Prevention of venous thromboembolism with an oral factor Xa inhibitor, YM150, after total hip arthroplasty. A dose finding study (ONYX-2)

The safety and efficacy of NOACs versus LMWH for thromboprophylaxis after THA or TKA: A systemic review and meta-analysis

The differences in the safety and efficacy of anticoagulation between different types of new oral anticoagulants(NOACs) and low molecular weight heparin(LMWH) are still controversial. The main purposes of this study were to analyze safety and efficacy of NOACs versus LMWH for thromboprophylaxis, and perform subgroup analyses stratified by individual NOACs and different populations after total hip arthroplasty (THA) or total knee arthroplasty (TKA). Literature search was performed in PubMed, EMBASE, Cochrane Library, CNKI and Wanfang databases until June 31, 2022. This systematic review and meta-analysis included 46 randomized controlled trials (RCT) with 39, 924 patients. We evaluated the safety and efficacy of thromboprophylaxis between LMWH and NOACs. NOACs were more effective in reducing deep vein thrombosis (DVT) (RR0.59; 95%CI 0.49-0.71) and adverse events (RR: 0.96; 95%CI: 0.93-0.99) than LMWH. The subgroup analyses for different anticoagulants revealed that rivaroxaban (RR:0.49; 95%CI:0.36-0.66), apixaban (RR: 0.54; 95%CI: 0.36-0.81) and edoxaban (RR:0.49; 95%CI: 0.32-0.75) have the lower risk of DVT than LMWH. Apixaban (RR:0.89; 95%CI: 0.80-1.00) had superior prevention of bleeding to LMWH. Edoxaban exhibited a lower risk of VTE (RR: 0.46; 95%CI: 0.33-0.65), advantage events (RR: 0.87; 95%CI: 0.82-0.93), and drug-related adverse events (DRAEs) (RR: 0.64; 95%CI: 0.53-0.76) than LMWH. East Asian population was superior to western population for preventing DVT, advantage events, and DRAE using NOACs. In conclusion, NOACs are more effective than LMWH at preventing DVT and adverse events after arthroplasty. Apixaban has lower bleeding than LMWH, and East Asian populations may benefit more than western population from NOACs.

Joint 2022 European Society of Thoracic Surgeons and The American Association for Thoracic Surgery guidelines for the prevention of cancer-associated venous thromboembolism in thoracic surgery

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis and pulmonary embolism, is a potentially fatal but preventable postoperative complication. Thoracic oncology patients undergoing surgical resection, often after multimodality induction therapy, represent among the highest risk groups for postoperative VTE. Currently there are no VTE prophylaxis guidelines specific to these thoracic surgery patients. Evidenced-based recommendations will help clinicians manage and mitigate risk of VTE in the postoperative period and inform best practice.

OBJECTIVE

These joint evidence-based guidelines from The American Association for Thoracic Surgery and the European Society of Thoracic Surgeons aim to inform clinicians and patients in decisions about prophylaxis to prevent VTE in patients undergoing surgical resection for lung or esophageal cancer.

METHODS

The American Association for Thoracic Surgery and the European Society of Thoracic Surgeons formed a multidisciplinary guideline panel that included broad membership to minimize potential bias when formulating recommendations. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used, including GRADE Evidence-to-Decision frameworks, which were subject to public comment.

RESULTS

The panel agreed on 24 recommendations focused on pharmacological and mechanical methods for prophylaxis in patients undergoing lobectomy and segmentectomy, pneumonectomy, and esophagectomy, as well as extended resections for lung cancer.

CONCLUSIONS

The certainty of the supporting evidence for the majority of recommendations was judged as low or very low, largely due to a lack of direct evidence for thoracic surgery. The panel made conditional recommendations for use of parenteral anticoagulation for VTE prevention, in combination with mechanical methods, over no prophylaxis for cancer patients undergoing anatomic lung resection or esophagectomy. Other key recommendations include: conditional recommendations for using parenteral anticoagulants over direct oral anticoagulants, with use of direct oral anticoagulants suggested only in the context of clinical trials; conditional recommendation for using extended prophylaxis for 28 to 35 days over in-hospital prophylaxis only for patients at moderate or high risk of thrombosis; and conditional recommendations for VTE screening in patients undergoing pneumonectomy and esophagectomy. Future research priorities include the role of preoperative thromboprophylaxis and the role of risk stratification to guide use of extended prophylaxis.

Efficacy of 11 anticoagulants for the prevention of venous thromboembolism after total hip or knee arthroplasty: A systematic review and network meta-analysis

BACKGROUND

To systematically review the efficacy of 11 anticoagulants in the treatment of venous thromboembolism (VTE) after total hip or knee arthroplasty.

METHODS

PubMed, Cochrane Library, Embase, Web of Science, China National Knowledge Infrastructure, Wanfang Data, VIP, and China Biology Medicine databases were electronically searched for studies assessing the efficacy of different anticoagulants for the prevention of VTE after total hip or knee arthroplasty from January 1, 2010, to January 27, 2022. Two reviewers independently screened the literature, extracted data, and graded the evidence using Confidence in Network Meta-Analysis. The network meta-analysis was then performed using Stata 16.0 software and R 4.1.0 software.

RESULTS

A total of 61 articles were included. The results of network meta-analysis showed that apixaban, edoxaban, fondaparinux, rivaroxaban, and darexaban were the most effective anticoagulants for the prevention of deep vein thrombosis in patients undergoing total hip or knee arthroplasty (P < .05), while there was no difference in the efficacy among the anticoagulants for the prevention of pulmonary embolism (P > .05).

CONCLUSION

Apixaban, edoxaban, fondaparinux, rivaroxaban, and darexaban have the best efficacy for the prevention of VTE after total hip or knee arthroplasty.

Joint 2022 European Society of Thoracic Surgeons and The American Association for Thoracic Surgery guidelines for the prevention of cancer-associated venous thromboembolism in thoracic surgery

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis and pulmonary embolism, is a potentially fatal but preventable postoperative complication. Thoracic oncology patients undergoing surgical resection, often after multimodality induction therapy, represent among the highest risk groups for postoperative VTE. Currently there are no VTE prophylaxis guidelines specific to these thoracic surgery patients. Evidenced-based recommendations will help clinicians manage and mitigate risk of VTE in the postoperative period and inform best practice.

