Edoxaban: A Comprehensive Review of the Pharmacology and Clinical Data for the Management of Atrial Fibrillation and Venous Thromboembolism

Perioperative Management of Traditional and Direct Oral Anticoagulants in Hip Fracture Patients

Hip fractures are an increasingly common injury in the senior population and almost always require surgical fixation or prosthetic replacement. These surgeries, according to the American Academy of Orthopaedic Surgeons, are considered high-risk for bleeding, especially in a population fraught with comorbidities and often presenting on anticoagulation medications. Direct oral anticoagulants represent a class of drugs that have been becoming more popular in use in this population, with many benefits over the historically used Warfarin. There are recommendations for preoperative discontinuation and postoperative resumption of these medications, which can be more readily managed for elective surgeries. However, there is a paucity of literature detailing best practice guidelines for the perioperative management of direct oral anticoagulants when a patient presents with a hip fracture. This review article summary of the periprocedural management of DOACs for hip surgery was developed by examining the American College of Chest Physicians evidence-based clinical practice guidelines, Perioperative Guidelines on Antiplatelet and Anticoagulant Agents written by anesthesiologists, various retrospective studies, and drug labels for pharmacokinetic data. These recommendations should be used as a guideline, along with the collaboration of multidisciplinary hospital teams during inpatient admission, to manage these complex patients.

Distinct pleiotropic effects of direct oral anticoagulants on cultured endothelial cells: a comprehensive review

Direct Oral Anticoagulants (DOACs) have simplified the treatment of thromboembolic disease. In addition to their established anticoagulant effects, there are indications from clinical and preclinical studies that DOACs exhibit also non-anticoagulant actions, such as anti-inflammatory and anti-oxidant actions, advocating overall cardiovascular protection. In the present study, we provide a comprehensive overview of the existing knowledge on the pleiotropic effects of DOACs on endothelial cells (ECs) in vitro and their underlying mechanisms, while also identifying potential differences among DOACs. DOACs exhibit pleiotropic actions on ECs, such as anti-inflammatory, anti-atherosclerotic, and anti-fibrotic effects, as well as preservation of endothelial integrity. These effects appear to be mediated through inhibition of the proteinase-activated receptor signaling pathway. Furthermore, we discuss the potential differences among the four drugs in this class. Further research is needed to fully understand the pleiotropic effects of DOACs on ECs, their underlying mechanisms, as well as the heterogeneity between various DOACs. Such studies can pave the way for identifying biomarkers that can help personalize pharmacotherapy with this valuable class of drugs.

Physiologically-based pharmacokinetic pharmacodynamic parent-metabolite model of edoxaban to predict drug-drug-disease interactions: M4 contribution

This study aimed to develop a physiologically-based pharmacokinetic pharmacodynamic (PBPK/PD) parent-metabolite model of edoxaban, an oral anticoagulant with a narrow therapeutic index, and to predict pharmacokinetic (PK)/PD profiles and potential drug-drug-disease interactions (DDDIs) in patients with renal impairment. A whole-body PBPK model with a linear additive PD model of edoxaban and its active metabolite M4 was developed and validated in SimCYP for healthy adults with or without interacting drugs. The model was extrapolated to situations including renal impairment and drug-drug interactions (DDIs). Observed PK and PD data in adults were compared with predicted data. The effect of several model parameters on the PK/PD response of edoxaban and M4 was investigated in sensitivity analysis. The PBPK/PD model successfully predicted PK profiles of edoxaban and M4 as well as anticoagulation PD responses with or without the influence of interacting drugs. For patients with renal impairment, the PBPK model successfully predicted the fold change in each impairment group. Inhibitory DDI and renal impairment had a synergistic effect on the increased exposure of edoxaban and M4, and their downstream anticoagulation PD effect. Sensitivity analysis and DDDI simulation show that renal clearance, intestinal P-glycoprotein activity, and hepatic OATP1B1 activity are the major factors affecting edoxaban-M4 PK profiles and PD responses. Anticoagulation effect induced by M4 cannot be ignored when OATP1B1 is inhibited or downregulated. Our study provides a reasonable approach to adjust the dose of edoxaban in several complicated scenarios especially when M4 cannot be ignored due to decreased OATP1B1 activity.

Use of anticoagulant drugs in patients with atrial fibrillation. Does adherence to therapy have a prognostic impact?

Anticoagulant therapy represents a pivotal element that strongly influences the thromboembolic risk of non-valvular atrial fibrillation (NVAF) subjects. The main purpose of this review was to identify issues and suggest strategies to improve the oral anticoagulants (OACs) treatment adherence, which is the most important predictor of NVAF outcome. Advantages, efficacy, and impact of these drugs on patients' prognosis were revealed in important clinical trials on large cohorts of patients and are often prescribed nowadays. A real-life data registry, the Global Anticoagulant Registry in the Field-Atrial Fibrillation (GARFIELD-AF) analyzed the profile and outcome of patients diagnosed with NVAF receiving oral antithrombotic treatment. The observations gathered in the registry were crucial for identifying relevant elements that clinicians must improve, such as adherence strategies and predisposing factors that correlated with stroke. Adherence to OACs in AF patients is essential from the viewpoint of clinical efficacy and safety. Major adverse events and negative outcome are correlated with a weak anticoagulation control caused by an ineffective treatment adherence strategy. Solving the issue of oral anticoagulation adherence is possible using new technologies, but future directions should be explored. Mobile phone applications centered on patients' needs, telemedicine programs that evaluate patients' evolution and detect adverse reactions or events, encouraging an adequate management of the event without interruption of OACs, represent perspectives with a major impact on treatment adherence.

