Inhibitor Of Coagulation Factor Xa Research Articles

Rivaroxaban, a direct inhibitor of coagulation factor Xa, attenuates adverse cardiac remodeling in rats by regulating the PAR-2 and TGF-β1 signaling pathways.

Factor Xa (FXa) not only plays an active role in the coagulation cascade but also exerts non-hemostatic signaling through the protease-activated receptors (PARs). This study aimed to investigate whether the FXa inhibitor, Rivaroxaban (RIV), attenuates adverse cardiac remodeling in rats with myocardial infarction (MI) and to identify the underlying molecular mechanisms it uses. An MI model was induced in eight-week-old, male Wistar rats, by permanent ligation of the left anterior descending coronary artery. MI rats were randomly assigned to receive RIV or protease-activated receptors 2-antagonist (PAR-2 antagonist, FSLLRY) treatment for four weeks. Histological staining, echocardiography and hemodynamics were used to assess the cardioprotective effects of RIV. Meanwhile, pharmacological approaches of agonist and inhibitor were used to observe the potential pathways in which RIV exerts antifibrotic effects in neonatal rat cardiac fibroblasts (CFs). In addition, real-time PCR and western blot analysis were performed to examine the associated signaling pathways. RIV presented favorable protection of left ventricular (LV) cardiac function in MI rats by significantly reducing myocardial infarct size, ameliorating myocardial pathological damage and improving left ventricular (LV) remodeling. Similar improvements in the PAR-2 antagonist FSLLRY and RIV groups suggested that RIV protects against cardiac dysfunction in MI rats by ameliorating PAR-2 activation. Furthermore, an in vitro model of fibrosis was then generated by applying angiotensin II (Ang II) to neonatal rat cardiac fibroblasts (CFs). Consistent with the findings of the animal experiments, RIV and FSLLRY inhibited the expression of fibrosis markers and suppressed the intracellular upregulation of transforming growth factor β1 (TGFβ1), as well as its downstream Smad2/3 phosphorylation effectors in Ang II-induced fibrosis, and PAR-2 agonist peptide (PAR-2 AP) reversed the inhibition effect of RIV. Our findings demonstrate that RIV attenuates MI-induced cardiac remodeling and improves heart function, partly by inhibiting the activation of the PAR-2 and TGF-β1 signaling pathways.

Antiplatelet Aggregation Properties of Cirsilineol: A Novel Inhibitor of Blood Coagulation Factor Xa.

A small natural substance called cirsilineol (CSL), which was discovered in the plant Artemisia vestita, is lethal to many cancer cells and has antioxidant, anticancer, and antibacterial properties. Here, we investigated the underlying mechanisms of the antithrombotic action of CSL. We demonstrated that CSL has antithrombotic efficacy comparable to rivaroxaban, a direct blood coagulation factor Xa (FXa) inhibitor employed as a positive control, in inhibiting the enzymatic activity of FXa and the platelet aggregation induced by adenosine diphosphate (ADP) and U46619, a thromboxane A2 analog. The expression of P-selectin, the phosphorylation of myristoylated alanine-rich C kinase substrate by U46619 or ADP, and the activation of PAC-1 in platelets were inhibited by CSL. Nitric oxide production was increased by CSL in ADP- or U46619-treated human umbilical vein endothelial cells (HUVECs), although excessive endothelin-1 secretion was suppressed. CSL demonstrated strong anticoagulant and antithrombotic effects in a mouse model of arterial and pulmonary thrombosis. Our findings suggest that CSL is a potential pharmacological candidate for a novel class of anti-FXa and antiplatelet medications.

Pharmacokinetics of a microdosed cocktail of three direct oral anticoagulants in children with congenital heart defects: study protocol for a single-centre clinical trial (DOAC-Child)

IntroductionDirect oral anticoagulants (DOACs) are direct inhibitors of coagulation factor Xa and are frequently used in adults for different indications such as deep vein thrombosis or non-valvular atrial fibrillation. Paediatric...

Preparation and blood compatibility of polyethersulfone dialysis membrane modified by apixaban as coagulation factor Xa inhibitor.

