Direct oral anticoagulants: evidence and unresolved issues

Combined drug anti-deep vein thrombosis therapy based on platelet membrane biomimetic targeting nanotechnology

After orthopedic surgeries, such as hip replacement, many patients are prone to developing deep vein thrombosis (DVT), which in severe cases can lead to fatal pulmonary embolism or major bleeding. Clinical intervention with high-dose anticoagulant therapy inevitably carries the risk of bleeding. Therefore, a targeted drug delivery system that adjusts local DVT lesions and potentially reduces drug dosage and toxic side effects important. In this study, we developed a targeted drug delivery platelet-derived nanoplatform (AMSNP@PM-rH/A) for DVT treatment that can simultaneously deliver a direct thrombin inhibitor (DTI) Recombinant Hirudin (rH), and the Factor Xa inhibitor Apixaban (A) by utilizing Aminated mesoporous silica nanoparticles (AMSNP). This formulation exhibits improved biocompatibility and blood half-life and can effectively eliminate deep vein thrombosis lesions and achieve therapeutic effects at half the dosage. Furthermore, we employed various visualization techniques to capture the targeted accumulation and release of a platelet membrane (PM) coating in deep vein thrombosis and explored its potential targeting mechanism.

Transitioning between therapeutic anticoagulants: a clinicians guide to switching patients to or from DOAC therapy

INTRODUCTION

The transition to or from direct oral anticoagulants (DOACs) is common in clinical practice.

AREAS COVERED

A literature search was conducted on PubMed, Google Scholar, and UpToDate up to March 2024 for conditions and approaches for transitioning from one agent to the other. No randomized clinical trials were retrieved except for two studies regarding switching to DOAC in well-conducted vitamin K antagonist (VKA) therapy. A narrative review was conducted addressing the conditions for switching from one agent to the other, such as thromboembolic events and major bleeding during anticoagulation, development or worsening of kidney or liver failure, initiation of interfering drugs, adverse events such as allergic reactions, frailty, patients' preferences, and affordability. During transitions from one anticoagulant to the other, the risk of both thromboembolic and bleeding complications should be minimized. The current approaches for such transitions are derived from those employed in clinical trials evaluating DOAC and from product information.

EXPERT OPINION

Many uncertainties remain regarding those circumstances requiring a change in anticoagulant strategies, as they lack evidence-based guidance. It can be envisaged that the problem of switching to and from DOAC will need additional studies especially addressing the conditions and the best approach to such transitions.

Venous Thromboembolism Prevention in Rehabilitation: A Review and Practice Suggestions

ABSTRACT

Venous thromboembolism is a frequent complication of acute hospital care, and this extends to inpatient rehabilitation. The timely use of appropriate thromboprophylaxis in patients who are at risk is a strong, evidence-based patient safety priority that has reduced clinically important venous thromboembolism, associated mortality and costs of care. While there has been extensive research on optimal approaches to venous thromboembolism prophylaxis in acute care, there is a paucity of high-quality evidence specific to patients in the rehabilitation setting, and there are no clinical practice guidelines that make recommendations for (or against) thromboprophylaxis across the broad spectrum of rehabilitation patients. Herein, we provide an evidence-informed review of the topic with practice suggestions. We conducted a series of literature searches to assess the risks of venous thromboembolism and its prevention related to inpatient rehabilitation as well as in major rehabilitation subgroups. Mobilization alone does not eliminate the risk of venous thromboembolism after another thrombotic insult. Low molecular weight heparins and direct oral anticoagulants are the principal current modalities of thromboprophylaxis. Based on the literature, we make suggestions for venous thromboembolism prevention and include an approach for consideration by rehabilitation units that can be aligned with local practice.

Full-dose rivaroxaban in patients with a history of bariatric surgery: bridging the knowledge gap through a phase 1 study

BACKGROUND

Bariatric surgery (BS) induces significant changes in gastrointestinal anatomy, potentially influencing the pharmacokinetics of orally administered drugs such as rivaroxaban.

OBJECTIVES

This phase 1 study aimed to assess the pharmacokinetics and safety of full-dose rivaroxaban in post-BS patients.

METHODS

The ABSORB (Rivaroxaban Pharmacokinetics and Pharmacodynamics After Bariatric Surgery and in Morbid Obesity) study was a single-center, nonrandomized, multiple-dose, parallel-design bioequivalence trial. Adult patients with stable weight after Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) were compared with subjects with class III obesity and healthy controls. Participants received 20 mg of rivaroxaban daily for 8 days.

RESULTS

Post-BS patients exhibited altered rivaroxaban pharmacokinetics, suggesting reduced absorption. Mean area under the concentration-time curve from time 0 to 24 hours after the first dose (RYGB, 1806.8 ng.h/mL; SG, 1648.9 ng.h/mL) was lower compared with that in controls (1893.5 ng.h/mL). At steady state, the area under the concentration-time curve values remained lower in BS groups (RYGB, 2129.9 ng.h/mL; SG, 1946.4 ng.h/mL) than in controls (2224.8 ng.h/mL). The maximum concentration after the first dose was lower in post-RYGB subjects (214.9 ng/mL) than in controls (264.1 ng/mL). This difference was less pronounced at steady state (RYGB, 256.9 ng/mL vs controls, 288.8 ng/mL). Neither BS group met bioequivalence criteria compared with controls, whereas the group with class III obesity met bioequivalence criteria compared with controls at steady state.

CONCLUSION

Rivaroxaban displayed minor pharmacokinetic variations in post-BS patients. Given reported interindividual variability in the general population, these variations are unlikely to be of clinical significance. Our findings support rivaroxaban use in BS patients, emphasizing the need for further research in this area.

Impact of elevated direct factor Xa inhibitor plasma levels on perioperative blood loss in patients undergoing urgent surgery

INTRODUCTION

Data on the perioperative bleeding risk associated with elevated plasma levels of direct factor Xa inhibitors (FXa inhibitors) are limited. This study examines perioperative red blood cell (RBC) loss in patients undergoing urgent surgery with a residual FXa inhibitor level exceeding 100 mcg/L and without preoperative FXa inhibitor reversal.

METHODS

This retrospective analysis includes data from 32 patients who underwent urgent noncardiac surgery between 2018 and 2022. This study aims to analyze perioperative RBC loss in patients undergoing urgent surgery with a residual FXa inhibitor level exceeding 100 mcg/L and without preoperative FXa inhibitor antidote-based reversal or unspecific treatment with 4-factor prothrombin complex concentrate (PCC). All patients were managed using a watch-and-wait strategy.

RESULTS

The last determination of FXa inhibitor plasma concentration prior to surgery showed a median of 245 mcg/L (IQR 144-345), with a median time interval of 3.8 h (IQR 2.4-7.2) before incision. Median RBC loss during surgery was 49 mL (IQR 0-253), 189 mL (IQR 104-217) until POD1 and 254 mL (IQR 58-265) until POD3. Only one patient required intraoperative treatment with 4-factor-PCC and none required reversal with andexanet alfa. Linear regression models found no significant influence of FXa inhibitor plasma levels on intraoperative RBC loss. Rivaroxaban was associated with higher RBC loss until postoperative Day 1 compared with apixaban. No thromboembolic events were observed.

CONCLUSION

Despite markedly elevated plasma concentrations of residual direct FXa inhibitors, perioperative RBC loss was limited in patients undergoing urgent noncardiac surgery. The intraoperative watch-and-wait strategy with selective intraoperative FXa inhibitor reversal or treatment only when required appears to be an appropriate approach.

Perioperative Management of Patients Taking Direct Oral Anticoagulants: A Review

Importance

Direct oral anticoagulants (DOACs), comprising apixaban, rivaroxaban, edoxaban, and dabigatran, are commonly used medications to treat patients with atrial fibrillation and venous thromboembolism. Decisions about how to manage DOACs in patients undergoing a surgical or nonsurgical procedure are important to decrease the risks of bleeding and thromboembolism.

Observations

For elective surgical or nonsurgical procedures, a standardized approach to perioperative DOAC management involves classifying the risk of procedure-related bleeding as minimal (eg, minor dental or skin procedures), low to moderate (eg, cholecystectomy, inguinal hernia repair), or high risk (eg, major cancer or joint replacement procedures). For patients undergoing minimal bleeding risk procedures, DOACs may be continued, or if there is concern about excessive bleeding, DOACs may be discontinued on the day of the procedure. Patients undergoing a low to moderate bleeding risk procedure should typically discontinue DOACs 1 day before the operation and restart DOACs 1 day after. Patients undergoing a high bleeding risk procedure should stop DOACs 2 days prior to the operation and restart DOACs 2 days after. With this perioperative DOAC management strategy, rates of thromboembolism (0.2%-0.4%) and major bleeding (1%-2%) are low and delays or cancellations of surgical and nonsurgical procedures are infrequent. Patients taking DOACs who need emergent (<6 hours after presentation) or urgent surgical procedures (6-24 hours after presentation) experience bleeding rates up to 23% and thromboembolism as high as 11%. Laboratory testing to measure preoperative DOAC levels may be useful to determine whether patients should receive a DOAC reversal agent (eg, prothrombin complex concentrates, idarucizumab, or andexanet-α) prior to an emergent or urgent procedure.

