Pharmacokinetics and Pharmacodynamics of Edoxaban, a Non-Vitamin K Antagonist Oral Anticoagulant that Inhibits Clotting Factor Xa

Edoxaban enfolded beta-1,4-poly-d-glucosamine nanoparticles for targeting eponym Stuart-Prower factor for treatment of venous thrombosis

The present research looked for ways to develop shielded nanoparticles (NPs)-drug transporters made of chitosan (CS) to enhance the bioavailability of edoxaban tosylate monohydrate (ETM) for oral administration by examining the correlation among design aspects and data from experiments using response surface methodology (RSM). ETM-loaded CS nanoparticles (ETM-CS-NPs) were developed using the ionic gelation of CS with tripolyphosphate (TPP). Utilising Zeta-sizer and scanning electron microscopy, the ETM-CS-NPs were evaluated for particle size (PS), zeta potential (ZP), surface morphology, polydispersity index (PDI), entrapment efficiency (EE) and drug loading (DL). Drug and polymer interactions in NPs were assessed using Fourier transform infra-red spectroscopy. The response surface approach and Design-Expert software optimised the ETM-CS-NPs. Using RSM, the effects of independent variables such as the amount of CS, the amount of TPP, and the amount of glacial acetic acid on PS, PDI and ZP were analysed. The optimal combination of PS (354.8 nm), PDI (0.509), ZP (43.7 + mV), % EE (70.3 ± 1.3) and % DL (9.1 ± 0.4) has been identified for the optimised ETM-CS-NPs. ETM-CS-NPs' anticoagulant activity was evaluated using activated partial thromboplastin time (aPTT), prothrombin time (PT) and thrombin time (TT) assays. In conclusion, a practical and consistent method has been established, and its application has been proven in vitro, indicating its utility for future studies of the biological distribution of ETM-CS-NPs in vivo for specific antithrombotic treatments.

Novel Drug-Drug Interaction of Potential Rifabutin-Induced Edoxaban Failure: A Case Report

Purpose: To report an incident of a breakthrough deep vein thrombosis (DVT) and potential example of a drug-drug interaction in a patient treated with edoxaban and rifabutin who was being treated for respiratory tuberculosis. Case: A 76-year-old male presented with anemia requiring transfusion and subsequent shortness of breath that was later diagnosed to be respiratory tuberculosis. He experienced a prolonged hospital stay due to persistently positive Mycobacterium tuberculosis respiratory samples and a complicated social situation that required continuous hospitalization for approximately five months. During his treatment the patient was transitioned from apixaban to edoxaban due to a drug-drug interaction with rifabutin. He subsequently had a DVT while on edoxaban after two months of therapy that would require him to transition to warfarin. Conclusion: This case represents an example of a potentially significant drug-drug interaction between edoxaban and rifabutin. Other direct oral anticoagulants (DOACs) exhibit a potential drug-drug interaction that limit their effectiveness when used with rifamycins. This report describes the first known case of a patient experiencing a DVT after prolonged edoxaban use in combination with rifabutin. Treatment with DOACs for patients taking concomitant cytochrome P450 (CYP) inducers such as rifabutin may be more complicated than previously believed.

More early bleeds associated with high baseline direct oral anticoagulant levels in atrial fibrillation: the MAS study

ABSTRACT

Treatment with direct oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) is effective and safe. However, bleeding complications still occur. Whether DOAC level measurement may further improve treatment efficacy and safety is still an open issue. In the "Measure and See" study, venous blood was collected 15-30 days after DOAC initiation in patients with AF who were then followed up for 1 year to record the occurrence of major and clinically relevant nonmajor bleeding. DOAC plasma levels were measured in 1 laboratory, and results were kept blind to patients and treating doctors. Trough DOAC levels were assessed in 1657 patients (957 [57.7%] and 700 patients treated with standard and low-dose, respectively). Fifty bleeding events were recorded during 1606 years of follow-up (3.11% pt/yrs). Fifteen bleeding events (4.97% pt/yrs) occurred in patients with C-trough standardized values in the highest activity class (>0.50), whereas 35 events (2.69% pt/yrs) occurred in those with values in the 2 lower classes (≤0.50, P = .0401). Increasing DOAC levels and low-dose DOAC use were associated with increased bleeding risk in the first 3 months of treatment. Overall, 19% of patients receiving low doses had standardized values in the highest class. More bleeding occurred in patients on low (4.3% pt/yrs) vs standard (2.2% pt/yrs; P = .0160) dose DOAC. Early measurement of DOAC levels in patients with AF identified many individuals with high levels despite the low doses use and had more bleeding risk during the first 3 months of treatment. This trial was registered at www.ClinicalTrials.gov as #NCT03803579.