Blood purification therapy is widely used in the treatment of critically ill patients. However, most dialysis membranes are prone to thrombosis. Activated coagulation factor X (FXa) functions at the intersection of intrinsic, extrinsic, and common coagulation pathways and plays a central role in thrombogenesis. To date, few dialysis membranes that directly inhibit FXa have been reported. We modified a polyethersulfone(PES) membrane using apixaban as an FXa inhibitor and investigated the performance of this membrane (AMPES). The contact angle of the modified membrane was reduced. PWF and retention rates of BSA were increased, demonstrating good hydrophilicity and dialysis performance. Albumin adsorption was reduced from 141.8±15.5 to 114.1±6.9μgcm-2. Reduced protein adsorption, especially targeted anti-FXa effect, inhibited the activation of intrinsic, extrinsic, and common coagulation pathways, as evidenced by significant prolongations of activated partial thromboplastin time, prothrombin time, and thrombin time by 145.04, 46.84 and 11.46s, respectively. Furthermore, we determined the FXa concentration of each group, and found that the modified membrane had better anticoagulant performance through the inhibition of FXa. Favorable antiplatelet activity was also demonstrated. Thromboelastogram was used to comprehensively evaluate the anticoagulant and antithrombotic activities of the modified membrane. The R value was increased by 43.1min, while the reduction in α angle was 42.5°. The coagulation comprehensive index reduction was 34.3. In addition, C3a and C5a were decreased by 15.3% and 30.4%, respectively. Furthermore, in vitro cytotoxicity and erythrocyte stability testing as well as in vivo murine experiments demonstrated the biosafety of the modified membrane. These results indicate that the AMPES dialysis membrane has an excellent potential for clinical applications.

Pharmacotherapy for pulmonary embolism: new anticoagulants

Background: Pulmonary embolism is associated with reduced survival and considerable economic burden worldwide. In Korea, the incidence of pulmonary embolism has been gradually increasing. Older individuals are at an increased risk for pulmonary embolism and anticoagulation-related bleeding events. Typically, heparin and vitamin K antagonists are employed to treat pulmonary embolism; however, these agents present numerous limitations. Hence, novel anticoagulants with improved safety and efficacy profiles are urgently needed.Current Concepts: Direct oral anticoagulants (DOACs), including direct thrombin (coagulation factor II) inhibitors and selective inhibitors of coagulation factor Xa, have emerged as alternative agents. Phase III, large-scale clinical trials have revealed that DOACs are non-inferior to standard therapy during initial and long-term treatment of pulmonary embolism, considering the safety profile. Evidence-based clinical guidelines recommend that primary care clinicians employ DOACs over warfarin to achieve anticoagulation.Discussion and Conclusion: For over 70 years, the standard therapy for most patients with pulmonary embolism has involved heparin administration, overlapped and followed by a vitamin K antagonist. Recently developed DOACs against coagulation factor Xa or thrombin might overcome limitations of standard therapy, including the need for injection and regular dose adjustment with laboratory monitoring. These limitations hinder the management of patients with pulmonary embolism and negatively impact the patient’s quality of life. Four DOACs, including apixaban, dabigatran, edoxaban, and rivaroxaban, are currently available for treating pulmonary embolism in Korea, which could simplify the therapeutic strategy.

Alboserpin, the Main Salivary Anticoagulant from the Disease Vector Aedes albopictus, Displays Anti-FXa-PAR Signaling In Vitro and In Vivo.

Blood-feeding arthropods secrete potent salivary molecules, which include platelet aggregation inhibitors, vasodilators, and anticoagulants. Among these molecules, Alboserpin, the major salivary anticoagulant from the mosquito vector Aedes albopictus, is a specific inhibitor of the human coagulation factor Xa (FXa). In this study, we investigated the anti-inflammatory properties of Alboserpin, in vitro and in vivo. In vitro, Alboserpin inhibited FXa-induced protease-activated receptor (PAR)-1, PAR-2, PAR-3, VCAM, ICAM, and NF-κB gene expression in primary dermal microvascular endothelial cells. Alboserpin also prevented FXa-stimulated ERK1/2 gene expression and subsequent inflammatory cytokine release (MCP-1, TNF-α, IL-6, IL-8, IL-1β, IL-18). In vivo, Alboserpin reduced paw edema induced by FXa and subsequent release of inflammatory cytokines (CCL2, MCP-1, IL-1α, IL-6, IL-1β). Alboserpin also reduced FXa-induced endothelial permeability in vitro and in vivo. These findings show that Alboserpin is a potent anti-inflammatory molecule, in vivo and in vitro, and may play a significant role in blood feeding.