Conclusions and Relevance

When patients who are taking a DOAC require an elective surgical or nonsurgical procedure, standardized management protocols can be applied that do not require testing DOAC levels or heparin bridging. When patients taking a DOAC require an emergent, urgent, or semiurgent surgical procedure, anticoagulant reversal agents may be appropriate when DOAC levels are elevated or not available.

Therapeutic Potential of FXI Inhibitors: Hype or Hope?

Significant advancements have shaped the landscape of anticoagulant therapy in the past two decades, including the introduction of direct oral anticoagulants (DOACs), characterized by favorable safety and efficacy profiles and reduced drug-to-drug or food interaction resulting in excellent patient compliance. However, residual concerns still exist with standard-of-care anticoagulant therapy, including the inability to use DOACs in several clinical settings and the need to further reduce the risk of bleeding. Recent improvements in the understanding of the mechanisms behind thrombus formation have led to the awareness that the intrinsic pathway of the coagulation cascade may play an important role in pathological thrombosis, but not in hemostasis. This has represented the rationale for targeting this pathway with factor XI (FXI) inhibitors, with the aim of uncoupling hemostasis and thrombosis. Clinical evidence from patients with FXI deficiency further supports this concept. A number of compounds with different mechanisms of action have been developed to target FXI (i.e., asundexian, abelacimab, Ionis-FXIRx, milvexian, osocimab, and Xisomab 3G). To date, the majority of available trials have not gone beyond completion of phase 2 and results are conflictive making it difficult to appraise the clinical benefit of these compounds in the different clinical settings where they have been tested (i.e., atrial fibrillation, acute ischemic stroke, acute myocardial infarction, end-stage renal disease, total knee arthroplasty). Moreover, the largest phase 3 randomized trial designed to test the efficacy of asundexian over apixaban in patients with atrial fibrillation, the OCEANIC-AF, has been prematurely stopped as a result of the inferior efficacy of asundexian. In this review we discuss the pharmacological properties and available evidence generated thus far for factor XI inhibitors, providing a perspective on the current state of these drugs.

Antithrombotic Effect of Oil from the Pulp of Bocaiúva-Acrocomia aculeata (Jacq.) Lodd. ex Mart. (Arecaceae)

The study aimed to evaluate the antithrombotic action of Acrocomia aculeata pulp oil (AAPO) in natura, in an in vitro experimental model. AAPO was obtained by solvent extraction, and its chemical characterization was performed by gas chromatography coupled to a mass spectrometer (GC-MS). In vitro toxicity was evaluated with the Trypan Blue exclusion test and in vivo by the Galleria mellonella model. ADP/epinephrine-induced platelet aggregation after treatment with AAPO (50, 100, 200, 400, and 800 μg/mL) was evaluated by turbidimetry, and coagulation was determined by prothrombin activity time (PT) and activated partial thromboplastin time (aPTT). Platelet activation was measured by expression of P-selectin on the platelet surface by flow cytometry and intraplatelet content of reactive oxygen species (ROS) by fluorimetry. The results showed that AAPO has as major components such as oleic acid, palmitic acid, lauric acid, caprylic acid, and squalene. AAPO showed no toxicity in vitro or in vivo. Platelet aggregation decreased against agonists using treatment with different concentrations of AAPO. Oil did not interfere in PT and aPTT. Moreover, it expressively decreased ROS-induced platelet activation and P-selectin expression. Therefore, AAPO showed antiplatelet action since it decreased platelet activation verified by the decrease in P-selectin expression as well as in ROS production.

Antiphospholipid antibodies in patients with antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a rare systemic autoimmune disease characterized by recurrent pregnancy morbidity or thrombosis in combination with the persistent presence of antiphospholipid antibodies (aPLs) in plasma/serum. Antiphospholipid antibodies are a heterogeneous, overlapping group of autoantibodies, of which anti-β2-glycoprotein I (aβ2GPI), anticardiolipin (aCL) antibodies and antibodies that prolong plasma clotting time in tests in vitro known as lupus anticoagulant (LAC) are included in the laboratory criteria for the diagnosis of APS. The presence of LAC antibodies in plasma is indirectly determined by measuring the length of coagulation in two tests - activated partial thromboplastin time (aPTT) and diluted Russell's viper venom time (dRVVT). The concentration of aβ2GPI and aCL (immunglobulin G (IgG) and immunoglobulin M (IgM) isotypes) in serum is directly determined by solid-phase immunoassays, either by enzyme-linked immunosorbent assay (ELISA), fluoroimmunoassay (FIA), immunochemiluminescence (CLIA) or multiplex flow immunoassay (MFIA). For patient safety, it is extremely important to control all three phases of laboratory testing, i.e. preanalytical, analytical and postanalytical phase. Specialists in laboratory medicine must be aware of interferences in all three phases of laboratory testing, in order to minimize these interferences. The aim of this review was to show the current pathophysiological aspects of APS, the importance of determining aPLs-a in plasma/serum, with an emphasis on possible interferences that should be taken into account when interpreting laboratory findings.

Evolving Strategies for Use of Phytochemicals in Prevention and Long-Term Management of Cardiovascular Diseases (CVD)

This report describes major pathomechanisms of disease in which the dysregulation of host inflammatory processes is a major factor, with cardiovascular disease (CVD) as a primary model, and reviews strategies for countermeasures based on synergistic interaction between various agents, including drugs and generally regarded as safe (GRAS) natural medical material (NMM), such as Ginkgo biloba, spice phytochemicals, and fruit seed flavonoids. The 15 well-defined CVD classes are explored with particular emphasis on the extent to which oxidative stressors and associated ischemia-reperfusion tissue injury contribute to major symptoms. The four major categories of pharmaceutical agents used for the prevention of and therapy for CVD: statins, beta blockers (β-blockers), blood thinners (anticoagulants), and aspirin, are presented along with their adverse effects. Analyses of major cellular and molecular features of drug- and NMM-mediated cardioprotective processes are provided in the context of their development for human clinical application. Future directions of the evolving research described here will be particularly focused on the characterization and manipulation of calcium- and calcineurin-mediated cascades of signaling from cell surface receptors on cardiovascular and immune cells to the nucleus, with the emergence of both protective and pathological epigenetic features that may be modulated by synergistically-acting combinations of drugs and phytochemicals in which phytochemicals interact with cells to promote signaling that reduces the effective dosage and thus (often) toxicity of drugs.

Comparative Bleeding Risk of Brand Vs Generic Rivaroxaban in Elderly Inpatients with Atrial Fibrillation

Objective

Atrial fibrillation (AF) is the most common abnormal heart rhythm in elderly patients. Rivaroxaban has been widely used for stroke prevention. The anticoagulant response to rivaroxaban increases with age, which may make elderly patients susceptible to adverse outcomes resulting from small differences in bioavailability between generic and brand products.

Methods

We designed a cohort study of ≥65-year-old inpatients with AF. Sociodemographic and laboratory measures of qualified patients who received brand or generic rivaroxaban for at least 72 hours at the study hospital from January 2021 to June 2023 were collected retrospectively. The primary outcome was the incidence of bleeding.

Results

A total of 1008 qualifying patients were included for analysis, with 626 (62.1%) receiving brand rivaroxaban and 382 (37.9%) receiving generic rivaroxaban. After propensity score matching and weighting to account for confounders, the odds ratios comparing brand vs generic rivaroxaban (95% confidence intervals) for the bleeding was 1.15 (0.72-1.82). Results from subgroup analyses of patients with age ≥85, HAS-BLED score ≥ 3, containment of antiplatelet drugs, and female patients were consistent with the primary analysis.

Conclusion

It provides evidence regarding the clinical safety outcome of generic rivaroxaban in the elderly AF population that may be particularly susceptible to adverse outcomes resulting from small allowable differences in pharmacokinetics.

Venous thromboembolism: diagnostic advances and unaddressed challenges in management

PURPOSE OF REVIEW

This review summarizes recent advances in developing targeted diagnostics for venous thromboembolism (VTE) and unaddressed knowledge gaps in patient management. Without addressing these critical data needs, the morbidity in VTE patients will persist.

RECENT FINDINGS

Recent studies investigating plasma protein profiles in VTE patients have identified key diagnostic targets to address the currently unmet need for low-cost, confirmatory, point-of-care VTE diagnostics. These studies and a growing body of evidence from animal model studies have revealed the importance of inflammatory and vascular pathology in driving VTE, which are currently unaddressed targets for VTE therapy. To enhance the translation of preclinical animal studies, clinical quantification of thrombus burden and comparative component analyses between modeled VTE and clinical VTE are necessary.

SUMMARY

Lead candidates from protein profiling of VTE patients' plasma offer a promising outlook in developing low cost, confirmatory, point-of-care testing for VTE. Additionally, addressing the critical knowledge gap of quantitatively measuring clinical thrombi will allow for an array of benefits in VTE management and informing the translatability of experimental therapeutics.