OBJECTIVE

These joint evidence-based guidelines from The American Association for Thoracic Surgery and the European Society of Thoracic Surgeons aim to inform clinicians and patients in decisions about prophylaxis to prevent VTE in patients undergoing surgical resection for lung or esophageal cancer.

METHODS

The American Association for Thoracic Surgery and the European Society of Thoracic Surgeons formed a multidisciplinary guideline panel that included broad membership to minimize potential bias when formulating recommendations. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used, including GRADE Evidence-to-Decision frameworks, which were subject to public comment.

RESULTS

The panel agreed on 24 recommendations focused on pharmacological and mechanical methods for prophylaxis in patients undergoing lobectomy and segmentectomy, pneumonectomy, and esophagectomy, as well as extended resections for lung cancer.

CONCLUSIONS

The certainty of the supporting evidence for the majority of recommendations was judged as low or very low, largely due to a lack of direct evidence for thoracic surgery. The panel made conditional recommendations for use of parenteral anticoagulation for VTE prevention, in combination with mechanical methods, over no prophylaxis for cancer patients undergoing anatomic lung resection or esophagectomy. Other key recommendations include: conditional recommendations for using parenteral anticoagulants over direct oral anticoagulants, with use of direct oral anticoagulants suggested only in the context of clinical trials; conditional recommendation for using extended prophylaxis for 28 to 35 days over in-hospital prophylaxis only for patients at moderate or high risk of thrombosis; and conditional recommendations for VTE screening in patients undergoing pneumonectomy and esophagectomy. Future research priorities include the role of preoperative thromboprophylaxis and the role of risk stratification to guide use of extended prophylaxis. (J Thorac Cardiovasc Surg 2022;▪:1-31).

Ranking the efficacy of anticoagulants for the prevention of venous thromboembolism after total hip or knee arthroplasty: A systematic review and a network meta-analysis

BACKGROUND

Anticoagulants are essential in the prevention of venous thromboembolism. However, the effectiveness and safety of different anticoagulants have always been controversial. Therefore, we aimed to expand the sample of anticoagulant results and rank the efficacy and safety of 19 anticoagulants in the prevention of venous thromboembolism when total knee or total hip arthroplasty procedure is performed.

METHODS

A systematic review and network meta-analysis of randomized trials of adult patients undergoing total hip or knee arthroplasty were conducted. The trials were identified from PubMed, Web of Science, Cochrane Library, and Embase databases, in which anticoagulants were used as interventions randomized controlled trial. The incidence of venous embolism and bleeding are the key outcomes of assessing the efficacy of intervention drugs. We used the Physical Therapy Evidence Database (PEDro) to assess risk bias and used pairwise comparison and network meta-analysis with random effects to estimate the summary relative risk. The study has been registered with PROSPERO, number CRD42020200747.

RESULTS

From the 4083 identified manuscripts, 45,067 participants from 53 randomized trials were included in the analysis and randomly assigned to 19 anticoagulants. With Enoxaparin as a control, Rivaroxaban (risk difference 0.07, 95 % credible interval 0.06 to 0.08), Edoxaban (RD 0.09, 95 % CrI 0.08 to 0.11), and Apixaban (RD 0.05, 95 % CrI 0.04 to 0.06) had the best effect in preventing VTE. However, in terms of comprehensive bleeding rate, Apixaban, Edoxaban, and Darexaban were the most effective and stable. Although effective in preventing VTE, bleeding remains relatively high in Rivaroxaban. Enoxaparin is low-molecular-weight heparin that is widely used in clinics, and although its overall efficacy is not the best, its efficacy and safety are very stable.

CONCLUSION

According to the available data, Apixaban, Edoxaban, and Darexaban are better than any anticoagulants in the prevention of VTE and bleeding during total knee or total hip arthroplasty. In our study, Fondaparinux, Eribaxaban, Dalteparin, Betrixaban, Bemiparin, Reviparin, Acenocoumarol, and Tinzaparin were scarce in the included studies, therefore, more evidence is needed to prove their efficacy and safety.

Risk of Major Gastrointestinal Bleeding With New vs Conventional Oral Anticoagulants: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

There is controversy over whether use of non-vitamin K antagonist oral anticoagulants (NOACs) associates with increased risk of major gastrointestinal bleeding (GIB) compared with conventional therapies (such as vitamin K antagonists or anti-platelet agents). We performed a systematic review and meta-analysis of data from randomized controlled trials and high-quality real-world studies.

METHODS

We performed a systematic search of the MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov Website databases (through Oct 12, 2018) for randomized controlled trials and high-quality real-world studies that reported major GIB events in patients given NOACs or conventional therapy. Relative risks (RRs) for randomized controlled trials and adjusted hazard ratios (aHRs) for real-world studies were calculated separately using random-effects models.

RESULTS

We analyzed data from 43 randomized controlled trials (183,752 patients) and 41 real-world studies (1,879,428 patients). The pooled major rates of GIB for patients on NOACs (1.19%) vs conventional treatment (0.92%) did not differ significantly (RR from randomized controlled trials, 1.09; 95% CI, 0.91-1.31 and aHR from real-world studies, 1.02; 95% CI, 0.94-1.10; P_interaction=.52). Rivaroxaban, but not other NOACs, was associated with an increased risk for major GIB (RR from randomized controlled trials, 1.39; 95% CI, 1.17-1.65 and aHR from real-world studies, 1.14; 95% CI, 1.04-1.23; P_interaction = .06). Analyses of subgroups, such as patients with different indications, dosage, or follow-up time, did not significantly affect results. Meta-regression analysis failed to detect any potential confounding to impact the primacy outcome.

CONCLUSIONS

In a systematic review and meta-analysis of data from randomized controlled trials and real-world studies, we confirmed that there is no significant difference in risk of major GIB between patients receiving NOACs vs conventional treatment. Rivaroxaban users had a 39% increase in risk for major GIB.

