Apixaban: A Clinical Pharmacokinetic and Pharmacodynamic Review

Building lactams by highly selective hydrodeoxygenation of cyclic imides using an alumina-supported AgRe bimetallic nanocatalyst

The rational design of robust nanocatalysts containing the suitable active sites for building relevant organic compounds, such as lactams, is a desired approximation towards the development of a sustainable fine chemistry field. In that sense, the design of a proper nanomaterial able to mediate the selective hydrodeoxygenation of cyclic imides to lactams with high tolerance to the preservation of aromatic rings remains rather unexplored. Here, we show the design of a bimetallic AgRe nanomaterial with notable activity and selectivity to mediate this transformation affording more than 60 lactams from the corresponding imides. Interestingly, in this work we disclose that the optimal AgRe nanocatalyst is constituted by AgReO4 nanoaggregates that undergo an in situ hydrogenative dispersion to form the active centers composed by Ag0 nanoparticles and ReOx species. Deep characterization, together with kinetic and mechanistic studies, have revealed that the intimate Ag-Re contact intrinsic to AgReO4 species is key for the formation of the most active catalytic sites and the proper bimetallic cooperation required for mediating the desired process.

Modeling and Simulation to Inform Apixaban Dosing in Pediatrics With Acute Lymphoblastic Leukemia or Lymphoblastic Lymphoma Treated With Asparaginase

Apixaban could be a potential treatment option for the prevention of venous thromboembolism (VTE) in children with acute lymphoblastic leukemia (ALL) or lymphoblastic lymphoma (LL). This analysis describes an updated two-compartment population pharmacokinetic (PPK) model that characterizes the PK variability of apixaban in pediatric patients with ALL or LL treated with asparaginase using PK data from a phase III study (PREVAPIX). Patient type of ALL or LL was found to be a significant covariate on the apparent central volume of distribution (Vc/F) and first-order absorption rate (Ka). Pediatric patients (aged 9 months to < 18 years) with ALL or LL had a 52.4% lower Ka compared with adults; this was 81.1% lower than other pediatric patients (9 months to < 18 years) at risk of VTE. Apixaban Vc/F was estimated to be 43.1% lower in pediatric patients compared with adult patients. The updated PPK model was used to simulate and confirm apixaban fixed-dose by weight-tiered regimen-achieved target exposures in pediatric patients (aged 28 days to < 18 years) with ALL or LL. In addition, a PK/pharmacodynamic (PD) analysis was performed using a linear regression model to characterize the relationship between anti-FXa activity (AXA) and apixaban concentration in pediatric patients with ALL or LL. The characterization of apixaban PK and PK/PD in this analysis contributes to evidence that apixaban could be a potential antithrombotic option in pediatric patients.

Peak and trough concentrations of apixaban and rivaroxaban in adult patients: a systematic review and meta-analysis

BACKGROUND

Apixaban and rivaroxaban are activated factor X (FXa) inhibitors commonly used for treatment of venous thromboembolism and stroke prevention in patients with atrial fibrillation. While routine monitoring of their concentrations is not recommended, but it may be beneficial in certain situations. Expected peak and trough concentrations remain poorly understood, with most data derived from small studies.

OBJECTIVES

To establish the average peak and trough concentrations of apixaban and rivaroxaban from real-world studies.

METHODS

PubMed, Scopus, and Web of Science were searched until October 2023 for observational studies reporting apixaban and rivaroxaban concentrations. Meta-regression was used to examine factors influencing these concentrations.

RESULTS

Sixteen studies involving 1054 apixaban and 1321 rivaroxaban patients were pooled using random-effects model. Mean apixaban peak concentrations were 157 ng/mL (95% CI, 127-187) for 2.5 mg and 228 ng/mL (95% CI, 204-252) for 5 mg, with trough concentrations of 77 ng/mL (95% CI, 56-98) and 113 ng/mL (95% CI, 101-124), respectively. Mean rivaroxaban peak concentrations were 168 ng/mL (95% CI, 104-232) for 10 mg, 225 ng/mL (95% CI, 192-257) for 15 mg, and 229 ng/mL (95% CI, 193-264) for 20 mg, with trough concentrations of 23 ng/mL (95% CI, 13-32), 31 ng/mL (95% CI, 26-36), and 36 ng/mL (95% CI, 25-47), respectively. Meta-regression revealed age and creatinine clearance correlated with apixaban peak concentrations. Creatinine clearance correlated with apixaban and rivaroxaban trough concentrations.

CONCLUSION

The pooled mean concentrations align with expected concentration ranges reported in different pharmacokinetic studies.

In Vivo pharmacokinetic interactions of ribociclib with rivaroxaban and apixaban in rats: implications for increased drug exposure and dose adjustments

Background

Apixaban (API) and rivaroxaban (RIVA) are orally available inhibitors of coagulation factor Xa and are commonly used to treat cancer-related venous thrombosis. Ribociclib (RIBO), a first-line treatment for hormone receptor-positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) advanced breast cancer, is an inhibitor of CYP3A4, P-gp, and BCRP. Given the potential for these drugs to be co-administered in clinical settings, there is limited information regarding the pharmacokinetic drug-drug interactions (DDIs) between ribociclib and these anticoagulants. This study aimed to evaluate the extent of DDIs between ribociclib and rivaroxaban or apixaban in rats and to explore the optimization of drug dosing strategies.

Methods

Male Sprague-Dawley rats were divided into 9 groups (n = 6), receiving ribociclib, apixaban, rivaroxaban, ribociclib with rivaroxaban, ribociclib with apixaban, and combinations with reduced doses and time intervals. Blood concentrations were measured using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Pharmacokinetic parameters such as AUC, Cmax, CLz/F, and Vz/F.

Results

Ribociclib significantly increased exposure to both rivaroxaban and apixaban, with a greater impact on rivaroxaban. Specifically, ribociclib increased the AUC0-t, AUC0-∞ and Cmax of rivaroxaban (normal dose) by about 2.4-fold, 2.1-fold and 1.8-fold, while increasing apixaban exposure by about 60.82%, with a trend towards an increase in Cmax that was not statistically significant. When co-administered with ribociclib, even at a reduced dosage of 1 mg/kg, rivaroxaban exhibited a significant increase in exposure, with the AUC increasing by 2.3-fold and Cmax by 1.3-fold. Despite the reduction in dosage, the pharmacokinetic effect of ribociclib on rivaroxaban persisted. While administration of rivaroxaban 12 h after ribociclib resulted in a less pronounced increase in exposure compared to the normal-dose group. The results of qRT-PCR showed that ribociclib reduced the expression of Cyp3a1 and Abcg2 in rat intestine.

Discussion

This research highlights the need for careful consideration of dosing regimens to minimize toxicity risk and optimize the safety of clinical co-administration of ribociclib with rivaroxaban.

Rapid Determination of Xa Inhibitor Activity in Blood Using a Microfluidic Device that Measures Platelet Deposition and Fibrin Generation Under Flow

Background

Patients taking direct oral anticoagulants (DOACs) often present complicated scenarios following major bleeding, stroke, or emergency surgery. Rapid whole blood assays of DOAC levels would aid clinical decisions such as the need for DOAC reversal.

Methods

We developed a single-use, storage-stable, eight-channel microfluidic device to estimate factor Xa (FXa) inhibitor (apixaban or rivaroxaban) levels in venous thromboembolism or atrial fibrillation patients. The assay simultaneously measured whole blood clotting dynamics on collagen/tissue factor (TF; wall shear rate, 200 -1 ) under four ex vivo conditions: no-treatment control, high dose Factor Xa inhibition, low dose or high dose FXa reversal agent (andexanet alfa). Fibrin and platelet deposition dynamics were monitored via two-color epifluorescence microscopy. Plasma samples were also evaluated by LC-MS/MS for DOAC concentrations.

Results

Experiments with healthy volunteer blood spiked with DOAC verified device performance (DOAC IC 50 ∼120 nM) and confirmed that andexanet alfa added to healthy donor blood had no off-target effect on platelet or fibrin signal. Patient whole blood monitored for 15 to 25 minutes (17 minutes mean runtime) allowed calculation of functional DOAC concentrations ranging from 2 to 500 nM that correlated well with LC-MS/MS determination of apixaban or rivaroxaban (R 2  = 0.7 or 0.9, respectively). Platelet dysfunction was not observed in any patient on DOAC. For a threshold of 100 nM DOAC, the area under the curve (AUC) was found to be 0.881 for apixaban and 0.933 for rivaroxaban.

Conclusion

Microfluidic testing of whole blood can provide a rapid estimate of DOAC levels over the on-therapy range.

In vitro Assessment of Drug Adsorption Profiles during Hemoadsorption Therapy

INTRODUCTION

The use of hemoadsorption devices is increasingly gaining impact as an adjunct therapy for various critical conditions in ICU patients, including systemic hyperinflammation, cytokine release syndrome, sepsis, and more. A key concern in this therapy is its impact on the plasma levels of concurrently administered drugs, which could potentially be reduced to subtherapeutic levels, affecting patient care. The present study investigates the adsorption behavior of various drugs in an in vitro hemoadsorption model using human whole blood, aiming to provide insights for optimizing drug dosing during hemoadsorption therapy.