Proximal femur fractures in patients taking anti-coagulants: has anything changed?

With an ever-ageing population, the incidence of hip fractures is increasing worldwide. Increasing age is not just associated with increasing fractures but also increasing comorbidities and polypharmacy.

Consequently, a large proportion of patients requiring hip fracture surgery (HFS) are also prescribed antiplatelet and anti-coagulant medication. There remains a clinical conundrum with regards to how such medications should affect surgery, namely with regards to anaesthetic options, timing of surgery, stopping and starting the medication as well as the need for reversal agents.

Herein, we present the up-to-date evidence on HFS management in patients taking blood-thinning agents and provide a summary of recommendations based on the existing literature.

Incidence of upper extremity deep vein thrombosis in the retrosternal reconstruction after esophagectomy

Background

Upper extremity deep vein thrombosis (UEDVT) is relatively rare but cannot be negligible because it can cause fatal complications. Although it is reported that the occurrence rate of UEDVT has increased due to central venous catheter (CVC), cancer, and surgical invasion, there is still limited information for esophagectomy. The aim of this study was to evaluate the clinical factors, including CVC placement and thromboprophylaxis approach, as well as retrosternal space’s width as a predictive factor for UEDVT in patients receiving esophagectomy.

Methods

This study included 66 patients who underwent esophagectomy with retrosternal reconstruction using a gastric tube. All patients routinely underwent contrast-enhanced computed tomography (CT) on the 4th postoperative day. Low-molecular-weight-heparin (LMWH) was routinely administered by the 2nd postoperative day. To evaluate retrosternal space’s width, (a) The distance from sternum to brachiocephalic artery and (b) the distance from sternum to vertebra were measured by preoperative CT, and the ratio of (a) to (b) was defined as the width of retrosternal space.

Results

Among all patients, 11 (16.7%) suffered from UEDVT, and none was preoperatively received CVC placement, while 7 were inserted in non-UEDVT cases. Retrosternal space’s width in patients with UEDVT was significantly smaller than that in patients without UEDVT (0.17 vs. 0.26; P < 0.0001). A cutoff value of the width was 0.21, which has high sensitivity (87%) and specificity (82%) for UEDVT prediction, respectively.

Conclusion

The existence of CVC may not affect the development of UEDVT, but preoperative evaluation of retrosternal ratio may predict the occurrence of UEDVT.

Direct oral anticoagulants for use in paediatrics

With the increasing incidence of thromboembolism in children and improvement in management for patients with medically complex diseases, expanded availability of safe and effective anticoagulant medications is needed. Traditionally, the most common anticoagulants used for the treatment or prevention of venous thromboembolism or embolic stroke in children were either unfractionated heparin or the low-molecular-weight heparins. These medications require either intravenous access or daily subcutaneous injections, in addition to multiple venepunctures to monitor drug concentrations. Direct oral anticoagulants provide an alternative, and potentially safer, choice for children, as they are available in oral formulations and do not require drug monitoring. With the approval of the direct factor Xa inhibitor, rivaroxaban (by the European Medicines Agency and Health Canada), and the direct thrombin inhibitor, dabigatran (by the European Medicines Agency and US Food and Drug Administration), the field of paediatric anticoagulation is changing. In this Review, we provide an overview of the four direct oral anticoagulants approved in adults for the treatment and prevention of thrombosis and the completed and ongoing paediatric trials.

The value and limitations of new oral anticoagulant plasma level assessments

The class of new oral anticoagulants (NOACs) has been developed to provide reliable oral anticoagulation without the need for therapeutic drug monitoring. Based on phase I and II trials and pharmacokinetic and pharmacodynamic modeling, fixed drug doses have been selected for large phase III clinical trials for each currently available NOAC. In these trials, the use of the fixed dose without plasma level assessments was shown to be at least as effective and at least as safe as vitamin K antagonists with continuous therapeutic drug monitoring. Real world evidence reaffirms that the use of a fixed NOAC dose without plasma level assessment is safe and effective in a large variety of patients. Nevertheless, measurement of NOAC plasma levels can add information that may be useful in some clinical scenarios. This review discusses the possible use cases, the limitations, and the practical implementation of measuring NOAC plasma concentrations.

Potential clinical applications of phytopharmaceuticals for the in-patient management of coagulopathies in COVID-19

Thrombotic complications occur in many cardiovascular pathologies and have been demonstrated in COVID‐19. The currently used antithrombotic drugs are not free of adverse reactions, and COVID‐19 patients in particular, when treated with a therapeutic dose of an anticoagulant do not receive mortality benefits. The clinical management of COVID‐19 is one of the most difficult tasks for clinicians, and the search for safe, potent, and effective antithrombotic drugs may benefit from exploring naturally bioactive molecules from plant sources. This review describes recent advances in understanding the antithrombotic potential of herbal drug prototypes and points to their future clinical use as potent antithrombotic drugs. Although natural products are perceived to be safe, their clinical and therapeutic applications are not always apparent or accepted. More in‐depth studies are necessary to demonstrate the clinical usefulness of plant‐derived, bioactive compounds. In addition, holistic approaches in systematic investigations and the identification of antithrombotic mechanisms of the herbal bioactive molecule(s) need to be conducted in pre‐clinical studies. Moreover, rigorous studies are needed to compare the potency of herbal drugs to that of competitor chemical antithrombotic drugs, and to examine their interactions with Western antithrombotic medicines. We have also proposed a road map to improve the commercialization of phytopharmaceuticals.