American Society of Hematology 2019 guidelines for management of venous thromboembolism: prevention of venous thromboembolism in surgical hospitalized patients

BACKGROUND

Venous thromboembolism (VTE) is a common source of perioperative morbidity and mortality.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support decision making about preventing VTE in patients undergoing surgery.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline-development process, including performing systematic reviews. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 30 recommendations, including for major surgery in general (n = 8), orthopedic surgery (n = 7), major general surgery (n = 3), major neurosurgical procedures (n = 2), urological surgery (n = 4), cardiac surgery and major vascular surgery (n = 2), major trauma (n = 2), and major gynecological surgery (n = 2).

CONCLUSIONS

For patients undergoing major surgery in general, the panel made conditional recommendations for mechanical prophylaxis over no prophylaxis, for pneumatic compression prophylaxis over graduated compression stockings, and against inferior vena cava filters. In patients undergoing total hip or total knee arthroplasty, conditional recommendations included using either aspirin or anticoagulants, as well as for a direct oral anticoagulant over low-molecular-weight heparin (LMWH). For major general surgery, the panel suggested pharmacological prophylaxis over no prophylaxis, using LMWH or unfractionated heparin. For major neurosurgery, transurethral resection of the prostate, or radical prostatectomy, the panel suggested against pharmacological prophylaxis. For major trauma surgery or major gynecological surgery, the panel suggested pharmacological prophylaxis over no prophylaxis.

Darexaban (YM150) versus enoxaparin for the prevention of venous thromboembolism after total hip arthroplasty: a randomised phase IIb dose confirmation study (ONYX-3)

This double-blind, double-dummy, randomised, phase IIb study (NCT00902928) evaluated different dosing regimens of darexaban compared with enoxaparin (randomised 1:1:1:1:1 to 15 mg twice daily [bid], 30 mg once daily [qd], 30 mg bid or 60 mg qd or enoxaparin 40 mg qd) in patients undergoing elective total hip arthroplasty. Patients, investigators, pharmacists and sponsor were all blinded to treatment allocation. Darexaban administration started 6-10 hours (h) post-surgery. Enoxaparin 40 mg qd administration started 12 ± 2 h before surgery. Treatment continued for 35 days. Bilateral venography was performed on Day 10 ± 2. The primary efficacy outcome was total VTEs (composite of proximal/distal deep-vein thrombosis, pulmonary embolism) or death, at Day 12. Total VTE rates were similar across all groups. There was no apparent difference in efficacy between onceand twice-daily darexaban (odds ratio [OR] 1.00; 95% confidence interval [CI] 0.71–1.42; p=0.988), or total daily dose (30 mg/day vs 60 mg/day; OR 0.81; 95% CI 0.57–1.15; p=0.244). There was no significant difference in major and/or clinically relevant non-major bleeding between darexaban qd or bid, or between total daily doses of 30 mg or 60 mg, and also for any dosing regimen of darexaban vs enoxaparin. Darexaban was well tolerated, without signs of liver toxicity. In conclusion, darexaban, administered qd or bid, and at total daily doses of 30 mg or 60 mg, appears to be effective for VTE prevention and was well tolerated. Data suggest no significant differences between a once- or twice-daily dosing regimen.

Functional characterisation of Vizottin, the first factor Xa inhibitor purified from the leech Haementeria vizottoi

The strategic position of factor Xa (FXa) in blood coagulation makes it a compelling target for the development of new anticoagulants. Bloodsucking animals have in their salivary glands mixtures of anticoagulants, which could be used for designing novel antithrombotic compounds. Herein, we describe Vizottin, the first FXa inhibitor from the salivary complex of the leech Haementeria vizottoi. Vizottin was purified by gel filtration and reverse-phase chromatography, and shown to have anticoagulant effects in human plasma, prolonging the recalcification time in a dose-dependent manner (IC50 40 nM). Vizottin induced blood incoagulability in FX-deficient plasma, whereas in normal and reconstituted plasma, Vizottin doubled the prothrombin time at 160 nM. This peptide competitively inhibited human FXa (Ki 2 nM) like FXa inhibitors from other leeches, albeit via a distinct mechanism of action. At high concentrations, vizottin inhibited the amidolytic activity of factor VIIa/tissue factor (IC50 96.4 nM). Vizottin inhibited FXa in the prothrombinase complex and Gla-domainless FXa. Moreover, vizottin did not interfere with FX activation induced by RVV-X, a known enzyme that requires the Gla-domain of FX for activation. Competition experiments in the presence of FXa and GGACK-FXa (active site blocked) demonstrated that the inhibition of FXa by vizottin is through binding to the active site rather than an exosite. This novel inhibitor appears to exert its inhibitory effects through direct binding to the active site of FXa in a time-dependent manner, but not involving a tight-binding model. In this context, vizottin is a promising model for designing novel anticoagulants for the treatment of thrombotic diseases.

Oral direct factor Xa inhibitor versus enoxaparin for thromboprophylaxis after hip or knee arthroplasty: Systemic review, traditional meta-analysis, dose-response meta-analysis and network meta-analysis

OBJECTIVES

To analyze the efficacy and safety of direct factor Xa inhibitors for thromboprophylaxis after total hip or knee replacement. To delineate the dose response effect of direct factor Xa inhibitors. To compare the efficacy between any two direct factor Xa inhibitors.

DESIGN

Systemic review, traditional meta-analysis, dose-response meta-analysis and network meta-analysis.

DATA SOURCE

PubMed, EMBASE and Cochrane Library.

STUDY SELECTION

Randomized controlled trials of rivaroxaban, apixaban, betrixaban, darexaban and edoxaban were compared with enoxaparin for thromboprophylaxis after total hip or knee replacement. Two reviewers independently checked the quality of RCTs. Another two investigators independently extracted data. The primary efficacy outcomes (composite of deep venous thrombosis, non-fatal pulmonary embolism and death of all causes) and the primary bleeding outcomes (major bleeding and non-major but clinically relevant bleeding) were summarized for meta-analysis. Stata software was used for traditional meta-analysis and dose-response meta-analysis, and Winbugs software was used for network meta-analysis.

