Comparative Pharmacodynamics and Pharmacokinetics of Oral Direct Thrombin and Factor Xa Inhibitors in Development

[Translated article] Rivaroxaban versus enoxaparin for thromboprophylaxis in orthopedic surgery: A meta-analysis

INTRODUCTION

Venous thromboembolism is highly associated with orthopedic surgery, so thromboprophylaxis is an important consideration for orthopedic surgeons. The new oral anticoagulants have clear advantages for clinical practice.

OBJECTIVES

To analyze the efficacy and safety of rivaroxaban versus enoxaparin for thromboprophylaxis in different orthopedic surgeries.

MATERIAL AND METHODS

Systematic electronic search of clinical trials was carried out. Data extraction of efficacy outcomes (deep venous thrombosis, pulmonary embolism and death) and safety outcomes (major bleeding and clinically relevant bleeding) was realized.

RESULTS

Six randomized and controlled clinical trials were included in this meta-analysis. Compared with enoxaparin the risk of venous thromboembolism was lower with rivaroxaban both in different orthopedic surgeries (RR: 0.51; 95% CI: 0.36-0.73; p=.0002). This result was even better and more homogeneous in the analysis of symptomatic deep venous thrombosis outcome (RR: 0.43; 95% CI: 0.28-0.65; p<.0001; I2=0%; p=.49). The risk of bleeding was not significantly higher with rivaroxaban (RR: 1.20; 95% CI: 0.97-1.49; p=.09).

CONCLUSIONS

Rivaroxaban should be considerate such as a more effective alternative for thromboprophylaxis in orthopedic surgery.

Rivaroxaban versus enoxaparin for thromboprophylaxis in orthopedic surgery: A meta-analysis

INTRODUCTION

Venous thromboembolism is highly associated with orthopedic surgery, so thromboprophylaxis is an important consideration for orthopedic surgeons. The new oral anticoagulants have clear advantages for clinical practice.

OBJECTIVES

To analyze the efficacy and safety of rivaroxaban versus enoxaparin for thromboprophylaxis in different orthopedic surgeries.

MATERIAL AND METHODS

Systematic electronic search of clinical trials was carried out. Data extraction of efficacy outcomes (deep venous thrombosis, pulmonary embolism and death) and safety outcomes (major bleeding and clinical relevant bleeding) was realized.

RESULTS

Six randomized and controlled clinical trials were included in this meta-analysis. Compared with enoxaparin the risk of venous thromboembolism was lower with rivaroxaban both in different orthopedic surgeries (RR: 0.51; 95% CI: 0.36-0.73; P=.0002). This result was even better and more homogeneous in the analysis of symptomatic deep venous thrombosis outcome (RR: 0.43; 95% CI: 0.28-0.65; P<.0001; I2=0%; P=.49). The risk of bleeding was not significantly higher with rivaroxaban (RR: 1.20; 95% CI: 0.97-1.49; P=.09).

CONCLUSIONS

Rivaroxaban should be considerate such as a more effective alternative for thromboprophylaxis in orthopedic surgery.

Impact of Banhabaekchulcheonmatang (Banxia Baizhu Tianma Tang) and Hwangryeonhaedoktang (Huang Lian Jie Du Tang) on edoxaban: Herb-drug interaction study in healthy subjects

ETHNOPHARMACOLOGICAL RELEVANCE

Concurrent use of traditional herbal medicines and conventional drugs, particularly for stroke treatment, is widespread, raising concerns about potential drug interactions.

AIM OF THE STUDY

This clinical study aimed to investigate interactions between edoxaban, a direct oral anticoagulant, and two traditional herbal medicines commonly used for stroke: Banhabaekchulcheonmatang (BBCT) and Hwangryeonhaedoktang (HRHDT).

MATERIALS AND METHODS

Korean healthy volunteers participated in a randomized, open-label, three-period, three-treatment, two-sequence clinical study. Treatments consisted of a single oral dose of edoxaban tablet (60 mg) in the presence or absence of multiple doses of BBCT or HRHDT three times daily for six days. Pharmacokinetic and pharmacodynamic parameters of edoxaban and its active metabolite M4 were assessed following administration of edoxaban alone or in co-administration with BBCT or HRHDT.

RESULTS

When edoxaban was co-administered with BBCT or HRHDT, the area under the curve (AUC) of edoxaban remained unaffected. However, its peak concentrations (Cmax) were decreased by 18.5%-28.1%. Similarly, co-administration of edoxaban with BBCT or HRHDT slightly decreased the AUC of M4 and reduced its Cmax by 16.8%-27.1%. Results revealed that BBCT and HRHDT had a minor impact on pharmacokinetics of edoxaban and M4. Despite alterations in systemic exposures, all pharmacodynamic parameters of edoxaban derived from activated partial thromboplastin time and prothrombin time were equivalent irrespective of herbal medicine co-administration.

CONCLUSIONS

These findings contribute to our understanding of potential interactions between conventional anticoagulants and traditional herbal medicines, highlighting the need for comprehensive evaluation in clinical practice.

Effect of low-dose rivaroxaban on bleeding events in low-weight patients with nonvalvular atrial fibrillation: a retrospective propensity score-matched cohort study

Objective

To investigate the effect of low-dose rivaroxaban on bleeding events in low-weight patients with nonvalvular atrial fibrillation.

Methods

A retrospective study was conducted in patients with nonvalvular atrial fibrillation (weight ≤ 60 kg) who were admitted to the Department of Cardiology of Jiangxi Provincial People's Hospital from June 1, 2022, to December 12, 2022 and received anticoagulant therapy with rivaroxaban. The patients were divided into standard-dose group (15-20 mg) and low-dose group (10-15 mg). The patients were followed up for an average of 15 months by outpatient examination, telephone follow-up, or medical record inquiry of readmission patients. The bleeding events of the two groups were recorded during the follow-up period, and the two groups were balanced by propensity score weighting.

Results

A total of 198 patients with NVAF and body weight ≤60 kg receiving rivaroxaban anticoagulation therapy were enrolled, including 65 patients in the standard-dose group (15-20 mg) and 133 patients in the low-dose group (10-15 mg). In this study, only 24.1% (65/241) of the patients followed the standard dose of rivaroxaban. There was no significant difference in the incidence of bleeding events between the two groups after the balance of baseline characteristics (age) (P > 0.05). This was also consistent in patients weighing less than 50 kg.

Conclusions

In the real world, in lower-weight patients with nonvalvular atrial fibrillation, a reduced dose of rivaroxaban did not reduce the risk of bleeding, and this was consistent in patients weighing less than 50 kg.

Global trends in research of venous thromboembolism associated with lower limb joint arthroplasty: A bibliometric analysis

This study aims to visualize publications related to venous thromboembolism (VTE) and lower limb joint arthroplasty to identify research frontiers and hotspots, providing references and guidance for further research. We retrieved original articles published from 1985 to 2022 and their recorded information from the Web of Science Core Collection. The search strategy used terms related to knee or hip arthroplasty and thromboembolic events. Microsoft Excel was used to analyze the annual publications and citations of the included literature. The rest of the data were analyzed using the VOSviewer, citespace and R and produced visualizations of these collaborative networks. We retrieved 3543 original articles and the results showed an overall upward trend in annual publications. The United States of America had the most significant number of publications (Np) and collaborative links with other countries. McMaster University had the greatest Np. Papers published by Geerts WH in 2008 had the highest total link strength. Journal of Arthroplasty published the most articles on the research of VTE associated with lower limb joint arthroplasty. The latest research trend mainly involved "general anesthesia" "revision" and "tranexamic acid." This bibliometric study revealed that the research on VTE after lower limb joint arthroplasty is developing rapidly. The United States of America leads in terms of both quantity and quality of publications, while European and Canadian institutions and authors also make significant contributions. Recent research focused on the use of tranexamic acid, anesthesia selection, and the VTE risk in revision surgeries.