Total Content and Composition of Phenolic Compounds from Filipendula Genus Plants and Their Potential Health-Promoting Properties

This current article was dedicated to the determination of the composition of phenolic compounds in extracts of four species of the genus Filipendula in order to establish a connection between the composition of polyphenols and biological effects. A chemical analysis revealed that the composition of the extracts studied depended both on the plant species and its part (leaf or flower) and on the extractant used. All four species of Filipendula were rich sources of phenolic compounds and contained hydrolyzable tannins, condensed tannins, phenolic acids and their derivatives, and flavonoids. The activities included data on those that are most important for creating functional foods with Filipendula plant components: the influence on blood coagulation measured by prothrombin and activated partial thromboplastin time, and on the activity of the digestive enzymes (pancreatic amylase and lipase). It was established that plant species, their parts, and extraction methods contribute meaningfully to biological activity. The most prominent result is as follows: the plant organ determines the selective inhibition of either amylase or lipase; thus, the anticoagulant activities of F. camtschatica and F. stepposa hold promise for health-promoting food formulations associated with general metabolic disorders.

Unified Methodology for the Primary Preclinical In Vivo Screening of New Anticoagulant Pharmaceutical Agents from Hematophagous Organisms

The development of novel anticoagulants requires a comprehensive investigational approach that is capable of characterizing different aspects of antithrombotic activity. The necessary experiments include both in vitro assays and studies on animal models. The required in vivo approaches include the assessment of pharmacokinetic and pharmacodynamic profiles and studies of hemorrhagic and antithrombotic effects. Comparison of anticoagulants with different mechanisms of action and administration types requires unification of the experiment scheme and its adaptation to existing laboratory conditions. The rodent thrombosis models in combination with the assessment of hemostasis parameters and hematological analysis are the classic methods for conducting preclinical studies. We report an approach for the comparative study of the activity of different anticoagulants in vivo, including the investigation of pharmacodynamics and the assessment of hemorrhagic effects (tail-cut bleeding model) and pathological thrombus formation (inferior vena cava stenosis model of venous thrombosis). The reproducibility and uniformity of our set of experiments were illustrated on unfractionated heparin and dabigatran etexilate (the most common pharmaceuticals in antithrombic therapy) as comparator drugs and an experimental drug variegin from the tick Amblyomma variegatum. Variegin is notorious since it is a potential analogue of bivalirudin (Angiomax, Novartis AG, Basel, Switzerland), which is now being actively introduced into antithrombotic therapy.

Oral anticoagulants: A plausible new treatment for Alzheimer's disease?

Alzheimer's disease (AD) and cardiovascular disease (CVD) are strongly associated. Both are multifactorial disorders with long asymptomatic phases and similar risk factors. Indeed, CVD signatures such as cerebral microbleeds, micro-infarcts, atherosclerosis, cerebral amyloid angiopathy and a procoagulant state are highly associated with AD. However, AD and CVD co-development and the molecular mechanisms underlying such associations are not understood. Here, we review the evidence regarding the vascular component of AD and clinical studies using anticoagulants that specifically evaluated the development of AD and other dementias. Most studies reported a markedly decreased incidence of composite dementia in anticoagulated patients with atrial fibrillation, with the highest benefit for direct oral anticoagulants. However, sub-analyses by differential dementia diagnosis were scarce and inconclusive. We finally discuss whether anticoagulation could be a plausible preventive/therapeutic approach for AD and, if so, which would be the best drug and strategy to maximize clinical benefit and minimize potential risks. LINKED ARTICLES: This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Toward Genetic Testing of Rivaroxaban? Insights from a Systematic Review on the Role of Genetic Polymorphism in Rivaroxaban Therapy

BACKGROUND

Investigations into the rivaroxaban response from the perspective of genetic variation have been relatively recent and wide in scope, whereas there is no consensus on the necessity of genetic testing of rivaroxaban. Thus, this systematic review aims to thoroughly evaluate the relationship between genetic polymorphisms and rivaroxaban outcomes.

METHODS

The PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Chinese databases were searched to 23 October 2022. We included cohort studies reporting the pharmacogenetic correlation of rivaroxaban. Outcomes measured included efficacy (all-cause mortality, thromboembolic events and coagulation-related tests), safety (major bleeding, clinically relevant non-major bleeding [CRNMB] and any hemorrhage), and pharmacokinetic outcomes. A narrative synthesis was performed to summarize findings from individual studies according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the reporting guideline for Synthesis Without Meta-Analysis.

RESULTS

A total of 12 studies published between 2019 and 2022 involving 1364 patients were included. Ten, one, and six studies focused on the ABCB1, ABCG2, and CYP gene polymorphisms, respectively. Pharmacokinetic outcomes accounted for the majority of the outcomes reported (n = 11), followed by efficacy (n = 5) [including prothrombin time (PT) or international normalized ratio (n = 3), platelet inhibition rate (PIR) or platelet reactivity units (PRUs; n = 1), thromboembolic events (n = 1)], and safety (n = 5) [including major bleeding (n = 2), CRNMB (n = 2), any hemorrhage (n = 1)]. For ABCB1 gene polymorphism, the relationship between PT and ABCB1 rs1045642 was inconsistent across studies, however there was no pharmacogenetic relationship with other efficacy outcomes. Safety associations were found in ABCB1 rs4148738 and major bleeding, ABCB1 rs4148738 and CRNMB, ABCB1 rs1045642 and CRNMB, and ABCB1 rs2032582 and hemorrhage. Pharmacokinetic results were inconsistent among studies. For ABCG2 gene polymorphism, no correlation was observed between ABCG2 rs2231142 and dose-adjusted trough concentration (Cmin/D). For CYP gene polymorphisms, PIR or PRUs have a relationship with CYP2C19 rs12248560, however bleeding or pharmacokinetic effects did not show similar results.

CONCLUSIONS

Currently available data are insufficient to confirm the relationship between clinical or pharmacokinetic outcomes of rivaroxaban and gene polymorphisms. Proactive strategies are advised as a priority in clinical practice rather than detection of SNP genotyping.

CLINICAL TRIALS REGISTRATION

PROSPERO registration number CRD42022347907.

A comparative in vitro study of the anticoagulant effect of branded versus generic rivaroxaban

BACKGROUND

Several generic formulations of rivaroxaban were recently marketed to be used interchangeably with their branded equivalent. However, there have been no previously published studies that directly compared the in vitro anticoagulant effect of branded vs. generic rivaroxaban. The aim of this in vitro study was to compare the effects of three raw rivaroxaban materials, obtained from the branded (Xarelto®) and two generic (Rivarolto® and Rivaroxaban Sandoz®) rivaroxaban formulations on an array of coagulation assays.

METHODS

A pool of normal plasma was spiked with several concentrations of the three rivaroxaban (range 50-750 ng/ml). The concentrations were assessed with a rivaroxaban calibrated anti-Xa assay and confirmed by ultra-high-performance liquid chromatography-mass spectrometry coupled with tandem mass spectrometry (UHPLC-MS/MS). The following assays were performed: Prothrombin time (PT), activated Partial Thromboplastin time (aPTT), Diluted Russell's Viper Venom Test (dRVVT), Thrombin time (TT), Clauss Fibrinogen, Factor VII, VIII and IX assays, and thromboelastography.

RESULTS

The results obtained by the three rivaroxaban at similar concentrations were comparable. Increasing concentrations of the three rivaroxaban showed a strong positive correlation with the PT, aPTT and dRVVT assays (r > 0.95, p < 0.01 for all), and a strong negative correlation with the Factors assays (r < -0.95, p < 0.01 for all). TT and Clauss Fibrinogen were not affected by rivaroxaban. No significant difference was identified in the mean assays' results obtained by the three rivaroxaban.

CONCLUSION

This study showed that the branded and generic rivaroxaban exert an identical in vitro anticoagulant effect across a wide range of concentrations.

How I treat pediatric venous thromboembolism in the DOAC era

ABSTRACT

The direct oral anticoagulants (DOACs) rivaroxaban and dabigatran are newly licensed for the treatment and prevention of venous thromboembolism (VTE) in children and mark a renaissance in pediatric anticoagulation management. They provide a convenient option over standard-of-care anticoagulants (heparins, fondaparinux, and vitamin K antagonists) because of their oral route of administration, child-friendly formulations, and significant reduction in monitoring. However, limitations related to therapeutic monitoring when needed and the lack of approved reversal agents for DOACs in children raise some safety concerns. There is accumulating experience of safety and efficacy of DOACs in adults for a broad scope of indications; however, the cumulative experience of using DOACs in pediatrics, specifically for those with coexisting chronic illnesses, is sparse. Consequently, clinicians must often rely on their experience for treating VTE and extrapolate from data in adults while using DOACs in children. In this article, the authors share their experience of managing 4 scenarios that hematologists are likely to encounter in their day-to-day practice. Topics addressed include (1) appropriateness of indication; (2) use for special populations of children; (3) considerations for laboratory monitoring; (4) transition between anticoagulants; (5) major drug interactions; (6) perioperative management; and (7) anticoagulation reversal.