Direct oral anticoagulants: A review for the non-specialist

Thrombin inhibitors and direct factor Xa inhibitors represent a major breakthrough in the field of anticoagulation pharmacotherapy. These novel agents have replaced warfarin as the oral anticoagulant of choice in certain indications, as they possess equal or superior efficacy and better safety profiles. They have a quick onset of action, predictable pharmacokinetic properties and minimal drug and food interactions. So they do not require frequent blood monitoring and dose adjustments as with warfarin. Considering all the advantages, there seems to be a rapid increase in the number of patients who are started on these novel anticoagulants. In this review, we highlight the pharmacology of these direct oral anticoagulants and the evidence-based indications for their use. We aim to provide a clinical overview for the non-specialist who may be called upon to manage a patient who is currently on one of these novel anticoagulants.

Drugs in phase I and II clinical development for the prevention of stroke in patients with atrial fibrillation

INTRODUCTION

Atrial fibrillation is the most frequently diagnosed cardiac arrhythmia globally and is associated with ischemic stroke and heart failure. Patients with atrial fibrillation are typically prescribed long-term anticoagulants in the form of either vitamin K antagonists or non-vitamin K antagonist oral anticoagulants; however, both carry a potential risk of adverse bleeding.

AREAS COVERED

This paper sheds light on emerging anticoagulant agents which target clotting factors XI and XII, or their activated forms - XIa and XIIa, respectively, within the intrinsic coagulation pathway. The authors examined data available on PubMed, Scopus, and the clinical trials registry of the United States National Library of Medicine (www.clinicaltrials.gov).

EXPERT OPINION

Therapies targeting factors XI or XII can yield anticoagulant efficacy with the potential to reduce adverse bleeding. Advantages for targeting factor XI or XII include a wider therapeutic window and reduced bleeding. Long-term follow-up studies and a greater understanding of the safety and efficacy are required. Atrial fibrillation is a chronic disease and therefore the development of oral formulations is key.

Edoxaban in Cardiovascular Disease Management: Review

In the past decade, direct oral anticoagulants (DOACs) have transformed the world of anti-thrombotic therapy. Edoxaban is the most recently approved DOAC. Though intended for use primarily in stroke prevention, it has found applications in various other conditions including thromboembolic and peripheral arterial disease. This review aims to provide a detailed outline of the growing indications, evidence for use in special populations, pharmacogenetics, and side effect profile of edoxaban.

Review Article: Gastrointestinal Bleeding Risk with Direct Oral Anticoagulants

PURPOSE

Although direct oral anticoagulants (DOACs) are associated with an overall favourable safety profile, the risk of gastrointestinal bleeding with DOACs compared with vitamin K antagonists (VKAs) remains controversial. Accordingly, we aimed to provide a focused overview of the risk of gastrointestinal bleeding associated with dabigatran, rivaroxaban, apixaban and edoxaban and its management.

METHODS

We reviewed published studies reporting on DOACs with gastrointestinal bleeding as an outcome, including randomised controlled trials (RCTs), retrospective database studies and large-scale prospective cohort studies.

RESULTS

Cumulative evidence confirms no notable difference in major gastrointestinal bleeding risk between DOACs and VKAs. Moreover, gastrointestinal bleeding in DOAC-treated patients seems less severe and requires less intensive management. The main cause of upper gastrointestinal bleeding in DOAC-treated patients appears to be gastroduodenal ulcers, whereas lower gastrointestinal bleedings are mainly due to diverticula followed by angiodysplasia and haemorrhoids. The lack of head-to-head RCTs with DOACs precludes drawing conclusions on the DOAC with the lowest gastrointestinal bleeding risk. Prescribing physicians should be aware of risk factors for DOAC-related gastrointestinal bleeding (e.g. age > 65, heavy alcohol use, uncontrolled hypertension, hepatic or renal dysfunction, active cancer, anaemia) and adopt preventive measures accordingly. Management of DOAC-associated major gastrointestinal bleeding involves temporary discontinuation of the DOAC, investigation of the bleeding source and treatment of bleeding with fluid resuscitation combined with transfusion and endoscopic haemostasis.

CONCLUSION

DOACs as a class do not increase the risk of major gastrointestinal bleeding compared to VKAs, which supports their continued use for different anticoagulant indications.

Characteristics of patients with atrial fibrillation prescribed edoxaban in Belgium and The Netherlands: insights from the ETNA-AF-Europe study

BACKGROUND

Studies on the use of non-vitamin K antagonist oral anticoagulants in unselected patients with atrial fibrillation (AF) show that clinical characteristics and dosing practices differ per region, but lack data on edoxaban.

METHODS

With data from Edoxaban Treatment in routiNe clinical prActice for patients with AF in Europe (ETNA-AF-Europe), a large prospective observational study, we compared clinical characteristics (including the dose reduction criteria for edoxaban: creatinine clearance 15-50 mL/min, weight ≤60 kg, and/or use of strong p-glycoprotein inhibitors) of patients from Belgium and the Netherlands (BeNe) with those from other European countries (OEC).

RESULTS

Of all 13,639 patients in ETNA-AF-Europe, 2579 were from BeNe. BeNe patients were younger than OEC patients (mean age: 72.3 vs 73.9 years), and had lower CHA2DS2-VASc (mean: 2.8 vs 3.2) and HAS-BLED scores (mean: 2.4 vs 2.6). Patients from BeNe less often had hypertension (61.6% vs 80.4%), and/or diabetes mellitus (17.3% vs 23.1%) than patients from OEC. Moreover, relatively fewer patients in BeNe were prescribed the reduced dose of 30 mg edoxaban (14.8%) than in OEC (25.4%). Overall, edoxaban was dosed according to label in 83.1% of patients. Yet, 30 mg edoxaban was prescribed in the absence of any dose reduction criteria in 36.9% of 30 mg users (5.5% of all patients) in BeNe compared with 35.5% (9.0% of all patients) in OEC.