Head-to-head ex vivo comparison of clinically used direct anticoagulant drugs

An imbalance in coagulation is associated with cardiovascular events. For prevention and treatment, anticoagulants, currently mainly xabans and gatrans, are used. The purpose of the present study was to provide a head-to-head comparison since there are no studies directly evaluating these novel anticoagulants. An additional aim was to find whether selected anthropological and biochemical factors can affect their anticoagulant properties as they are used in fixed doses. In this cross-sectional study, blood from 50 generally healthy donors was collected, and coagulation responses to dabigatran, argatroban, rivaroxaban, and apixaban, at a concentration of 1 μM, were analyzed. Heparin was used as a positive control. Prothrombin time (PT) expressed as international normalized ratio (INR) and activated partial thromboplastin time (aPTT) were measured and compared. Rivaroxaban was the most active according to PT/INR while argatroban according to aPTT. The ex vivo anticoagulant effect measured by INR correlated inversely with body mass index (BMI) in all four anticoagulants tested. Shortening of aPTT was associated with higher cholesterol and triglyceride levels. No sex-related differences were observed in response to the anticoagulant treatments. As this was an ex vivo study and pharmacokinetic factors were not included, the influence of BMI is of high therapeutic importance.

Thrombotic events associated with low baseline direct oral anticoagulant levels in atrial fibrillation: the MAS study

ABSTRACT

Although effective and safe, treatment with direct oral anticoagulants (DOAC) in atrial fibrillation (AF) is still associated with thrombotic complications. Whether the measurement of DOAC levels may improve treatment efficacy is an open issue. We carried out the observational, prospective, multicenter Measure and See (MAS) study. Blood was collected 15 to 30 days after starting DOAC treatment in patients with AF who were followed-up for 1 year. Plasma samples were centralized for DOAC level measurement. Patients' DOAC levels were converted into drug/dosage standardized values to allow a pooled analysis in a time-dependent, competitive-risk model. The measured values were transformed into standardized values (representing the distance of each value from the overall mean) by subtracting the DOAC-specific mean value from the original values and dividing by the standard deviation. Trough and peak DOAC levels were assessed in 1657 and 1303 patients, respectively. In total, 21 thrombotic complications were recorded during 1606 years of follow-up (incidence of 1.31% of patients per year). Of 21 thrombotic events, 17 occurred in patients whose standardized activity levels were below the mean of each DOAC (0); the incidence was the highest (4.82% of patients per year) in patients whose standardized values were in the lowest class (-1.00 or less). Early measurement of DOAC levels in patients with AF allowed us to identify most of the patients who, having low baseline DOAC levels, subsequently developed thrombotic complications. Further studies are warranted to assess whether thrombotic complications may be reduced by measuring baseline DOAC levels and modifying treatment when indicated. This trial was registered at www.ClinicalTrials.gov as #NCT03803579.

Preclinical Study on a Novel Fluoroderivative of Dabigatran Etexilate in Animal Models

ABSTRACT

Here, the fluorinated derivative, R1, was synthesized from the fluorinated dabigatran derivative (R0). The in vivo pharmacokinetic characteristics of orally administered R1, R0 injection, and dabigatran etexilate in rats were compared. Safety evaluation results showed no significant changes in the QRS wave or PR and QT intervals in rat lead II electrocardiograms. The possible toxicity of R1 was studied using the limit test method, and no obvious toxicity occurred in mice after the acute oral administration of R1. R1 inhibited thrombin-induced platelet aggregation in a dose-dependent manner, had an inhibitory effect on platelet aggregation induced by arachidonic acid and adenosine diphosphate, could significantly prolong prothrombin time and activated partial thromboplastin time, and increased fibrinogen levels. R1 is the optimal candidate compound from among more than 100 candidate compounds designed and synthesized by our research group. It was first selected through preliminary in vitro anticoagulant activity screening and further through in vivo mouse activity testing. A systematic pharmacodynamic study showed that R1 was superior to the raw material drug dabigatran ester; particularly, the absolute bioavailability of R1 increased by 206%, and this can overcome the low bioavailability defect associated with the marketed drug dabigatran ester. Another safety assessment of R1 indicated that there were no risks of acute poisoning in rats and cardiac toxicity in mice or rats. Therefore, R1 can be considered a new candidate anticoagulant compound with great potential and significance for further clinical research.

An eco-friendly ultra-performance liquid chromatography-mass spectrometry method for quantification of rivaroxaban and ticagrelor in rat plasma: grapefruit interactions

Aim: An eco-friendly ultra-performance liquid chromatography-tandem mass spectrometry method was developed to study the pharmacokinetics of rivaroxaban and ticagrelor in rat plasma, utilizing moxifloxacin as an internal standard. The food-drug interaction between grapefruit juice and these drugs was also investigated. Methods: Liquid-liquid extraction was used. A nonporous stationary phase Agilent® Poroshell 120EC C18 column was used with methanol: 0.1% aqueous formic acid (95:5 v/v) as a mobile phase. The detection was performed in multiple reaction monitoring mode using positive electrospray ionization. The method's validation was conducted in accordance with US FDA and European Medicines Agency guidelines. Results & conclusion: Grapefruit juice should be ingested with caution in patients treated with antithrombotic medications as it may increase their plasma concentration, inducing bleeding, and requires close clinical monitoring.

Oral direct thrombin inhibitors or oral factor Xa inhibitors versus conventional anticoagulants for the treatment of pulmonary embolism

BACKGROUND

Pulmonary embolism (PE) is a potentially life-threatening condition in which a clot can migrate from the deep veins, most commonly in the leg, to the lungs. Conventional treatment of PE used unfractionated heparin (UFH), low molecular weight heparin (LMWH), fondaparinux, and vitamin K antagonists (VKAs). Recently, two forms of direct oral anticoagulants (DOACs) have been developed: oral direct thrombin inhibitors (DTIs) and oral factor Xa inhibitors. DOACs have characteristics that may be favourable to conventional treatment, including oral administration, a predictable effect, no need for frequent monitoring or re-dosing, and few known drug interactions. This review reports the efficacy and safety of these drugs in the long-term treatment of PE (minimum duration of three months). This is an update of a Cochrane Review first published in 2015.  OBJECTIVES: To assess the efficacy and safety of oral DTIs and oral factor Xa inhibitors versus conventional anticoagulants for the long-term treatment of PE.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases, the World Health Organization International Clinical Trials Registry Platform and the ClinicalTrials.gov trials registers to 2 March 2022. We checked the reference lists of relevant articles for additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which people with a PE confirmed by standard imaging techniques were allocated to receive an oral DTI or an oral factor Xa inhibitor compared with a conventional anticoagulant or compared with each other for the long-term treatment of PE (minimum duration three months).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were recurrent PE, recurrent venous thromboembolism (VTE), and deep vein thrombosis (DVT). Secondary outcomes were all-cause mortality, major bleeding, and health-related quality of life. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified five additional RCTs with 1484 participants for this update. Together with the previously included trials, we have included ten RCTs with a total of 13,073 participants. Two studies investigated an oral DTI (dabigatran) and eight studies investigated oral factor Xa inhibitors (three rivaroxaban, three apixaban, and two edoxaban). The studies were of good methodological quality overall.  Meta-analysis showed no clear difference in the efficacy and safety of oral DTI compared with conventional anticoagulation in preventing recurrent PE (odds ratio (OR) 1.02, 95% confidence interval (CI) 0.50 to 2.04; 2 studies, 1602 participants; moderate-certainty evidence), recurrent VTE (OR 0.93, 95% CI 0.52 to 1.66; 2 studies, 1602 participants; moderate-certainty evidence), DVT (OR 0.79, 95% CI 0.29 to 2.13; 2 studies, 1602 participants; moderate-certainty evidence), and major bleeding (OR 0.50, 95% CI 0.15 to 1.68; 2 studies, 1527 participants; moderate-certainty evidence). We downgraded the certainty of evidence by one level for imprecision due to the low number of events. There was also no clear difference between the oral factor Xa inhibitors and conventional anticoagulation in the prevention of recurrent PE (OR 0.92, 95% CI 0.66 to 1.29; 3 studies, 8186 participants; moderate-certainty evidence), recurrent VTE (OR 0.83, 95% CI 0.66 to 1.03; 8 studies, 11,416 participants; moderate-certainty evidence), DVT (OR 0.77, 95% CI 0.48 to 1.25; 2 studies, 8151 participants; moderate-certainty evidence), all-cause mortality (OR 1.16, 95% CI 0.79 to 1.70; 1 study, 4817 participants; moderate-certainty evidence) and major bleeding (OR 0.71, 95% CI 0.36 to 1.41; 8 studies, 11,447 participants; low-certainty evidence); the heterogeneity for major bleeding was significant (I2 = 79%). We downgraded the certainty of the evidence to moderate and low because of imprecision due to the low number of events and inconsistency due to clinical heterogeneity. None of the included studies measured health-related quality of life.