Perioperative Management of Patients Taking Direct Oral Anticoagulants: A Review

Importance

Direct oral anticoagulants (DOACs), comprising apixaban, rivaroxaban, edoxaban, and dabigatran, are commonly used medications to treat patients with atrial fibrillation and venous thromboembolism. Decisions about how to manage DOACs in patients undergoing a surgical or nonsurgical procedure are important to decrease the risks of bleeding and thromboembolism.

Observations

For elective surgical or nonsurgical procedures, a standardized approach to perioperative DOAC management involves classifying the risk of procedure-related bleeding as minimal (eg, minor dental or skin procedures), low to moderate (eg, cholecystectomy, inguinal hernia repair), or high risk (eg, major cancer or joint replacement procedures). For patients undergoing minimal bleeding risk procedures, DOACs may be continued, or if there is concern about excessive bleeding, DOACs may be discontinued on the day of the procedure. Patients undergoing a low to moderate bleeding risk procedure should typically discontinue DOACs 1 day before the operation and restart DOACs 1 day after. Patients undergoing a high bleeding risk procedure should stop DOACs 2 days prior to the operation and restart DOACs 2 days after. With this perioperative DOAC management strategy, rates of thromboembolism (0.2%-0.4%) and major bleeding (1%-2%) are low and delays or cancellations of surgical and nonsurgical procedures are infrequent. Patients taking DOACs who need emergent (<6 hours after presentation) or urgent surgical procedures (6-24 hours after presentation) experience bleeding rates up to 23% and thromboembolism as high as 11%. Laboratory testing to measure preoperative DOAC levels may be useful to determine whether patients should receive a DOAC reversal agent (eg, prothrombin complex concentrates, idarucizumab, or andexanet-α) prior to an emergent or urgent procedure.

Conclusions and Relevance

When patients who are taking a DOAC require an elective surgical or nonsurgical procedure, standardized management protocols can be applied that do not require testing DOAC levels or heparin bridging. When patients taking a DOAC require an emergent, urgent, or semiurgent surgical procedure, anticoagulant reversal agents may be appropriate when DOAC levels are elevated or not available.

Pharmacokinetics, Pharmacodynamics, and Safety of Edoxaban in Pediatric Subjects: A Phase I Single-Dose Study

This was an open-label, single-dose, phase I study to characterize the pharmacokinetics (PKs), pharmacodynamics (PDs), and safety of edoxaban in pediatric subjects from birth to 18 years at risk for venous thromboembolism (VTE). Children requiring anticoagulant therapy were enrolled into 5 age cohorts (0 to < 6 months (N = 12), 0.5 to < 2 years (N = 13), 2 to < 6 years (N = 13), 6 to < 12 years (N = 13), and 12 to < 18 years (N = 15)) receiving tablet or oral suspension of edoxaban at doses expected to be equivalent to 30 or 60 mg once daily (q.d.) in adult subjects with VTE. Sixty-six pediatric subjects were enrolled and completed the study. Edoxaban plasma concentration peaked between 1 and 3 hours and declined rapidly until 4-8 hours. The range of mean total apparent clearance across 5 age cohorts at low and high doses was 0.47 to 1.11 L/h/kg. The ranges of mean volume of central compartment and apparent peripheral volume were 2.31 to 3.59 L/kg and 1.92 to 4.14 L/kg, respectively. Across all age groups, the estimated median exposures were within the 0.5- to 1.5-fold of the median area under the plasma drug concentration-time curve (AUC) in adult subjects receiving corresponding doses (30 mg q.d. for low dose and 60 mg q.d. for high dose). In all age groups, PD parameters (prothrombin time, activated partial thromboplastin time, and anti-Factor Xa activity) showed a linear PK-PD relationship and were in line with previous adult data. The results support further evaluation of the pediatric doses in larger pivotal trials.