METHODS

The study assessed the removal rates and clearances of several drugs, namely, apixaban, argatroban, carbamazepine, oxcarbazepine, lamotrigine, phenytoin, valproate, levosimendan, methylene blue, and metformin, by circulating the blood through CytoSorb adsorbers in an in vitro setup.

RESULTS

Significant removal (75 to 100% of the initial concentration) and high initial plasma clearances (approximately 10-25 mL/min) were observed for most of the tested drugs within the first 30-60 min of recirculation. Lower removal rates and clearances were noted for valproate (approximately 40% and 5 mL/min) and metformin (approximately 15% and 1 mL/min).

CONCLUSION

The findings indicate considerable differences in the adsorption of the tested drugs and should be confirmed by additional in vivo studies with careful monitoring of drug levels throughout the course of therapy. Understanding the in vivo dynamics is crucial for adjusting dosages appropriately during hemoadsorption use to ensure therapeutic efficacy and patient safety.

Physiologically Based Biopharmaceutics Model of Apixaban for Biopharmaceutics Risk Assessment

Background/Objectives: This study applies a Physiologically Based Biopharmaceutics Modeling (PBBM) framework to predict the bioavailability (BA) and bioequivalence (BE) of apixaban, a borderline BCS Class III/IV drug. It investigates how formulation factors, such as particle size, granulation method, and dissolution conditions, affect apixaban's in vivo behavior under fasting conditions. Methods: A PBBM approach was developed by integrating physicochemical, formulation, and drug-related parameters to simulate dissolution and absorption using a middle-out strategy for combining in silico, in vitro, and in vivo data. The Noyes-Whitney equation was used to predict dissolution influenced by particle size, granulation type, and in vitro dissolution conditions. This information was added to a compartmental absorption model of the gastrointestinal track connected to a classical compartmental model characterizing apixaban's disposition. Results: The study validated the apixaban PBBM predictions by comparing simulated and observed pharmacokinetic profiles across several doses and immediate release formulations (solution and tablets) administered through the oral route. Results demonstrated acceptable prediction accuracy for BA and BE under various conditions. The model's simulations identified a dissolution safe space, enabling regulatory and development insights into acceptable formulation characteristics. Conclusions: These findings highlight the potential of PBBM in streamlining drug development, reducing clinical studies, and supporting regulatory decisions. Specifically, for apixaban, the study demonstrated that particle sizes below 120 µm ensure BE with reference formulations, while formulations with faster dissolution rates, such as smaller particle sizes, align closely with BCS biowaiver criteria. This research emphasizes PBBM as a valuable tool for optimizing drug quality and lifecycle management.

Hemorrhage risk associated with triple antithrombotic therapy: a focused real-world pharmacovigilance disproportional analysis study

BACKGROUND

Triple antithrombotic therapy (TAT), combining dual antiplatelet therapy (DAPT) with oral anticoagulants, is commonly used in patients requiring long-term anticoagulation following acute coronary syndrome or percutaneous coronary intervention. However, TAT may increase the risk of hemorrhage. There is a dearth of data regarding the risks of bleeding with various oral anticoagulants in TAT in comparison with DAPT and individual anticoagulants and antiplatelets due to which we carried out the present study examining the real-world pharmacovigilance data.

METHODS

Data were extracted from the USFDA Adverse Event Reporting System (AERS) from March 2004 to June 2024 using the Standardized MedDRA Query (SMQ) code for "haemorrhages." We employed the "case-non-case" approach in disproportionality analysis to detect safety signals for hemorrhage among anticoagulant, antiplatelet, dual antiplatelet and triple antithrombotic combinations. Reports including combinations of DAPT (acetylsalicylic acid and clopidogrel) with oral anticoagulants (acenocoumarol, apixaban, dabigatran, edoxaban, rivaroxaban, and warfarin) were analyzed. Signal detection used both frequentist (reporting odds ratio [ROR], proportional reporting ratio and Bayesian (Bayesian Confidence Propagation Neural Network, Multi-Item Gamma Poisson Shrinker algorithms. The lower limit of 95% confidence interval of ROR above 1 indicates higher reporting risk of bleeding. Following outcomes were evaluated for each TAT: death, disability and hospitalization.

RESULTS

Of 20,626 unique reports, 812 involved TAT, 3,820 DAPT, and 15,995 individual antiplatelets. Most cases occurred in elderly patients (age ≥ 65 years) with a predominance of male patients. Rivaroxaban combined with DAPT presented the highest hemorrhage signal (ROR: 82.84; 95% CI, 60.77-112.92), while apixaban showed the lowest (ROR: 13.11; 95% CI, 9.39-18.3) and the other anticoagulants are as follows: warfarin (ROR: 15.96; 95% CI: 18.36), dabigatran (ROR: 27.32; 95% CI: 20.03-37.26) and acenocoumarol (ROR: 43.98; 95% CI: 17.21-112.4). Mortality and hospitalization rates varied significantly among treatments, with rivaroxaban linked to the highest mortality.

CONCLUSION

This study highlights the elevated hemorrhage risk associated with TAT, particularly with rivaroxaban, while apixaban appears safer in terms of bleeding and mortality. These findings underscore the need for cautious monitoring of bleeding outcomes with anticoagulant regimens, particularly rivaroxaban combinations for optimizing patient outcomes. However, the signals obtained in this study need to be validated in future trials.

Bleeding Complications Following Paracentesis in Patients Taking Apixaban

Background Both ascites and thrombosis are common complications of liver disease. Abdominal paracentesis to drain ascites has a low reported risk of hemorrhage, but it is unknown how exposure to direct oral anticoagulants (DOACs) such as apixaban increases this risk. Objectives We aim to quantify the rate of major bleeding and identify additional risk factors for bleeding in patients on apixaban undergoing paracentesis. Methods We performed a retrospective cohort study for all patients exposed to apixaban within seven days prior to paracentesis at a single US academic hospital between January 1, 2016, and April 1, 2022. Abstracted data included the presence or absence of hemorrhagic complications, dosing and timing of apixaban administration, and patient comorbidities. Results We identified 365 paracenteses in 91 unique patients. There were 20 (5.5%) reported hemorrhages, nine (2.5%) of which were plausibly related to the procedure. Four (1.1%) patients suffered fatal hemorrhage. Patients taking 10 mg twice daily of apixaban (3/8, 38%), co-prescription of apixaban with more than one additional antiplatelet or anticoagulant (3/16, 19%), apixaban taken within six hours of the procedure (6/37, 16%), and inpatient status (8/158, 5.1%) were associated with bleeding. While internal medicine residents (3/38, 7.9%) had a higher rate of hemorrhage than interventional radiologists (6/289, 2.1%), this difference was negligible when restricted to inpatients (3/38 versus 5/100). Conclusions The rate of bleeding after paracentesis for patients taking apixaban was much higher than historical estimates. Apixaban exposure, especially on high doses, within six hours of the procedure or on additional anticoagulant medications, significantly increases the rate of hemorrhagic complications of paracentesis.

Optimizing Anticoagulation Strategies in Patients With Atrial Fibrillation and Valvular Heart Disease: A Comprehensive Evidence-Based Review

Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, significantly increases the risk of thromboembolism and stroke. Its coexistence with valvular heart disease (VHD) further complicates management due to elevated risks of thromboembolism, bleeding, and mortality. This review explores the pathophysiology of AF and its interaction with VHD, focusing on diagnostic tools like echocardiography and risk stratification scores such as CHA2DS2-VASc and HAS-BLED. Vitamin K antagonists (VKAs) remain the cornerstone of anticoagulation therapy in high-risk VHD populations, particularly in patients with mechanical heart valves or moderate-to-severe mitral stenosis (MS). VKAs have demonstrated proven efficacy in reducing thromboembolic events in these subgroups, supported by decades of clinical evidence. However, their use requires frequent international normalized ratio (INR) monitoring and is associated with higher bleeding risks, posing challenges in long-term management. Despite these limitations, VKAs are indispensable in these populations due to the lack of robust evidence supporting the safety and efficacy of direct oral anticoagulants (DOACs) in these high-risk groups. Ongoing clinical trials, such as the RIVER trial, aim to evaluate the role of DOACs in VHD. However, current guidelines continue to recommend VKAs as the standard of care for these patients. In contrast, DOACs offer significant advantages in non-valvular AF and selected VHD populations. Their predictable pharmacokinetics, fewer dietary restrictions, and lower risks of intracranial hemorrhage make them a preferred choice for many patients. Landmark trials and meta-analyses, including RE-LY, ROCKET-AF, and ARISTOTLE, have demonstrated the safety and efficacy of DOACs in non-valvular AF and certain VHD subgroups. However, DOACs are contraindicated in high-risk VHD populations, such as those with mechanical valves or moderate-to-severe MS, due to insufficient evidence and potential risks of thromboembolic events. Evolving guidelines from leading societies emphasize individualized approaches and collaborative decision-making in anticoagulation therapy. While DOACs are preferred for most AF patients, VKAs remain essential for high-risk VHD patients. Future advancements, such as factor XIa inhibitors, hold promise for improving outcomes and safety in these complex populations. This review provides a comprehensive framework for clinicians to navigate the complexities of anticoagulation in AF and VHD, ensuring evidence-based, patient-centered care.