CONCLUSION

There were several notable differences between BeNe and OEC regarding clinical characteristics and dosing practices in patients prescribed edoxaban, which are relevant for the local implementation of dose evaluation and optimisation.

TRIAL REGISTRATION

NCT02944019; Date of registration: October 24, 2016.

Review of Medical Therapies for the Management of Pulmonary Embolism

Traditionally, the management of patients with pulmonary embolism has been accomplished with anticoagulant treatment with parenteral heparins and oral vitamin K antagonists. Although the administration of heparins and oral vitamin K antagonists still plays a role in pulmonary embolism management, the use of these therapies are limited due to other options now available. This is due to their toxicity profile, clearance limitations, and many interactions with other medications and nutrients. The emergence of direct oral anticoagulation therapies has led to more options now being available to manage pulmonary embolism in inpatient and outpatient settings conveniently. These oral therapeutic options have opened up opportunities for safe and effective pulmonary embolism management, as more evidence and research is now available about reversal agents and monitoring parameters. The evolution of the pharmacological management of pulmonary embolism has provided us with better understanding regarding the selection of anticoagulants. There is also a better understanding and employment of anticoagulants in pulmonary embolism in special populations, such as patients with liver failure, renal failure, malignancy, and COVID-19.

Characteristics of patients with atrial fibrillation prescribed edoxaban in Belgium and the Netherlands: insights from the ETNA-AF-Europe study

Background

Studies on the use of non-vitamin K antagonist oral anticoagulants in unselected patients with atrial fibrillation (AF) show that clinical characteristics and dosing practices differ per region, but lack data on edoxaban.

Methods

With data from Edoxaban Treatment in routiNe clinical prActice for patients with AF in Europe (ETNA-AF-Europe), a large prospective observational study, we compared clinical characteristics (including the dose reduction criteria for edoxaban: creatinine clearance 15–50 ml/min, weight ≤60 kg, and/or use of strong p‑glycoprotein inhibitors) of patients from Belgium and the Netherlands (BeNe) with those from other European countries (OEC).

Results

Of all 13,639 patients in ETNA-AF-Europe, 2579 were from BeNe. BeNe patients were younger than OEC patients (mean age: 72.3 vs 73.9 years), and had lower CHA₂DS₂-VASc (mean: 2.8 vs 3.2) and HAS-BLED scores (mean: 2.4 vs 2.6). Patients from BeNe less often had hypertension (61.6% vs 80.4%), and/or diabetes mellitus (17.3% vs 23.1%) than patients from OEC. Moreover, relatively fewer patients in BeNe were prescribed the reduced dose of 30 mg edoxaban (14.8%) than in OEC (25.4%). Overall, edoxaban was dosed according to label in 83.1% of patients. Yet, 30 mg edoxaban was prescribed in the absence of any dose reduction criteria in 36.9% of 30 mg users (5.5% of all patients) in BeNe compared with 35.5% (9.0% of all patients) in OEC.

Conclusion

There were several notable differences between BeNe and OEC regarding clinical characteristics and dosing practices in patients prescribed edoxaban, which are relevant for the local implementation of dose evaluation and optimisation.

Trial registration

NCT02944019; Date of registration 24 October 2016

Electronic supplementary material

The online version of this article (10.1007/s12471-020-01518-7) contains supplementary material, which is available to authorized users.

Repurposing Known Drugs as Covalent and Non-covalent Inhibitors of the SARS-CoV-2 Papain-Like Protease

In the absence of an approved vaccine, developing effective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antivirals is essential to tackle the current pandemic health crisis due to the coronavirus disease 2019 (COVID-19) spread. As any traditional drug discovery program is a time-consuming and costly process requiring more than one decade to be completed, in silico repurposing of existing drugs is the preferred way for rapidly selecting promising clinical candidates. We present a virtual screening campaign to identify covalent and non-covalent inhibitors of the SARS-CoV-2 papain-like protease (PLpro) showing potential multitarget activities (i.e., a desirable polypharmacology profile) for the COVID-19 treatment. A dataset including 688 phase III and 1,702 phase IV clinical trial drugs was downloaded from ChEMBL (version 27.1) and docked to the recently released crystal structure of PLpro in complex with a covalently bound peptide inhibitor. The obtained results were analyzed by combining protein-ligand interaction fingerprint similarities, conventional docking scores, and MM-GBSA-binding free energies and allowed the identification of some interesting candidates for further in vitro testing. To the best of our knowledge, this study represents the first attempt to repurpose drugs for a covalent inhibition of PLpro and could pave the way for new therapeutic strategies against COVID-19.

Association of risk factors and bleeding complications in Asian patients taking edoxaban

AIMS

Asian patients are known to be more prone to bleeding complications than patients of other ethnicities. Therefore, there are possibilities of other risk factors that should be given special consideration for dosage adjustment in this specific ethnic group. This study aimed to investigate the risk factors for bleeding complications in Asian patients under appropriate edoxaban dosage regimens.

METHODS

Data on patients taking proper dosages, based on the Lixiana package insert, were analysed. Univariate and multivariable analyses were conducted to evaluate associations between risk factors and bleeding outcomes. Subgroup analysis was performed on high-risk patients for bleeding complications whose edoxaban dose was reduced according to the package insert.