AUTHORS' CONCLUSIONS

Available evidence shows there is probably little or no difference between DOACs and conventional anticoagulation in the prevention of recurrent PE, recurrent VTE, DVT, all-cause mortality, and major bleeding. The certainty of evidence was moderate or low. Future large clinical trials are required to identify if individual drugs differ in effectiveness and bleeding risk, and to explore effect differences in subgroups, including people with cancer and obesity.

Oral direct thrombin inhibitors or oral factor Xa inhibitors versus conventional anticoagulants for the treatment of deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is a condition in which a clot forms in the deep veins, most commonly of the leg. It occurs in approximately one in 1000 people. If left untreated, the clot can travel up to the lungs and cause a potentially life-threatening pulmonary embolism (PE). Previously, a DVT was treated with the anticoagulants heparin and vitamin K antagonists. However, two forms of direct oral anticoagulants (DOACs) have been developed: oral direct thrombin inhibitors (DTIs) and oral factor Xa inhibitors, which have characteristics that may be favourable compared to conventional treatment, including oral administration, a predictable effect, lack of frequent monitoring or dose adjustment and few known drug interactions. DOACs are now commonly being used for treating DVT: recent guidelines recommended DOACs over conventional anticoagulants for both DVT and PE treatment. This Cochrane Review was first published in 2015. It was the first systematic review to measure the effectiveness and safety of these drugs in the treatment of DVT. This is an update of the 2015 review.  OBJECTIVES: To assess the effectiveness and safety of oral DTIs and oral factor Xa inhibitors versus conventional anticoagulants for the long-term treatment of DVT.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 1 March 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which people with a DVT, confirmed by standard imaging techniques, were allocated to receive an oral DTI or an oral factor Xa inhibitor compared with conventional anticoagulation or compared with each other for the treatment of DVT.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were recurrent venous thromboembolism (VTE), recurrent DVT and PE. Secondary outcomes included all-cause mortality, major bleeding, post-thrombotic syndrome (PTS) and quality of life (QoL). We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified 10 new studies with 2950 participants for this update. In total, we included 21 RCTs involving 30,895 participants. Three studies investigated oral DTIs (two dabigatran and one ximelagatran), 17 investigated oral factor Xa inhibitors (eight rivaroxaban, five apixaban and four edoxaban) and one three-arm trial investigated both a DTI (dabigatran) and factor Xa inhibitor (rivaroxaban). Overall, the studies were of good methodological quality. Meta-analysis comparing DTIs to conventional anticoagulation showed no clear difference in the rate of recurrent VTE (odds ratio (OR) 1.17, 95% confidence interval (CI) 0.83 to 1.65; 3 studies, 5994 participants; moderate-certainty evidence), recurrent DVT (OR 1.11, 95% CI 0.74 to 1.66; 3 studies, 5994 participants; moderate-certainty evidence), fatal PE (OR 1.32, 95% CI 0.29 to 6.02; 3 studies, 5994 participants; moderate-certainty evidence), non-fatal PE (OR 1.29, 95% CI 0.64 to 2.59; 3 studies, 5994 participants; moderate-certainty evidence) or all-cause mortality (OR 0.66, 95% CI 0.41 to 1.08; 1 study, 2489 participants; moderate-certainty evidence). DTIs reduced the rate of major bleeding (OR 0.58, 95% CI 0.38 to 0.89; 3 studies, 5994 participants; high-certainty evidence).   For oral factor Xa inhibitors compared with conventional anticoagulation, meta-analysis demonstrated no clear difference in recurrent VTE (OR 0.85, 95% CI 0.71 to 1.01; 13 studies, 17,505 participants; moderate-certainty evidence), recurrent DVT (OR 0.70, 95% CI 0.49 to 1.01; 9 studies, 16,439 participants; moderate-certainty evidence), fatal PE (OR 1.18, 95% CI 0.69 to 2.02; 6 studies, 15,082 participants; moderate-certainty evidence), non-fatal PE (OR 0.93, 95% CI 0.68 to 1.27; 7 studies, 15,166 participants; moderate-certainty evidence) or all-cause mortality (OR 0.87, 95% CI 0.67 to 1.14; 9 studies, 10,770 participants; moderate-certainty evidence). Meta-analysis showed a reduced rate of major bleeding with oral factor Xa inhibitors compared with conventional anticoagulation (OR 0.63, 95% CI 0.45 to 0.89; 17 studies, 18,066 participants; high-certainty evidence).  AUTHORS' CONCLUSIONS: The current review suggests that DOACs may be superior to conventional therapy in terms of safety (major bleeding), and are probably equivalent in terms of efficacy. There is probably little or no difference between DOACs and conventional anticoagulation in the prevention of recurrent VTE, recurrent DVT, pulmonary embolism and all-cause mortality. DOACs reduced the rate of major bleeding compared to conventional anticoagulation. The certainty of evidence was moderate or high.

Current and emerging drug strategies for the prevention of venous thromboembolism in acutely ill medical inpatients

INTRODUCTION

Venous thromboembolism (VTE) is a common complication in patients hospitalized for acute medical illnesses. Therefore, medical inpatients require a careful VTE and bleeding risk assessment to drive optimal strategies for VTE prevention. Low molecular weight heparin and fondaparinux have long been used for inhospital prophylaxis for patients at increased risk of VTE. The selection of patients who require post-discharge prophylaxis, and the role of direct oral anticoagulants remain debated. New molecules currently under development may contribute to improve the risk benefit of VTE prevention in this setting.

AREAS COVERED

This text summarizes the evidence on approved treatments and on other drugs for the prevention of VTE in acutely ill medical patients. The main focus is on their pharmacological proprieties, clinical efficacy and safety, and the current license approved by the FDA (Food and Drug Administration) and EMA (European Medicines Agency), giving the readers a way to compare available drugs to date. The trials presented consider both inhospital and extended prophylaxis.

EXPERT OPINION

Thanks to the potentially favorable safety profile, factor XI inhibitors may play a role in the prevention of VTE in this setting. The expert opinion section discusses pharmacological properties, prophylaxis trials, and potential clinical applications of this novel class of drugs.