Unveiling the role of sex in the metabolism of indoxyl sulfate and apixaban

Chronic Kidney Disease (CKD) is associated with heightened risk of thrombosis. Prescription of anticoagulants is key to manage it; however, CKD patients have shown an increased risk of bleeding under anticoagulation therapy compared to non-CKD patients. We hypothesized that the sex could modify the metabolism of indoxyl sulfate (IS), a uremic toxin and Apixaban. Our intoxication model shows that higher doses of IS and apixaban accumulate in the plasma of female mice because of expression differences in efflux transporters and cytochromes in the liver, ileum and kidneys, when compared to males. Furthermore, we found that accumulation of apixaban in females contributes to increased bleeding. Transcriptional analysis of liver samples revealed elevated Sult1a1 but reduced Abcg2 and Cyp3a11 in female mice, while in the kidneys the expression rates of Oat1 and Oat3 were respectively lower and higher than those observed in males, potentially affecting drug clearance. Whole proteomics liver analysis confirmed the previous transcriptional results at the protein level and revealed that sex had a major influence in regulating both coagulation and drug metabolism pathways. Thus, our findings underline the need for inclusive clinical and preclinical trials to accurately reflect sex-specific metabolic variations, and to consider CKD-specific changes to optimize dosing, minimize side effects, and improve patient outcomes.

New oral anticoagulants-induced spinal epidural haematomas: case series and review of literature

Spontaneous spinal epidural haematoma (SSEH) is a rare cause of acute spinal cord compression. This condition is often associated with use of anticoagulant drugs, coumarins or new oral anticoagulants, such as direct factor Xa inhibitor and direct thrombin inhibitor. The manifestation of severe neurological deficits is common and can lead to catastrophic consequences if not diagnosed early. Standard therapy is decompressive laminectomy, although spontaneous recoveries have been reported. Due to the rarity of this pathologic entity, only sporadic case reports and associated reviews are available. We report a case series of 4 patients diagnosed with spontaneous spinal epidural haematoma induced by new oral anticoagulants. Spontaneous spinal haematoma is a rare pathologic entity and therefore difficult to diagnose. For patients receiving long term anti-coagulant therapy, SSEH should be included in the differential diagnosis. Prompt surgical evacuation of the haematoma and haemostasis leads to favourable neurological outcome, whereas delay in treatment can be disastrous.

Effect of furmonertinib on the pharmacokinetics of rivaroxaban or apixaban in vivo

Furmonertinib, a third generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), is used for non-small cell lung cancer (NSCLC). Rivaroxaban and apixaban are direct oral anticoagulants (DOACs) used for venous thromboembolism (VTE), which is a frequent comorbid with NSCLC. They are substrates of CYP3A4, P-gp and BCRP, whereas furmonertinib is an inhibitor of P-gp and BCRP. This study aimed to disclose the extent of effect of furmonertinib on the pharmacokinetics of rivaroxaban or apixaban. Rats were divided into four groups (n = 6) that received rivaroxaban (group 1), furmonertinib and rivaroxaban (group 2), apixaban (group 3), furmonertinib and apixaban (group 4). The concentrations of drugs were measured by an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Furmonertinib increased the Cmax and AUC0-t of rivaroxaban by 1.66 and 2.07-fold, whereas decreased the CLz/F by 1.70-fold and Vz/F 1.27-fold. Furthermore, furmonertinib caused similar changes in apixaban pharmacokinetics. The pharmacokinetic results suggest that it is essential to alert the effect of furmonertinib on the pharmacokinetics of rivaroxaban or apixaban in clinical practice.

Dispersive solid phase extraction of apixaban from human plasma samples prior to capillary electrophoresis determination using zirconium-based metal organic frameworks prepared by different modulator and solvent

Here, a zirconium-based metal organic framework-dispersive solid phase extraction method was established as an efficient, robust, and accurate approach for quantifying apixabanin human plasma samples prior to capillary electrophoresis with diode array detection. Various types of metal organic frameworks based on UiO-66-NH2 were synthesized by altering modulators and solvents and applied as sorbents in the extraction procedure. Among the tested sorbents, UiO-66-NH2 prepared in dimethylformamide in the presence of acetic acid was found to be the best sorbent in this method for the extraction of apixaban with high extraction efficiency comparable to other types of UiO-66-NH2 metal organic frameworks. The extraction and preconcentration of apixaban were carried out by adding 5 mg of synthesized sorbent to a 5 mL sample solution, followed by vortexing for 3 min. After discarding the supernatant, the adsorbed analyte was eluted from the sorbent surface using 60 µL acetonitrile under vortexing for 2 min. The effective parameters of the offered method were optimized and validated using a one-parameter-at-a- time strategy. The detection and quantification limits of the method were 9.9 and 32 ng mL-1 in plasma and 1.5 and 4.9 ng mL-1 in deionized water, respectively. The method was linear ranging from 4.9 to 1000 ng mL-1 in deionized water and from 32 to 500 ng mL-1 in plasma, respectively. The enrichment factor and extraction recovery values were 44 % and 53 %, respectively. The relative standard deviations were ≤6.2 % for intra- and inter-day precisions. Finally, the proposed method was successfully employed to quantify apixaban in human plasma samples.

Effectiveness and Safety of Dose-Specific DOACs in Patients With Atrial Fibrillation: A Systematic Review and Network Meta-Analysis

Background: Dose adjustments of direct-acting oral anticoagulants (DOACs) for atrial fibrillation are based on pivotal clinical trials assessing their effectiveness and safety in controlled settings. However, the appropriateness of these dosing strategies in real-world practice is uncertain. The purpose of this study is to compare the effectiveness and safety of dose-specific DOACs with those of warfarin. Methods: This study retrieved articles from MEDLINE, Embase, and CENTRAL until March 5, 2024. Primary outcomes were the incidence of stroke/systemic embolisms (S/SEs) and major bleeding (MB). Direct pairwise meta-analyses compared each dose-specific DOAC with warfarin. Heterogeneity was assessed using Higgin's I 2 and Q statistics, while publication bias was evaluated through funnel plots and Begg's and Egger's tests, with adjusted pooled estimates calculated via trim-and-fill and precision-effect estimate with standard error (PET-PEESE) methods. A network analysis was conducted, with additional comparisons made using a Bayesian random-effects model for indirect evidence. Results: A total of 32 studies with 2,332,770 patients were included. Both standard-dose (SD) and low-dose (LD) DOACs significantly reduced S/SE, except for LD apixaban and LD edoxaban. Rivaroxaban did not show significant difference in MB compared to warfarin. In East Asian patients, all doses of DOACs exhibited lower hazard ratios (HRs) for S/SE and MB than those observed in the primary analysis, with LD rivaroxaban significantly reducing MB, a finding not observed in the primary analysis. Rank probability analysis indicated that the dose-specific DOACs had different safety profiles and small but meaningful differences in effectiveness. SD apixaban (S/SE: second, MB: second) and edoxaban (S/SE: first, MB: fourth) and LD edoxaban (S/SE: fourth, MB: first) had high ranks. LD apixaban had the most significant difference in rank for S/SE from SD apixaban, ranking eighth compared to second. Conclusions: This study found that all DOACs provided comparable or superior effectiveness and safety to warfarin. SD apixaban, SD edoxaban, and LD edoxaban achieved a favorable balance between preventing S/SE and MB risk.

Formulation Optimization and Characterization of Solid Lipid Nanoparticles of Apixaban

BACKGROUND

Unpredictable situations such as clotting of blood, deep vein thrombosis, and pulmonary embolism arise in the body, which is the leading cause of mortality. Such conditions generally arise after surgery as well as after treatment with oral anticoagulant agents. Apixaban is a novel oral anticoagulant widely recommended for the prevention and treatment of strokes and blood clots suffering from nonvalvular atrial fibrillation by suppressing factor Xa. Apixaban has a log P of 2.71 with poor solubility and reported maximum bioavailability of approximately 50%.

OBJECTIVE

Hence, the current research mainly focused on the improvement of solubility, bioavailability, and therapeutic efficacy of Apixaban via solid lipid nanoparticles (SLN).

METHODS

The SLN was developed using the hot-homogenization method using a high-pressure homogenizer. The drug-lipid compatibility study was assessed by the FTIR, and the thermal analysis was performed using differential scanning calorimetry (DSC). During the scrutiny of lipids, the highest solubility of Apixaban was estimated in the glyceryl monostearate, hence selected for the formulation. Moreover, the colloidal solution was stabilized by the polyethylene glycol 200. The Design of Expert software (Version 13, Stat-Ease) was implemented for the optimization analysis by considering the 3-independent factors and 2-dependent parameters. The Patents on the SLN are Indian 202321053691, U.S. Patent, 10,973,798B2, U.S. Patent, U.S. Patent 2021/0069121A1, U.S. Patent 2022/0151945A1.

RESULTS

Box-Behnken design was applied along with ANOVA, which showed a p-value less than 0.05 for the dependent parameters such as particle size and entrapment efficiency (p-value: 0.0476 and 0.0379). The optimized batch F10 showed a particle size of 167.1 nm, -19.5 mV zeta potential, and an entrapment efficiency of 87.32%. The optimized batch F10 was lyophilized and analyzed by Scanning electron microscopy (SEM), which showed a particle size of 130 nm. The solid powder was filled into the capsule for oral delivery.