Design, Synthesis, and Evaluation of New Hybrid Derivatives of 5,6-Dihydro-4H-pyrrolo[3,2,1-ij]quinolin-2(1H)-one as Potential Dual Inhibitors of Blood Coagulation Factors Xa and XIa

Cardiovascular diseases caused by blood coagulation system disorders are one of the leading causes of morbidity and mortality in the world. Research shows that blood clotting factors are involved in these thrombotic processes. Among them, factor Xa occupies a key position in the blood coagulation cascade. Another coagulation factor, XIa, is also a promising target because its inhibition can suppress thrombosis with a limited contribution to normal hemostasis. In this regard, the development of dual inhibitors as new generation anticoagulants is an urgent problem. Here we report the synthesis and evaluation of novel potential dual inhibitors of coagulation factors Xa and XIa. Based on the principles of molecular design, we selected a series of compounds that combine in their structure fragments of pyrrolo[3,2,1-ij]quinolin-2-one and thiazole, connected through a hydrazine linker. The production of new hybrid molecules was carried out using a two-stage method. The reaction of 5,6-dihydropyrrolo[3,2,1-ij]quinoline-1,2-diones with thiosemicarbazide gave the corresponding hydrazinocarbothioamides. The reaction of the latter with DMAD led to the target methyl 2-(4-oxo-2-(2-(2-oxo-5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-1(2H)-ylidene)hydrazineyl)thiazol-5(4H)-ylidene)acetates in high yields. In vitro testing of the synthesized molecules revealed that ten of them showed high inhibition values for both the coagulation factors Xa and XIa, and the IC50 value for some compounds was also assessed. The resulting structures were also tested for their ability to inhibit thrombin.

Is spontaneous echo contrast associated with device-related thrombus or embolic events after left atrial appendage occlusion? - Insights from the multicenter German LAARGE registry

BACKGROUND

Interventional left atrial appendage occlusion (LAAO) provides an alternative to oral anticoagulation (OAC) for prophylaxis of thromboembolic events (TEs) in nonvalvular atrial fibrillation patients, predominantly in those with high bleeding risk and contraindications for long-term OAC. Although spontaneous echo contrast (SEC) is a well-known risk factor for atrial thrombus formation, little is known about whether this means an increased risk of device-related thrombus (DRT) or TEs following LAAO.

METHODS

This substudy of the prospective, multicenter German LAARGE registry assessed two groups according to absence (SEC -) or presence of SEC (SEC +) in preprocedural cardiac imaging. Clinical and echocardiographic parameters were registered up to 1 year after LAAO.

RESULTS

Five hundred eighty-eight patients (SEC - 85.5 vs. SEC + 14.5%) were included. More SEC + patients were implanted for OAC non-compliance (11.8 vs. 4.6%, p = 0.008) and a higher proportion received only antiplatelet therapy without OAC at hospital discharge (96.5 vs. 86.0%, p = 0.007). The SEC + patients had larger LA diameters (50 (47; 54) vs. 47 (43; 51) mm, p < 0.001), wider LAA ostia (21 (19; 23) vs. 20 (17; 22) mm at 45°, p = 0.011), and lower left ventricular ejection fraction (50 (45; 60) vs. 60 (50; 60) %, p < 0.001) on admission. Procedural success was very high in both groups (98.1%, p = 1.00). Periprocedural major adverse cardiac and cerebrovascular events and other major complications were rare in both groups (3.8 vs. 4.7%, p = 0.76). At follow-up, DRT was only detected in the SEC - group (3.8 vs. 0%, p = 1.00). The rates of TEs (SEC - 1.2 vs. SEC + 0%, p = 1.00) after hospital discharge and 1-year mortality (SEC - 12.0 vs. SEC + 11.8%, p = 0.96) were not significantly different between the two groups.

CONCLUSIONS

Presence of SEC at baseline was not associated with an increased rate of DRT or TEs at 1-year follow-up after LAAO in LAARGE.

Effectiveness and Safety of Different Oral Anticoagulants with P-glycoprotein/ CYP3A4 Inhibitors: A Network Meta-analysis

BACKGROUND

Metabolism of oral anticoagulants (OAC) is affected by P-glycoprotein (P-gp)/ CYP3A4 enzyme. However, the P-gp/CYP3A4 inhibitors are unavoidably used with OACs.

METHODS

Medline, Cochrane, and Embase were systematically searched for randomized controlled trials and cohort studies from inception till 23rd November, 2022 to assess the safety and effectiveness of OACs when concomitantly used with P-gp/CYP3A4 inhibitors. The primary outcomes were major bleeding and gastrointestinal (GI) bleeding. Secondary outcomes were stroke/systemic embolism (SE), all-cause mortality, any bleeding as well as intracranial hemorrhage (ICH). We estimated summary odds ratios (OR) with 95% credible intervals (CI) using pairwise and network meta-analysis with random effects.

RESULTS

A total of 11 studies involving 37,973 patients were included. When concomitantly used with P-pg/ CYP3A4 inhibitors, network meta-analysis indicated that dabigatran, apixaban, and edoxaban were associated with significantly lower risk of major bleeding compared to rivaroxaban, with ORs of 0.56, 0.51 and 0.48, respectively. Rivaroxaban and dabigatran were associated with a significantly increased risk of GI bleeding than warfarin, apixaban and edoxaban. Dabigatran and apixaban were linked with significantly lower risk of any bleeding compared with warfarin (ORs were 0.75 and 0.68, respectively) or rivaroxaban (ORs were 0.67 and 0.60, respectively). Apixaban (OR 0.32) and edoxaban (OR 0.35) were associated with a lower risk of ICH compared with warfarin. There was no difference between any OACs in terms of stroke/SE or all-cause mortality.

CONCLUSION

When concomitantly used with P-gp/CYP3A4 inhibitors, apixaban and edoxaban were associated with a lower risk of bleeding, though no significant difference in effectiveness was observed among all OACs.

Idarucizumab for Emergency Reversal of the Anticoagulant Effects of Dabigatran: Final Results of a Japanese Postmarketing Surveillance Study

INTRODUCTION

Idarucizumab, a monoclonal antibody fragment that rapidly reverses the anticoagulant effects of dabigatran, was approved in Japan in September 2016, at which time an all-case, postmarketing surveillance (PMS) study was initiated to collect data on idarucizumab in Japanese patients. Interim results were published previously, and the final results are reported herein.

METHODS

This multicenter, open-label, uncontrolled, non-interventional PMS study was conducted in Japanese patients who received idarucizumab at the approved dose (2 × 2.5 g/50 ml) and had uncontrolled bleeding (group A) or required an emergency procedure (group B). The primary endpoint was the frequency of adverse drug reactions (ADRs). The secondary endpoint was the maximum extent of reversal of the anticoagulant effects of dabigatran, within 4 h of idarucizumab administration, based on activated partial thromboplastin time (aPTT).

RESULTS

The final analysis included 804 patients. ADRs during the idarucizumab treatment and post-treatment periods were reported in 17 of 542 patients (3.1%) in group A and 12 of 240 patients (5.0%) in group B. Thrombotic events were reported in 22 patients (4.1%) in group A and 15 patients (6.3%) in group B, and hypersensitivity occurred in four (0.7%) and five patients (2.1%), respectively. Among 793 patients evaluated for effectiveness, 78 in group A and 26 in group B had aPTT data at baseline (immediately before idarucizumab administration) and within 4 h of idarucizumab administration; in these patients, median maximum percentage reversal within 4 h of idarucizumab administration was 100%.

CONCLUSIONS

The final analysis from the PMS study confirms previous findings suggesting that idarucizumab can safely and effectively reverse the anticoagulant effects of dabigatran in Japanese patients in clinical practice. The results support the continued use of idarucizumab in Japan.

TRIAL REGISTRATION

This study is registered with ClinicalTrials.gov (NCT02946931).

Levetiracetam Interaction with Direct Oral Anticoagulants: A Pharmacovigilance Study

BACKGROUND

Levetiracetam is widely used in post-stroke epilepsy. However, it is suspected to possess P-glycoprotein (P-gp) induction properties, and therefore, a potentially significant interaction with direct oral anticoagulants (DOACs). We aimed to search for ischemic stroke signals with levetiracetam and the DOACs.

METHODS

In this retrospective pharmacovigilance study, we used the FAERS database to identify ischemic stroke events associated with DOACs and concomitant use of levetiracetam. We evaluated disproportionate reporting by the adjusted reporting odds ratio (adjROR) and the lower bound of the shrinkage 95% confidence interval. When shrinkage is positive, an increased risk of a specific adverse event occurrence is emphasized over the sum of the individual risks when these same drugs are used separately.

RESULTS

We identified 1841 (1.5%), 3731 (5.3%), 338 (4.9%), and 1723 (1.3%) ischemic stroke reports with apixaban, dabigatran, edoxaban, and rivaroxaban, respectively. The adjROR of the interaction effect was 3.57 (95% CI 2.81-4.58) between DOACs and levetiracetam. The shrinkage analysis detected an interaction between each of the DOACs and levetiracetam. The logistic model and shrinkage analysis failed to detect an interaction when queried for hemorrhagic stroke. A significant signal in the classical enzyme inducer, carbamazepine, strengthened our results (adjROR; 8.47, 95% CI 5.37-13.36).

