out, the K/KO balance decreased significantly due to an accumulation of vitamin KO. On the contrary, when VKORC1 was overexpressed, the balance remained unchanged, demonstrating a limitation of the VKOR activity. This limitation was shown to be due to an insufficient expression of the activation partner of VKORC1, as overexpressing the protein disulfide isomerase (PDI) overcomes the limitation. This study is the first to demonstrate a functional interaction between VKORC1 and the PDI enzyme.

Direct oral anticoagulants in pediatric venous thromboembolism: Review of approved products rivaroxaban and dabigatran

Venous thromboembolism is a major hospital acquired complication in the pediatric population over the last two-decades, with a 130% increase in the past decade. Direct oral anticoagulants (DOACs) are a newer class of anticoagulant medication for the treatment and prophylaxis of VTEs that provide the primary advantages of an oral route of administration without a requirement to adjust dosing to achieve a therapeutic level. It is anticipated that these medications will quickly replace parenteral anticoagulants and clinicians should familiarize themselves with DOACs. In this article, we provide an overview of the pharmacological properties of DOACs, with a specific focus on rivaroxaban and dabigatran, which have been approved for use in pediatric patients. Each drug's characteristics are discussed along with data from their respective clinical trials.

Evolving Paradigm of Prothrombin Time Diagnostics with Its Growing Clinical Relevance towards Cardio-Compromised and COVID-19 Affected Population

Prothrombin time (PT) is a significant coagulation (hemostasis) biomarker used to diagnose several thromboembolic and hemorrhagic complications based on its direct correlation with the physiological blood clotting time. Among the entire set of PT dependents, candidates with cardiovascular ailments are the major set of the population requiring lifelong anticoagulation therapy and supervised PT administration. Additionally, the increasing incidence of COVID affected by complications in coagulation dynamics has been strikingly evident. Prolonged PT along with sepsis-induced coagulopathy (SIC score > 3) has been found to be very common in critical COVID or CAC-affected cases. Considering the growing significance of an efficient point-of-care PT assaying platform to counter the increasing fatalities associated with cardio-compromised and coagulation aberrations propping up from CAC cases, the following review discusses the evolution of lab-based PT to point of care (PoC) PT assays. Recent advances in the field of PoC PT devices utilizing optics, acoustics, and mechanical and electrochemical methods in microsensors to detect blood coagulation are further elaborated. Thus, the following review holistically aims to motivate the future PT assay designers/researchers by detailing the relevance of PT and associated protocols for cardio compromised and COVID affected along with the intricacies of previously engineered PoC PT diagnostics.

Complete biosynthesis of a sulfated chondroitin in Escherichia coli

Sulfated glycosaminoglycans (GAGs) are a class of important biologics that are currently manufactured by extraction from animal tissues. Although such methods are unsustainable and prone to contamination, animal-free production methods have not emerged as competitive alternatives due to complexities in scale-up, requirement for multiple stages and cost of co-factors and purification. Here, we demonstrate the development of single microbial cell factories capable of complete, one-step biosynthesis of chondroitin sulfate (CS), a type of GAG. We engineer E. coli to produce all three required components for CS production–chondroitin, sulfate donor and sulfotransferase. In this way, we achieve intracellular CS production of ~27 μg/g dry-cell-weight with about 96% of the disaccharides sulfated. We further explore four different factors that can affect the sulfation levels of this microbial product. Overall, this is a demonstration of simple, one-step microbial production of a sulfated GAG and marks an important step in the animal-free production of these molecules.

Chondroitin sulfate (CS) is a type of sulfated glycosaminoglycan that is manufactured by extraction from animal tissues for the treatment of osteoarthritis and in drug delivery applications. Here, the authors report the development of single microbial cell factories capable of compete, one-step biosynthesis of animal-free CS production in E. coli.