Design and synthesis of tricyclic benzo[1, 3]oxazinyloxazolidinones as blood coagulation factor Xa inhibitors

The coagulation enzyme factor Xa (FXa) is a valuable target for developing anticoagulants to treat thrombotic diseases. In this work, we designed and synthesized a series of conformationally restricted compounds containing the benzo[1,3]oxazinyloxazolidinone scaffold. The target compounds were synthesized by 11 steps reaction. The preliminary SAR showed that on the phenyl ring of benzo[1,3]oxazinyloxazolidinone, lactam replacements at the 6-position were favorable for FXa inhibition. Compound 16b showed good FXa inhibitory activity with an IC50 of 0.43 μM. The results indicate that benzo[1,3]oxazinyloxazolidinone is a promising scaffold for developing FXa inhibitors as antithrombotic agents.

Non-vitamin K antagonist oral anticoagulants for COVID-19 thrombosis

Thrombotic complications appear to be a major predictor of death in COVID-19 patients, and multiple studies have shown that anticoagulants can help to improve the outcome. The Food and Drug Administration’s acceptance of non-vitamin K antagonist oral anticoagulants (NOACs) has sparked much excitement about their potential as a replacement for existing oral anticoagulants. NOACs target a single clotting factor, often activated factor X or thrombin, and involve the coagulation factor Xa inhibitors including apixaban, edoxaban, and rivaroxaban, and the thrombin inhibitor dabigatran. COVID-19 is an infectious disease that causes thrombotic events by inducing a pro-inflammatory and prothrombotic condition. This article provides a comprehensive overview of the mechanism behind enhanced thrombogenicity accompanying COVID-19, the clinical range of NOACs, and the role of NOACs in treatment of COVID-19 based on recent investigations and clinical trials.

Thromboembolic Complications in a Pediatric Patient Population: Treatment with Direct Oral Anticoagulants. Monitoring of Treatment Efficiency with D-Dimer Levels and Safety Profile By Thromboelastogram

Direct oral anticoagulants (DOAC) such as the thrombin inhibitor Dabigatran and the coagulation factor Xa inhibitors Apixaban and Rivaroxaban have been in clinical use for the past 5-6 years. Familiarity with their use in the general pediatric population with thrombosis secondary to inflammatory disorders and rheumatologic disease is currently not as prevalent due to the widespread more conventional anticoagulation practice with the fractionated heparins in particular Lovenox. In this report we would like to summarize our experience in a pediatric patient population ranging from 3- 17 years with thrombotic disease. Of 55 patients with various thrombotic events 16 patients were treated with DOAC. There were 5 patients who had underlying inflammatory disease including COVID. Thrombotic complications included arterial as well as venous thrombotic events. All patients had elevated D-Dimer levels ranging from 360-4000 mcg/ml on diagnosis and normalized with successful anticoagulation. All patients had resolution of thrombosis. Thrombelastogram (TEG) were obtained on isolated patients during therapy and were useful to balance anticoagulation to prevent hemorrhagic complications.In conclusion, DOAC are a safe and effective alternative to LMW Heparin in pediatric patients with arterial or venous thrombosis. Monitoring should include determination of D-Dimer levels for efficacy of treatment and TEG in cases with arterial disease where bleeding may be a secondary complication of therapy. DisclosuresNo relevant conflicts of interest to declare.