CONCLUSIONS

Our study shows a strong signal for the levetiracetam interaction with the DOACs. Our findings suggest implementation of a drug monitoring strategy.

Prospection of Peptide Inhibitors of Thrombin from Diverse Origins Using a Machine Learning Pipeline

Thrombin is a key enzyme involved in the development and progression of many cardiovascular diseases. Direct thrombin inhibitors (DTIs), with their minimum off-target effects and immediacy of action, have greatly improved the treatment of these diseases. However, the risk of bleeding, pharmacokinetic issues, and thrombotic complications remain major concerns. In an effort to increase the effectiveness of the DTI discovery pipeline, we developed a two-stage machine learning pipeline to identify and rank peptide sequences based on their effective thrombin inhibitory potential. The positive dataset for our model consisted of thrombin inhibitor peptides and their binding affinities (KI) curated from published literature, and the negative dataset consisted of peptides with no known thrombin inhibitory or related activity. The first stage of the model identified thrombin inhibitory sequences with Matthew's Correlation Coefficient (MCC) of 83.6%. The second stage of the model, which covers an eight-order of magnitude range in KI values, predicted the binding affinity of new sequences with a log room mean square error (RMSE) of 1.114. These models also revealed physicochemical and structural characteristics that are hidden but unique to thrombin inhibitor peptides. Using the model, we classified more than 10 million peptides from diverse sources and identified unique short peptide sequences (<15 aa) of interest, based on their predicted KI. Based on the binding energies of the interaction of the peptide with thrombin, we identified a promising set of putative DTI candidates. The prediction pipeline is available on a web server.

Strategies for Perioperative Optimization in Upper Extremity Fracture Care

Perioperative optimization in upper extremity fracture care must balance the need for timely treatment with the benefits of medical optimization. Care pathways directed at optimizing glycemic control, chronic anticoagulation, smoking history, nutrition, and frailty can reduce surgical risk in upper extremity fracture care. The development of multidisciplinary approaches that tie risk modification with risk stratification is needed.

Sailing between scylla and charybdis-anticoagulation dilemma in a patient with calciphylaxis and mechanical cardiac valve replacement: a case report and literature review

Calciphylaxis is a rare and life-threatening condition in patients with end-stage kidney disease (ESKD). In this case report, we reported a 72-year-old female who had undergone aortic and mitral mechanical valve replacement 22 years ago due to rheumatic aortic and mitral stenosis. Following the valve replacement, she initiated warfarin treatment. Five years ago, she received a diagnosis of uremia and has since been undergoing regular hemodialysis. Ten months prior to her current admission, she experienced excruciating pain and was diagnosed with calciphylaxis. Additionally, an electrocardiogram revealed atrial fibrillation, while echocardiography indicated that the aortic and mitral mechanical valves were appropriately positioned, with normal perivalvular surroundings and good valve leaflet activity. No noticeable thrombosis was observed in the left atrium or left atrial appendage. Color Doppler imaging showed moderate stenosis in the lower extremity arteries, with no venous thromboembolism present. Extensive eggshell-like calcification within the arterial media was detected. The patient was managed with regular hemodialysis, symptomatic treatments (including anticoagulation and analgesia), and sodium thiosulfate. Unfortunately, symptomatic management provided limited relief, and during the one-month follow-up period, the patient passed away due to septic shock. Currently, there is insufficient conclusive evidence regarding alternative influential anticoagulants or appropriate prosthetic valve selection. For individuals with ESKD receiving maintenance hemodialysis, early identification, diagnosis, and treatment of calciphylaxis are of paramount importance.

New Therapeutic Targets for the Prevention and Treatment of Venous Thromboembolism With a Focus on Factor XI Inhibitors

FXI (factor XI) and FXII (factor XII) have emerged as targets for new anticoagulants that have the potential to be both more efficacious and safer than the currently available direct oral anticoagulants for the prevention and treatment of venous thromboembolism. In this review, we discuss the role of FXI and FXII in the pathogenesis of venous thromboembolism, explain why FXI is a better target, and explain why FXI inhibitors have potential advantages over currently available anticoagulants. Finally, we describe the FXI inhibitors under development and discuss their potential to address unmet needs in venous thromboembolism management.

The Effect of Direct Oral Anticoagulants on Gastric Mucosa and Helicobacter Pylori Prevalence in Dyspeptic Patients: A Retrospective Cross-Sectional Study

Background and aim Although direct oral anticoagulants (DOACs) are widely used and their side effects related to bleeding at various body sites have been well studied in the literature, less is known about their local impact on gastric mucosa. Some studies suggest that the higher risk of gastrointestinal (GI) bleeding associated with DOACs may be due to their direct local anticoagulant effects on the gastric mucosa. In this study, we aim to evaluate whether this potential local effect has a favorable outcome on the gastric mucosa and the prevalence of Helicobacter pylori (HP).  Materials and methods A total of 125 patients with dyspepsia were included in the study. Sixty patients who had been using a DOAC for at least one month were classified as the "DOAC group," while 65 patients who had not used DOACs were designated as the "control group." Demographic, laboratory, and pathological findings for these patients were retrospectively analyzed from their medical files. Results Patients in the DOAC group were significantly less likely to have antral gastritis (AnG) (p = 0.028), while the frequencies of HP and atrophic gastritis (AtG) were similar between the two groups. Although not statistically significant, the DOAC group showed fewer instances of intestinal metaplasia (IM) and a higher number of upper GI ulcers. Patients who had been using DOACs for more than 12 months had increased incidences of IM, upper GI ulcers, AnG, and HP compared to those who had been using DOACs for 12 months or less. The Rivaroxaban subgroup showed significantly lower HP positivity compared to patients using other DOACs (p = 0.042). Among all subgroups, the Rivaroxaban group had the lowest frequency of AnG (p = 0.024). Conclusion While DOACs seem to prevent AnG, HP, and IM at their early use stages, unfavorable gastric mucosa manifestations might increase with prolonged use. Higher upper GI ulcer prevalence is another controversial result of this issue. Rivaroxaban shines amongst other DOACs with its lesser HP and AnG association. These exciting findings should be supported by randomized controlled trials with large patient populations.

Comparison of the efficacy and safety between rivaroxaban and dabigatran in the treatment of acute portal vein thrombosis in cirrhosis

BACKGROUND

New oral anticoagulants (NOACs) have been becoming prevalent in recent years and are increasingly used in the treatment of port vein thrombosis. The difference of the efficacy and safety between rivaroxaban and dabigatran remains unclear in the treatment of cirrhotic patients with acute portal vein thrombosis (PVT).

METHODS

This retrospective study included all consecutive cirrhotic patients with acute portal vein thrombosis in our institute from January 2020 to December 2021. The patients received oral anticoagulation with rivaroxaban or dabigatran. The demographic, clinical, and imaging data of patients were collected. The diagnosis of acute PVT was confirmed by imaging examinations. The severity of liver cirrhosis was assessed using Child-Pugh score and Model for End-Stage Liver Disease (MELD) score. Outcomes included recanalization (complete, partial, and persistent occlusion), liver function, bleedings, and survival. The log-rank test was used to compare Kaplan-Meier distributions of time-to-event outcomes. The Cox proportional hazards model was used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs).

RESULTS

A total of 94 patients were included, 52 patients (55%) received rivaroxaban and 42 (45%) with dabigatran. The complete and partial recanalization of PVT was observed in 41 patients. There was no significant difference in complete recanalization, partial recanalization, and persistent occlusion between the two groups. With multivariate analysis, D-dimer (HR 1.165, 95% CI 1.036-1.311, p = 0.011) was independent predictors of complete recanalization. The Child-Pugh score (p = 0.001) was significantly improved in both two groups after anticoagulation, respectively. However, there was no difference between the two groups. The probability of survival was 94%, 95% in the rivaroxaban and dabigatran groups (log-rank p = 0.830). Major bleedings were reported in 3 patients (6%) in rivaroxaban group and 1 patient (2%) in dabigatran group (p = 0.646). Six patients (12%) in rivaroxaban group experienced minor bleeding, and five (12%) from dabigatran group (p = 0.691).

CONCLUSIONS

The efficacy and safety were comparable between rivaroxaban and dabigatran in the treatment of cirrhotic patients with acute portal vein thrombosis. And D-dimer can contribute to the prediction of PVT recanalization in cirrhotic patients.

Management of Patients Treated with Direct Oral Anticoagulants in Clinical Practice and Challenging Scenarios

It is well established that direct oral anticoagulants (DOACs) are the cornerstone of anticoagulant strategy in atrial fibrillation (AF) and venous thromboembolism (VTE) and should be preferred over vitamin K antagonists (VKAs) since they are superior or non-inferior to VKAs in reducing thromboembolic risk and are associated with a lower risk of intracranial hemorrhage (IH). In addition, many factors, such as fewer pharmacokinetic interactions and less need for monitoring, contribute to the favor of this therapeutic strategy. Although DOACs represent a more suitable option, several issues should be considered in clinical practice, including drug-drug interactions (DDIs), switching to other antithrombotic therapies, preprocedural and postprocedural periods, and the use in patients with chronic renal and liver failure and in those with cancer. Furthermore, adherence to DOACs appears to remain suboptimal. This narrative review aims to provide a practical guide for DOAC prescription and address challenging scenarios.