Treating cancer-associated venous thromboembolism: A practical approach

Venous thromboembolism (VTE) is a common and potentially life-threatening complication in patients with cancer. Both cancer and its treatments increase the risk of developing VTE. Specific cancer types and individual patient comorbidities increase the risk of developing cancer-associated VTE, and the risk of bleeding is increased with anticoagulation therapies. The aims of this article are to summarize the latest evidence for treating cancer-associated VTE, discuss the practical considerations involved, and share best practices for VTE treatment in patients with cancer. The article pays particular attention to challenging contexts including patients with brain, lung, gastrointestinal, and genitourinary tumors and those with hematological malignancies. Furthermore, the article summarizes specific clinical scenarios that require additional treatment considerations, including extremes of body weight, nausea and gastrointestinal disturbances, compromised renal function, and anemia, and touches upon the relevance of drug-drug interactions. Historically, vitamin K antagonists and low-molecular-weight heparins (LMWHs) have been used as therapy for cancer-associated VTE. The development of direct oral anticoagulants has provided additional treatment options, which, in certain instances, offer advantages over LMWHs. There are numerous factors that need to be considered when treating cancer-associated VTE, and although various treatment guidelines are helpful, they do not reflect each unique scenario that may arise in clinical practice. This article provides a summary of the latest evidence and a practical approach for treating cancer-associated VTE.

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

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

Edoxaban-Induced Vanishing Bile Duct Syndrome: A Case Report With Review of the Literature

Edoxaban is an oral, highly selective, direct factor X-inhibitor approved by the European Medical Agency for the prevention of stroke in non-valvular atrial fibrillation. Edoxaban is contraindicated in patients with severe hepatic insufficiency and, among adverse effects, serum bilirubin level and gamma-glutamyl transpeptidase elevation are described as common events. We report the case of an 82-year-old man with hepatocellular carcinoma who developed a fatal vanishing bile duct syndrome (VBDS) a few weeks after the administration of edoxaban for non-valvular atrial fibrillation. To the best of our knowledge, this is the first report to describe a case of acute VBDS possibly related to edoxaban.

Effect of Clarithromycin, a Strong CYP3A and P-glycoprotein Inhibitor, on the Pharmacokinetics of Edoxaban in Healthy Volunteers and the Evaluation of the Drug Interaction with Other Oral Factor Xa Inhibitors by a Microdose Cocktail Approach

PURPOSE

We assessed the differential effect of clarithromycin, a strong inhibitor of cytochrome P450 (CYP) 3A4 and P-glycoprotein, on the pharmacokinetics of a regular dose of edoxaban and on a microdose cocktail of factor Xa inhibitors (FXaI). Concurrently, CYP3A activity was determined with a midazolam microdose.

METHODS

In an open-label fixed-sequence trial in 12 healthy volunteers, the pharmacokinetics of a microdosed FXaI cocktail (μ-FXaI; 25 μg apixaban, 50 μg edoxaban, and 25 μg rivaroxaban) and of 60 mg edoxaban before and during clarithromycin (2 x 500 mg/d) dosed to steady-state was evaluated. Plasma concentrations of study drugs were quantified using validated ultra-performance liquid chromatography-tandem mass spectrometry methods.

RESULTS

Therapeutic clarithromycin doses increased the exposure of a therapeutic 60 mg dose of edoxaban with a geometric mean ratio (GMR) of the area under the plasma concentration-time curve (AUC) of 1.53 (90 % CI: 1.37-1.70; p < 0.0001). Clarithromycin also increased the GMR (90% CI) of the exposure of microdosed FXaI apixaban to 1.38 (1.26-1.51), edoxaban to 2.03 (1.84-2.24), and rivaroxaban to 1.44 (1.27-1.63). AUC changes observed for the therapeutic edoxaban dose were significantly smaller than those observed with the microdose (p < 0.001).

CONCLUSION

Clarithromycin increases FXaI exposure. However, the magnitude of this drug interaction is not expected to be clinically relevant. The edoxaban microdose overestimates the extent of the drug interaction with the therapeutic dose, whereas AUC ratios for apixaban and rivaroxaban were comparable to the interaction with therapeutic doses as reported in the literature.