CONCLUSION

The marked improvement in solubility and bioavailability was achieved with F10- loaded Apixaban via Solid lipid nanoparticles. Moreover, the sustained released profile also minimizes the unseen complications that occur due to the clotting of blood.

The Influence of High Body Mass Index (BMI > 35 kg/m2) on Apixaban Plasma Concentration in Patients with Atrial Fibrillation

PURPOSE

Apixaban, a direct oral anticoagulant is administered for stroke prevention in atrial fibrillation patients. Dosing adjustment is guided by renal function, age, and body weight. However, no data exist on its pharmacokinetics in patients with a body mass index (BMI) ≥ 35 kg/m2. The aim was to investigate the effects of BMI ≥ 35 kg/m2 on trough plasma concentrations of apixaban in patients with atrial fibrillation.

METHODS

This prospective study compared steady-state trough concentrations of apixaban in patients with a BMI ≥ 35 kg/m2 and patients with a BMI < 35 kg/m2.

RESULTS

Sixty patients were included. In patients receiving 5 mg apixaban twice daily, the median trough plasma concentration was 29% lower in patients with a BMI ≥ 35 kg/m2 than in those with a BMI < 35 kg/m2 (148.9 ng/ml, interquartile range [IQR] 94.5-205.6, compared to 209.1 ng/ml, IQR 167-266.8 ng/ml, respectively; P = 0.044). However, median trough concentrations fell within the manufacturer's predicted range for effective steady-state apixaban exposure. A similar trend was observed with 2.5 mg apixaban twice daily, although statistical significance was not reached. Multivariate analysis revealed no correlation between BMI values and trough concentrations.

CONCLUSION

BMI ≥ 35 kg/m2 patients exhibited lower apixaban trough concentrations, while remaining within the manufacturer's established range for effective steady-state apixaban, suggesting that dose adjustment is unnecessary for this specific patient group.

Direct Oral Anticoagulants in Patients With ESRD and Kidney Transplantation

Direct oral anticoagulant (DOAC) use has significantly increased because major medical organizations endorse their role for conditions in which anticoagulation is indicated. Owing to important pharmacokinetic properties, the use of apixaban and rivaroxaban requires careful consideration in at-risk populations such as those with kidney disease. Both apixaban and rivaroxaban undergo some degree of renal elimination, and thus total drug exposure is increased in patients with renal insufficiency and/or those undergoing renal replacement therapy (RRT). The available clinical trial and real-world data in this population suggests that apixaban is likely at least comparably effective as warfarin at preventing thromboembolic events and is likely safer when evaluating bleeding risk. Rivaroxaban data is more limited, and the reported results are more discordant. Both apixaban and rivaroxaban have been used successfully in patients with end-stage renal disease (ESRD) undergoing kidney transplant listing as well as in the posttransplant setting. Prospective clinical trials evaluating the safety and efficacy of apixaban and rivaroxaban in various conditions where anticoagulation is indicated should include patients with ESRD and kidney transplant recipients to help further define the role that these important novel agents should play in these complex patient populations.

Spinal Anesthesia in Elderly Patients With Femoral Neck Fractures on Apixaban Therapy: A Case Series

This case series reviews surgeries involving elderly patients with femoral neck fractures on apixaban who underwent spinal anesthesia (SA) within 72 hours of their last dose. Despite patients being on anticoagulation, no neurological complications occurred, suggesting SA may be practical in cases where the benefits of timely surgery outweigh the potential risks, including apixaban discontinuation for a period of less than the recommended 72 hours with detectable levels of the drug remaining in the plasma. Quantitative apixaban measurements offered useful anticoagulation status insights, though safe thresholds remain undefined.

Comparison of Apixaban and Aspirin in Preventing Portal Vein Thrombosis after Laparoscopic Splenectomy for Cirrhotic Hypersplenism

BACKGROUND

 Portal vein system thrombosis (PVST) is a frequent and possibly fatal concurrent disorder following splenectomy. The optimal anticoagulant to prevent PVST following splenectomy remains unclear.

OBJECTIVES

 The purpose of this study was to compare the safety and efficacy of apixaban versus aspirin in preventing PVST after laparoscopic splenectomy (LS) for cirrhotic hypersplenism.

METHODS

 In this single-center randomized controlled trial, 80 patients with liver cirrhosis who received LS were randomly allocated to two treatment arms that were treated with apixaban or aspirin for 6 months. The primary effectiveness outcome was PVST formation after LS.

RESULTS

 We excluded four patients who withdrew from the study. The dynamic incidence of PVST, main and intrahepatic branches of PVST, and splenic vein thrombosis in the 6 postoperative months were all significantly lower in the apixaban treatment arm compared to the aspirin treatment arm (all P <0.001). Significantly lower incidences of PVST, main and intrahepatic branches of PVST, and splenic vein thrombosis in apixaban treatment arm started from postoperative day 7, month 1, and day 7 compared to the aspirin treatment arm respectively (all P <0.05). Multiple logistic regression analysis revealed that apixaban was an independent protective factor for PVST at postoperative month 3, as compared with aspirin (relative risk, 0.057; 95% confidence interval, 0.013-0.248; P <0.001).

CONCLUSION

 Compared with aspirin, apixaban could earlier and more effectively prevent PVST following LS for cirrhotic hypersplenism. Apixaban can be chosen as a priority treatment option versus aspirin, contributing to a lower risk of PVST.

Using the AQbD Approach, Development and Validation of a Simple, Rapid Stability Indicating Chromatographic Method for Quantification of Related Impurities of Apixaban

Apixaban is a new oral anticoagulant that has been approved by the United States Food and Drug Administration for the prevention of stroke and other cardiovascular complications in people with non-valvular atrial fibrillation. Then, later, it was given the green light to treat deep venous thrombosis and pulmonary embolism. The biggest challenge in the development of pharmaceutical drugs is comprehending science- and risk-based techniques for developing and maintaining analytical procedures appropriate for evaluating the quality of drug substances and drug products. The improved technique provides a methodical strategy to acquire and improve understanding of an analytical method. The current study discusses the related substances method development for an apixaban drug substance employing a regulated authority refined and approved approach of the quality-by-design concept. For the quantification of impurities, and apixaban drug substance, a simple, quick and stability-indicating reverse-phase liquid chromatographic method was developed using a full factorial design. The separation between apixaban and its nine impurities was accomplished using an Zorbax Stable Bond Phenyl, 150 × 4.6 mm, 5 μm column. The mobile-phase components for gradient elution at a flow rate of 1.2 mL/min were chosen to be a mixture of water, acetonitrile, methanol and perchloric acid in various ratios with a total run time of 15 min. Chromatograms were extracted at 278 nm after a 5 μL solution injection. According to regulatory requirements, the developed method has been validated for its intended purpose.

Safety and efficacy of apixaban versus vitamin K antagonists in patients undergoing dialysis: a systematic review and meta-analysis

BACKGROUND

This review aims to evaluate the safety and efficacy of apixaban vs. vitamin K antagonists (VKAs) in patients on dialysis.

METHODS

All types of studies published on PubMed, Embase, CENTRAL, and Web of Science up to 10 September 2023 and comparing outcomes of apixaban vs. VKA in dialysis patients were eligible.

RESULTS

Two randomized controlled trials (RCTs) and six retrospective studies were included. Apixaban treatment was associated with significantly lower risk of major bleeding (RR: 0.61; 95% CI: 0.48, 0.77; I2 = 50%) and clinically relevant non-major bleeding (RR: 0.82, 95% CI: 0.68, 0.98, I2 = 9%) compared to VKA. Meta-analysis also showed that the risk of gastrointestinal bleeding (RR: 0.74, 95% CI: 0.64, 0.85, I2 = 16%) and intracranial bleeding (RR: 0.64, 95% CI: 0.49, 0.84, I2 = 0%) was significantly reduced with apixaban. Meta-analysis showed no difference in the risk of ischemic stroke (RR: 0.40, 95% CI: 0.06, 2.69, I2 = 0%), mortality (RR: 1.26, 95% CI: 0.74, 2.16, I2 = 94%) and recurrent venous thromboembolism (RR: 1.02, 95% CI: 0.87, 1.21, I2 = 0%) between the two groups. Subgroup analysis of RCTs showed no difference in bleeding outcomes.

CONCLUSIONS

Low-quality evidence from a mix of RCTs and retrospective studies shows that apixaban may have better safety and equivalent efficacy as compared to VKA in dialysis patients. Apixaban treatment correlated with significantly reduced risk of major bleeding and clinically relevant nonmajor bleeding in observational studies but not in RCTs. The predominance of retrospective data warrants caution in the interpretation of results.

Apixaban removal during emergency surgery for type A acute aortic dissection: a prospective cohort study

BACKGROUND

Acute type A aortic dissection (ATAAD) has a high mortality, and acute aortic repair is the only curative treatment. In patients treated with factor Xa (FXa) inhibitors, the risk of severe disease-related complications such as cardiac tamponade and hemodynamic shock must be balanced against the potential for severe perioperative bleeding. The aim was to study intraoperative changes in plasma levels of the FXa inhibitor apixaban when using hemoadsorption during acute thoracic aortic repair.