利伐沙班的定量检测：拉曼光谱法与远红外吸收光谱法

Rivaroxaban is a new type of oral anticoagulant, which has the advantages of definite curative effect, good safety and convenient use, so it is often used in the prevention and treatment of venous thromboembolic diseases and stroke prevention of non valvular atrial fibrillation. Due to the concentration of rivaroxaban in patients, it will affect the inhibition of coagulation factor Xa, which leads to individual differences in the clinical response of patients and affects the final treatment effect. In order to use rivaroxaban more reasonably, it is necessary to monitor the concentration of rivaroxaban in human blood or urine. For the clinical needs, based on the advantages of far-infrared fingerprint spectrum and Raman characteristic spectrum in effective identification and quantitative analysis of substances, Fourier transform infrared spectrometer and laser confocal Raman spectroscopy system were used to identify and quantitatively detect rivaroxaban in liquid state. In this paper, the change of far-infrared absorption spectrum of rivaroxaban with its concentration was detected by Fourier transform infrared spectrometer, and then the change of Raman spectrum of rivaroxaban with its concentration was detected by laser confocal Raman spectroscopy system. Finally, the accuracy of far-infrared spectroscopy method and Raman method was compared. After comparison, it is proved that the accuracy of far-infrared detection is 2 times higher than that of Raman spectrum detection. These results are of great significance for the use of rivaroxaban in clinical medicine.

Bleeding is increased in amyloid precursor protein knockout mouse

BackgroundAmyloid precursor protein (APP) is highly expressed in platelets. APP is the precursor to amyloid beta (Aβ) peptides that accumulate in cerebral amyloid angiopathy and plaques in Alzheimer disease. APP and its metabolites interact with many components of the coagulation system, and have both anticoagulant and procoagulant properties, but it is unclear if APP contributes to hemostasis in vivo. ObjectivesTo determine whether APP contributes to hemostasis in mice, including when inhibitors of coagulation are administered. MethodsBlood loss in APP knockout (KO) mice was measured in liver laceration and tail transection models of hemorrhage. Blood loss was also measured following tail transection in mice given an inhibitor of coagulation factor Xa (apixaban), platelet inhibitors (aspirin + clopidogrel), tissue‐type plasminogen activator (t‐PA), or the antifibrinolytic tranexamic acid (TXA). Results and DiscussionBlood loss from liver lacerations was similar between APP KO mice and wild‐type (WT) mice, but APP KO mice bled more from tail transections. When mice were challenged with aspirin + clopidogrel, the difference in bleeding between APP KO and WT mice was abrogated. In contrast, a difference in bleeding between the strains persisted when mice were treated with apixaban, t‐PA, or TXA. Blood collected from APP KO mice and analyzed with thromboelastography had longer clotting times, and the clots were less stiff and more susceptible to fibrinolysis compared to blood from WT mice. ConclusionsThe absence of APP measurably increases bleeding in mice, which is consistent with a role for platelet‐derived APP and Aβ peptides in hemostasis.

An Update on the Reversal of Non-Vitamin K Antagonist Oral Anticoagulants.

Non-vitamin K antagonist oral anticoagulants (NOACs) include thrombin inhibitor dabigatran and coagulation factor Xa inhibitors rivaroxaban, apixaban, edoxaban, and betrixaban. NOACs have several benefits over warfarin, including faster time to the achieve effect, rapid onset of action, fewer documented food and drug interactions, lack of need for routine INR monitoring, and improved patient satisfaction. Local hemostatic measures, supportive care, and withholding the next NOAC dose are usually sufficient to achieve hemostasis among patients presenting with minor bleeding. The administration of reversal agents should be considered in patients on NOAC's with major bleeding manifestations (life-threatening bleeding, or major uncontrolled bleeding), or those who require rapid anticoagulant reversal for an emergent surgical procedure. The Food and Drug Administration (FDA) has approved two reversal agents for NOACs: idarucizumab for dabigatran and andexanet alfa for apixaban and rivaroxaban. The American College of Cardiology (ACC), American Heart Association (AHA), and Heart Rhythm Society (HRS) have released an updated guideline for the management of patients with atrial fibrillation that provides indications for the use of these reversal agents. In addition, the final results of the ANNEXA-4 study that evaluated the efficacy and safety of andexanet alfa were recently published. Several agents are in different phases of clinical trials, and among them, ciraparantag has shown promising results. However, their higher cost and limited availability remains a concern. Here, we provide a brief review of the available reversal agents for NOACs (nonspecific and specific), recent updates on reversal strategies, lab parameters (including point-of-care tests), NOAC resumption, and agents in development.