Synthesis, characterization and anticoagulant activity of chitosan derivatives

Chitosan derivatives are reported as anticoagulants in the literature. This work was undertaken to develop novel chitosan derivatives as anticoagulants. The sulfonated derivatives of chitosan were formed by the reaction of chitosan derivatives with chlorosulfonic acid in N,N-dimethylformamide. The structures of these derivatives were established by FTIR and ¹H NMR spectra. The prepared derivatives were evaluated for their in vivo anticoagulant effects by the tail bleeding method in Wistar rats utilizing nicoumalone as a standard drug. The results revealed that the sulfonation of the chitosan increases its anticoagulant activity. The developed compounds exhibited faster onset of action and potency than nicoumalone after one hour of the drug administration. The sulphated N-alkyl derivatives of chitosan were more potent anticoagulants than sulfated quaternary derivatives/sulfated chitosan. It is also suggested to develop analogs of Ethyl chitosan sulfate (4b) and Benzyl chitosan sulfate (4c), which may provide some more fruitful anticoagulants having faster onset of action as well as longer duration of action and possessing a balanced hydrophilic/lipophilic character.

Direct oral anticoagulants for extended treatment of venous thromboembolism: insights from the EINSTEIN CHOICE study

The risk of recurrence of venous thromboembolism (VTE) persists after interruption of the initial anticoagulation therapy. New evidence shows that direct oral anticoagulants are effective for extended treatment of VTE and may reduce the risk of all-cause mortality. The optimal duration of anticoagulation after VTE is, however, controversial and complicated by the need for individualised assessment and balance between thrombosis and bleeding risks. Three direct oral anticoagulants (rivaroxaban, apixaban and dabigatran) have been studied for extended treatment of VTE. Dabigatran was shown to be safer than vitamin K antagonists and similarly effective for the prevention of recurrent VTE. Dabigatran, apixaban and rivaroxaban resulted in significant decreases in the rate of recurrent symptomatic VTE when compared to placebo, without a statistically significant difference in the risk of major bleeding. The latest guidelines of the American College of Chest Physicians suggest the use of low-dose aspirin to prevent VTE recurrence in patients who want to stop anticoagulation. In the randomised, double-blind, phase 3 EINSTEIN CHOICE trial, once-daily rivaroxaban at doses of 20 mg or 10 mg and 100 mg of aspirin were compared in VTE patients for whom there was clinical equipoise for extended anticoagulation. Either a treatment dose (20 mg) or a prophylactic dose (10 mg) of rivaroxaban significantly reduced the risk of VTE recurrence without a significant increase in bleeding risk compared with aspirin. The EINSTEIN CHOICE trial included patients with provoked or unprovoked VTE. Patients with VTE provoked by minor persistent or minor transient risk factors enrolled in this trial had not-negligible VTE recurrence rates. These new findings on extended therapy suggest the possibility of anticoagulation regimens at intensities tailored to the patients' risk profiles and VTE characteristics, with a shift of the risk-benefit balance in favour of extended treatment.

Protective effects of gelsolin in acute pulmonary thromboembolism and thrombosis in the carotid artery of mice

The present study provides first evidence on the role of plasma gelsolin in protecting pulmonary thromboembolism and thrombosis in a mouse model. Gelsolin is the most abundant actin depolymerizing protein in plasma and its significantly depleted values have been reported in metabolic disorders including cardiovascular diseases and myocardial infarction. Though gelsolin replacement therapy (GRT) has been shown to be effective in some animal models, no such study has been reported for thrombotic diseases that are acutely in need of bio-therapeutics for immediate and lasting relief. Here, using mice model and recombinant human gelsolin (rhuGSN), we demonstrate the antithrombotic effect of gelsolin in ferric chloride induced thrombosis in carotid artery and thrombin induced acute pulmonary thromboembolism. In thrombosis model, arterial occlusion time was significantly enhanced upon subcutaneous (SC) treatment with 8 mg of gelsolin per mice viz. 15.83 minutes vs. 8 minutes in the placebo group. Pertinently, histopathological examination showed channel formation within the thrombi in the carotid artery following injection of gelsolin. Fluorescence molecular tomography imaging further confirmed that administration of gelsolin reduced thrombus formation following carotid artery injury. In thrombin-induced acute pulmonary thromboembolism, mice pretreated with aspirin or gelsolin showed 100 and 83.33% recovery, respectively. In contrast, complete mortality of mice was observed in vehicle treated group within 5 minutes of thrombin injection. Overall, our studies provide conclusive evidence on the thrombo-protective role of plasma gelsolin in mice model of pulmonary thromboembolism and thrombosis.