TRIAL REGISTRATION

EudraCT Number: 2018-002490-22.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Oral anticoagulant therapy in older adults

Patients aged ≥65 years not only account for the majority of patients with atrial fibrillation (AF) and venous thromboembolism (VTE), they are also at a higher risk of morbidity, mortality, and undertreatment than younger patients. Several age-related physiological changes with effects on drug pharmacokinetics/-dynamics and blood vessel fragility as well as the higher prevalence of geriatric conditions such as frailty, multimorbidity, polypharmacy, fall risk, dementia, and malnutrition make older persons more vulnerable to disease- and anticoagulation-related complications. Moreover, because older patients with AF/VTE are underrepresented in oral anticoagulation (OAC) trials, evidence on OAC in older adults with AF/VTE is mainly based on subgroup analyses from clinical trials and observational studies. A growing body of such limited evidence suggests that direct oral anticoagulants (DOACs) may be superior in terms of efficacy and safety compared to vitamin K antagonists in older persons with AF/VTE and that specific DOACs may have a differing risk-benefit profile. In this narrative review, we summarize the evidence on epidemiology of AF/VTE, impact of age-related physiological changes, efficacy/safety of OAC, specifically considering individuals with common geriatric conditions, and review OAC guideline recommendations for older adults with AF/VTE. We also propose a research agenda to improve the evidence basis on OAC older individuals with AF/VTE, including the conduct of advanced age-specific and pragmatic studies using less restrictive eligibility criteria and patient-reported health outcomes, in order to compare the effectiveness and safety of different DOACs, and investigate lower-dose regimens and optimal OAC durations in older patients.

Andexanet Alfa for Edoxaban Reversal and Associated Thromboelastography Changes in Surgical Pulmonary Embolectomy

Andexanet alfa neutralizes factor Xa inhibitors in critical bleeding situations. However, in cardiac surgery with cardiopulmonary bypass (CPB), heparin resistance induced by andexanet alfa should be a concern, and the lack of point-of-care monitoring of plasma concentration of factor Xa inhibitors makes it difficult to decide when to administer andexanet alfa. A 69-year-old man underwent emergency surgery for acute pulmonary thromboembolism. The patient had been on edoxaban until the day before the surgery. Withdrawal from CPB required venoarterial extracorporeal membrane oxygenation due to right heart failure, followed by severe bleeding that required massive transfusion. Despite adequate coagulation factor replacement, bleeding persisted and citrated kaolin-reaction time (CK-R) on thromboelastography (TEG) was prolonged. Administering andexanet alfa achieved excellent hemostasis without any thrombosis and normalized the prolonged CK-R of TEG. This is the first report of a change in TEG findings before and after administration of andexanet alfa in a cardiac surgery patient taking factor Xa inhibitor. Monitoring CK-R in TEG may help evaluate the anticoagulant effect of factor Xa inhibitors and the reversal effect of andexanet alfa.

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

ABSTRACT

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

Time Course of the Interaction Between Oral Short-Term Ritonavir Therapy with Three Factor Xa Inhibitors and the Activity of CYP2D6, CYP2C19, and CYP3A4 in Healthy Volunteers

BACKGROUND

We investigated the effect of a 5-day low-dose ritonavir therapy, as it is used in the treatment of COVID-19 with nirmatrelvir/ritonavir, on the pharmacokinetics of three factor Xa inhibitors (FXaI). Concurrently, the time course of the activities of the cytochromes P450 (CYP) 3A4, 2C19, and 2D6 was assessed.

METHODS

In an open-label, fixed sequence clinical trial, the effect and duration of a 5-day oral ritonavir (100 mg twice daily) treatment on the pharmacokinetics of three oral microdosed FXaI (rivaroxaban 25 µg, apixaban 25 µg, and edoxaban 50 µg) and microdosed probe drugs (midazolam 25 µg, yohimbine 50 µg, and omeprazole 100 µg) was evaluated in eight healthy volunteers. The plasma concentrations of all drugs were quantified using validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods and pharmacokinetics were analysed using non-compartmental analyses.

RESULTS

Ritonavir increased the exposure of apixaban, edoxaban, and rivaroxaban, but to a different extent the observed area under the plasma concentration-time curve (geometric mean ratio 1.29, 1.46, and 1.87, respectively). A strong CYP3A4 inhibition (geometric mean ratio > 10), a moderate CYP2C19 induction 2 days after ritonavir (0.64), and no alteration of CYP2D6 were observed. A CYP3A4 recovery half-life of 2.3 days was determined.