Edoxaban Exerts Antioxidant Effects Through FXa Inhibition and Direct Radical-Scavenging Activity.

The interplay between oxidative stress, inflammation, and tissue fibrosis leads to the progression of chronic kidney disease (CKD). Edoxaban, an activated blood coagulation factor Xa (FXa) inhibitor, ameliorates kidney disease by suppressing inflammation and tissue fibrosis in animal models. Interestingly, rivaroxaban, another FXa inhibitor, suppresses oxidative stress induced by FXa. Thus, FXa inhibitors could be multitargeted drugs for the three aforementioned risk factors for the progression of CKD. However, the exact mechanism responsible for eliciting the antioxidant effect of FXa inhibitors remains unclear. In this study, the antioxidant effect of edoxaban was evaluated. First, the intracellular antioxidant properties of edoxaban were evaluated using human proximal tubular cells (HK-2 cells). Next, direct radical scavenging activity was measured using the electron spin resonance and fluorescence analysis methods. Results show that edoxaban exhibited antioxidant effects on oxidative stress induced by FXa, indoxyl sulfate, and angiotensin II in HK-2 cells, as well as the FXa inhibitory activity, was involved in part of the antioxidant mechanism. Moreover, edoxaban exerted its antioxidative effect through its structure-specific direct radical scavenging activity. Edoxaban exerts antioxidant effects by inhibiting FXa and through direct radical-scavenging activity, and thus, may serve as multitargeted drugs for the three primary risk factors associated with progression of CKD.

Phase I Study of Direct Coagulation Factor Xa Inhibitor SYHA136 Tablets in Chinese Healthy Volunteers

Phase I Study of Direct Coagulation Factor Xa Inhibitor SYHA136 Tablets in Chinese Healthy Volunteers

How can the results of the COMPASS trial benefit patients with coronary or peripheral artery disease in Poland?

Aspirin decreases the risk of recurrent thrombotic events in patients with coronary artery disease or peripheral artery disease but the risk of recurrent events remains high. Long‑term dual antiplatelet therapy or the combination of aspirin and warfarin further reduces the risk of recurrent events, but at the cost of increased bleeding, and neither of these treatments reduce mortality. The COMPASS (Cardiovascular Outcomes in People Using Anticoagulation Strategies) randomized controlled trial involving 27 395 patients from 602 sites in 33 countries (Poland: 9 sites, 518 patients) tested whether low‑dose anticoagulant therapy with the coagulation factor Xa inhibitor rivaroxaban given alone or combined with aspirin reduced thrombotic risk compared with aspirin in patients with apparently stable chronic coronary and/or peripheral artery disease. In patients treated with the combination of rivaroxaban 2.5 mg twice daily and aspirin 100 mg once daily, compared with aspirin alone, the primary outcome of the composite of cardiovascular death, stroke, or myocardial infarction was decreased by 24% (hazard ratio, 0.76; 95% confidence interval, 0.66 to 0.86; P <0.001), and mortality by 18% at the cost of a 70% increase in major bleeding but no significant increase in fatal or intracranial bleeding. Results were consistent in patients with coronary artery disease or peripheral artery disease, and the greatest absolute benefit was evident in the highest risk patients, including those with polyvascular disease, mild or moderate heart failure, chronic kidney disease, or diabetes. These results establish the combination of low‑dose rivaroxaban and aspirin as a highly effective treatment to decrease morbidity and mortality rates in patients with atherosclerotic vascular disease..