MATERIALS AND METHODS

This is a single-center prospective cohort study. Eight apixaban-treated patients presenting with ATAAD underwent acute thoracic aortic repair with intraoperative hemoadsorption with CytoSorb. Apixaban concentrations were measured at the start of cardiopulmonary bypass (CPB) and after 5, 15, 30, 60, and 90 min of CPB, at CPB weaning, 30 min after CPB weaning and 24 h postoperatively, using ultraperformance liquid chromatography-mass spectrometry (UPLC-MS).

RESULTS

After 30 min of CPB with hemoadsorption, mean apixaban concentration (±SD) was reduced by 59% from 108 (±69) µg/l to 44 (±20) µg/l (P=0.009). There was a further reduction to 37 (±17) µg/l at CPB weaning (P=0.008). Apixaban concentration displayed an increase to 56 (±29) µg/l 24 h postoperatively (P=0.01). In-hospital mortality was 25%. The mean 24H chest tube drainage volume was 621 (±136) ml.

CONCLUSION

Intraoperative hemoadsorption lowers apixaban levels in patients undergoing emergency surgery for ATAAD. Further research is needed to determine its impact on perioperative bleeding complications and mortality.

Comparison of the pharmacokinetics and pharmacodynamics of apixaban and rivaroxaban in dogs

BACKGROUND

Comparative pharmacokinetics and pharmacodynamics (PK/PD) of apixaban and rivaroxaban have not been studied in dogs and the propensity of these drugs to cause hypercoagulability after discontinuation is unknown.

HYPOTHESIS

Compare the PK/PD of clinical dosing regimens of PO apixaban and rivaroxaban administered repeatedly to healthy dogs and assess the effect of abrupt drug discontinuation on coagulation.

ANIMALS

Six University-owned, purpose-bred, middle-aged, mixed-breed dogs (4 male, 2 female).

METHODS

Dogs were given apixaban or rivaroxaban PO at 0.5 mg/kg q12h for 7 days with a 14-day washout period between drugs. Plasma drug concentrations were quantitated, and anticoagulant effects were measured using clotting times, calibrated anti-Xa bioactivity assays, and measurements of thrombin generation. The potential for rebound hypercoagulability was assessed by measuring D-dimers, thrombin-antithrombin (TAT) complexes, and antithrombin activity after drug discontinuation.

RESULTS

Plasma drug concentrations and anti-Xa bioactivities were closely correlated for both drugs, but drug concentrations varied considerably among dogs, despite consistent dose regimens. Thrombin generation variables were significantly correlated with the anti-Xa bioactivity of both drugs and no significant differences in the effects of apixaban and rivaroxaban on thrombin generation were observed. Drug discontinuation had no effect on D-dimer concentrations. The concentration of TAT complexes decreased after apixaban discontinuation and did not change after rivaroxaban discontinuation.

CONCLUSIONS AND CLINICAL IMPORTANCE

Repeated PO administration of apixaban or rivaroxaban to healthy dogs produced comparable anticoagulant effects measured by inhibition of thrombin formation. Rebound hypercoagulability after drug discontinuation was not observed and weaning of these drugs in clinical patients might not be necessary.

Dependence of clot structure and fibrinolysis on apixaban and clotting activator

Background

Anticoagulants prevent the formation of potentially fatal blood clots. Apixaban is a direct oral anticoagulant that inhibits factor (F)Xa, thereby impeding the conversion of prothrombin into thrombin and the formation of blood clots. Blood clots are held together by fibrin networks that must be broken down (fibrinolysis) to restore blood flow. Fibrinolysis is initiated when tissue plasminogen activator (tPA) converts plasminogen to plasmin, which binds to and degrades a fibrin fiber. The effects of apixaban on clot structure and lysis have been incompletely studied.

Objectives

We aimed to study apixaban effects on clot structure, kinetics, and fibrinolysis using thrombin (low or high concentration) or tissue factor (TF) to activate clot formation.

Methods

We used a combination of confocal and scanning electron microscopy and turbidity to analyze the structure, formation kinetics, and susceptibility to lysis when plasma was activated with low concentrations of thrombin, high concentrations of thrombin, or TF in the presence or absence of apixaban.

Results

We found that the clotting activator and apixaban differentially modulated clot structure and lytic potential. Low thrombin clots with apixaban lysed quickly due to a loose network and FXa cleavage product's cofactor with tPA; high thrombin clots lysed faster due to FXa cleavage product's cofactor with tPA; TF generated loose clots with restricted lysis due to their activation of thrombin activatable fibrinolytic inhibitor.

Conclusion

Our study elucidates the role of apixaban in fibrinolytic pathways with different clotting activators and can be used for the development of therapeutic strategies using apixaban as a cofactor in fibrinolytic pathways.

Breaking boundaries: exploring recent advances in anticoagulation and thrombosis management: a comprehensive review

Background

Thromboembolic disorders globally contribute to morbidity and mortality, emphasizing adequate anticoagulation and thrombosis management. Therapeutic advances are essential in preventing complications like pulmonary embolism, stroke, and myocardial infarction. This review summarizes recent anticoagulation advances, current challenges, future directions, and novel anticoagulants and drug delivery systems on clinical outcomes.

Methods

This paper assesses the effectiveness and safety of new anticoagulants through a systematic review of recent clinical trials, meta-analyses, and guideline publications. Key studies, including PACIFIC-AF, RIVER, ENAVLE, ENVISAGE-TAVI AF, and ARCADIA, were analyzed to provide a perspective on therapeutic advancements.

Results

The review highlights key findings from vital clinical trials. Asundexian, in the PACIFIC-AF trial, demonstrated a 34% reduction in bleeding events compared to Apixaban. In the RIVER trial, Rivaroxaban reduced significant bleeding events by 20% compared to warfarin in patients with bioprosthetic mitral valves. In the ENAVLE trial, Edoxaban achieved a 3.7% decrease in thromboembolic events compared to warfarin without increasing significant bleeding rates. In the ENVISAGE-TAVI AF trial, edoxaban was noninferior to VKAs in preventing thromboembolic events but showed a slight increase in major bleeding events by 1.5%. Lastly, the ARCADIA trial highlighted that apixaban did not significantly reduce recurrent stroke risk compared to aspirin, with both treatments having an annualized stroke rate of 4.4%.

Conclusion

Advances in anticoagulant therapies and drug delivery systems aim to enhance patients' clinical outcomes for thromboembolic disorders. While recent trials show promising data, ongoing patient-specific responses and monitoring challenges require further research. Continuous innovation and investigation are essential to refine anticoagulation practices and tailor treatments.

An interactive dose optimizer based on population pharmacokinetic study to guide dosing of methotrexate in Chinese patients with osteosarcoma

PURPOSE

Osteosarcoma is a rare tumor with an incidence of 4.4 cases per million per year in adolescent. High-dose methotrexate (HD-MTX) is the standard first-line chemotherapeutic agent for osteosarcoma. However, its efficacy can vary significantly among individuals due to wide pharmacokinetic variability. Despite this, only a few population pharmacokinetics (popPK) models based on Chinese patients with osteosarcoma have been reported. Thus, this study aimed to develop a HD-MTX popPK model and an individual model-based dose optimizer for osteosarcoma therapy.

METHOD

A total of 680 MTX serum concentrations from 57 patients with osteosarcoma were measured at the end of MTX infusion and 10 h, 24 h, 48 h, and 72 h after the start of infusion. Using the first-order conditional estimation method with NONMEM, a popPK model was estimated. Goodness-of-fit plots, visual predictive checks, and bootstrap analysis were generated to evaluate the final model. A dose optimizer tool was developed based on the validated models using R Shiny. Additionally, clinical data from 12 patients with newly diagnosed osteosarcoma were collected and used as the validation set to preliminarily verify the predictive ability of the popPK model and the dose optimizer tool.

RESULTS

Body surface area (BSA) was the most significant covariate for compartment distribution. Creatinine clearance (CrCL) and co-administration of NSAIDs were introduced as predictors for central compartmental and peripheral compartmental clearance, respectively. Co-administration of NSAIDs was associated with significantly higher MTX concentrations at 72 h (p = 0.019). The dose optimizer tool exhibited a high consistency in predicting MTX AUC compared to the actual AUC (r = 0.821, p < 0.001) in the validation set.

CONCLUSION

The dose optimizer tool could be used to estimate individual PK parameters, and optimize personalized MTX therapy in particular patients.

Apixaban-Induced Esophagitis Dissecans Superficialis-Case Report and Literature Review

Novel direct oral anticoagulants (DOACs) are prescribed worldwide in the treatment of non-valvular atrial fibrillation. Adverse reactions have been reported following the use of DOACs. One notable trend in the literature is the growing number of reported cases of esophagitis dissecans superficialis (EDS) generated by DOAC use. We hereby report the case of a 73-year-old woman who presented to the hospital with asthenia, dysphagia, and melena two days prior to admission. The patient had taken apixaban due to non-valvular paroxysmal atrial fibrillation for a few weeks. The biological panel showed moderate anemia with a hemoglobin level of 7.7 g/dL Apixaban-induced EDS was diagnosed by the characteristic endoscopic findings. The patient received treatment with a proton pump inhibitor (pantoprazole) in a double dose. Also, an iron treatment was recommended for a period of six months. The follow-up endoscopy at one month confirmed the healing of the esophageal lesions. The case was discussed with the cardiologist. The first anticoagulant treatment proposed after discharge was a vitamin K antagonist (acenocumarol) but the patient refused this medication and thus it was decided to initiate rivaroxaban. Although DOACs have demonstrated their efficacy in the prevention and treatment of stroke and thromboembolism among the aging demographic, cases of DOAC-induced EDS will continue to pose numerous challenges for physicians worldwide.