Dilemmas in the Choice of Adequate Therapeutic Treatment in Patients with Acute Pulmonary Embolism—From Modern Recommendations to Clinical Application

Pulmonary thromboembolism is a very common cardiovascular disease, with a high mortality rate. Despite the clear guidelines, this disease still represents a great challenge both in diagnosis and treatment. The heterogeneous clinical picture, often without pathognomonic signs and symptoms, represents a huge differential diagnostic problem even for experienced doctors. The decisions surrounding this therapeutic regimen also represent a major dilemma in the group of patients who are hemodynamically stable at initial presentation and have signs of right ventricular (RV) dysfunction proven by echocardiography and positive biomarker values (pulmonary embolism of intermediate–high risk). Studies have shown conflicting results about the benefit of using fibrinolytic therapy in this group of patients until hemodynamic decompensation, due to the risk of major bleeding. The latest recommendations give preference to new oral anticoagulants (NOACs) compared to vitamin K antagonists (VKA), except for certain categories of patients (patients with antiphospholipid syndrome, mechanical valves, pregnancy). When using oral anticoagulant therapy, special attention should be paid to drug–drug interactions, which can lead to many complications, even to the death of the patient. Special population groups such as pregnant women, obese patients, patients with antiphospholipid syndrome and the incidence of cancer represent a great therapeutic challenge in the application of anticoagulant therapy. In these patients, not only must the effectiveness of the drugs be taken into account, but great attention must be paid to their safety and possible side effects, which is why a multidisciplinary approach is emphasized in order to provide the best therapeutic option.

Direct oral anticoagulants after bariatric surgery-What is the evidence?

BACKGROUND

Obesity is a global epidemic and bariatric surgery is used with increasing frequency to treat its complications. The extent to which bariatric surgery alters the efficacy, safety, and pharmacokinetics of direct oral anticoagulants (DOACs) is unknown.

AIMS

In this review, we summarize the evidence supporting the use of DOACs after bariatric surgery and apply our findings to resolve several clinical cases.

MATERIALS & METHODS

We systematically searched MEDLINE, EMBASE, Cochrane Library, CINAHL and ClinicalTrials.gov from January 1, 2000, to June 15, 2021 for randomized and non-randomized studies evaluating the use of DOACs for any indication after bariatric surgery. Two reviewers independently screened titles, abstracts, and full-text articles. Clinical and pharmacokinetic outcomes were pooled by random-effects meta-analysis with inverse variance weighting. We used the Newcastle-Ottawa scale to assess risk of bias in non-randomized studies and assessed the certainty of evidence with GRADE.

RESULTS

From 2519 records, we included 28 studies (n = 3229 patients): no randomized trials, 7 cohort studies, 6 case series, and 15 case reports. Incidence rates for arterial thromboembolism, venous thromboembolism and major bleeding were: 0.73 (95% confidence interval [CI]: 0.01-5.10), 2.45 (95% CI: 0.40-7.94), and 3.40 (95% CI: 0.80-9.36) events per 100 patient-years, respectively. The pooled proportion of peak direct oral anticoagulant drug levels within the expected range was 58% (95% CI: 39%-74%).

CONCLUSION

There appears be substantial risk of DOAC malabsorption after bariatric surgery that could affect clinical outcomes, however the certainty of evidence was very low.

PROSPERO

CRD42020202636.

Effect of uninterrupted dabigatran or rivaroxaban on achieving ideal activated clotting time to heparin response during catheter ablation in patients with atrial fibrillation

BACKGROUND

Uninterrupted use of oral anticoagulants before atrial fibrillation (AF) ablation can reduce the incidence of perioperative thromboembolic events. However, the effect of new oral anticoagulants on activated clotting time (ACT) in response to heparin during AF ablation in Chinese populations remains unknown. The aim of the present retrospective study was to investigate the value of ACTs in response to intraoperative heparin administration in patients using dabigatran or rivaroxaban.

METHODS

From January 2018 to December 2021, a total of 173 patients undergoing AF ablation were included in the study, in which 101 patients were treated with dabigatran, 72 patients were treated with rivaroxaban. The intraoperative ACT values were examined in both groups. The incidence of periprocedural complications was evaluated.

RESULTS

Initial heparin dosage (88 ± 19 U/kg vs. 78 ± 27 U/kg, P < 0.05), total heparin dosage (137 ± 41 U/kg vs. 106 ± 52 U/kg, P < 0.05) during the ablation procedure were higher in the dabigatran group than those in the rivaroxaban group. Mean ACT (280 ± 36 s vs. 265 ± 30 s, P < 0.05), and the percentage of ACTs within the therapeutic range (250-350 s) (74% ± 26% vs. 60% ± 29%, P < 0.05) were significantly lower in the dabigatran group than those in the rivaroxaban group, particularly in male patients. Furthermore, the average time of achieving the target ACT (250-350 s) was also found longer in the dabigatran group (P < 0.05) as compared with the rivaroxaban group. No significant difference was found in the incidence of periprocedural complications between the two groups.

CONCLUSIONS

The anticoagulant effect of uninterrupted rivaroxaban therapy appears to be more stable and efficient than dabigatran administration during catheter ablation in patients with AF.

Impact of the COVID-19 pandemic on England's national prescriptions of oral vitamin K antagonist (VKA) and direct-acting oral anticoagulants (DOACs): an interrupted time series analysis (January 2019-February 2021)

BACKGROUND

Direct-acting oral anticoagulants (DOACs) were developed as an alternative to warfarin to treat and prevent thromboembolism, including stroke prevention in non-valvular atrial fibrillation patients. The COVID-19 pandemic could increase the risk of stroke and/or the risk of bleeding in patients due to nonadherence or sub/supra-optimal dosing.

OBJECTIVE

To investigate DOAC prescription trends in England's community settings during the complete first wave of COVID-19 pandemic.

METHODS

Descriptive and interrupted time series (ITS) analyses were conducted to examine the prescription patterns of DOACs (dabigatran, rivaroxaban, apixaban and edoxaban) and warfarin for primary care patients in the English Prescribing Dataset from January 2019 to February 2021, with March 2020 as the cut-off point.

RESULTS

A 19% increase in mean DOAC's accompanied with 20% warfarin prescriptions decline was observed. ITS modelling showed an increase in DOAC prescription volume in March 2020 (+7 million items, p = 0.008). The pre-existing upward trend in DOAC prescriptions slowed during the period (-427,000 items, p = 0.007). Apixaban was the most frequently used DOAC and had the largest step-change in March 2020 (+5 million items, p = 0.010). The mean monthly combined cost of DOACs and warfarin was higher during the period. DOAC prescription trends were consistent across England's regions. Conclusion: The overall oral anticoagulants use in this period was lower than expected, indicating a medical needs gap, possibly due to adherence issues. The potential clinical and logistical consequences warrant further study to identify contributing factors and mitigate avoidable risks.

A Review of Direct-acting Oral Anticoagulants and Their Use in Solid Organ Transplantation

Direct-acting oral anticoagulant (DOAC) use has increased dramatically since their introduction because of the growing evidence of proven efficacy and enhanced safety compared with warfarin and the low-molecular-weight heparins in the general population. Unfortunately, there is a dearth of quality data regarding the safety and efficacy of the DOACs in patients awaiting organ transplant and those who received a solid organ transplant. This review aims to evaluate the available literature and considerations regarding anticoagulation use in transplant recipients, focusing on preoperative, perioperative, and postoperative DOAC use.

Effect of polypharmacy on bleeding with rivaroxaban versus vitamin K antagonist for treatment of venous thromboembolism

BACKGROUND

Polypharmacy, including use of inhibitors of CYP3A4 and P-glycoprotein (P-gp), is common in patients with venous thromboembolism (VTE) and is associated with increased bleeding.