Coagulatory active constituents of Malus pumila Mill. flowers

Background

The flowers of Malus pumila Mill (Rosaceae) is rich in resources, but lack of medicinal value research. Chemical constituents of the same family M. pumila have coagulatory activity. Considering the coagulatory activity could be beneficial for various cardiovascular diseases, the aim of this study is to evaluate coagulatory active constituents of M. pumila flowers.

Methods

Chemical constituents of M. pumila flowers were isolated by various column chromatographies, and their coagulatory activity were evaluated by activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT) and fibrinogen (FIB) in vitro.

Results

Nine compounds were isolated from M. pumila flowers, and identified as kaempferol-3-O-β-d-glucopyranoside (1), kaempferol-7-O-β-d-glucopyranoside (2), kaempferol-3-O-α-l-arabinofuranoside (3), phloridzin (4), kaempferol (5), phloretin (6), β-sitosterol (7), lupeol (8) and pyracanthoside (9). Compounds 1–9 were isolated from the flowers for the first time, compounds 1, 2 and 9 were isolated from the genus for the first time. Compound 2 could significantly shorten APTT, TT and PT, but significantly decrease the content of FIB. Compound 3 could shorten PT. Compound 4 could significantly shorten TT and PT, but significantly decrease the content of FIB. Compound 5 shortened APTT. Compound 6 and 7 could significantly shorten APTT and PT. Compound 9 was able to prolong TT and decrease the content of FIB, but shorten PT.

Conclusions

Compounds 2–7 possessed significant procoagulant activity in vitro, compound 9 had anticoagulant activity in vitro, which showed coagulation potential of compounds from M. pumila flowers, as a new source of bioactive molecules for therapeutic purposes.

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.

Direct oral anticoagulants: analysis of worldwide use and popularity using Google Trends

BACKGROUND

Four direct oral anticoagulants (DOACs) have been approved for clinical use by many medicines regulatory agencies around the world. Due to increasing use of these drugs in routine practice, we planned an original study to investigate their worldwide diffusion using a popular Web-search engine.

METHODS

Two electronic searches were performed using Google Trends, the former using the keywords "warfarin" AND "heparin" AND "fondaparinux", and the latter using the keywords "warfarin" AND "dabigatran" AND "rivaroxaban" AND "apixaban" AND "edoxaban", both using the search criterion "prescription drug". No language restriction was applied, and the searches were carried out from the first date available in Google Trends (January 1^st, 2004) to present time (June 1^st, 2017).

RESULTS

The median Google Trends score of warfarin (i.e., 86) was consistently higher than that of heparin (54; P<0.001), fondaparinux (6; P<0.001), dabigatran (11; P<0.001), rivaroxaban (5; P<0.001), apixaban (1; P<0.001) and edoxaban (1; P<0.001). Specific analysis of the trends shows that the score of warfarin exhibits a highly significant decrease over time (r=-0.40; P<0.001), whilst that of heparin has remained virtually unchanged (r=0.12; P=0.127), and that of fondaparinux has marginally increased (r=0.16; P=0.038). As regards DOACs, the scores of these drugs significantly increased during the search period (dabigatran, r=0.79; rivaroxaban, r=0.99; apixaban, r=0.98; edoxaban, r=0.78; all P<0.001). When the analysis was limited to the past five years, the dabigatran score significantly decreased (r=-0.57; P<0.001), whereas that of the other DOACs exhibited an even sharper increase. Most Google searches for DOACs were performed in North America, central-eastern Europe and Australia.

CONCLUSIONS

The results of our analysis suggest that the popularity of DOACs is constantly increasing around the world, whereas that of warfarin has exhibited a constant and inexorable decline.