[Proper use of oral anticoagulants in the elderly patient]

Direct oral anticoagulants (DOACs) are tending to supplant antivitamin K inhibitors (VKAs) in their common indications, dominated in elderly patients by atrial fibrillation and venous thromboembolism. Nevertheless, it remains necessary to know how best to use VKAs for which there are still indications. It is also important not to assume that AODs can be prescribed without risk, while ignoring certain particularities in their handling, particularly in the most fragile patients with co-morbidities and multiple medications.

Reimbursement and use of oral anticoagulants during 2014-2022 - A register-based study

Background

Vitamin K antagonists, warfarin in particular, have been the mainstay of anticoagulation therapy, but their use has declined in many countries since direct oral anticoagulants (DOACs) have entered the market.

Objective

To examine utilization trends of oral anticoagulants (OACs) in Finland considering the reimbursement of DOACs and changes to national treatment guidelines for the treatment of atrial fibrillation (AF).

Methods

Both public, aggregated data on reimbursed OAC dispensations and individual-level data on electronic dispensations during 2014-2022 were applied. Data on electronic dispensations during 2015-2016 were used to study OAC initiations. Data on entitlements to reimbursement for DOACs came from public data.

Results

In 2014, there were almost 20,000 DOAC users, rising to 214,000 in 2022. The number of warfarin users declined since 2015 from over 181,000 to around 59,000 users in 2022, DOACs exceeding warfarin in the number of users in 2019. The total DOAC costs were higher than warfarin costs each year. Rivaroxaban was the most widely used DOAC during 2014-2018, and apixaban during 2019-2022. In 2015, there were more warfarin (56.7%) than DOAC (43.3%) initiators, but the result was opposite for 2016 (warfarin 39.4%, DOACs 60.6%). The number of individuals entitled to reimbursement for DOACs has increased steadily, and in 2022, there were over 196,000 individuals entitled to this reimbursement due to AF.

Conclusions

The uptake of DOACs in Finland appears to have been gradual and slower than in many other countries. During the 2010s, the treatment guidelines for AF were more cautious in recommending DOACs than the European guidelines. The use of DOACs increased as their reimbursement became less restrictive.

Positive Allosteric Modulation of Antithrombin's Inhibitory Activity by RNA Aptamers

The leading cause of death in adults in the United States is cardiovascular disease, with mortality and morbidity mainly attributed to thromboembolism. Heparin is the most common therapy used for treating venous and arterial thrombosis. Heparin effectively accelerates the inhibition of coagulation proteases thrombin and factor Xa through the serine protease inhibitor (serpin) antithrombin (AT). Heparin is an essential therapeutic anticoagulant because of its effectiveness and the availability of protamine sulfate as an antidote. However, heparin therapy has several limitations. Thus, new anticoagulants, including direct thrombin inhibitors (ie, argatroban) and low-molecular-weight heparins (ie, fondaparinux), are used to treat some thromboembolic disorders. We developed and characterized a family of novel RNA-based aptamers that bind AT using two novel selection schemes. One of the aptamers, AT-16, accelerates factor Xa inhibition by AT in the absence of heparin. AT-16's effect on thrombin inhibition by AT is less effective compared to factor Xa. AT-16 induces a conformational change in AT that is different from that induced by heparin. This study demonstrates that an AT-specific RNA aptamer, AT-16, exhibits a positive allosteric modulator effect on AT's inhibition of factor Xa.

Atrial giant cell myocarditis with preserved left ventricular function: a case report and literature review

Giant cell myocarditis (GCM) is a rare and fatal inflammatory disorder induced by T-lymphocytes, typically affecting young adults. Generally, this disease presents with a rapidly progressive course and a very poor prognosis. In recent years, atrial GCM (aGCM) has been recognized as a clinicopathological entity distinct from classical GCM. As described by retrievable case reports, although its histopathological manifestations are highly similar to those of classical GCM, this entity is characterized by preserved left ventricular function and atrial arrhythmias, without ventricular arrhythmias. aGCM tends to show benign disease progression with a better clinical prognosis compared with the rapid course and poor prognosis of vGCM. We report a patient with aGCM with a history of renal abscess whose persistent myocardial injury considered to be associated with a history of renal abscess. Infection could be a potential trigger for the development of aGCM in this patient. An extensive literature review was also performed and the following three aspects were summarized: (1) Epidemiology and histopathological characteristics of aGCM; (2) The role of imaging in the evaluation of aGCM; (3) Diagnostic points and therapeutic decisions in aGCM.

Unresolved issues in the use of direct acting oral anticoagulants

INTRODUCTION

Currently approved direct oral anticoagulants (DOACs) target thrombin or coagulation factor Xa. Administered in fixed doses without routine laboratory monitoring, DOACs have simplified the approach to oral anticoagulation, when previously the choice was limited to vitamin K antagonists (VKAs).

AREA COVERED

We discuss a) unresolved issues related to optimal use of DOACs and b) new developments including the potential for FXIa inhibitors to be effective and safer anticoagulants.

EXPERT OPINION

By simplifying oral anticoagulation, DOACs have facilitated the uptake of anticoagulation. The DOACs are approved for stroke prevention in atrial fibrillation and for the prevention and treatment of venous thromboembolism, and their indications are expanding to include the prevention of atherothrombosis. DOACs have now replaced vitamin K antagonists (VKAs) for most indications, but not all. DOACs are inferior to VKAs for patients with mechanical heart valves, left ventricular assist device, rheumatic atrial fibrillation, and those with antiphospholipid syndrome, and their safety and efficacy are uncertain in some populations (e.g. advanced renal and liver disease). Impediments to use include concerns for bleeding and cost. The newly developed FXIa and FXIIa inhibitors have the potential to be safer than current anticoagulants, but phase 3 trials are needed to confirm their clinical efficacy and safety.

First-in-human trial of SAR107375E, a novel small molecule anticoagulant with dual inhibition of factor Xa and factor IIa

BACKGROUND

SAR107375E is a direct dual inhibitor of both Factor Xa and Factor IIa and has shown potent anticoagulation activity in vitro and animals. This study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of single ascending intravenous doses of SAR107375E in healthy Chinese adult subjects.

METHODS

In this randomized, double-blind, placebo-controlled trial, 60 healthy Chinese adult subjects were administered intravenously single ascending doses (0.5, 1.5, 3.0, 5.0, 7.5, 10.0, 15.0, or 20.0 mg) of SAR107375E (N = 44) or placebo (N = 16). Plasma and urine concentrations of SAR107375E were measured and used to calculate pharmacokinetic parameters. Coagulation functions were measured and compared with baseline values. Treatment-emergent adverse events were recorded to evaluate safety.

RESULTS

In plasma, from the 0.5 to 20.0 mg dose group, t1/2 is 1.51-4.00 h, Cmax is 59.05-1360 ug/L, and AUC0-t is 25.01-528.45 h*ug/L. And it shows dose proportionality in the 5.0-20.0 mg range. Activated partial thromboplastin time and Ecarin clotting time correlated linearly with drug plasma concentration. No serious adverse events were reported during the study.

CONCLUSION

SAR107375E exhibits good safety and tolerability, predictable pharmacokinetics and pharmacodynamics.

CLINICAL TRIAL REGISTRATION

www.chinadrugtrials.org.cn, identifier is CTR20211082.

Determination of Anti-Xa Inhibitor Plasma Concentrations Using a Universal Edoxaban Calibrator

A universal calibrator for the determination of all anti-Xa inhibitors would support laboratory processes. We aimed to test the clinical performance of an anti-Xa assay utilizing a universal edoxaban calibrator to determine clinically relevant concentrations of all anti-Xa inhibitors. Following a pilot study, we enrolled 553 consecutive patients taking rivaroxaban, edoxaban, or apixaban from nine study centers in a prospective cross-sectional study. The Technochrom^® anti-Xa assay was conducted using the Technoview^® edoxaban calibrator. Using ultra-high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS), anti-Xa inhibitor drug concentrations were determined. Sensitivities and specificities to detect three clinically relevant drug concentrations (30 µgL^-1, 50 µgL^-1, 100 µgL^-1) were determined. Overall, 300 patients treated with rivaroxaban, 221 with apixaban, and 32 with edoxaban were included. The overall correlation coefficient (r_s) was 0.95 (95% CI 0.94, 0.96). An area under the receiver operating characteristic curve of 0.96 for 30 µgL^-1, 0.98 for 50 µgL^-1, and 0.99 for 100 µgL^-1 was found. The sensitivities were 92.3% (95% CI 89.2, 94.6), 92.7% (89.4, 95.1), and 94.8% (91.1, 97.0), respectively (specificities 82.2%, 93.7%, and 94.4%). In conclusion, the clinical performance of a universal, edoxaban-calibrated anti-Xa assay was solid and most drug concentrations were predicted correctly.