RESULTS

Twenty trials with 38,507 subjects in the intention-to-treat population were included. Compared with enoxaparin, the risk of total venous thromboembolism was lower with rivaroxaban (relative risk 0.70, 95% confidence interval 0.60 to 0.81), apixaban (0.62, 0.47 to 0.81), and edoxaban (0.62, 0.39 to 0.97) and similar to darexaban (0.96, 0.84 to 1.11) and betrixaban (1.28, 0.97 to 1.68). Compared with enoxaparin, the risk of major or clinically relevant non-major bleeding was higher with rivaroxaban (1.52, 1.14 to 2.02), lower with betrixaban (0.34, 0.14 to 0.84) and similar to apixaban (0.88, 0.73 to 1.05), darexaban (0.85, 0.66 to 1.09) or edoxaban (1.30, 0.72 to 2.33). The risk of major and clinically relevant non-major bleeding of rivaroxaban had a linear relationship with its treatment doses; the risk of total venous thromboembolism of betrixaban and darexaban had linear relationships with their respective treatment doses. There was no linear nor non-liner relationships between the effect of apixaban and its treatment dose. The ranking of total venous thromboembolism risk from low to high was: rivaroxaban, apixaban, edoxaban, enoxaparin, darexaban, and betrixaban. The ranking of major and clinically relevant non-major bleeding from low to high was: betrixaban, enoxaparin, darexaban, edoxaban, apixaban, and rivaroxaban.

CONCLUSIONS

Direct oral factor Xa inhibitors are more effective to prevent venous thromboembolism after total hip or knee replacement. Their anticoagulant effect was not necessarily compromised with a higher bleeding risk. Rivaroxaban, apixaban and edoxaban showed a better anticoagulant effect, as compared with enoxaparin. Rivaroxaban had a higher bleeding rate, while apixaban and edoxaban did not show significantly higher bleeding risks.

A Phase II, double-blind, randomized, parallel group, dose-finding study of the safety and tolerability of darexaban compared with warfarin in patients with non-valvular atrial fibrillation: the oral factor Xa inhibitor for prophylaxis of stroke in atrial fibrillation study 2 (OPAL-2)

BACKGROUND

Darexaban (YM150) is a novel oral anticoagulant that directly inhibits factor Xa.

OBJECTIVES

To investigate the optimal daily dose regimen of YM150 in subjects with non-valvular atrial fibrillation (NVAF).

METHODS

In this multicenter, double-blind, double-dummy, randomized, parallel-group, dose-confirmation study (NCT00938730), patients with NVAF were randomized to darexaban 15 mg bid, 30 mg qd, 30 mg bid, 60 mg qd, 60 mg bid or 120 mg qd, or warfarin qd. The primary endpoint was the incidence of adjudicated major and/or clinically relevant non-major bleeding events. Secondary endpoints included efficacy, pharmacodynamics, safety and tolerability.

RESULTS

A total of 1297 patients were randomized and finally included in the trial (median age, 66 [range 30-89] years; 68.8% male): 981 completed treatment for a median of 28 weeks (interquartile range, 24-36). At daily doses of 30-60 mg, darexaban bid resulted in fewer bleeding events than darexaban qd. For darexaban 120 mg, the bid regimen produced more bleeding events than the qd regimen. Although few efficacy endpoints occurred, these decreased with increasing daily darexaban dose. Darexaban decreased plasma D-dimer levels (index of thrombogenesis) after 4 weeks of treatment by 21.5-33.8% compared with baseline, which was comparable with warfarin at the higher darexaban doses. Darexaban was well tolerated with no liver toxicity.

CONCLUSIONS

In this Phase II study in patients with NVAF, a lower bleeding rate was observed in the 120 mg daily darexaban group compared with warfarin with a reduction in plasma D-dimer as marker for hemostasis. Further investigation of the optimal dose of darexaban for the prevention of stroke in patients with NVAF would need to be considered.

Risk factors for venous thromboembolism of total hip arthroplasty and total knee arthroplasty: a systematic review of evidences in ten years

Background

Risk factors for venous thromboembolism (VTE) of total joint arthroplasty (TJA) have been examined by many studies. A comprehensive systematic review of recent findings of high evidence level in this topic is needed.

Methods

We conducted a PubMed search for papers published between 2003 and 2013 that provided level-I and level-II evidences on risk factors for VTE of TJA. For each potential factors examined in at least three papers, we summarize the the number of the papers and confirmed the direction of statistically significant associations, e.g. “risk factor” “protective factor” or “controversial factor”.

Results

Fifty-four papers were included in the systematic review. Risk factors found to be associated with VTE of both total hip arthroplasty and total knee arthroplasty included older age, female sex, higher BMI, bilateral surgery, surgery time > 2 hours. VTE history was found as a VTE risk factor of THA but an controversial factor of TKA. Cemented fixation as compared to cementless fixation was found as a risk factor for VTE only of TKA. TKA surgery itself was confirmed as a VTE risk factor compared with THA surgery.

Conclusions

This systematic review of high level evidences published in recent ten years identified a range of potential factors associated with VTE risk of total joint arthroplasty. These results can provide informations in this topic for doctors, patients and researchers.

The additional benefit of graduated compression stockings to pharmacologic thromboprophylaxis in the prevention of venous thromboembolism in surgical inpatients

OBJECTIVE

The evidence base supporting the use of graduated compression stockings (GCS) for venous thromboembolism (VTE) prevention has been challenged, and there appears to be a lack of evidence for the additional benefit of GCS to pharmacologic thromboprophylaxis. This study aimed to summarize and quality assess the existing evidence concerning whether GCS offer a significant benefit in addition to pharmacologic thromboprophylaxis in surgical inpatients.

METHODS

A systematic review of published literature was performed. Inclusion criteria were (1) randomized controlled trials (RCTs), (2) surgical inpatients, (3) study arms examining prophylactic-dose pharmacologic thromboprophylaxis alone or in conjunction with GCS, and (4) outcome of VTE.

RESULTS

In the review, 1025 articles were screened, of which 27 RCTs were included. Six RCT study arms included patients with GCS in conjunction with pharmacologic thromboprophylaxis, whereas 22 RCT study arms included patients treated with pharmacologic thromboprophylaxis alone. One RCT had both of its study arms included in the systematic review. The total number of patients that received pharmacologic thromboprophylaxis alone was 12,481. Of these patients, 1292 (10.4%) suffered VTE. The total number of patients that received GCS in conjunction with pharmacologic thromboprophylaxis was 1283. Of these patients, 75 had VTE (5.8%). Heterogeneity analysis demonstrated that the results of included study arms were significantly heterogeneous, precluding a valid summation analysis.