Emerging Role of Direct Oral Anticoagulants in the Management of Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) and heparin-induced thrombocytopenia with thrombosis (HITT) are rare but potentially limb- and life-threatening complications of heparin therapy. Continuation of heparin or low-molecular-weight heparin is contraindicated due to platelet activation in the presence of (heparin-dependent) HIT antibodies. Primary treatment options currently include argatroban, fondaparinux, or bivalirudin. However, the parenteral administration routes and interference of argatroban with traditional coagulation markers complicate management. The goal of this review is to assess the viability of direct oral anticoagulants as an alternative treatment option in patients with HIT/HITT. Their use in HIT/HITT is reasonable, given absent cross-reactivity preformed with HIT antibodies. Furthermore, their rapid onset of action and induction of effective anticoagulation provide a favorable basis for their use in this condition. Herein, we summarize 3 studies and 8 case reports comprising 56 patients in whom direct oral anticoagulants were used in the treatment of HIT/HITT.

Surprising absence of heparin in the intestinal mucosa of baby pigs

Heparin, a member of a family of molecules called glycosaminoglycans, is biosynthesized in mucosal mast cells. This important anticoagulant polysaccharide is primarily produced by extraction of the mast cell-rich intestinal mucosa of hogs. There is concern about our continued ability to supply sufficient heparin to support the worldwide growth of advanced medical procedures from the static population of adult hogs used as food animals. While the intestinal mucosa of adult pigs is rich in anticoagulant heparin (containing a few hundred milligrams per animal), little is known about how the content of heparin changes with animal age. Using sophisticated mass spectral analysis we discovered that heparin was largely absent from the intestinal mucosa of piglets. Moreover, while the related, nonanticoagulant heparan sulfate glycosaminoglycan was present in significant amounts we found little chondroitin sulfate E also associated with mast cells. Histological evaluation of piglet intestinal mucosa showed a very low mast cell content. Respiratory mast cells have been reported in baby pigs suggesting that there was something unique about the piglets used in the current study. These piglets were raised in the relatively clean environment of a university animal facility and treated with antibiotics over their lifetime resulting in a depleted microbiome that greatly reduced the number of mast cells and heparin content of the intestinal mucosal in these animals. Thus, from the current study it remains unclear whether the lack of intestinal mast cell-derived heparin results from the young age of these animals or their exposure to their depleted microbiome.

In vitro Anti-Thrombotic Activity of Extracts from Blacklip Abalone (Haliotis rubra) Processing Waste

Waste generated from the processing of marine organisms for food represents an underutilized resource that has the potential to provide bioactive molecules with pharmaceutical applications. Some of these molecules have known anti-thrombotic and anti-coagulant activities and are being investigated as alternatives to common anti-thrombotic drugs, like heparin and warfarin that have serious side effects. In the current study, extracts prepared from blacklip abalone (Haliotis rubra) processing waste, using food grade enzymes papain and bromelain, were found to contain sulphated polysaccharide with anti-thrombotic activity. Extracts were found to be enriched with sulphated polysaccharides and assessed for anti-thrombotic activity in vitro through heparin cofactor-II (HCII)-mediated inhibition of thrombin. More than 60% thrombin inhibition was observed in response to 100 μg/mL sulphated polysaccharides. Anti-thrombotic potential was further assessed as anti-coagulant activity in plasma and blood, using prothrombin time (PT), activated partial thromboplastin time (aPTT), and thromboelastography (TEG). All abalone extracts had significant activity compared with saline control. Anion exchange chromatography was used to separate extracts into fractions with enhanced anti-thrombotic activity, improving HCII-mediated thrombin inhibition, PT and aPTT almost 2-fold. Overall this study identifies an alternative source of anti-thrombotic molecules that can be easily processed offering alternatives to current anti-thrombotic agents like heparin.

How we treat bleeding associated with direct oral anticoagulants

Direct oral anticoagulants are at least as effective as vitamin K antagonists for the prevention and treatment of thromboembolism. Unfortunately, differently from vitamin K antagonists, they have the great drawback of lacking specific antidotes in the case of bleeding or emergency situations such as trauma, stroke requiring thrombolysis, and urgent surgery. The progressive development of antidotes for these new drugs, which, it is hoped, will become available in the near future, will allow better and safer management of the rapid reversal of their anticoagulant effect.