Apixaban Anticoagulation in Children and Young Adults Supported With the HeartMate 3 Ventricular Assist Device

There is a growing population of pediatric and adult patients supported with the HeartMate 3 ventricular assist device (HM3 VAD) all of whom require anticoagulation. Apixaban is an anticoagulant requiring less testing than warfarin which has been shown to be effective in other indications. We report five pediatric and young adult patients managed on HM3 VAD with apixaban anticoagulation for 1589 days of VAD support between January 6, 2019 and January 7, 2022. The median age was 17 years and the weight was 69 kg. Four patients had congenital heart disease (2 single-ventricle Fontan circulation, and 2 biventricular circulations) and one had dilated cardiomyopathy. Apixaban was initiated at a median of 7 days postoperatively and doses were titrated based on peak apixaban-specific anti-Xa chromogenic analysis levels (goal 150-250 ng/ml). All patients received aspirin 81 mg daily. There was one major hemocompatibility-related event observed (outflow graft thrombus in the setting of medication nonadherence and chronic VAD infection); there was no major bleeding, death, or stroke. Three patients underwent heart transplantation and two remain on VAD support. In this limited series, apixaban paired with a level-based dosing regimen and low-dose aspirin provided safe and effective antithrombosis with only one hemocompatibility-related event related to medication non-adherence.

Potential anticoagulant of traditional chinese medicine and novel targets for anticoagulant drugs

BACKGROUND

Anticoagulants are the main drugs used for the prevention and treatment of thrombosis. Currently, anticoagulant drugs are primarily multitarget heparin drugs, single-target FXa inhibitors and FIIa inhibitors. In addition, some traditional Chinese drugs also have anticoagulant effects, but they are not the main direction of treatment at present. But the anticoagulant drugs mentioned above, all have a common side effect is bleeding. Many other anticoagulation targets are under investigation. With further exploration of coagulation mechanism, how to further determine new anticoagulant targets and how to make traditional Chinese medicine play anticoagulant role have become a new field of exploration.

PURPOSE

The purpose of the study was to summarize the recent research progress on coagulation mechanisms, new anticoagulant targets and traditional Chinese medicine.

METHODS

A comprehensive literature search was conducted using four electronic databases, including PubMed, Embase, CNKI, Wanfang database and ClinicalTrials.gov, from the inception of the study to 28 Feb 2023. Key words used in the literature search were "anticoagulation", "anticoagulant targets", "new targets", "coagulation mechanisms", "potential anticoagulant", "herb medicine", "botanical medicine", "Chinese medicine", "traditional Chinese medicine", "blood coagulation factor", keywords are linked with AND/OR. Recent findings on coagulation mechanisms, potential anticoagulant targets and traditional Chinese medicine were studied.

RESULTS

The active components extracted from the Chinese medicinal herbs, Salvia miltiorrhiza, Chuanxiong rhizoma, safflower and Panax notoginseng have obvious anticoagulant effects and can be used as potential anticoagulant drugs, but the risk of bleeding is unclear. TF/FVIIa, FVIII, FIX, FXI, FXII, and FXIII have all been evaluated as targets in animal studies or clinical trials. FIX and FXI are the most studied anticoagulant targets, but FXI inhibitors have shown stronger advantages.

CONCLUSION

This review of potential anticoagulants provides a comprehensive resource. Literature analysis suggests that FXI inhibitors can be used as potential anticoagulant candidates. In addition, we should not ignore the anticoagulant effect of traditional Chinese medicine, and look forward to more research and the emergence of new drugs.

Clinical Studies with Anticoagulants that Have Changed Clinical Practice

Anticoagulant therapy is the cornerstone of treatment and prevention of arterial and venous thromboembolism. Taking a historical perspective, starting in the 1960s, and progressing through to 2022, we discuss key clinical trials of anticoagulants that have changed clinical practice, and examine obstacles encountered in bringing these anticoagulants to the clinic. The design of some of the early studies that shaped clinical practice was poor by current standards, but their results were influential because nothing better was available. Both heparin and vitamin K antagonists had been in clinical use for several decades before well-designed trials in the 1980s optimized their dosing and enhanced their safety and efficacy. Low-molecular-weight heparin then replaced unfractionated heparin because it had a more predictable dose-response and a longer half-life, thereby allowing it to be used conveniently in out-of-hospital settings. More recently, direct oral anticoagulants became the oral anticoagulants of choice for most indications because they were shown to be at least as safe and effective as vitamin K antagonists when used in fixed doses without the need for laboratory monitoring. The design of the trials that led to the approval of the direct oral anticoagulants was excellent, but further studies are required to optimize their dosing in selected patients who were underrepresented in these trials.

Aneurysmal Subarachnoid Hemorrhage in Hospitalized Patients on Anticoagulants-A Two Center Matched Case-Control Study

Objective-Direct oral anticoagulants (DOAC) are replacing vitamin K antagonists (VKA) for the prevention of ischemic stroke and venous thromboembolism. We set out to assess the effect of prior treatment with DOAC and VKA in patients with aneurysmal subarachnoid hemorrhage (SAH). Methods-Consecutive SAH patients treated at two (Aachen, Germany and Helsinki, Finland) university hospitals were considered for inclusion. To assess the association between anticoagulant treatments on SAH severity measure by modified Fisher grading (mFisher) and outcome as measured by the Glasgow outcome scale (GOS, 6 months), DOAC- and VKA-treated patients were compared against age- and sex-matched SAH controls without anticoagulants. Results-During the inclusion timeframes, 964 SAH patients were treated in both centers. At the time point of aneurysm rupture, nine patients (0.93%) were on DOAC treatment, and 15 (1.6%) patients were on VKA. These were matched to 34 and 55 SAH age- and sex-matched controls, re-spectively. Overall, 55.6% of DOAC-treated patients suffered poor-grade (WFNS_4-5) SAH compared to 38.2% among their respective controls (p = 0.35); 53.3% of patients on VKA suffered poor-grade SAH compared to 36.4% in their respective controls (p = 0.23). Neither treatment with DOAC (aOR 2.70, 95%CI 0.30 to 24.23; p = 0.38), nor VKA (aOR 2.78, 95%CI 0.63 to 12.23; p = 0.18) were inde-pendently associated with unfavorable outcome (GOS_1-3) after 12 months. Conclusions-Iatrogenic coagulopathy caused by DOAC or VKA was not associated with more severe radiological or clinical subarachnoid hemorrhage or worse clinical outcome in hospitalized SAH patients.

Are Factor Xa Inhibitors Efficacious for Ischemic Stroke Prevention in Patients Without Atrial Fibrillation? Evidence From Randomized Clinical Trials

BACKGROUND

Clinical trials provide conflicting evidence regarding oral factor Xa inhibitors for prevention of ischemic stroke in patients without a history of atrial fibrillation (AF).

METHODS

We performed a critical appraisal of randomized clinical trials that tested oral factor Xa inhibitors in patients without AF that reported ischemic stroke.

RESULTS

Considering the 11 trials that reported > 10 ischemic strokes during follow-up (97,578 participants, 1195 ischemic strokes), 1 tested apixaban (57 strokes), 1 betrixaban (52 strokes), and 9 rivaroxaban (1086 strokes). In 7 trials with placebo comparisons, numerically fewer ischemic strokes occurred among those assigned factor Xa inhibitors in 7 of 8 randomized comparisons (range of hazard ratios [HRs], 0.89-0.51), including statistically significant reductions in 2 trials that compared rivaroxaban 2.5 mg twice daily vs placebo on a background of aspirin in patients with cardiovascular disease, COMPASS (HR, 0.51; 95% confidence interval [CI], 0.38-0.68) and COMMANDER-HF (HR, 0.64; 95% CI, 0.43-0.95). Compared with aspirin in 4 trials, oral factor Xa inhibitors were associated with fewer ischemic strokes in 2, with statistically significant reduction in 1 (rivaroxaban 5 mg twice daily in COMPASS; HR, 0.69; 95% CI, 0.53-0.90). Major bleeding was increased by oral factor Xa inhibitors in all 7 placebo-controlled trials (HR range, 1.42-4.08), with statistically significant increases reported in 5 trials, and in all 4 aspirin-controlled trials (all statistically significant increases; HR range, 1.52-2.72).

CONCLUSIONS

Aggregate evidence on the basis of placebo comparisons from randomized trials supports the potential for oral factor Xa inhibitors to reduce ischemic stroke in patients without AF, but major bleeding is increased.

Effect of Rivaroxaban vs Enoxaparin on Major Cardiac Adverse Events and Bleeding Risk in the Acute Phase of Acute Coronary Syndrome: The H-REPLACE Randomized Equivalence and Noninferiority Trial

IMPORTANCE

Parenteral enoxaparin is a preferred anticoagulant used in the acute phase for patients with acute coronary syndrome (ACS). The safety and efficacy of short-term low-dose rivaroxaban in this clinical setting remain unknown.

OBJECTIVE

To compare the safety and efficacy of rivaroxaban vs enoxaparin in the acute phase of ACS.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter, prospective, open-label, active-controlled, equivalence and noninferiority trial was conducted from January 2017 through May 2021 with a 6-month follow-up at 21 hospitals in China. Participants included patients with ACS missing the primary reperfusion window or before selective revascularization. Data were analyzed from November 2021 to November 2022.