Effect of rivaroxaban on the injury during endotoxin-induced damage to human umbilical vein endothelial cells

To evaluate the effect and mechanism of rivaroxaban, an inhibitor of coagulation factor Xa (FXa), on endotoxin-induced injury to human umbilical vein endothelial cells (HUVEC). When cultured HUVEC grow to 80% fusion, they were divided into four groups according to the random number method: blank control group (DMEM medium), lipopolysaccharide (LPS) group (cells were challenged by 100 μg/L LPS for 16 hours), FXa+LPS group (cells were challenged by LPS for 16 hours after they were cultured with 100 nmol/L FXa for 24 hours), and FXa +RIV+LPS group (cells were challenged by LPS for 16 hours after they were cultured with 100 nmol/L FXa and 1 μmol/L rivaroxaban for 24 hours). After each group of cells were challenged with LPS, the cell activity was detected by the cell proliferation and toxicity kit (CCK-8); the cell migration ability was detected by cell scratch experiments; the abilities of cells migration were measured by scratch-wound-healing assay; the apoptosis of cells were evaluated using flow cytometry; the endothelial barrier of cells was assessed by Transwell and Evans blue; the levels of tumor necrosis factor-α (TNF-α), interleukin (IL-1β, IL-6) were detected by the enzyme linked immunosorbent assay (ELISA); the expressions of nuclear factor-ΚB (NF-ΚB) and mitogen activated protein kinase (MAPK) signaling pathway were detected by Western Blot. Compared with blank control group, the cell viability in LPS group was significantly decreased, and the migration ability, number of apoptotic cells, and barrier permeability of endothelial cells was significantly increased, the levels of TNF-α, IL-1β and IL-6 were significantly increased, and the expressions of phosphorylation of c-Jun N-terminal kinase (p-JNK), phosphorylation of p38MAPK (p-p38MAPK), phosphorylation of transforming growth factor kinase 1 (p-TAK1) and phosphorylation of NF-ΚBp65 (p-NF-ΚBp65) were significantly increased. It indicated that LPS could stimulate the inflammatory response of vascular endothelial cells, and had a significant impact on cell activity, apoptosis and function. There was no significant difference in above indexes between FXa+LPS group and LPS group, except for the level of IL-6 being higher in FXa+LPS group. Compared with FXa+LPS group, in FXa+RIV+LPS group, the cell activity was significantly increased (A value: 0.42±0.02 vs. 0.33±0.02), and migration ability was significantly decreased (folds: 1.78±0.17 vs. 2.24±0.20), the number of apoptotic cells was significantly decreased [(11.30±0.70)% vs. (21.03±0.19)%], and permeability of monolayers endothelial cells was significantly decreased [(149±12)% vs. (253±15)%], the levels of inflammatory cytokines were significantly decreased [IL-1β (ng/L): 163.2±20.7 vs. 477.8±20.2, IL-6 (ng/L): 69.3±0.5 vs. 238.0±24.1, TNF-α (ng/L): 117.0±13.1 vs. 196.2±4.5], the expressions of p-TAK1 and p-NF-ΚBp65 were significantly decreased (p-TAK1/TAK1: 0.74±0.09 vs. 1.85±0.15, p-NF-ΚBp65/NF-ΚBp65: 1.15±0.17 vs. 2.36±0.20), with statistically significant differences (all P < 0.05). There was no significant difference in the p-JNK, p-p38MAPK expressions between FXa+RIV+LPS group and FXa+LPS group (p-JNK/JNK: 1.64±0.12 vs. 1.65±0.15, p-p38MAPK/p38MAPK: 2.31±0.32 vs. 2.35±0.20, both P > 0.05). Rivaroxaban can effectively relieve the inflammatory response of HUVEC stimulated by LPS, which may be related to the inhibition of NF-ΚB signaling pathway activation rather than MAPK signaling pathway.

Design and synthesis of novel 3,4-diaminobenzoyl derivatives as antithrombotic agents with improved solubility

To obtain a highly selective, direct coagulation factor Xa (FXa) inhibitor with excellent antithrombotic activity and improved solubility, a series of novel 3,4-diaminobenzoyl derivatives were designed and synthesized based on reported structure–activity relationship analysis of FXa inhibitors. Preliminary solubility test showed that the decrease of intramolecular hydrogen bonds and the change of rigid structure could effectively improve physicochemical property of compounds. The synthesized compound 7ab could significantly prolong prothrombin time at a concentration of 40 nM compared with Apixaban. Docking investigation of 7ab with FXa protein revealed that the several groups could form multiple hydrogen bonds with amino acid residues ALA-190, ASP-189 and GLY-216. These results indicated that compound 7ab might serve as a potential anticoagulant agent.