CONCLUSIONS

The additional benefit of GCS to pharmacologic thromboprophylaxis in surgical inpatients is not clear on the basis of existing data. Further clinical trials directly evaluating this clinical question are recommended.

Latest developments in anticoagulant drug discovery

Thromboembolic diseases have increased in number over the past years. Oral anticoagulants impair the formation and progression of thrombotic processes and are therefore of great importance in the treatment of these diseases. Until recently, vitamin K antagonists were used to block the coagulation system. But these agents display a lot of interactions besides their narrow therapeutic range and have potential risk of hemorrhage complications. Therefore, other factors of the coagulation cascade are currently being explored as therapeutic targets for the development of novel anticoagulants. This review will provide an overview of new drugs promising more effectiveness in the treatment of arterial and venous embolism. Furthermore, pharmacodynamics and drug interactions regarding new anticoagulants will be reported.

Clinical Pharmacokinetics, Pharmacodynamics, Safety and Tolerability of Darexaban, an Oral Direct Factor Xa Inhibitor, in Healthy Elderly Japanese Subjects

The clinical pharmacokinetics, pharmacodynamics, safety and tolerability of darexaban after single and multiple once-daily doses of 60, 120, and 240 mg in healthy elderly Japanese subjects were assessed. Following oral administration, darexaban was rapidly and extensively metabolized to darexaban glucuronide, which is an active glucuronide metabolite. Plasma concentrations of darexaban glucuronide increased with dose, and Cmax and AUC increased dose-dependently after both single and repeated doses. Cumulative urinary excretion of darexaban glucuronide up to 24 hours after repeated doses ranged from 28.59% to 36.50%. PT-INR, aPTT, and FXa activity were prolonged or decreased dose-dependently after both single and repeated doses of darexaban. The time-profile of pharamcodynamic parameters closely followed the time-concentration profile of darexaban glucuronide. Five adverse events occurred in the present study (4: darexaban [16.7%]; 1: placebo [8.3%]), all of which were mild in severity and required no treatment.

The new oral anticoagulants in atrial fibrillation: once daily or twice daily?

The new anticoagulants (NOACs) tested for prevention or treatment of venous thromboembolism (VTE), stroke prevention in atrial fibrillation (AF), and acute coronary syndromes (ACS) differ in bioavailability, metabolism, route of excretion and interaction with other drugs, but have remarkably similar pharmacokinetics, with very similar half lives. However the choice of dosing regimens in different clinical conditions has been different for the various NOACs, and has been established on the basis of widely different considerations, including the clinical setting (venous versus arterial thrombosis), the indications (prophylaxis versus treatment), the likelihood of concomitant antiplatelet drugs, and marketing opportunities; these latter were based on the knowledge that patients' compliance is generally better with once daily than with twice daily dosing. Current prevailing wisdom is that peak plasma drug concentrations are important determinants of bleeding: since a fractioning of the total daily dose into a twice daily regimen reduces peak plasma drug concentrations compared with once daily dosing, this should maximize safety. However, recent pharmacokinetic analyses of a phase II study with edoxaban in AF found that bleeding, with the same daily dosing, was less frequent with once daily dosing than with twice daily dosing, and correlated - better than other pharmacokinetic parameters - through drug concentrations. Higher rates of bleeding have been also reported with the twice daily versus once daily dosing of darexaban in a phase II study in ACS. These results may lead to a rethinking on the pathophysiology of bleeding in the setting of anticoagulation.

The pharmacokinetics of darexaban are not affected to a clinically relevant degree by rifampicin, a strong inducer of P-glycoprotein and CYP3A4

AIMS

We investigated the effects of rifampicin on the pharmacokinetics (PK) of the direct clotting factor Xa inhibitor darexaban (YM150) and its main active metabolite, darexaban glucuronide (YM-222714), which almost entirely determines the antithrombotic effect.

METHODS

In this open-label, single-sequence study, 26 healthy men received one dose of darexaban 60 mg on day 1 and oral rifampicin 600 mg once daily on days 4-14. On day 11, a second dose of darexaban 60 mg was given with rifampicin. Blood and urine were collected after study drug administration on days 1-14. The maximal plasma drug concentration (C(max)) and exposure [area under the plasma concentration-time curve from time zero to time of quantifiable measurable concentration; (AUC(last)) or AUC(last) extrapolated to infinity (AUC(∞))] were assessed by analysis of variance of PK. Limits for statistical significance of 90% confidence intervals for AUC and C(max) ratios were predefined as 80-125%.

RESULTS

Darexaban glucuronide plasma exposure was not affected by rifampicin; the geometric mean ratio (90% confidence interval) of AUC(last) with/without rifampicin was 1.08 (1.00, 1.16). The C(max) of darexaban glucuronide increased by 54% after rifampicin [ratio 1.54 (1.37, 1.73)]. The plasma concentrations of darexaban were very low (<1% of darexaban glucuronide concentrations) with and without rifampicin. Darexaban alone or in combination with rifampicin was generally safe and well tolerated.

CONCLUSIONS

Overall, rifampicin did not affect the PK profiles of darexaban glucuronide and darexaban to a clinically relevant degree, suggesting that the potential for drug-drug interactions between darexaban and CYP3A4 or P-glycoprotein-inducing agents is low.