INTERVENTIONS

Participants were randomized 1:1:1 to oral rivaroxaban 2.5 mg or 5 mg or 1 mg/kg subcutaneous enoxaparin twice daily in addition to dual antiplatelet therapy (DAPT; aspirin 100 mg and clopidogrel 75 mg once daily) for a mean of 3.7 days.

MAIN OUTCOMES AND MEASURES

The primary safety end point was bleeding events, as defined by the International Society on Thrombosis and Haemostasis, and the primary efficacy end point was major adverse cardiovascular events (MACEs), including cardiac death, myocardial infarction, rerevascularization, or stroke during the 6-month follow-up.

RESULTS

Of 2055 enrolled patients, 2046 (99.6%) completed the trial (mean [SD] age 65.8 [8.2] years, 1443 [70.5%] male) and were randomized to enoxaparin (680 patients), rivaroxaban 2.5 mg (683 patients), or rivaroxaban 5 mg (683 patients). Bleeding rates were 46 patients (6.8%) in the enoxaparin group, 32 patients (4.7%) in the rivaroxaban 2.5 mg group, and 36 patients (5.3%)in the rivaroxaban 5 mg group (rivaroxaban 2.5 mg vs enoxaparin: noninferiority hazard ratio [HR], 0.68; 95% CI, 0.43 to 1.07; P = .005; rivaroxaban 5 mg vs enoxaparin: noninferiority HR, 0.88; 95% CI, 0.70 to 1.09; P = .001). The incidence of MACEs was similar among groups, and noninferiority was reached in the rivaroxaban 5 mg group (HR, 0.60; 95% CI, 0.31 to 1.16, P = .02) but not in the rivaroxaban 2.5 mg group (HR, 0.68; 95% CI, 0.36 to 1.30; P = .05) compared with the enoxaparin group.

CONCLUSIONS AND RELEVANCE

In this equivalence and noninferiority trial, oral rivaroxaban 5 mg showed noninferiority to subcutaneous enoxaparin (1 mg/kg) for patients with ACS treated with DAPT during the acute phase. Results of this feasibility study provide useful information for designing future randomized clinical trials with sufficient sample sizes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03363035.

Factor XI inhibitors: cardiovascular perspectives

Anticoagulants are the cornerstone for prevention and treatment of thrombosis but are not completely effective, and concerns about the risk of bleeding continue to limit their uptake. Animal studies and experience from patients with genetic coagulation factor XI deficiency suggesting that this factor is more important for thrombosis than for haemostasis raises the potential for drugs that target factor XI to provide safer anticoagulation. Multiple factor XI inhibitors are currently under evaluation in clinical trials, including parenterally administered antisense oligonucleotides, monoclonal antibodies, and orally active small-molecule inhibitors. Promising results of phase 2 trials in patients undergoing major orthopaedic surgery, and in those with end-stage kidney disease, atrial fibrillation and acute coronary syndromes have led to large phase 3 trials that are currently ongoing. We here review premises for the use of these agents, results so far accrued, ongoing studies, and perspectives for future patient care.

Safety Signal Evaluation of a Risk of Syncope and Dizziness Not Related to Bleeding or Stroke in Direct Oral Anticoagulant-treated Patients

PURPOSE

In clinical studies, rivaroxaban treatment has been associated with increased incidence of syncope not related to bleeding, anemia, or stroke. The study objective was to evaluate the occurrence of dizziness and/or syncope not related to bleeding, anemia, or stroke in patients treated with direct oral anticoagulants (DOACs).

METHODS

A retrospective, observational, comparative study of adult patients diagnosed with atrial fibrillation and treated with DOACs was conducted using digital retrieval of medical records. Primary outcomes were an emergency department (ED) visit or hospitalization due to syncope, fall, or dizziness. Cases related to bleeding, anemia, or stroke were excluded. Separate examination of a sample of records validated the data.

FINDINGS

Of 6467 eligible patients, 256 (4%) were hospitalized or referred to the ED due to fall, syncope, or dizziness during a mean observation period of 20.1 months. After multivariate regression analysis, statistically independent risk factors were found to be age (hazard ratio [HR] = 1.04, P < 0.0001) and benzodiazepine use (HR = 1.33, P = 0.03). No statistically significant difference was found among the different DOAC types regarding the primary outcome (apixaban and rivaroxaban HR = 0.97, P = 0.85; dabigatran and rivaroxaban HR = 1.2, P = 0.386).

IMPLICATIONS

The study results failed to confirm the claimed association between the use of a DOAC and syncopal symptoms unrelated to bleeding, anemia, or stroke in this relatively large Israeli patient population. Age and benzodiazepine treatment were significant independent risk factors of these events.

Analysis of Clinical and Laboratory Risk Factors of Post-Traumatic Intracranial Hemorrhage in Patients on Direct Oral Anticoagulants with Mild Traumatic Brain Injury: An Observational Multicenter Cohort

BACKGROUND

Assessing the risk of intracranial hemorrhage (ICH) in patients with a mild traumatic brain injury (MTBI) who are taking direct oral anticoagulants (DOACs) is challenging. Currently, extensive use of computed tomography (CT) is routine in the emergency department (ED).

OBJECTIVE

This study aims to investigate whether the clinical and laboratory characteristics presented at the ED evaluation can also estimate the risk of post-traumatic ICH in DOAC-treated patients with MTBI.

METHODS

A retrospective observational study was conducted in three EDs in Italy from January 1, 2016 to March 15, 2020. All patients treated with DOACs who were evaluated for an MTBI in the ED were enrolled. The primary outcome of the study was the presence of post-traumatic ICH in the head CT performed in the ED.

RESULTS

Of 930 patients on DOACs with MTBI who were enrolled, 6.8% (63 of 930) had a post-traumatic ICH and 1.5% (14 of 930) were treated with surgery or died as a result of the ICH. None of the laboratory factors were associated with an increased risk of ICH. On multivariate analysis, previous neurosurgical intervention, major trauma dynamic, post-traumatic loss of consciousness, post-traumatic amnesia, Glasgow Coma Scale score of 14, and evidence of trauma above the clavicles were associated with a higher risk of post-traumatic ICH. The net clinical benefit provided by risk factor assessment appears superior to the strategy of performing CT on all DOAC-treated patients.

CONCLUSIONS

Assessment of the clinical characteristics presented at ED admission can help identify DOAC-treated patients with MTBI who are at risk of ICH.

Local Tranexamic Acid for Preventing Hemorrhage in Anticoagulated Patients Undergoing Dental and Minor Oral Procedures: A Systematic Review and Meta-Analysis

Dental procedures have posed challenges in managing anticoagulated patients due to early reports of oral hemorrhage. This study aims to evaluate the risks of postoperative bleeding with the local application of tranexamic acid. A systematic search was conducted until 31 March 2022, with keywords including tranexamic acid, oral hemorrhage, dental, and/or coagulation. The following databases were searched: PubMed, Scopus, Web of Science, CINAHL Plus, and Cochrane Library. Statistical analysis was conducted using Review Manager 5.4. In total, 430 patients were pooled in with the local application of tranexamic acid using mouthwash, irrigation, and compression with a gauze/gauze pad. The mean age was 61.8 years in the intervention group and 58.7 in the control group. Only 4 patients in the intervened group out of the 210 discontinued the trial due to non-drug-related adverse events. The risk difference was computed as -0.07 (p = 0.05), meaning that patients administered with local antifibrinolytic therapy for postoperative bleeding reduction for dental procedures were at a 7% less risk of oral bleeding. Current evidence on managing anticoagulated patients undergoing dental or oral procedures remains unclear. The present study presents favorable outcomes of postoperative bleeding with local tranexamic acid used in the postoperative period.

Small molecules in the treatment of COVID-19

The outbreak of COVID-19 has become a global crisis, and brought severe disruptions to societies and economies. Until now, effective therapeutics against COVID-19 are in high demand. Along with our improved understanding of the structure, function, and pathogenic process of SARS-CoV-2, many small molecules with potential anti-COVID-19 effects have been developed. So far, several antiviral strategies were explored. Besides directly inhibition of viral proteins such as RdRp and Mpro, interference of host enzymes including ACE2 and proteases, and blocking relevant immunoregulatory pathways represented by JAK/STAT, BTK, NF-κB, and NLRP3 pathways, are regarded feasible in drug development. The development of small molecules to treat COVID-19 has been achieved by several strategies, including computer-aided lead compound design and screening, natural product discovery, drug repurposing, and combination therapy. Several small molecules representative by remdesivir and paxlovid have been proved or authorized emergency use in many countries. And many candidates have entered clinical-trial stage. Nevertheless, due to the epidemiological features and variability issues of SARS-CoV-2, it is necessary to continue exploring novel strategies against COVID-19. This review discusses the current findings in the development of small molecules for COVID-19 treatment. Moreover, their detailed mechanism of action, chemical structures, and preclinical and clinical efficacies are discussed.