Thin film microextraction of apixaban from plasma based on the covalent organic framework coated on a mesh prior to liquid chromatography-tandem mass spectrometry

In this research, a new covalent organic framework was synthesized and utilized as a coating in thin film microextraction for the extraction of apixaban from plasma samples. This coating was applied to the mesh modified through immersion in a HF solution. The extracted drug was then analyzed using liquid chromatography-tandem mass spectrometry. By combining the high specific surface area and selectivity of the covalent organic framework, along with integrating the innovative thin film microextraction method and a sensitive analysis system, an efficient analytical approach was achieved. The target analyte was preconcentrated and extracted by immersing of the covalent organic framework-coated mesh as an absorbent into the biological sample. Subsequently, a sonication process was conducted for a specific duration. Following this, the extracted analyte was desorbed using acetonitrile as the elution solvent. The effective parameters of the proposed technique were optimized by using "one-parameter-at-a-time" strategy and the optimal conditions were selected. By integrating the developed method notable achievements were made in the terms of low limits of detection and quantification (0.17 and 0.56 µg/L, respectively), a wide linear range (0.05-250 µg/L), intra- and inter day precisions (with relative standard deviations of ≤14 %), as well as satisfactory extraction recoveries (53 % and 54 % in plasma and deionized water, respectively). Hence, it can be concluded that the introduced technique exhibits high efficiency and reliability when applied to biological samples.

Apixaban dosing in hemodialysis - can drug level monitoring mitigate controversies?

BACKGROUND

Inconsistent study results and contradictory recommendations from health authorities regarding the use of apixaban in patients on hemodialysis have generated considerable uncertainty among clinicians, making investigations of appropriate dosing an unmet need.

METHODS

We analyzed pre-dialysis apixaban drug levels from a tertiary care dialysis unit, comparing 2.5 mg once versus twice daily dosing. We applied mixed-effects models including dialysis modality, adjusted standard Kt/V, ultrafiltration, and dialyzer characteristics. We included an exploratory analysis of bleeding events and compared the drug levels of our dialysis patients to those from non-CKD reference populations taking the standard dose of 5 mg twice daily.

RESULTS

We analyzed 143 drug levels from 24 patients. Mean (SD) age at first drug level measurement was 64.7 (15.9) years (50 % female), median (IQR) follow-up was 12.5 (5.5 - 21) months. For the apixaban 2.5 mg once and twice daily groups, median (IQR) drug levels were 54.4 (< 40 - 72.1) and 71.3 (48.8 - 104.1) ng/mL respectively (P < 0.001). Levels were below the detection limit in 30 % (with 2.5 mg once daily) and 14 % (with 2.5 mg twice daily) respectively. Only dosing group (twice versus once daily) was independently associated with higher drug levels (P = 0.002). Follow-up did not suggest accumulation. The 95th percentile of drug levels did not exceed those of non-CKD populations taking 5 mg twice daily. Median (IQR) drug levels before a bleeding (8 episodes) were higher than those without a subsequent bleeding: 111.6 (83.1 - 129.3) versus 54.8 (< 40 - 77.1) ng/mL (P < 0.001). Concomitant antiplatelet therapy was used in 86% of those with bleeding events versus 6% without bleeding events (P < 0.001).

CONCLUSIONS

Drug monitoring may be a contributory tool to increase patient safety. Despite non-existing target ranges, drug levels on both edges of the spectrum (e.g. below detectability or beyond the 95th percentiles of reference populations) may improve decision-making in highly individualized risk-benefit analyses.

Platelet Proteomics and Tissue Metabolomics Investigation for the Mechanism of Aspirin Eugenol Ester on Preventive Thrombosis Mechanism in a Rat Thrombosis Model

Platelet activation is closely related to thrombosis. Aspirin eugenol ester (AEE) is a novel medicinal compound synthesized by esterifying aspirin with eugenol using the pro-drug principle. Pharmacological and pharmacodynamic experiments showed that AEE has excellent anti-inflammatory, antioxidant, and inhibitory platelet activation effects, preventing thrombosis. However, the regulatory network and action target of AEE in inhibiting platelet activation remain unknown. This study aimed to investigate the effects of AEE on platelets of thrombosed rats to reveal its regulatory mechanism via a multi-omics approach. The platelet proteomic results showed that 348 DEPs were identified in the AEE group compared with the model group, of which 87 were up- and 261 down-regulated. The pathways in this result were different from previous results, including mTOR signaling and ADP signaling at P2Y purinoceptor 12. The metabolomics of heart and abdominal aortic tissue results showed that the differential metabolites were mainly involved in steroid biosynthesis, the citric acid cycle, phenylalanine metabolism, phenylalanine, tyrosine, and tryptophan biosynthesis, and glutathione metabolism. Molecular docking results showed that AEE had a better binding force to both the COX-1 and P2Y12 protein. AEE could effectively inhibit platelet activation by inhibiting COX-1 protein and P2Y12 protein activity, thereby inhibiting platelet aggregation. Therefore, AEE can have a positive effect on inhibiting platelet activation.

Modelling the effects of 4-factor prothrombin complex concentrate for the management of factor Xa-associated bleeding

The management of factor Xa (FXa) inhibitor-associated bleeding remains a clinical challenge. Massive bleeding is often associated with complex coagulopathy and, thus, the sole reversal of FXa inhibitors might not be sufficient to restore hemostasis, requiring instead a multimodal approach. Four-factor prothrombin complex concentrate (4F-PCC) is widely recognized as a viable treatment option for FXa inhibitor-associated bleeding. Here, we applied computational models to explore the effect 4F-PCC has on the coagulation cascade and restoration of thrombin generation in a system that simulates a patient that has received a FXa inhibitor. The coagulation model is largely based on a previously developed model with modifications incorporated from various other published sources. The model was calibrated and validated using data from a phase 3 clinical trial of vitamin K antagonist reversal with 4F-PCC. Using the parameters and initial conditions determined during the calibration and validation process, the prothrombin time (PT) test simulations predicted a PT of 11.4 seconds. The model successfully simulated the effects of rivaroxaban and apixaban on total thrombin concentration and showed that 4F-PCC increased thrombin generation in the presence of rivaroxaban or apixaban.

Efficient Generation of Protein Pockets with PocketGen

Designing protein-binding proteins is critical for drug discovery. However, the AI-based design of such proteins is challenging due to the complexity of ligand-protein interactions, the flexibility of ligand molecules and amino acid side chains, and sequence-structure dependencies. We introduce PocketGen, a deep generative model that simultaneously produces both the residue sequence and atomic structure of the protein regions where ligand interactions occur. PocketGen ensures consistency between sequence and structure by using a graph transformer for structural encoding and a sequence refinement module based on a protein language model. The bilevel graph transformer captures interactions at multiple scales, including atom, residue, and ligand levels. To enhance sequence refinement, PocketGen integrates a structural adapter into the protein language model, ensuring that structure-based predictions align with sequence-based predictions. PocketGen can generate high-fidelity protein pockets with superior binding affinity and structural validity. It operates ten times faster than physics-based methods and achieves a 95% success rate, defined as the percentage of generated pockets with higher binding affinity than reference pockets. Additionally, it attains an amino acid recovery rate exceeding 64%.

Real-World Use and Outcomes of Apixaban for Early Post-Surgical Fontan Thromboprophylaxis

Patients with Fontan physiology are at heightened risk of thrombosis related to passive venous return leading to increased stasis, as well as acquired thrombophilia from congestive hepatopathy. Variability exists for post-Fontan thromboprophylaxis, with no consensus on best practices. Direct oral anticoagulants offer advantages over conventional anticoagulants including fewer drug-drug interactions, no dietary restrictions, and less frequent monitoring. Herein, we report our single center experience utilizing apixaban thromboprophylaxis in children post-Fontan procedure. Single center, retrospective, cohort study evaluating apixaban thromboprophylaxis dosing strategies, efficacy, and safety in children admitted post-Fontan procedure at Boston Children's Hospital. Between September 2019 and December 2023, 62 children, median age 3.2 years (2.1-10.5 years), weight 13.9 kg (9.5-56.3 kg) received apixaban at a median of 93 days post-Fontan (7-1421 days). Over a total of 93 days of apixaban exposure, there was 1 treatment-related thrombosis event (0.07 per 1000 person-days on apixaban) and 3 combined treatment-related clinically relevant non-major (CRNM) and major bleeding events (0.22 per 1000 person-days on apixaban). Apixaban for post-Fontan thromboprophylaxis was feasible with low rates of bleeding and thrombosis.