Darexaban (YM150), an oral direct factor Xa inhibitor, has no effect on the pharmacokinetics of digoxin

To investigate the impact of the direct Factor Xa inhibitor darexaban administered in a modified-release formulation (darexaban-MR) on the pharmacokinetic (PK) profile of digoxin. In this Phase I, randomized, double-blind, two-period crossover study (8 days for each treatment, 10 days washout), 24 healthy subjects received darexaban-MR 120 mg once/day (qd) + digoxin 0.25 mg qd in one treatment period, and placebo + digoxin 0.25 mg qd in the other treatment period. Blood for PK assessment of digoxin and darexaban was obtained in serial profile on day 8, as well as pre-dose on day 6-7; urinary PK samples were obtained up to 24 h after the last dose on day 8. A lack of interaction was determined if 90 % confidence intervals (CIs) for the geometric mean ratios (GMR) of digoxin C max,ss and AUC0-24h,ss with and without darexaban-MR co-administration were within 0.80-1.25 limits. Pharmacodynamic activity was assessed by international normalized ratio and activated partial thromboplastin time. Twenty-three subjects completed the study. The GMR (90 % CI) for C max,ss and AUC0-24h,ss of digoxin plus darexaban versus digoxin plus placebo was 1.03 (90 % CI: 0.94-1.12) and 1.11 (90 % CI: 1.05-1.17), respectively. The 90 % CI for the GMRs fell within the limits of 0.80-1.25, indicating a lack of drug-drug interaction. Co-administration of digoxin with darexaban-MR was well tolerated, with no unexpected treatment-emergent adverse events or safety concerns. Co-administration of darexaban-MR did not impact the steady-state PK profile of digoxin.

Darexaban: anticoagulant effects in mice and human plasma in vitro, antithrombotic effects in thrombosis and bleeding models in mice and effects of anti-inhibitor coagulant complex and recombinant factor VIIa

Here, we investigated the anticoagulant effects of darexaban in mice and human plasma in vitro, effects of darexaban in thrombosis and bleeding models in mice, and reversal effects of anti-inhibitor coagulant complex (ACC) and recombinant factor VIIa (rFVIIa) on anticoagulant effects of darexaban. In mice, darexaban inhibited FXa activity in plasma with an ED50 value of 24.8 mg/kg. Both darexaban and warfarin prolonged prothrombin time (PT) at 3 mg/kg and 0.3 mg/kg/day, respectively. PT and activated partial thromboplastin time (aPTT) prolonged by darexaban were dose-dependently reversed by intravenously-administered rFVIIa, significantly so at 1 mg/kg. In a pulmonary thromboembolism (PE) mouse model, both darexaban and warfarin dose-dependently reduced the mortality rate, significantly so at 10 mg/kg and 3 mg/kg/day, respectively. In a FeCl3-induced venous thrombosis (VT) mouse model, darexaban (0.3-10 mg/kg) dose-dependently decreased the thrombus protein content, significantly so at doses of 3 mg/kg or higher. In a tail-transection mouse model, darexaban had no significant effect on the amount of blood loss at doses up to 10 mg/kg, while warfarin showed a dose-dependent increase in blood loss, significantly so from 1 mg/kg/day. Darexaban and its metabolite darexaban glucuronide significantly prolonged PT and aPTT in human plasma in vitro, and while rFVIIa concentration-dependently reversed the prolonged PT in this plasma, ACC dose-dependently reversed both PT and aPTT changes prolonged by darexaban. Taken together, these results suggest that darexaban has a potential to be an oral anticoagulant with a better safety profile than warfarin, and that rFVIIa and ACC may be useful as antidotes to darexaban in cases of overdose.

Darexaban for the Prevention of Venous Thromboembolism in Asian Patients Undergoing Orthopedic Surgery

Objective:

To evaluate the efficacy and safety of darexaban (YM150) in Asian patients undergoing total hip or total knee arthroplasty.

Methods:

In 2 phase II/III multicenter, randomized, double-blind, placebo-controlled, parallel-group studies, patients were randomized to oral darexaban 15 mg twice daily (bid), darexaban 30 mg bid, oral placebo bid, or subcutaneous enoxaparin 20 mg bid. Primary efficacy outcome for both studies was total venous thromboembolism (VTE) incidence.

Results:

Both darexaban doses were statistically significantly superior to placebo for total VTE incidence (hip study: darexaban 15 mg bid [2.9%] vs placebo [17.1%], P < .001; darexaban 30 mg bid [5.2%] vs placebo [17.1%], P = .003; and knee study: darexaban 15 mg bid [27.2%] vs placebo [52.8%], P = .002; darexaban 30 mg bid [15.5%] vs placebo [52.8%], P < .001). In both studies, the incidence of bleeding events was low across all treatment groups.

Conclusion:

Darexaban is effective and well tolerated as VTE prophylaxis in Asian patients undergoing elective major orthopedic surgery.

Novel drugs for oral anticoagulation pharmacotherapy

Long-term anticoagulation with warfarin is the mainstay of treatment in patients with diseases with high thromboembolic potential, such as atrial fibrillation. However, warfarin therapy carries a number of inherent limitations, including slow onset and offset of action, interindividual variability, food and drug interactions, lack of selectivity and a narrow therapeutic window. Recently developed oral anticoagulants that selectively block key factors in the coagulation cascade, with no need for monitoring or dose adjustment, have the potential to replace warfarin in clinical practice. The safety and efficacy of these agents in patients with atrial fibrillation, venous thromboembolisms and acute coronary syndromes have been the object of numerous recent large-scale clinical investigations. This article provides an overview of the evidence currently available on the use of novel, orally available, selective anticoagulants in patients at risk for thromboembolic events.

Darexaban (YM150) prevents venous thromboembolism in Japanese patients undergoing major abdominal surgery: Phase III randomized, mechanical prophylaxis-controlled, open-label study

INTRODUCTION

Darexaban (YM150) is an oral direct factor Xa inhibitor in clinical development for prophylaxis of venous thromboembolism (VTE) after major orthopaedic surgery. The objective of this study was to assess the efficacy and safety of darexaban 15 mg twice daily (bid) in Japanese patients undergoing major abdominal surgery.

MATERIALS AND METHODS

In a Phase III, multicentre, randomized, open-label, mechanical prophylaxis-controlled, parallel-group study, adult patients (aged ≥ 40 years) were randomized to darexaban 15 mg bid or mechanical prophylaxis, for 28 days. The primary efficacy outcome was incidence of total VTE at Day 12. Adverse events (AEs) and bleeding events were recorded throughout the study.