METHODS

In 8246 patients included in the EINSTEIN-VTE studies for acute VTE, we evaluated the effect of polypharmacy on bleeding and on the relative differences between rivaroxaban and enoxaparin/vitamin K antagonist (VKA). We assessed the incidence of clinically relevant bleeding (major and clinically relevant nonmajor bleeding) by number of comedications (none, 1-3, ≥4) at baseline, and by use of CYP3A4 and/or P-gp inhibitors. Interaction between rivaroxaban versus enoxaparin/VKA and comedication was assessed by Cox regression analysis with pinteraction estimates.

RESULTS

With increasing number of comedications, the incidence of clinically relevant bleeding rose from 5.7% to 13.3% in rivaroxaban recipients and from 9.1% to 11.1% in enoxaparin/VKA recipients. Whereas rivaroxaban was associated with a reduced bleeding risk compared with enoxaparin/VKA in patients without comedication (hazard ratio [HR] 0.6, 95% confidence interval [CI] 0.4-0.9), the risk was similar in patients with ≥4 comedications (HR 1.2, 95% CI 0.97-1.5, pinteraction .002). Use of CYP3A4 and/or P-gp inhibitors was associated with a doubled bleeding risk compared with no use, without a difference between rivaroxaban and enoxaparin/VKA.

CONCLUSION

We conclude that fixed-dose rivaroxaban as compared with enoxaparin followed by dose-adjusted VKA is not associated with an increased bleeding risk in patients with VTE administered polypharmacy in general and CYP3A4 and/or P-gp inhibitors specifically. This implies that the observed increased bleeding risks with polypharmacy and use of CYP3A4 and/or P-gp inhibitors are likely explained by comorbidities and frailty, and not by pharmacokinetic interactions.

Development and Validation of UPLC-MS/MS Method for Quantifying of Free and Total Dabigatran in Human Plasma: An Application for a Bioequivalence Study

Dabigatran etexilate mesylate (DABE), a prodrug, quickly changes in our bodies after its oral administration into dabigatran (DAB). Accordingly, detecting DABE in plasma is practically unmanageable. A UPLC-MS/MS technique was developed and validated to compute free DAB in participants. For the first time, the central composite design- a type of response surface methodology- was utilized for optimizing variables affecting the cleavage of glucuronide bond. Additionally, the pharmacokinetic parameters of generic medication (okanadab) were determined, and the obtained outcomes were compared to those of branded drug (pradaxa®). The sample preparation was done using methanol as a protein precipitant and the separation was achieved via ACQUITY UPLC BEH C18 column (2.1x50mm, 1.7μm). The elution was isocratically conducted using 10mM ammonium formate: methanol (72:28, v/v) as a mobile phase (MP) and the flow rate was 0.25mL/min. Multiple reaction monitoring (MRM) and positive electrospray ionization (ESI) were used. The determination was performed within 1min, and the calibration growth curve was established over a range of (1.19 - 475) ng/mL using dabigatran-d3 as a tagged internal standard (IS). Bioequivalence research was validated following FDA guidelines for bio-analytical procedures and acceptable outcomes were achieved. The outcomes for okanadab and pradaxa® did not differ significantly.

Idarucizumab reverses dabigatran-induced anticoagulation in treatment of gastric bleeding: A case report

BACKGROUND

The drug instructions for dabigatran recommend adjusting the dosage to 110 mg twice daily for patients with bleeding risk, and performing at least one renal function test per year for patients with moderate renal impairment. However, owing to chronic insidiously worsening renal insufficiency, dabigatran can still accumulate abnormally, necessitating therapy with idarucizumab to reverse the anticoagulation due to severe erosive gastritis with widespread stomach mucosal bleeding.

CASE SUMMARY

A 76-year-old woman with a history of atrial fibrillation who took dabigatran 110 mg twice daily as directed to lessen the chance of stroke, was transported to the hospital with hematemesis and melena. Laboratory findings revealed severe life-threatening, blood-loss-induced anemia with a hemoglobin (Hb) level of 41.0 g/L and marked coagulation abnormalities with thrombin time (TT) > 180 s, most likely caused by dabigatran-induced metabolic disorder. Aggressive acid suppressive, hemostatic, and blood transfusion therapy resulted in the misconception that the bleeding was controlled, with subsequent rebleeding. Idarucizumab was administered in a timely manner to counteract dabigatran's anticoagulant impact, and 12 h later, TT was determined to be 17.4 s, which was within the normal range. Finally, the patient had no active bleeding signs and laboratory findings showed an Hb level of 104 g/L and TT of 17.7 s.

CONCLUSION

Renal function, coagulation function, and dabigatran concentration should be regularly monitored in older patients. Proton pump inhibitor and dabigatran coadministration is still controversial in preventing upper gastrointestinal tract bleeding.

Effects of direct oral anticoagulants dabigatran and rivaroxaban on the blood coagulation function in rabbits

The aim of this study was to explore the effects of dabigatran and rivaroxaban on the activities of various coagulation factors. To achieve that, 60 rabbits were randomly divided into experimental groups that received different doses of dabigatran or rivaroxaban. The effects of dabigatran and rivaroxaban on the activities of FII, FV, FVIII, FX, and activated protein C (APC) were analyzed. In the dabigatran groups, activated partial thromboplastin time and thromboplastin time (TT) were prolonged after drug administration, and the activities of FII, FV, FVIII, and FX were inhibited as the drug concentration increased. Low doses of dabigatran inhibited APC activity. In the rivaroxaban groups, APTT and TT were not significantly prolonged after drug administration. In contrast, the high-dose rivaroxaban group exhibited prolonged PT, and the degree of inhibition of the activities of FII, FV, FVIII, and FX increased as the drug concentration increased. Rivaroxaban had no significant effect on APC activity regardless of dosage. As the drug concentration increased, both NOACs had more significant inhibitory effects on the activities of FII, FV, FVIII, and FX. Low concentrations of dabigatran generated an inhibitory effect on APC activity, while high concentrations of dabigatran had no significant effect. Rivaroxaban had no significant effect on APC activity.

Role of Direct Oral Anticoagulation Agents as Thromboprophylaxis in Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is an autoimmune disorder that causes venous, arterial and small-vessel thrombosis, pregnancy loss, and premature birth. Cardiac valvular disease, renal thrombotic microangiopathy, thrombocytopenia, hemolytic anemia, and cognitive impairment are some of its other clinical symptoms. Antiphospholipid antibodies cause endothelial cells, monocytes, and platelets to become activated, as well as an increase in tissue factor and thromboxane A2. Complement activation might play a key function in pathogenesis. Long-term oral anticoagulation is used to treat thrombosis, and individuals having arterial episodes should be treated quickly. Patients with systemic lupus erythematosus (SLE), as well as those with solely obstetric antiphospholipid syndrome, should get primary thromboprophylaxis. Obstetric care is based on a combination of medical and obstetric high-risk management, as well as aspirin and heparin therapy. Possible supplementary therapy for this condition is hydroxychloroquine. Statins, rituximab, and novel anticoagulant medicines are all potential future treatments for non-pregnant individuals with antiphospholipid syndrome. We aim to review the role of direct-acting oral anticoagulants (DOACs) as thromboprophylactic drugs in the treatment of APS in this article. The treatment of venous thromboembolism has been transformed by a new class of DOACs. These drugs, such as rivaroxaban, function by inhibiting factor Xa directly. Not only do they have known anticoagulant actions, but they also obviate the need for dosage monitoring and modification, in contrast to warfarin. We conducted an exhaustive literature search of PubMed/MEDLINE and Google Scholar Indexes using the keywords "Antiphospholipid syndrome," "thromboprophylaxis," and "oral anticoagulants" up to September 2021. We found that DOACs have been shown to be non-inferior to warfarin in a variety of anticoagulation situations in a number of high-powered clinical studies. In many hypercoagulable conditions such as APS, DOACs are quickly establishing themselves as first-line therapy. This article is focused on comprehensively reviewing the mechanism of action of DOACs, their role as thromboprophylactic drugs, risks and complications of DOACs, and comparing their efficacy with the standard treatment protocol and warfarin.