Apixaban Use in Patients with Kidney Impairment: A Review of Pharmacokinetic, Interventional, and Observational Study Data

Chronic kidney disease (CKD) remains a significant global health issue and is a leading cause of mortality worldwide. Patients with CKD have an increased risk of developing atrial fibrillation (AF) and venous thromboembolism (VTE). While direct oral anticoagulants (DOACs) have become a standard of care for anticoagulation (AC) in patients with AF and VTE, the appropriate use of these agents in comorbid kidney impairment warrants detailed discussion. This scientific narrative review summarizes the effectiveness and safety of apixaban use in patients with renal dysfunction by assessing the current published pharmacokinetic, interventional, observational, and guideline data. Apixaban is a highly selective, orally active, direct inhibitor of factor Xa, with well-established pharmacokinetics and consistent clinical outcomes across a broad range of patient populations, including those with kidney impairment. Overall, the scientific literature has shown that apixaban has a favorable clinical efficacy and safety profile compared with vitamin K antagonists for patients with AF or VTE and comorbid kidney impairment. These data support the approved label dosing strategy of apixaban in reducing the risk of stroke/systemic embolism in patients with nonvalvular AF and in treating VTE across all ranges of kidney function. Both clinician experience and knowledge of patient-specific factors may be required in the management of comorbid patients with advanced CKD or those requiring dialysis, as data on these patients are limited.

Clinical Implications of Co-administering Apixaban with Key Interacting Medications

With many available data sources, clinicians need to consider the benefit-risk profile of individual anticoagulants when balancing the need for anticoagulation, including evaluating the risks in patients with comorbidities and potential drug-drug interactions. This narrative review presents clinical data across multiple phases of drug development for the use of apixaban, a selective factor Xa inhibitor, when taken concomitantly with other agents, and evaluates the benefit-risk profile of apixaban with these interacting medications. Key subgroup analyses from the phase 3 ARISTOTLE trial (NCT00412984) are presented using data from patients who received either concomitant inhibitors or inducers of cytochrome P450 3A4 and/or P‑glycoprotein. We also review the available evidence for the use of apixaban in patients with cancer-associated thromboembolism, as well as the use of apixaban in patients with COVID-19.

Is There an Alternative Oral Anticoagulation to Vitamin-K-Antagonists for Patients with Mechanical Aortic Valve Replacement? - A Literature Review

Current guidelines exclusively recommend vitamin-K-antagonists (VKA) as anticoagulation for patients after mechanical aortic valve replacement due to the increased postoperative risk of valve thrombosis and thrombo-embolism. Strict and regular assessments are mandatory during VKA therapy to ensure a potent anticoagulatory effect within the desired range. From the patients' perspective, VKA are associated with relevant interactions and side effects reducing the quality of life and contributing to a high number of patients not achieving the optimal therapeutic target. Direct oral anticoagulants (DOAC) have replaced VKA therapy in the past for several indications, e.g., atrial fibrillation. However, it is still unclear if DOACs could replace VKA therapy in patients after mechanical aortic valve replacement. While the PROACT-Xa study did not show a sufficient anticoagulatory effect of apixaban plus aspirin compared to VKA therapy in patients after mechanical aortic valve replacement, the direct thrombin inhibitor dabigatran and the oral factor Xa inhibitors apixaban and rivaroxaban showed promising results in comparable patient cohorts in smaller studies and case reports. Factor Xa inhibitors were able to prevent thrombosis and thrombo-embolic events in patients after mechanical aortic valve replacement. Therefore, factor Xa inhibitors or factor XI inhibitors could provide a potent alternative to VKA for patients after a mechanical aortic valve replacement.

Effects of the antitumor drugs adagrasib and asciminib on apixaban metabolism in vitro and in vivo

Apixaban is an oral anticoagulant that directly inhibits the target Factor Xa (FXa). In this study, we focused on the in vivo and in vitro effects of adagrasib and asciminib on apixaban metabolism, to discover potential drug-drug interactions (DDI) and explore their inhibitory mechanisms. The levels of apixaban and its metabolite, O-desmethyl-apixaban (M2), were determined by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). In vitro evaluation, the maximum half inhibitory concentration (IC50) of adagrasib in rat liver microsomes (RLM) and human liver microsomes (HLM) against apixaban was 7.99 μM and 117.40 μM, respectively. The IC50 value of asciminib against apixaban in RLM and HLM was 4.28 μM and 18.42 μM, respectively. The results of the analysis on inhibition mechanisms showed that adagrasib inhibited the metabolism of apixaban through a non-competitive mechanism, while asciminib inhibited the metabolism of apixaban through a mixed mechanism. Moreover, the interaction of apixaban with adagrasib and asciminib in Sprague-Dawley (SD) rats was also investigated. It was found that the pharmacokinetic characteristics of apixaban were significantly changed when combined with these two antitumor drugs, where AUC(0-t), AUC(0-∞), t1/2, Tmax, and Cmax were increased, while CLz/F was significantly decreased. But both drugs did not appear to affect the metabolism of M2 in a significant way. Consistent results from in vitro and in vivo demonstrated that both adagrasib and asciminib inhibited the metabolism of apixaban. It provided reference data for the future clinical individualization of apixaban.

Beyond Anticoagulation: A Comprehensive Review of Non-Vitamin K Oral Anticoagulants (NOACs) in Inflammation and Protease-Activated Receptor Signaling

Non-vitamin K oral anticoagulants (NOACs) have revolutionized anticoagulant therapy, offering improved safety and efficacy over traditional agents like warfarin. This review comprehensively examines the dual roles of NOACs-apixaban, rivaroxaban, edoxaban, and dabigatran-not only as anticoagulants, but also as modulators of inflammation via protease-activated receptor (PAR) signaling. We highlight the unique pharmacotherapeutic properties of each NOAC, supported by key clinical trials demonstrating their effectiveness in preventing thromboembolic events. Beyond their established anticoagulant roles, emerging research suggests that NOACs influence inflammation through PAR signaling pathways, implicating factors such as factor Xa (FXa) and thrombin in the modulation of inflammatory responses. This review synthesizes current evidence on the anti-inflammatory potential of NOACs, exploring their impact on inflammatory markers and conditions like atherosclerosis and diabetes. By delineating the mechanisms by which NOACs mediate anti-inflammatory effects, this work aims to expand their therapeutic utility, offering new perspectives for managing inflammatory diseases. Our findings underscore the broader clinical implications of NOACs, advocating for their consideration in therapeutic strategies aimed at addressing inflammation-related pathologies. This comprehensive synthesis not only enhances understanding of NOACs' multifaceted roles, but also paves the way for future research and clinical applications in inflammation and cardiovascular health.

Comparative Cardioprotective Effectiveness: NOACs vs. Nattokinase-Bridging Basic Research to Clinical Findings

The use of non-vitamin K antagonist oral anticoagulants (NOACs) has brought a significant progress in the management of cardiovascular diseases, considered clinically superior to vitamin K antagonists (VKAs) particularly in the prevention and treatment of thromboembolic events. In addition, numerous advantages such as fixed dosing, lack of laboratory monitoring, and fewer food and drug-to-drug interactions make the use of NOACs superior to VKAs. While NOACs are synthetic drugs prescribed for specific conditions, nattokinase (NK) is a natural enzyme derived from food that has potential health benefits. Various experimental and clinical studies reported the positive effects of NK on the circulatory system, including the thinning of blood and the dissolution of blood clots. This enzyme showed not only fibrinolytic activity due to its ability to degrade fibrin, but also an affinity as a substrate for plasmin. Recent studies have shown that NK has additional cardioprotective effects, such as antihypertensive and anti-atherosclerotic effects. In this narrative review, we presented the cardioprotective properties of two different approaches that go beyond anticoagulation: NOACs and NK. By combining evidence from basic research with clinical findings, we aim to elucidate the comparative cardioprotective efficacy of these interventions and highlight their respective roles in modern cardiovascular care.

Antithrombotic prophylaxis following total knee arthroplasty: a level I Bayesian network meta-analysis

INTRODUCTION

Venous thromboembolism (VTE) is a major concern following total knee arthroplasty (TKA). The optimal pharmacological prophylaxis remains, however, controversial. The present investigation compared several non-vitamin K antagonist oral anticoagulants commonly employed as VTE prophylaxis following TKA. A Bayesian network meta-analysis was conducted to compare apixaban, aspirin, dabigatran, edoxaban, enoxaparin, fondaparinux, and rivaroxaban. The outcomes of interest were to compare the rate of deep venous thrombosis (DVT), pulmonary embolism (PE), and major and minor haemorrhages.

METHODS

This study was conducted according to the PRISMA Extension Statement for Reporting of Systematic Reviews Incorporating Network Meta-Analyses of Health Care Interventions. In March 2024, PubMed, Web of Science, and Google Scholar were accessed with no time constraints. All randomised controlled trials (RCTs) comparing two or more drugs for the prevention of VTE following TKA were considered for inclusion.

RESULTS

Data from 29,678 patients were collected. Of them, 67% (19,884 of 29,678 patients) were women. The mean age of the patients was 66.8 ± 2.8 years, and the mean BMI was 29.2 ± 1.5 kg/m2. There was comparability in age, sex, and BMI at baseline. Apixaban 5 mg, dabigatran 220 mg, and rivaroxaban 10 mg were the most effective in reducing the rate of DVT. Apixaban 5 mg, enoxaparin 60 mg, and rivaroxaban 40 mg were the most effective in reducing the rate of PE. Apixaban 5 mg, rivaroxaban 10 mg, and apixaban 10 mg were associated with the lowest rate of major haemorrhages. Apixaban 5 mg and 20 mg, and dabigatran 220 mg were associated with the lowest rate of minor haemorrhages.

CONCLUSION

Administration of apixaban 5 mg demonstrated the best balance between VTE prevention and haemorrhage control following TKA.