RESULTS

In total, 346 patients were included. Among them, 32 patients experienced bleeding complications. Patients with weight ≤60 kg and with cancer showed around 3.3- and 3.4-fold increased risk of bleeding complications compared to heavier patients (>60 kg) and those without cancer, respectively. In subgroup analysis with high-risk patients who took low-dose edoxaban (15 and 30 mg), weight ≤60 kg remained a significant factor for bleeding outcomes.

CONCLUSION

This study showed that weight ≤60 kg and the presence of cancers could affect bleeding complications, which occurred despite proper edoxaban treatment in Asian patients. Therefore, more strict dosage guideline could be considered in populations with high proportions of Asian ethnicities.

Impact of Edoxaban on Thrombin-Dependent Platelet Aggregation

Edoxaban, a direct factor Xa inhibitor (FXa), is the fourth direct oral anticoagulant (DOAC) approved for clinical use. As the main adverse event is bleeding, it is relevant whether edoxaban has additional effects on platelet function. We aimed to assess in vitro aggregation in patients with atrial fibrillation (AF) receiving edoxaban. We evaluated 20 AF patients treated with edoxaban. We assessed light transmittance platelet aggregation (LTA) with 100 nmol/L γ-thrombin. The LTA was performed at 2 time-points. The thrombin-induced platelet aggregation was significantly lower 2 hours after edoxaban was taken compared to baseline measurement (27.25% ± 30.8% vs. 60.35% ± 33.3%). In addition, we also performed 16 subanalyses in order to identify the differences in the outcome of different comorbidities, age, dosage, liver and kidney function tests, and concomitant treatment. Results of the subgroup analyses were consistent with the findings of the main analysis; there was no apparent heterogeneity across the prespecified subgroups. The thrombin-induced platelet aggregation is reduced in non-valvular AF patients receiving edoxaban.

Relationship of Edoxaban Plasma Concentration and Blood Coagulation in Healthy Volunteers Using Standard Laboratory Tests and Viscoelastic Analysis

The capability of viscoelastic measurement parameters to screen anticoagulation activity of edoxaban in relation to its plasma concentrations was evaluated in 15 healthy male volunteers. Blood samples were drawn before the oral administration of edoxaban 60 mg and 2, 4, 6, 8, and 24 hours after administration. At each time, standard coagulation tests were performed, blood viscoelastic properties were measured with a thromboelastometry device ROTEM delta analyzer (Instrumentation Laboratory, Werfen, Barcelona, Spain), and edoxaban plasma concentrations were measured. Our primary interest was the possible correlation between edoxaban plasma concentrations and values for ROTEM ExTEM, and FibTEM. We also studied the correlation of edoxaban plasma concentrations with the results of standard coagulation tests. We saw the effect of a single dose of edoxaban most clearly in clotting time (CT) of ROTEM ExTEM and FibTEM. Changes in these parameters correlated significantly with edoxaban plasma concentrations up to 6 hours from the ingestion of the drug. Activated partial thromboplastin time, prothrombin time, and anti-factor Xa were also affected. Peak changes were observed 2 and 4 hours after administration of edoxaban. The changes were mostly reversed after 8 hours. In conclusion, ROTEM CT correlates significantly with edoxaban plasma concentrations and can be used to estimate the effect of edoxaban. ROTEM should be considered as part of the assessment of coagulation, with the big advantage of being readily available on site.

Moving towards ideal and appropriate models of anticoagulation management service

It is now known that thrombotic disorders such as venous thromboembolism, ischemic stroke, and myocardial infarction contribute significantly to global morbidity and mortality. Anticoagulation service must respond to this new development. Warfarin has continued to provide the backbone for anticoagulation service for decades but with considerable drawbacks. The introduction of nonVitamin K oral anticoagulants (NOACs) has created new challenges. This article seeks to discuss how the establishment of appropriate models of anticoagulation could contain the draw backs of the old anticoagulants and improve on the compliance, availability, affordability, and accessibility of newer anticoagulants. Successful anticoagulation has always been defined by a scientific balancing of the risk of thrombosis and the complication of hemorrhage. To be able to maintain such optimal anticoagulation requires rational drug prescription (physician factor), institutelization of monitoring of therapy (anticoagulation clinic factor) as well as active participation of patients receiving therapy (patient factor). New models of service can be created out of this triad in a bid to replace the old routine medical care model. New models of anticoagulation service should include appropriately trained professionals such as Physicians, Pharmacists, Clinical Pharmacologists, Nurses, and Laboratory Scientists who are knowledgeable in diagnostic, management, and monitoring of anticoagulation. The different models of anticoagulation service discussed in this article clearly demonstrate the need for restructuring of this life saving service particularly in the era of NOAC. Newer models of care that should provide safe, efficacious, and cost-effective services are needed.