Edoxaban and the Issue of Drug-Drug Interactions: From Pharmacology to Clinical Practice

Edoxaban, a direct factor Xa inhibitor, is the latest of the non-vitamin K antagonist oral anticoagulants (NOACs). Despite being marketed later than other NOACs, its use is now spreading in current clinical practice, being indicated for both thromboprophylaxis in patients with non-valvular atrial fibrillation (NVAF) and for the treatment and prevention of venous thromboembolism (VTE). In patients with multiple conditions, the contemporary administration of several drugs can cause relevant drug-drug interactions (DDIs), which can affect drugs' pharmacokinetics and pharmacodynamics. Usually, all the NOACs are considered to have significantly fewer DDIs than vitamin K antagonists; notwithstanding, this is actually not true, all of them are affected by DDIs with drugs that can influence the activity (induction or inhibition) of P-glycoprotein (P-gp) and cytochrome P450 3A4, both responsible for the disposition and metabolism of NOACs to a different extent. In this review/expert opinion, we focused on an extensive report of edoxaban DDIs. All the relevant drugs categories have been examined to report on significant DDIs, discussing the impact on edoxaban pharmacokinetics and pharmacodynamics, and the evidence for dose adjustment. Our analysis found that, despite a restrained number of interactions, some strong inhibitors/inducers of P-gp and drug-metabolising enzymes can affect edoxaban concentration, just as it happens with other NOACs, implying the need for a dose adjustment. However, our analysis of edoxaban DDIs suggests that given the small propensity for interactions of this agent, its use represents an acceptable clinical decision. Still, DDIs can be significant in certain clinical situations and a careful evaluation is always needed when prescribing NOACs.

Laboratory Monitoring of Direct Oral Anticoagulants (DOACs)

The introduction of direct oral anticoagulants (DOACs), such as dabigatran, rivaroxaban, apixaban, edoxaban, and betrixaban, provides safe and effective alternative to previous anticoagulant therapies. DOACs directly, selectively, and reversibly inhibit factors IIa or Xa. The coagulation effect follows the plasma concentration-time profile of the respective anticoagulant. The short half-life of a DOAC constrains the daily oral intake. Because DOACs have predictable pharmacokinetic and pharmacodynamic responses at a fixed dose, they do not require monitoring. However in specific clinical situations and for particular patient populations, testing may be helpful for patient management. The effect of DOACs on the screening coagulation assays such as prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT) is directly linked to reagent composition, and clotting time can be different from reagent to reagent, depending on the DOAC's reagent sensitivity. Liquid chromatography-mass spectrometry (LC-MS/MS) is considered the gold standard method for DOAC measurement, but it is time consuming and requires expensive equipment. The general consensus for the assessment of a DOAC is clotting or chromogenic assays using specific standard calibrators and controls. This review provides a short summary of DOAC properties and an update on laboratory methods for measuring DOACs.

Influence of ABCB1 Gene Polymorphism on Rivaroxaban Blood Concentration and Hemorrhagic Events in Patients With Atrial Fibrillation

Background and Objectives: Genetic data on the pharmacokinetics of rivaroxaban and identification of factors that affect its biotransformation, distribution, and excretion will allow for generation of algorithms for personalized use of this drug in patients with atrial fibrillation (AF). Here we tested the effects of ABCB1 (ATP-binding cassette subfamily B member 1) polymorphisms on the valley rivaroxaban blood concentration and on the frequency of hemorrhagic events in patients with AF and propose a personal anticoagulation therapy management protocol. Patients and Methods: This is a retrospective study. We enrolled Mongolian descent patients who met the criteria from May 2018 to August 2019 in Beijing and Fujian. Clinical data on gender, height, weight, liver and kidney functions, drug trough concentration, and drug dosage were collected; we recorded the bleeding events until 6 months after initiating the medication. ABCB1 single nucleotide polymorphisms including rs1128503, rs1045642, and rs4148738 were identified. After reaching the steady state of plasma concentration, the peripheral blood was collected to detect the trough rivaroxaban plasma concentrations before the next medication. Results: We included 155 patients in this study including 81 men and 74 women, with an average age of 71.98 ± 10.72 years. The distribution of ABCB1 genotypes conformed to the Hardy-Weinberg equilibrium. Multiple comparisons between wild (TT) and mutant (CT and CC) genotypes at the rs1045642 locus showed no significant differences of rivaroxaban trough concentrations (TT vs. CT, p = 0.586; TT vs. CC, p = 0.802; and CT vs. CC, p = 0.702). Multiple comparison between wild (TT) and mutant (CC) genotypes at the rs1128503 locus revealed a significant difference of rivaroxaban trough concentrations (TT vs. CC, p = 0.0421). But wild (TT) vs mutant (CT) genotypes and mutant CT vs mutant CC genotypes at the rs1128503 locus showed no significant differences of rivaroxaban trough concentrations (TT vs. CT, p = 0.0651; TT vs. CT, p = 0.6127). Multiple comparisons between wild (GG) and mutant (AG and AA) genotypes at the rs4148738 locus showed no significant differences of rivaroxaban trough concentrations (GG vs. AG, p = 0.341; GG vs. AA, p = 0.612; AG vs. AA, p = 0.649). There was no significant correlation between ABCB1 gene variation loci rs1045642, rs1128503, rs4148738 and bleeding events. Conclusion: rs1128503 locus variations are correlated with the serum concentration of rivaroxaban in patients of Mongolian descent. But no significant correlation between rs1128503 locus variations and bleeding events were obtained.

Effects of ticagrelor on the pharmacokinetics of rivaroxaban in rats

CONTEXT

Rivaroxaban and ticagrelor are two common drugs for the treatment of atrial fibrillation and acute coronary syndrome. However, the drug-drug interaction between them is still unknown.

OBJECTIVE

To investigate the effects of ticagrelor on the pharmacokinetics of rivaroxaban in rats both in vivo and in vitro.

MATERIALS AND METHODS

A sensitive and reliable UPLC-MS/MS method was developed for the determination of rivaroxaban in rat plasma. Ten Sprague-Dawley rats were randomly divided into ticagrelor pre-treated group (10 mg/kg/day for 14 days) and control group. The pharmacokinetics of orally administered rivaroxaban (10 mg/kg, single dose) with or without ticagrelor pre-treatment was investigated with developed UPLC-MS/MS method. Additionally, Sprague-Dawley rat liver microsomes were also used to investigate the drug-drug interaction between these two drugs in vitro.

RESULTS

The C _max (221.34 ± 53.33 vs. 691.18 ± 238.31 ng/mL) and the AUC_(0-t) (1060.97 ± 291.21 vs. 3483.03 ± 753.83 μg·h/L) of rivaroxaban increased significantly (p < 0.05) with ticagrelor pre-treatment. The MRT_(0-∞) of rivaroxaban increased from 4.41 ± 0.79 to 5.97 ± 1.11 h, while the intrinsic clearance decreased from 9.93 ± 2.55 to 2.89 ± 0.63 L/h/kg (both p < 0.05) after pre-treated with ticagrelor. Enzyme kinetic study indicated that ticagrelor decreased rivaroxaban metabolic clearance with the IC₅₀ value of 14.04 μmol/L.