CONCLUSION

This trial with three microdosed FXaI suggests that at most the rivaroxaban dose should be reduced during short-term ritonavir, and only in patients receiving high maintenance doses. Thorough time series analyses demonstrated differential effects on three different drug-metabolising enzymes over time with immediate profound inhibition of CYP3A4 and only slow recovery after discontinuation.

CLINICAL TRIAL REGISTRATION

EudraCT number: 2021-006643-39.

Real-world experience with edoxaban for anticoagulation in children at risk for coronary artery thrombosis

BACKGROUND

Direct oral anticoagulants have the potential to improve care in children requiring chronic anticoagulation. Edoxaban has favourable pharmacokinetics that could benefit younger patients but data on long-term safety and efficacy for specific paediatric indications are lacking.

STUDY AIMS

We present a single-centre experience using edoxaban in children who require chronic anticoagulation for large coronary artery aneurysms secondary to Kawasaki disease.

METHODS

Weight-based dosing of once-daily oral edoxaban was offered as alternative to standard anticoagulation for patients aged 1-18 years. Chart review was performed for a median follow-up period of 49 months on edoxaban. Steady-state pharmacokinetics and pharmacodynamics of edoxaban were also explored.

RESULTS

Sixteen patients on chronic therapy with edoxaban were included. No major bleeding events were reported. Two patients experienced coronary artery thrombosis after 23 and 38 months on edoxaban, 7 and 11 years after diagnosed with Kawasaki disease, respectively. This predicts 70% event-free rate at 12 years from diagnosis. Area under the curve estimates over the dosing interval of 24 hours were similar to those reported in adults.

CONCLUSIONS

Edoxaban use is feasible and well-tolerated for long-term use in paediatric population. We suggest appropriate exposure using weight-based once-daily dosing strategy that may be comparable to standard-of-care anticoagulation in prevention of coronary artery thrombosis. Larger studies are needed to evaluate long-term safety and efficacy of edoxaban in this population.

Pharmacogenetic considerations in therapy with novel antiplatelet and anticoagulant agents

Antiplatelets and anticoagulants are extensively used in cardiovascular medicine for the prevention and treatment of thrombosis in the venous and arterial circulations. Wide inter-individual variability has been observed in response to antiplatelets and anticoagulants, which triggered researchers to investigate the genetic basis of this variability. Data from extensive pharmacogenetic studies pointed to strong evidence of association between polymorphisms in candidate genes and the pharmacokinetics and pharmacodynamic action and clinical response of the antiplatelets clopidogrel and the anticoagulant warfarin. In this review, we conducted an extensive search on Medline for the time period of 2009-2023. We also searched the PharmGKB website for levels of evidence of variant-drug combinations and for drug labels and clinical guidelines. We focus on the pharmacogenetics of novel antiplatelets and anticoagulants while excluding acetylsalicylic acid, warfarin and heparins, and discuss the current knowledge with emphasis on the level of evidence.

Ex Vivo Antiplatelet Effects of Oral Anticoagulants

BACKGROUND

The impact of non-vitamin K antagonist oral anticoagulants (NOACs) on platelet function is still unclear. We conducted a comprehensive ex vivo study aimed at assessing the effect of the four currently marketed NOACs on platelet function.

METHODS

We incubated blood samples from healthy donors with concentrations of NOACs (50, 150 and 250 ng/mL), in the range of those achieved in the plasma of patients during therapy. We evaluated generation of thrombin; light transmittance platelet aggregation (LTA) in response to adenosine diphosphate (ADP), thrombin receptor-activating peptide (TRAP), human γ-thrombin (THR) and tissue factor (TF); generation of thromboxane (TX)B2; and expression of protease-activated receptor (PAR)-1 and P-selectin on the platelet surface.

RESULTS

All NOACs concentration-dependently reduced thrombin generation compared with control. THR-induced LTA was suppressed by the addition of dabigatran at any concentration, while TF-induced LTA was reduced by factor-Xa inhibitors. ADP- and TRAP-induced LTA was not modified by NOACs. TXB2 generation was reduced by all NOACs, particularly at the highest concentrations. We found a concentration-dependent increase in PAR-1 expression after incubation with dabigatran, mainly at the highest concentrations, but not with FXa inhibitors; P-selectin expression was not changed by any drugs.