Pharmacoepidemiologic Screening of Potential Oral Anticoagulant Drug Interactions Leading to Thromboembolic Events

Drug-drug interactions (DDIs) with oral anticoagulants may lead to under-anticoagulation and increased risk of thromboembolism. Although warfarin is susceptible to numerous DDIs, few studies have examined DDIs resulting in thromboembolism or those involving direct-acting oral anticoagulants (DOACs). We aimed to identify medications that increase the rate of hospitalization for thromboembolic events when taken concomitantly with oral anticoagulants. We conducted a high-throughput pharmacoepidemiologic screening study using Optum Clinformatics Data Mart, 2000-2016. We performed self-controlled case series studies among adult users of oral anticoagulants (warfarin, dabigatran, rivaroxaban, apixaban, and edoxaban) with at least one hospitalization for a thromboembolic event. Among eligible patients, we identified all oral medications frequently co-prescribed with oral anticoagulants as potential interacting precipitants. Conditional Poisson regression was used to estimate rate ratios comparing precipitant exposed vs. unexposed time for each anticoagulant-precipitant pair. To minimize within-person confounding by indication for the precipitant, we used pravastatin as a negative control object drug. Multiple estimation was adjusted using semi-Bayes shrinkage. We screened 1,622 oral anticoagulant-precipitant drug pairs and identified 226 (14%) drug pairs associated with statistically significantly elevated risk of thromboembolism. Using pravastatin as the negative control object drug, this list was reduced to 69 potential DDI signals for thromboembolism, 33 (48%) of which were not documented in the DDI knowledge databases Lexicomp and/or Micromedex. There were more DDI signals associated with warfarin than DOACs. This study reproduced several previously documented oral anticoagulant DDIs and identified potential DDI signals that deserve to be examined in future etiologic studies.

Practical considerations for the use of direct oral anticoagulants in oncology patients

Oncology patients are at a high risk of experiencing venous thromboembolism. Historically, venous thromboembolisms in cancer patients have been managed with low-molecular-weight heparin on the basis of the CLOT trial published in 2003. However, recent prospective data provide evidence for safe and effective direct oral anticoagulant use in this population. The purpose of this review article is to evaluate the current body of literature surrounding direct oral anticoagulant use in the oncology population and to highlight key practical considerations when prescribing these agents for patients with cancer.

Review of Direct Oral Anticoagulants and Guide for Effective Drug Utilization

Direct oral anticoagulants (DOACs) have been developed as a viable and in some cases superior alternative to warfarin. These agents have overcome some of the limitations of warfarin, which has a narrow therapeutic window and many food and drug interactions. DOACs have been demonstrated to have a more predictable and reliable pharmacology and, unlike warfarin, do not require frequent monitoring of anticoagulant effect. For these reasons, the use of DOACs is increasing. Despite the many positive attributes of these agents, limitations and contraindications do exist. An understanding of the pharmacology, indications, and contraindications is therefore crucial for effective patient management. We review the available agents to aid in effective drug utilization.

Periprocedural Anticoagulation Management For Nonoperating Room Anesthesia Procedures: A Clinical Guide

Non-operating room anesthesia presents unique challenges for anesthesiologists. Limited preprocedural optimization and unfamiliarity with the location and procedure itself add to the difficulties in delivering safe care for these patients. Management of chronic oral anticoagulation can prove especially problematic since risks of bleeding for non-operating room procedures vary widely and differ from traditional surgeries. In addition, many physicians may not be familiar with the growing number of newly approved oral anticoagulants and their periprocedural management. This review will examine common non-operating procedures, their risks of bleeding, as well as pharmacokinetics of oral anticoagulants available on the market and periprocedural management options.

Pharmacokinetics and pharmacodynamics of oral anticoagulants used in atrial fibrillation

INTRODUCTION

The availability of non-vitamin K antagonist oral anti-coagulants alongside vitamin K antagonists has offered a variety of options for anti-coagulation, but has also necessitated a good understanding of the pharmacological properties of each of these drugs prior to their use, to maximise the therapeutic benefit and minimise patient harm Areas covered: This review article outlines the pharmacokinetic and pharmacodynamic profiles of the currently licensed VKAs and NOACs that are most commonly used in clinical practice, with the aim of demonstrating how variations in these characteristics influence their use in clinical practice. A literature search was conducted on PubMed using keywords and relevant articles published by the 31^st of December 2018 were included. Expert opinion: The effect of a drug is determined by a combination of elements which include patient characteristics and external factors, in addition to its pharmacokinetic and pharmacodynamic properties. A good understanding of these is essential. Despite the wealth of information available, particularly on VKAs, our knowledge on the pharmacology responsible for certain drug effects and inter-individual variations is still limited. Increasing efforts are being made to understand these and include focus on pharmacogenomics and drug transporter proteins.

A Review on the New and Old Anticoagulants

Anticoagulants serve as the primary strategy for the prevention and treatment of both arterial and venous thromboembolism. Anticoagulants disrupt coagulation by interfering at various points in the coagulation cascade. This class of medications does not lyse clots that already exist; rather, it prevents thrombus formation and prevents or slows the extension of an existing clot. For decades, the standard therapy for patients requiring oral anticoagulation was warfarin. However, due to some of the shortcomings of warfarin, including the need for continuous routine monitoring, longtime onset and offset of anticoagulation effect, major food and drug interactions, and high incidence of bleeding, newer agents, termed direct oral anticoagulants, or DOACs were developed. This article will provide a review of clinically important information regarding the most commonly used anticoagulants and their reversal agents.