Isolation and Characterization of Poecistasin, an Anti-Thrombotic Antistasin-Type Serine Protease Inhibitor from Leech Poecilobdella manillensis.

Antistasin, first identified as a potent inhibitor of the blood coagulation factor Xa, is a novel family of serine protease inhibitors. In this study, we purified a novel antistasin-type inhibitor from leech Poecilobdella manillensis called poecistasin. Amino acid sequencing of this 48-amino-acid protein revealed that poecistasin was an antistasin-type inhibitor known to consist of only one domain. Poecistasin inhibited factor XIIa, kallikrein, trypsin, and elastase, but had no inhibitory effect on factor Xa and thrombin. Poecistasin showed anticoagulant activities. It prolonged the activated partial thromboplastin time and inhibited FeCl3-induced carotid artery thrombus formation, implying its potent function in helping Poecilobdella manillensis to take a blood meal from the host by inhibiting coagulation. Poecistasin also suppressed ischemic stroke symptoms in transient middle cerebral artery occlusion mice model. Our results suggest that poecistasin from the leech Poecilobdella manillensis plays a crucial role in blood-sucking and may be an excellent candidate for the development of clinical anti-thrombosis and anti-ischemic stroke medicines.

Development and Validation of a Stability-Indicating Liquid Chromatographic Method with Mass-Spectrometric Detection for the Analysis of Apixaban and Determination of Production Related Impurities

Apixaban is a novel anticoagulant drug acting as a direct, selective and reversible inhibitor of coagulation factor Xa. The purpose of this work was to develop and validate a sensitive, stability-indicating LC-MS method for the analysis of apixaban and estimation of production-related substances in the active pharmaceutical ingredient (API) and pharmaceutical dosage forms. The analyses were carried out on a Macherey-Nagel Nucleodur C18 column (250 × 4.6 mm, 5 μm particle size) with a mobile phase containing acetonitrile and water in gradient program at a flow rate of 0.8 mL/min, the column oven temperature 25°C, and the UV detection tuned to 270 nm. Apixaban was subjected to stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation, and found susceptible to acid and base hydrolysis conditions, while it was stable under thermal, photolytic, and oxidative degradation conditions. The degradation products were well resolved from the main peak and its impurities, proving the stability-indicating power of the proposed method. The proposed method was validated as per International Conference on Harmonization (ICH) guidelines. The method is suitable for practical routine analysis and it has been successfully applied to analyze apixaban in eliquis brand preparations. All analytical results were acceptable according to the pharmaceutical requirements.

Factor Xa inhibition by rivaroxaban attenuates cardiac remodeling due to intermittent hypoxia

Patients with obstructive sleep apnea (OSA) have a high prevalence of atrial fibrillation (AF). Rivaroxaban, a coagulation factor Xa inhibitor, has recently been reported to show pleiotropic effects. This study investigated the influence of rivaroxaban on cardiac remodeling caused by intermittent hypoxia (IH). Male C57BL/6J mice were exposed to IH (repeated cycles of 5% oxygen for 1.5 min followed by 21% oxygen for 5 min) for 28 days with/without rivaroxaban (12 mg/kg/day) or FSLLRY, a protease-activated receptor (PAR)-2 antagonist (10 μg/kg/day). IH caused endothelial cell degeneration in the small arteries of the right atrial myocardium and increased the level of %fibrosis and 4-hydroxy-2-nonenal protein adducts in the left ventricular myocardium. IH also increased the expression of PAR-2 as well as the phosphorylation of extracellular signal-regulated kinase (ERK)-1/2 and nuclear factor-kappa B (NF-κB) were increased in human cardiac microvascular endothelial cells. However, rivaroxaban and FSLLRY significantly suppressed these changes. These findings demonstrate that rivaroxaban attenuates both atrial and ventricular remodeling induced by IH through the prevention of oxidative stress and fibrosis by suppressing the activation of ERK and NF-κB pathways via PAR-2. Treatment with rivaroxaban could potentially become a novel therapeutic strategy for cardiac remodeling in patients with OSA and AF.