LEVEL OF EVIDENCE

Level I, network meta-analysis of RCTs.

Structural, Biochemical Characterization and Molecular Mechanism of Cerastokunin: A New Kunitz-Type Peptide with Potential Inhibition of Thrombin, Factor Xa and Platelets

The current investigation focused on separating Cerastes cerastes venom to produce the first Kunitz-type peptide. Based on its anti-trypsin effect, Cerastokunin, a 7.75 kDa peptide, was purified until homogenity by three steps of chromatography. Cerastokunin was found to include 67 amino acid residues that were obtained by de novo sequencing using LC-MALDI-MSMS. Upon alignment with Kunitz-type peptides, there was a high degree of similarity. Cerastokunin's 3D structure had 12% α-helices and 21% β-strands with pI 8.48. Cerastokunin showed a potent anticoagulant effect by inhibiting the protease activity of thrombin and trypsin as well as blocking the intrinsic and extrinsic coagulation pathways. In both PT and aPPT, Cerastokunin increased the blood clotting time in a dose-dependent way. Using Lys48 and Gln192 for direct binding, Cerastokunin inhibited thrombin, Factor Xa and trypsin as shown by molecular docking. Cerastokunin exhibited a dose-response blockade of PARs-dependent pathway platelet once stimulated by thrombin. An increased concentration of Cerastokunin resulted in a larger decrease of tail thrombus in the mice-carrageenan model in an in vivo investigation when compared to the effects of antithrombotic medications. At all Cerastokunin doses up to 6 mg/kg, no in vivo toxicity was seen in challenged mice over the trial's duration.

Minimally modified human blood coagulation factor X to bypass direct factor Xa inhibitors

BACKGROUND

Direct oral factor (F)Xa inhibitors are widely used as alternatives to conventional vitamin K antagonists in managing venous thromboembolism and nonvalvular atrial fibrillation. Unfortunately, bleeding-related adverse events remain a major concern in clinical practice. In case of bleeding or emergency surgery, rapid-onset reversal agents may be required to counteract the anticoagulant activity.

OBJECTIVES

The ability of FXa variants to bypass the direct oral FXa inhibitors was assessed.

METHODS

Human FXa variants were generated through substitution of phenylalanine 174 (F174) for either alanine, isoleucine, or serine. FXa variants were stably expressed in HEK293 cells and purified to homogeneity using ion-exchange chromatography.

RESULTS

F174-substituted human FX variants demonstrated efficacy in restoring thrombin generation in plasma containing direct FXa inhibitors (apixaban, rivaroxaban, edoxaban). Their ability to bypass the anticoagulant effects stems from a significantly reduced sensitivity for the direct FXa inhibitors due to a decrease in binding affinity determined using molecular dynamics simulations and free energy computation. Furthermore, F174 modification resulted in a partial loss of inhibition by tissue factor pathway inhibitor, enhancing the procoagulant effect of F174-substituted FX. Consequently, the F174A- and F174S-substituted FX variants effectively counteracted the effects of 2 widely used anticoagulants, apixaban and rivaroxaban, in plasma of atrial fibrillation and venous thromboembolism patients.

CONCLUSION

These human FX variants have the potential to serve as a rescue reversal strategy to overcome the effect of direct FXa inhibitors in case of life-threatening bleeding events or emergency surgical interventions.

Apixaban Pharmacokinetics and Bioequivalence of Two Tablet Formulations: A Randomized, Open-Label, Crossover Study, Fasting Condition in Healthy Indonesian Volunteers

The present study aimed to assess the bioequivalence of a new apixaban generic with reference formulation. Twenty-six healthy volunteers were recruited for an open-label, balanced, randomized, 2-treatment, 2-sequence, 2-period, single oral dose study. Following overnight fasting, each volunteer received 5 mg of apixaban test and reference formulations as single doses, separated by a 1-week washout period. Twenty blood samples were collected at predose and multiple time points between 0.5 and 72 hours after dosing. A validated ultra-performance liquid chromatography-tandem mass spectrometry detection method following a protein precipitation step was implemented to determine apixaban concentrations. Noncompartmental analysis was used to derive the pharmacokinetic parameters, which were then compared between the test and reference products using a multivariate analysis of variance. The pharmacokinetic parameters of the test product were not statistically different from the reference product, and the 90% confidence intervals of apixaban natural log-transformed area under the concentration-time curve from time 0 to infinity, area under the concentration-time curve from time 0 to the last measurable concentration, and maximum concentration were within 80%-125% based on the bioequivalence acceptance range criteria. The test and reference formulations of apixaban are bioequivalent in healthy subjects under fasting conditions.

Apixaban plasma concentrations before and after catheter ablation for atrial fibrillation

BACKGROUND

Catheter ablation in patients with atrial fibrillation is associated with a transient increase in thromboembolic risk and adequate anticoagulation is highly important. When patients are anticoagulated with apixaban, monitoring of plasma concentrations of the drug is not routinely performed. This study aimed to assess the influence of clinical patient characteristics, concomitant drug treatment and self-reported adherence on apixaban concentrations, and to describe the intra- and inter-individual variability in apixaban concentrations in this group of patients. Method Apixaban concentrations from 141 patients were measured in plasma one week before ablation and two, six and ten weeks after ablation, employing ultra-high performance liquid chromatography coupled with tandem mass spectrometry. In samples not obtained at trough, apixaban concentrations were adjusted to trough levels. Self-reported adherence was registered by means of the 8-item Morisky Medication Adherence Scale before and after ablation.

RESULTS

There were statistically significant, positive correlations between apixaban concentrations and increased age, female sex, lower glomerular filtration rate, higher CHA2DS2-VASc score, use of cytochrome P450 3A4 and/or p-glycoprotein inhibitors, and use of amiodarone. Self-reported adherence was generally high. The mean intra-individual and inter-individual coefficients of variation were 29% and 49%, respectively.

CONCLUSION

In patients undergoing catheter ablation for atrial fibrillation, age, sex, renal function, interacting drugs and cerebrovascular risk profile were all associated with altered plasma apixaban concentration. In this group of patients with a generally high self-reported adherence, intra-individual variability was modest, but the inter-individual variability was substantial, and similar to those previously reported in other patient apixaban-treated populations. If a therapeutic concentration range is established, there might be a need for a more flexible approach to apixaban dosing, guided by therapeutic drug monitoring.

Quality-by-Design-Driven Nanostructured Lipid Scaffold of Apixaban: Optimization, Characterization, and Pharmacokinetic Evaluation

Apixaban, an anticoagulant, is limited in its efficacy due to poor solubility, low bioavailability, and extensive metabolism. This study investigates the application of nanostructured lipid carriers (NLCs) to enhance the bioavailability of Apixaban. NLCs were prepared using the high-pressure homogenization method. The influence of independent variables, viz., the amount of Tween 80, HPH pressure, and the number of HPH cycles, were studied using a 23 factorial design. The average particle size, PDI, zeta potential, and entrapment efficiency of the optimized NLCs were found to be 232 ± 23 nm, with 0.514 ± 0.13 PDI and zeta potential of about -21.9 ± 2.1 mV, respectively. Additionally, concerning the thermal and crystallographic properties of the drug, the NLCs showed drug entrapment without altering its potency. The in-vitro drug release studies revealed an immediate release pattern, followed by sustained release for up to 48 h. In-vivo pharmacokinetic experiments demonstrated that Apixaban-loaded NLCs exhibited higher values of t1/2 (27.76 ± 1.18 h), AUC0-∞ (19,568.7 ± 1067.6 ng·h/mL), and Cmax (585.3 ± 87.6 ng/mL) compared to free drugs, indicating improved bioavailability. Moreover, a decrease in the elimination rate constant (Kel) reflected the sustained effect of Apixaban with NLCs. NLCs offer improved oral absorption rates and enhanced therapeutic impact compared to free drugs, potentially reducing dose frequency and improving patient outcomes.

Is anticoagulative therapy in systemic sclerosis to be reconsidered?

Systemic sclerosis is a rare disease with a high mortality rate. It is a multisystem connective tissue disease due to endothelial autoimmune activation along with tissue and vascular fibrosis, inducing vasculopathy, with an angiogenesis wasting. The endothelial damage provokes platelet activation and immune cell adhesion. The detachment of endothelial cells leads to the interaction of platelets and collagen present in the exposed subendothelial layer. This provokes the activation of several coagulative factors, inducing a pro-thrombotic condition by thrombin generation, which converts fibrinogen into fibrin. Moreover, thrombin has other functions, such as the induction of hyperplasia in smooth muscle cells and fibroblasts, thereby favouring fibrosis. An increased risk of venous thromboembolism has been found in systemic sclerosis, whereas pulmonary hypertension may be due to the obstruction of small pulmonary arteries. Pulmonary veno-occlusive disease may also occur. Warfarin showed inconsistent results, while the outcomes of a randomised, placebo-controlled clinical trial on apixaban versus placebo are still awaited. A new anticoagulation strategy based on anti-factor XI drugs is being developed, with the aim of achieving optimal anticoagulation along with a low risk of bleeding. The molecule types under investigation in this category include monoclonal antibodies, small molecules, natural inhibitors, antisense oligonucleotides, and aptamers. Patients with systemic sclerosis may be ideal candidates for clinical trials planned to analyse the efficacy and safety of these molecules.