RESULTS

The total VTE incidence at Day 12 was 2.6% in the darexaban 15 mg bid group (95% confidence interval [CI]: 0.32, 9.07), compared with 15.0% (95% CI: 5.71, 29.84) in the mechanical prophylaxis group. During the investigational period, the incidence of all bleeding events was 9.5% in the darexaban 15 mg bid group and 3.9% in the mechanical prophylaxis group. In the darexaban 15 mg bid group, one patient experienced major bleeding and five patients experienced clinically relevant non-major (CRNM) bleeding. No patients in the mechanical prophylaxis group experienced major and/or CRNM bleeding. AEs were reported in 71.4% of patients in the darexaban 15mg bid group and 76.5% of patients in the mechanical prophylaxis group; the most frequent AEs across both treatment groups were constipation and insomnia. No patients died during the study.

CONCLUSIONS

Based on these findings, darexaban is expected to be effective for the prevention of VTE in patients undergoing major abdominal surgery. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT00942435).

New and emerging anticoagulant therapy for atrial fibrillation and acute coronary syndrome

Abstract Thrombosis is an underlying cause of many cardiovascular disorders, and generation of thrombi in the arterial circulation can lead to unstable angina, myocardial infarction, or ischemic stroke. Antithrombotic therapy is widely used, with proven benefit to prevent ischemic stroke and thromboembolic events in patients with atrial fibrillation (AF) or to prevent further ischemic complications in patients with acute coronary syndrome (ACS). Traditional anticoagulants (including unfractionated heparin, low-molecular-weight heparin, and warfarin) and antiplatelet agents (including aspirin, clopidogrel, and prasugrel) are typically used for these indications. Limitations to their use include variable pharmacokinetic and pharmacodynamic profiles, inability to inhibit fibrin-bound thrombin, risk of heparin-induced thrombocytopenia, delayed onset of action, numerous drug interactions, need for substantial laboratory monitoring and dosage titrations, hyporesponsiveness or resistance, hypersensitivity, adverse events, and bleeding. To overcome some of the limitations of traditional agents, new antithrombotic agents under development are highly selective for specific coagulation factors blocking the synthesis of thrombin. Clinicians must have an understanding of the new anticoagulants to aid in the selection of appropriate therapies for patients. We describe the most relevant phases II and III clinical trials that evaluated several recent emerging anticoagulant drugs for use in patients with AF or ACS. The advantages of many new agents include predictable pharmaco-dynamic response and pharmacokinetic parameters, allowing for fixed oral dosing with no need for laboratory monitoring. For patients with AF, dabigatran is already approved for the prevention of stroke and systemic embolism, rivaroxaban appears to be an effective alternative to warfarin in high-risk patients, and apixaban may also be an effective alternative to aspirin in patients unable to take warfarin. Otamixaban shows promise as an intravenous alternative for patients with ACS in the acute care setting. Likewise, rivaroxaban, dabigatran, and darexaban with or without dual antiplatelet therapy may be beneficial for secondary prevention of ischemic events in patients with ACS.

Conflict of interest in the assessment of thromboprophylaxis after total joint arthroplasty: a systematic review

BACKGROUND

The choice of modalities for thromboprophylaxis after total joint arthroplasty is controversial. To address this issue, an evidence-based review of previous studies was performed. The characteristics of the studies selected for review can affect the final conclusion of an evidence-based review. One such characteristic, financial conflict of interest related to medical research, is a widespread concern. The purpose of the present study was to determine what proportion of studies on thromboprophylaxis after total joint arthroplasty were sponsored by industry and whether the assessments of thromboprophylaxis after total joint arthroplasty were associated with industry support.

METHODS

We searched PubMed for prospective, original, English-language studies, published from 2004 to 2010, on thromboprophylaxis after total joint arthroplasty. The funding sources of the articles were reviewed, and qualitative conclusions regarding the modality of interest for thromboprophylaxis after total joint arthroplasty were classified as being favorable, neutral, or unfavorable.

RESULTS

Seventy-one eligible articles were identified; fifty-two were funded by industry, and fourteen were not. The other five studies did not include information about the funding source. A significant association was observed between the funding source and qualitative conclusions (p = 0.033). Only two (3.8%) of the fifty-two industry-sponsored studies had unfavorable conclusions, whereas three (21.4%) of the fourteen non-industry-sponsored studies indicated that, depending on the clinical scenario, the modality examined was neither effective nor safe.

CONCLUSIONS

Most studies on thromboprophylaxis after total joint arthroplasty are sponsored by industry. Moreover, the qualitative conclusions in those studies are favorable to the use of the sponsored prophylactic agent.

RUBY-1: a randomized, double-blind, placebo-controlled trial of the safety and tolerability of the novel oral factor Xa inhibitor darexaban (YM150) following acute coronary syndrome

AIMS

To establish the safety, tolerability and most promising regimen of darexaban (YM150), a novel, oral, direct factor Xa inhibitor, for prevention of ischaemic events in acute coronary syndrome (ACS).

METHODS

In a 26-week, multi-centre, double-blind, randomized, parallel-group study, 1279 patients with recent high-risk non-ST-segment or ST-segment elevation ACS received one of six darexaban regimens: 5 mg b.i.d., 10 mg o.d., 15 mg b.i.d., 30 mg o.d., 30 mg b.i.d., or 60 mg o.d. or placebo, on top of dual antiplatelet treatment. Primary outcome was incidence of major or clinically relevant non-major bleeding events. The main efficacy outcome was a composite of death, stroke, myocardial infarction, systemic thromboembolism, and severe recurrent ischaemia.

RESULTS

Bleeding rates were numerically higher in all darexaban arms vs. placebo (pooled HR: 2.275; 95% CI: 1.13-4.60, P = 0.022). Using placebo as reference (bleeding rate 3.1%), there was a dose-response relationship (P = 0.009) for increased bleeding with increasing darexaban dose (6.2, 6.5, and 9.3% for 10, 30, and 60 mg daily, respectively), which was statistically significant for 30 mg b.i.d. (P = 0.002). There was no decrease (indeed a numerical increase in the 30 and 60 mg dose arms) in efficacy event rates with darexaban, but the study was underpowered for efficacy. Darexaban showed good tolerability without signs of liver toxicity.

CONCLUSIONS

Darexaban when added to dual antiplatelet therapy after ACS produces an expected dose-related two- to four-fold increase in bleeding, with no other safety concerns but no signal of efficacy. Establishing the potential of low-dose darexaban in preventing major cardiac events after ACS requires a large phase III trial. ClinicalTrials.gov Identifier: NCT00994292.