CONCLUSIONS

Our in vivo and in vitro results demonstrated that there is a drug-drug interaction between ticagrelor and rivaroxaban in rats. Further studies need to be carried out to verify whether similar interactions truly apply in humans and whether these interactions have clinical significance.

Bariatric Surgery can Lower the Efficacy of DOACs

A 39-year-old woman who was taking the contraceptive pill was admitted with right leg deep venous thrombosis (DVT). She was started on apixaban tablets, but after 8 days developed proximal progression of the DVT and pulmonary embolism. Her medical history later showed a history of sleeve gastrectomy. The patient responded to a vitamin K antagonist after heparin. The failure of the antithrombotic drug shed light on the efficacy and changed pharmacodynamics of direct oral anticoagulants (DOACs) after bariatric surgery in the absence of commercially available blood monitoring tests.

New oral anticoagulants for nonvalvular atrial fibrillation with stable coronary artery disease: A meta-analysis

BACKGROUND

New oral anticoagulants (NOACs) are effective and safe in patients with nonvalvular atrial fibrillation (NVAF). Limited evidence is available regarding outcomes for NVAF patients with stable coronary artery disease (CAD).

METHODS

A systematic search of Medline, Embase, and the Cochrane Register was performed. Two reviewers independently performed data extraction and quality assessment using the Cochrane Collaboration risk-of-bias assessment tool. We evaluated all primary publications and secondary analyses comparing NOACs with any other OAC agent for preventing stroke in patients with both NVAF and stable CAD from phase III clinical randomized control trials. The primary outcomes were stroke, systemic embolism (SE), major bleeding, and intracranial hemorrhage (ICH), and the secondary outcomes were cardiovascular (CV) death, all-cause death, and myocardial infarction (MI).

RESULTS

Four articles with a total of 19 266 patients were included in this study. The pooled results showed a relative risk for stroke/SE with NOACs of 0.83 (95% confidence interval [CI]: 0.71-0.97), for major bleeding 0.85 (95% CI: 0.63-1.14), for ICH 0.36 (95% CI: 0.19-0.54), for MI 1.00 (95% CI: 0.82-1.20), for CV death 0.94 (95% CI: 0.83-1.06), and for all-cause death 0.95 (95% CI: 0.85-1.07).

CONCLUSION

NOACs were effective in preventing stroke/SE and reducing the risk of ICH in patients with both NVAF and CAD.

New oral anticoagulants for nonvalvular atrial fibrillation with peripheral artery disease: a meta-analysis

BACKGROUND

New oral anticoagulants (NOACs) are as effective and safe as warfarin for patients with non-valvular atrial fibrillation (NVAF). Limited evidence is available regarding outcomes for NVAF patients with peripheral artery disease (PAD).

METHODS

A systematic search of Medline, Embase, and the Cochrane Library was performed. Two reviewers independently performed data extraction and quality assessment using the Cochrane Collaboration tool for assessing risk of bias. All primary publications and secondary analyses comparing NOACs with other oral anticoagulation regimens for the prevention of stroke in patients with both NVAF and PAD from phase III clinical trials were evaluated. The primary outcomes were stroke, systemic embolism (SE), major bleeding, and intracranial hemorrhage (ICH), and the secondary outcomes were cardiovascular (CV) mortality, all-cause mortality, and myocardial infarction (MI).

RESULTS

Three articles were included in this study. The pooled results showed a relative risk for stroke/SE with NOACs of 0.86 (95% confidence interval [CI]: 0.53-1.39), for major bleeding, 1.12 (95% CI: 0.70-1.81), for ICH, 0.47 (95% CI: 0.16-1.36), for CV mortality, 0.77 (95% CI: 0.57-1.04), for all-cause mortality, 0.91 (95% CI: 0.70-1.19), and for MI, 1.10 (95% CI: 0.64-1.90).

CONCLUSION

The findings show that NOACs are effective and safe for preventing stroke/SE in patients with both NVAF and PAD.

[SBA 2020: Regional anesthesia guideline for using anticoagulants update]

The development of protocols to prevent perioperative Venous Thromboembolism (VTE) and the introduction of increasingly potent antithrombotic drugs have resulted in concerns of increased risk of neuraxial bleeding. Since the Brazilian Society of Anesthesiology (SBA) 2014 guideline, new oral anticoagulant drugs were approved by international regulating agencies, and by ANVISA. Societies and organizations that try to approach concerns through guidelines have presented conflicting perioperative management recommendations. As a response to these issues and to the need for a more rational approach, managements were updated in the present narrative revision, and guideline statements made. They were projected to encourage safe and quality patient care, but cannot assure specific results. Like any clinical guide recommendation, they are subject to review as knowledge grows, on specific complications, for example. The objective was to assess safety aspects of regional analgesia and anesthesia in patients using antithrombotic drugs, such as: possible technique-associated complications; spinal hematoma-associated risk factors, prevention strategies, diagnosis and treatment; safe interval for discontinuing and reinitiating medication after regional blockade.

Perioperative management of anticoagulation

Periprocedural management of the anticoagulated patient can be as easy as continuing warfarin for a low bleeding risk procedure, holding a direct oral anticoagulant for 1 day prior and resuming 1 day later or as complex as emergent reversal with prothrombin complex concentrate, idarucizumab, or andexanet alfa. Patient-specific factors for thromboembolic risk and procedural bleeding risk determine timing of anticoagulation hold prior to and resumption after invasive procedures. Clinical trials and management studies in recent years have helped inform our approach to these patients, but much of the guidance is still based on expert consensus.

Impact of bariatric surgery on oral anticoagulants pharmacology, and consequences for clinical practice: a narrative review

The prevalence of obesity has been steadily increasing in recent years worldwide. At the same time bariatric surgery, the best therapeutic strategy to date in terms of sustainable weight loss and improvement of associated comorbidities has been also increasing. However, these surgeries, whether primarily restrictive or malabsorptive, raise questions about the pharmacology of oral drugs. Among widely used drugs, anticoagulants are the referent therapy to treat some cardiovascular diseases such as atrial fibrillation and venous thromboembolism. How bariatric surgery may impact pharmacological properties of oral anticoagulants, and more specifically, direct oral anticoagulants (DOACs) are difficult to anticipate. In this review, we describe available data concerning the potential impact of bariatric surgery on the pharmacology of oral anticoagulants. The vitamin K antagonists (VKAs) requirements for the same international normalized ratio target are reduced after bariatric surgery. Limited data available for dabigatran 150 mg twice daily indicate a risk of insufficient efficacy in atrial fibrillation after gastric bypass due to probable impaired absorption. Data for rivaroxaban at the prophylactic dose of 10 mg per day suggest no impact of bariatric surgery from 3 days to 8 months post-surgery. However, no conclusive data are available for other anticoagulants or the use of DOACs at therapeutic doses. To date, DOACs are not recommended in patients who have undergone bariatric surgery, because of limited available data. Pending new studies to confirm the predictable pharmacokinetics and safety of DOACs in this population, especially at therapeutic doses, VKAs remain the first option for chronic anticoagulation.

Expedient Approach to the Synthesis of Betrixaban

A new scalable route to synthesize the factor Xa (FXa) inhibitor betrixaban is disclosed. The product is obtained in a seven-step reaction sequence (in five stages using two one-pot reactions) starting from easily accessible 4-(N,N-dimethylcarbamimidoyl)benzoate. Effective isolation of intermediates, use of cost-effective amide formation and 2-methyltetrahydrofuran as an effective reaction solvent as well as for extraction in three of the stages, are key features. The strategy provides the desired product in 38% overall yield with high purity (>98%).