Pharmacogenomics of Novel Direct Oral Anticoagulants: Newly Identified Genes and Genetic Variants

Direct oral anticoagulants (DOAC) have shown an upward prescribing trend in recent years due to favorable pharmacokinetics and pharmacodynamics without requirement for routine coagulation monitoring. However, recent studies have documented inter-individual variability in plasma drug levels of DOACs. Pharmacogenomics of DOACs is a relatively new area of research. There is a need to understand the role of pharmacogenomics in the interpatient variability of the four most commonly prescribed DOACs, namely dabigatran, rivaroxaban, apixaban, and edoxaban. We performed an extensive search of recently published research articles including clinical trials and in-vitro studies in PubMed, particularly those focusing on genetic loci, single nucleotide polymorphisms (SNPs), and DNA polymorphisms, and their effect on inter-individual variation of DOACs. Additionally, we also focused on commonly associated drug-drug interactions of DOACs. CES1 and ABCB1 SNPs are the most common documented genetic variants that contribute to alteration in peak and trough levels of dabigatran with demonstrated clinical impact. ABCB1 SNPs are implicated in alteration of plasma drug levels of rivaroxaban and apixaban. Studies conducted with factor Xa, ABCB1, SLCOB1, CYP2C9, and VKORC1 genetic variants did not reveal any significant association with plasma drug levels of edoxaban. Pharmacokinetic drug-drug interactions of dabigatran are mainly mediated by p-glycoprotein. Strong inhibitors and inducers of CYP3A4 and p-glycoprotein should be avoided in patients treated with rivaroxaban, apixaban, and edoxaban. We conclude that some of the inter-individual variability of DOACs can be attributed to alteration of genetic variants of gene loci and drug-drug interactions. Future research should be focused on exploring new genetic variants, their effect, and molecular mechanisms that contribute to alteration of plasma levels of DOACs.

Edoxaban for Venous Thromboembolism Treatment-The New Kid on The Block for Latin America. A Practical Guide

Edoxaban, a direct factor Xa inhibitor (FXa), is the fourth direct oral anticoagulant (DOAC) approved for clinical use in the treatment of venous thromboembolism (VTE) in Latin America, following global approvals for this indication. Edoxaban features some particular characteristics when compared to the previously approved DOACs. This review summarizes the main properties of edoxaban, the outcomes results of its pivotal global clinical trials and the peculiar clinical features of this compound. This practical guide aims to help Latin America clinicians understand edoxaban, its proper indication and its use for the appropriate patients with VTE.

Use of direct oral anticoagulants for treatment of atrial fibrillation in patients with HIV: a review

PURPOSE OF REVIEW

Atrial fibrillation is increasingly common in the ageing population. Patients with atrial fibrillation and HIV have a higher stroke risk, with guidelines recommending anticoagulation in the majority. Whilst anticoagulation options have diversified in the last decade for the general population, there is limited evidence for the safety and efficacy of these medications when used concurrently with antiretroviral therapy. We review the potential for patients with HIV on antiretroviral therapy to have direct-acting oral anticoagulations (DOACs).

RECENT FINDINGS

Several case reports have been published in the past 5 years, as well as theoretical analyses of anticipated drug interactions, which provide a starting point to guide use of DOACs with antiretroviral medications.

SUMMARY

Caution is needed when prescribing DOACs in patients with atrial fibrillation and HIV due to potential drug interactions. Studies are lacking and current advice is based on case reports, expert opinion and knowledge of theoretical interactions.

Pharmacogenetics of novel oral anticoagulants: a review of identified gene variants & future perspectives

Novel oral anticoagulants (NOACs) are becoming a therapy of choice in everyday clinical practice after almost 50 years during which warfarin and related coumarin derivatives were used as the main anticoagulants. Advantages of NOACs over standard anticoagulants include their predictable pharmacodynamics and pharmacokinetics, stable plasma concentrations and less drug-drug and food-drug interactions. However, pharmacogenetics has its place in administration of NOACs, as considerable interindividual variations have been detected. In this review, previous findings in pharmacogenetics of dabigatran, rivaroxaban, apixaban and edoxaban are summarized, along with recommendations for studying genes encoding metabolically important enzymes for four selected NOACs. Future directions include identification of clinically relevant SNPs, and change in optimum dosage for patients who are carriers of significant variants.

Enhanced procoagulant activity of platelets after chemotherapy in non-small cell lung cancer

The procoagulant status of patients with non-small cell lung cancer (NSCLC) after chemotherapy is poorly characterized and the role of platelets in hypercoagulative state of NSCLC is unknown. The aim of this study was to evaluate the procoagulant activity (PCA) of platelets in NSCLC before and after chemotherapy. The subjects were 52 patients newly diagnosed with NSCLC. The patients had decreased clotting time compared with healthy subjects, and the thrombin-antithrombin complex increased 2.5-fold after chemotherapy. Platelets in the patients after chemotherapy had enhanced phosphatidylserine (PS) exposure, and shortened coagulation time as well as increased thrombin and fibrin formation of platelets compared with those before chemotherapy. Platelet-derived microparticles increased 2-fold at day 1 and peaked at day 2 post-chemotherapy. Treatment of cisplatin in vitro also resulted in upregulated intrinsic FXa and thrombin formation on platelets with a dose-dependent manner. Platelets treated with aspirin significantly decreased PCA. However, lactadherin blocked PS and inhibited the PCA approximately by 70%. Seven days after chemotherapy, PCA of platelets restored to the baseline as that before chemotherapy, indicating that within a week of chemotherapy patient platelets are highly procoagulant and effective intervention should be taken in case of thrombosis. Our results suggested that platelets after chemotherapy had elevated PCA and may contribute to the hypercoagulative state of NSCLC. Prophylactic anti-coagulant combined with anti-platelet therapy may play an inhibitory role in thrombotic complications in NSCLC.