Inhibitors of propagation of coagulation: factors V and X

Cardiovascular diseases are still the most important cause of morbidity and mortality in western countries and antithrombotic treatment is nowadays widely used. Drugs able to reduce coagulation activation are the treatment of choice for a number of arterial and/or venous thromboembolic conditions. Some of the drugs currently used for this purpose, such as heparins (UFH or LMWH) and VKA, have limitations consisting of a narrow therapeutic window and an unpredictable response with the need of laboratory monitoring in order to assess their efficacy and safety. These drawbacks have stimulated an active research aimed to develop new drugs able to act on single factors involved in the coagulation network, with predictable response. Intense experimental and clinical work on new drugs has focused on synthetic agents, which could preferably be administered orally and at fixed doses. The most advanced clinical development with new anticoagulants has been achieved for those inhibiting FXa and some of them, like fondaparinux, are already currently used in clinical practice. Other agents, such as rivaroxaban, apixaban, otamixaban and edoxaban are under development and have already been studied or are currently under investigation in large scale phase III clinical trials for prevention and treatment of venous thromboembolism, atrial fibrillation and acute coronary syndromes. Some of them have proved to be more effective than conventional therapy. Data on some agents inhibiting FVa are still preliminary and some of these drugs have so far been considered only in patients with disseminated intravascular coagulation secondary to sepsis.

Clinical pharmacology of direct and indirect factor Xa inhibitors

The limitations of conventional anticoagulants have stimulated the development of new anticoagulants. The central position of factor Xa (FXa) at the junction of the intrinsic and extrinsic pathways in the coagulation cascade means that direct and indirect FXa inhibitors have increasingly changed antithrombotic strategies. FXa inhibitors potently and selectively inhibit thrombin formation rather than thrombin activity. Direct FXa inhibitors may directly bind to FXa, whereas indirect inhibitors are dependent on antithrombin. Direct inhibitors may bind free FXa and, in contrast to indirect inhibitors, FXa within the prothrombinase complex or within clots as well. Fondaparinux is the prototype indirect FXa inhibitor and has been extensively studied in the prevention and treatment of thromboembolic diseases, including acute coronary syndromes. Due to a favourable efficacy and safety profile and convenient once-daily dosing without the need for monitoring, fondaparinux is preferentially recommended in recent guidelines dealing with antithrombotic treatment. A number of small-molecule direct FXa inhibitors are currently at different stages of clinical development. After an extensive clinical trial programme demonstrating superior efficacy without a significant increase in major bleeds compared with enoxaparin, rivaroxaban is now available for the prevention of thromboembolic events in patients undergoing orthopaedic surgery. Rivaroxaban also offers the convenience of oral once-daily dosing without the need for monitoring. Whereas most direct FXa inhibitors are orally active, otamixaban is administered intravenously, offering rapid on-off anticoagulant activity. Other compounds under development may offer additional options for tailored antithrombotic strategies according to differing indications, clinical situations and patient variables.

Pharmacoeconomics of dabigatran etexilate for prevention of thromboembolism after joint replacement surgery

Dabigatran etexilate (DE) is a novel oral anticoagulant indicated for the prevention of venous thromboembolism in patients undergoing total hip or total knee replacement surgery. The majority of these patients receive some kind of thromboprophylaxis, most commonly low-molecular-weight heparin (LMWH). However, the subcutaneous route of LMWH administration may act as a barrier to the continuation of effective anticoagulant prophylaxis after discharge from hospital. The oral route of DE administration may allow more patients to receive extended thromboprophylaxis and may reduce costs, such as those associated with nurse time for LMWH administrations, platelet monitoring, needlestick injuries and sharps disposal. This article presents an overview of the clinical evidence for DE and a systematic review of the economic evaluations of the drug.

New anticoagulants for the prevention of venous thromboembolism

Anticoagulant drugs have an essential role in the prevention and treatment of thromboembolic diseases. Currently available anticoagulants substantially reduce the incidence of thromboembolic events in a number of clinical conditions. However, these agents have limitations that strengthen the case for the development of new anticoagulants. An ideal anticoagulant should be at least as effective as those currently in use, as well as safe, simple to use, and widely applicable.The majority of new anticoagulants currently under investigation are small molecules with a selective and direct anti-Xa or antithrombin action, allowing oral administration in fixed doses. These new agents are in different phases of clinical development. The anti-Xa agent rivaroxaban and the antithrombin agent dabigatran are already available for the prophylaxis of venous thromboembolism in some countries. Apixaban is in an advanced phase of clinical development and several anti-Xa agents are currently approaching phase III clinical trials. Promising results in terms of efficacy and safety profiles have been obtained with these agents in different clinical conditions. Differences in pharmacokinetics and pharmacodynamics could offer the potential for individualized anticoagulant therapies in the near future.

Emerging antithrombotic agents for thromboprophylaxis, clinical potential and patient considerations

Patients undergoing major orthopedic surgery, total hip arthroplasty (THA) and total knee arthroplasty (TKA) are at high risk of venous thromboembolism, manifesting as deep vein thrombosis or pulmonary embolism. The recommended pharmacologic treatment options for thromboprophylaxis after major orthopedic surgery include the vitamin K antagonists (VKAs eg, warfarin), low molecular weight heparins (LMWHs; eg, enoxaparin) and the synthetic pentasaccharide fondaparinux. Most clinics use some kind of thromboprophylaxis routinely. However, due to the frequent need for coagulation monitoring (VKAs) and subcutaneous injections (LMWHs and fondaparinux) barriers exist to prescribing prophylaxis after discharge from hospital. Targeting specific components of the coagulation cascade has yielded several new antithrombotic agents for use as thromboprophylaxis after THA or TKA. Two of these, dabigatran etexilate and rivaroxaban, have already reached the markets in the European Union member states and Canada. Both are administered by the oral route, once-daily fixed dose and without the need to monitor the anticoagulant effect. Whether these new drugs facilitate guideline adherence, particularly in the outpatient settings and thereby improve the overall clinical outcomes remains to be shown.