A Brief Review of Cardiovascular Diseases, Associated Risk Factors and Current Treatment Regimes

Cardiovascular diseases (CVDs) are the leading cause of premature death and disability in humans and their incidence is on the rise globally. Given their substantial contribution towards the escalating costs of health care, CVDs also generate a high socio-economic burden in the general population. The underlying pathogenesis and progression associated with nearly all CVDs are predominantly of atherosclerotic origin that leads to the development of coronary artery disease, cerebrovascular disease, venous thromboembolism and, peripheral vascular disease, subsequently causing myocardial infarction, cardiac arrhythmias or stroke. The aetiological risk factors leading to the onset of CVDs are well recognized and include hyperlipidaemia, hypertension, diabetes, obesity, smoking and, lack of physical activity. They collectively represent more than 90% of the CVD risks in all epidemiological studies. Despite high fatality rate of CVDs, the identification and careful prevention of the underlying risk factors can significantly reduce the global epidemic of CVDs. Beside making favorable lifestyle modifications, primary regimes for the prevention and treatment of CVDs include lipid-lowering drugs, antihypertensives, antiplatelet and anticoagulation therapies. Despite their effectiveness, significant gaps in the treatment of CVDs remain. In this review, we discuss the epidemiology and pathology of the major CVDs that are prevalent globally. We also determine the contribution of well-recognized risk factors towards the development of CVDs and the prevention strategies. In the end, therapies for the control and treatment of CVDs are discussed.

Perioperative management of patients receiving non-vitamin K antagonist oral anticoagulants: up-to-date recommendations

Indications of non-vitamin K antagonist oral anticoagulants (NOACs), consisting of two types: direct thrombin inhibitor (dabigatran) and direct factor Xa inhibitor (rivaroxaban, apixaban, and edoxaban), have expanded over the last few years. Accordingly, increasing number of patients presenting for surgery are being exposed to NOACs, despite the fact that NOACs are inevitably related to increased perioperative bleeding risk. This review article contains recent clinical evidence-based up-to-date recommendations to help set up a multidisciplinary management strategy to provide a safe perioperative milieu for patients receiving NOACs. In brief, despite the paucity of related clinical evidence, several key recommendations can be drawn based on the emerging clinical evidence, expert consensus, and predictable pharmacological properties of NOACs. In elective surgeries, it seems safe to perform high-bleeding risk surgeries 2 days after cessation of NOAC, regardless of the type of NOAC. Neuraxial anesthesia should be performed 3 days after cessation of NOACs. In both instances, dabigatran needs to be discontinued for an additional 1 or 2 days, depending on the decrease in renal function. NOACs do not require a preoperative heparin bridge therapy. Emergent or urgent surgeries should preferably be delayed for at least 12 h from the last NOAC intake (better if > 24 h). If surgery cannot be delayed, consider using specific reversal agents, which are idarucizumab for dabigatran and andexanet alfa for rivaroxaban, apixaban, and edoxaban. If these specific reversal agents are not available, consider using prothrombin complex concentrates.

Treatment of the Dental Patient with Bleeding Dyscrasias: Etiologies and Management Options for Surgical Success in Practice

The oral health care provider sees a significant number of patients in his or her practice who suffer from systemic diseases affecting the ability to clot. These medical issues can be acquired or inherited bleeding dyscrasias requiring pharmacologic therapy during the perioperative period. Patients with inherited or acquired bleeding disorders require careful attention with respect to the assessment of bleeding risk. This article develops algorithms to manage acquired and inherited bleeding dyscrasias. These approaches include a discussion of the epidemiology of bleeding disorders in surgical patients, mechanism of hemostasis, and strategies for patient management based on the etiology of bleeding disorder.

Factor Xa Inhibitory Profile of Apixaban, Betrixaban, Edoxaban, and Rivaroxaban Does Not Fully Reflect Their Biologic Spectrum

The currently available oral anti-Xa agents are claimed to produce their anticoagulant and antithrombotic effects solely by the inhibition of factor Xa. This study profiled various anti-Xa drugs in routinely used laboratory assays to demonstrate that their effects are not solely related to the anti-Xa activities. Apixaban, betrixaban, edoxaban, and rivaroxaban were obtained commercially. Native and citrated whole blood was used for the activated clotting time (ACT) and thromboelastography (TEG). Citrated plasma was used for monitoring the prothrombin time (PT), activated partial thromboplastin time (aPTT), Heptest, and prothrombinase-induced clotting time (PiCT) tests. An amidolytic method was used for the determination of anti-Xa effects. Thrombin-induced fibrinokinetics was monitored optically. Thrombin generation studies were carried out using the calibrated automated thrombogram. All of the anti-Xa agents produced concentration- and assay-dependent effects. In the ACT at 2.5 μg/mL and TEG at 1.0 μg/mL, edoxaban exhibited the strongest anticoagulation effect. In the PiCT, PT, and aPTT assay at 1 μg/mL, edoxaban showed stronger effects than other agents. The half maximal inhibitory concentration of these agents for the inhibition of factor Xa ranged from 340 to >1000 ng/mL. In the thrombin generation inhibition assay, apixaban showed the strongest activity. In the fibrinokinetics, different anti-Xa agents produced varying degrees of inhibition. These results demonstrate that the measured anti-Xa activity alone does not fully reflect the overall biologic spectrum of these agents.

Surfing the Blood Coagulation Cascade: Insight into the Vital Factor Xa

Factor Xa (FXa) plays a key role in haemostasis, it is a central part of the blood coagulation cascade which catalyzes the production of thrombin and leads to clot formation and wound closure. Therefore, FXa is an attractive target for the development of new anticoagulant agents. In this review, we will first describe the molecular features of this fundamental protein in order to understand its mechanism of action, an essential background for the design of novel inhibitors by means of synthetic organic chemistry or using peptides obtained from recombinant methodologies. Then, we will review the current state of the synthesis of novel direct FXa inhibitors along with their mechanisms of action. Finally, approved reversal agents that aid in maintaining blood haemostasis by using these commercial drugs will also be discussed.

Stroke Prevention in Atrial Fibrillation: The Role of Oral Anticoagulation

Oral anticoagulation significantly reduces the risk of stroke in patients with atrial fibrillation (AF), and the decision to initiate therapy is based on assessing the patient's yearly risk of stroke. Although warfarin remains the drug of choice in patients with AF and artificial mechanical valves, the novel anticoagulation agents are becoming the drug of choice for all other patients with AF, because of their efficacy, safety, and ease of use. This article summarizes the current evidence for stroke prevention in AF, including valvular AF, subclinical AF, AF in patients with renal insufficiency, as well as stroke prevention around AF cardioversion.

[Perioperative handling of anticoagulation]

A growing number of patients in Germany receive a long-term prophylactic anticoagulation with phenprocoumone or one of the novel direct oral anticoagulants (NOAC), such as dabigatran, rivaroxaban or apixaban. The most common indication for an oral anticoagulant therapy is atrial fibrillation (approximately 75%) where the anticoagulant therapy can reduce the risk for an embolic event, particularly stroke by 60%. Operations carried out during such a therapy can result in major bleeding complications. On the other hand, suspending anticoagulant therapy can lead to an increased risk of thromboembolisms. Thus, the preoperative assessment should address the bleeding risk of the planned operation, the individual risk of thromboembolism, as well as other factors, such as patient age and renal function. If the individual assessment shows a substantial risk of perioperative bleeding when anticoagulant treatment is continued and a substantial risk of thromboembolism if the treatment is suspended, then a perioperative bridging, for example with low molecular weight heparin, is necessary. Perioperative bridging also leads to an increased risk of perioperative bleeding. Thus, undifferentiated bridging for all patients with atrial fibrillation with anticoagulant treatment is not recommended. Instead, the indications for a perioperative bridging should be decided according to individual risk profiles.