Adverse Drug Reactions and Cutaneous Manifestations Associated With Anticoagulation

Anticoagulants are amongst the most commonly prescribed medications worldwide. Although rare, localised and systemic drug reactions have been reported with anticoagulants that can lead to significant morbidity and mortality. Some of the first signs of drug reactions to anticoagulants are cutaneous changes that, when recognised early, can prevent significant complications. Dermatologists should be aware of these changes to make an early and accurate diagnosis. This is particularly important in instances of skin-induced necrosis caused by systemic toxicity to anticoagulants. This review discusses adverse drug reactions to the traditional anticoagulants, warfarin and heparin, and the newer direct oral anticoagulants (DOACs) such as the thrombin inhibitor, dabigatran, and the factor Xa inhibitors, rivaroxaban, apixaban, and edoxaban. In particular, this review provides dermatologists with a framework for early diagnosis and management of patients with drug reactions to anticoagulants and alerts them to potential bleeding complications associated with minor procedures.

Athletes and blood clots: individualized, intermittent anticoagulation management

Essentials Athletes on anticoagulants are typically prohibited from participation in contact sports. Short-acting anticoagulants allow for reconsideration of this precedent. An individualized pharmacokinetic/pharmacodynamics study can aid patient-specific management. Many challenges and unresolved issues exist regarding such tailored intermittent dosing.

SUMMARY

Athletes with venous thromboembolism (VTE) are typically prohibited from participating in contact sports during anticoagulation therapy, but such mandatory removal from competition can cause psychological and financial detriments for athletes and overlooks patient autonomy. The precedent of compulsory removal developed when options for anticoagulation therapy were more limited, but medical advances now allow for rethinking of the management of athletes with VTE. We propose a novel therapeutic approach to the treatment of athletes who participate in contact sports and require anticoagulation. A personalized pharmacokinetic/pharmacodynamics study of a direct oral anticoagulant can be performed for an athlete, which can inform the timing of medication dosing. Managed carefully, this can allow athletic participation when plasma drug concentration is minimal (minimizing bleeding risk) and prompt resumption of treatment after the risk of bleeding sufficiently normalizes (maximizing therapeutic time).

Use of direct oral anticoagulants for the prevention and treatment of thromboembolic disease in patients with reduced renal function: a short review of the clinical evidence

BACKGROUND

The use of direct oral anticoagulants (DOACs) is restricted by the limitations of clinical trials guiding therapy for patients with renal impairment, as many of these trials excluded patients with severe renal impairment. There are currently four agents available: dabigatran, rivaroxaban, apixaban, and edoxaban. The purpose of this review was to 1) describe current recommended dosing for each DOAC and published postmarketing data, including case reports, on the use of these agents in the renally impaired; and 2) discuss patient adherence and satisfaction and the cost of these agents.

MATERIALS AND METHODS

A literature search was conducted using Medline and Embase with the terms "dabigatran" or "rivaroxaban" or "apixaban" or "edoxaban" and "renal impairment". Clinical trials and case reports describing the use of DOAC therapy in patients with renal impairment were reviewed. A second search was conducted to find articles evaluating patient adherence, patient satisfaction, and pharmacoeconomics of DOACs.

RESULTS

There are a multitude of subgroup and post hoc analyses, as well as six case reports with dabigatran and one case report with apixaban, that provide insight for the clinical use of DOACs in patients with renal impairment. Dabigatran exhibits the greatest level of renal elimination, and there are data from clinical trials and several case reports that warrant reconsideration before use. Other DOACs may be a better option in patients with impaired renal function. Further, data from patient-adherence studies have suggested that DOACs that are dosed daily (rather than twice daily) are optimal and preferred. There does not appear to be a cost difference between DOACs and warfarin therapy.

CONCLUSION

DOAC therapy in patients with impaired renal function requires more critical review of study data, as these patients may have increased risk of bleeding. It is also valuable to consider patient preferences and cost when selecting the appropriate option for oral anticoagulation.

Edoxaban in Atrial Fibrillation and Venous Thromboembolism-Ten Key Questions and Answers: A Practical Guide

Edoxaban is the fourth non-vitamin K antagonist oral anticoagulant now available for clinical use in the prevention of stroke/systemic embolism in atrial fibrillation (AF) and in the treatment of venous thromboembolism (VTE), after the completion of large-scale randomized comparative clinical trials with the vitamin K antagonist warfarin. Edoxaban has some peculiar pharmacological properties and outcome data. Here a group of experts in AF and VTE answers a set of questions on its practical use, trying to define the profile of patients that would be most appropriate for its use.

The factor xa inhibitor edoxaban for the prevention of stroke and systemic embolism in patients with atrial fibrillation

INTRODUCTION

With the rising prevalence of nonvalvular atrial fibrillation (NVAF) in the general population, the development of new drugs for prevention of thromboembolic events is essential. Non-vitamin K antagonist oral anticoagulants (NOACs) have been shown to present a number of advantages over conventionally used agents, such as predictable pharmacokinetics and no requirement for continuous anticoagulant monitoring. The most recently approved NOAC for the NVAF indication is edoxaban. Several subgroup analyses from the edoxaban phase III ENGAGE AF-TIMI 48 trial have now been published, alongside meta-analysis data comparing the four currently approved NOACs. Consequently, an updated review of the literature is merited. Areas covered: A PubMed search using the terms 'edoxaban', 'non-vitamin K antagonist oral anticoagulant', 'ENGAGE AF-TIMI 48', and 'atrial fibrillation' was performed and results screened for the most relevant English language publications. The market position, pharmacological profile, clinical efficacy, safety and tolerability of edoxaban are presented and discussed. Expert commentary: Edoxaban has been shown to have an efficacy similar or superior to that of warfarin, with a potentially lower risk of major bleeding and predictable, dose-dependent pharmacology. In order to clarify its position within the NOAC market, head-to-head comparative studies are required.