CONCLUSIONS

Treatment with the NOACs is associated with measurable ex vivo changes in platelet function, arguing for antiplatelet effects beyond the well-known anticoagulant activities of these drugs. There are differences, however, among the NOACs, especially between dabigatran and the FXa inhibitors.

Being precise with anticoagulation to reduce adverse drug reactions: are we there yet?

Anticoagulants are potent therapeutics widely used in medical and surgical settings, and the amount spent on anticoagulation is rising. Although warfarin remains a widely prescribed oral anticoagulant, prescriptions of direct oral anticoagulants (DOACs) have increased rapidly. Heparin-based parenteral anticoagulants include both unfractionated and low molecular weight heparins (LMWHs). In clinical practice, anticoagulants are generally well tolerated, although interindividual variability in response is apparent. This variability in anticoagulant response can lead to serious incident thrombosis, haemorrhage and off-target adverse reactions such as heparin-induced thrombocytopaenia (HIT). This review seeks to highlight the genetic, environmental and clinical factors associated with variability in anticoagulant response, and review the current evidence base for tailoring the drug, dose, and/or monitoring decisions to identified patient subgroups to improve anticoagulant safety. Areas that would benefit from further research are also identified. Validated variants in VKORC1, CYP2C9 and CYP4F2 constitute biomarkers for differential warfarin response and genotype-informed warfarin dosing has been shown to reduce adverse clinical events. Polymorphisms in CES1 appear relevant to dabigatran exposure but the genetic studies focusing on clinical outcomes such as bleeding are sparse. The influence of body weight on LMWH response merits further attention, as does the relationship between anti-Xa levels and clinical outcomes. Ultimately, safe and effective anticoagulation requires both a deeper parsing of factors contributing to variable response, and further prospective studies to determine optimal therapeutic strategies in identified higher risk subgroups.

Iatrogenic intramuscular hematoma of the oblique muscles as a complication of technetium-99m-labeled pyrophosphate imaging-based computed tomography-guided core-needle biopsy in a patient with wild-type transthyretin cardiac amyloidosis

Technetium-99m-labeled pyrophosphate imaging-based computed tomography-guided core-needle biopsy of the internal oblique muscle with tracer uptake is a safe and sensitive extracardiac screening biopsy. It can provide histopathological confirmation of the deposition of amyloid transthyretin in patients with wild-type transthyretin cardiac amyloidosis. This case report presents the case of a 73-year-old man receiving triple anti-thrombotic therapy for atrial flutter and coronary stenting who underwent this biopsy to confirm the diagnosis of transthyretin cardiac amyloidosis. The biopsy needle reached the internal oblique muscle via the external oblique muscle between the skin and the target. A type 1 intramuscular hematoma involving these muscles developed subsequently; however, manual compression hemostasis prevented further increase in size. Since this biopsy often targets elderly patients receiving anti-thrombotic therapy who are at high risk of bleeding owing to multimorbidity and polypharmacy, efforts should be made to reduce the frequency of complications, particularly bleeding, which can lead to the development of intramuscular hematoma.

Pharmacokinetics and pharmacodynamics of direct oral anticoagulants

INTRODUCTION

Direct oral anticoagulants (DOACs) have overtaken vitamin K antagonists to become the most widely used method of anticoagulation for most indications. Their stable and predictable pharmacokinetics combined with relatively simple dosing, and the absence of routine monitoring has made them an attractive proposition for healthcare providers. Despite the benefits of DOACs as a class, important differences exist between individual DOAC drugs in respect of their pharmacokinetic and pharmacodynamic profiles with implications for dosing and reversal in cases of major bleeding.

AREAS COVERED

This review summarizes the state of knowledge relating to the pharmacokinetics of dabigatran (factor IIa/thrombin inhibitor) and apixaban, edoxaban and rivaroxaban (factor Xa) inhibitors. We focus on pharmacokinetic differences between the drugs which may have clinically significant implications.

EXPERT OPINION

Patient-centered care necessitates a careful consideration of the pharmacokinetic and pharmacodynamic differences between DOACs, and how these relate to individual patient circumstances. Prescribers should be aware of the potential for pharmacokinetic drug interactions with DOACs which may influence prescribing decisions in patients with multiple comorbidities. In order to give an appropriate dose of DOAC drugs, accurate estimation of renal function using the Cockcroft-Gault formula using actual body weight is necessary. An increasing body of evidence supports the use of DOACs in patients who are obese, and this is becoming more routine in clinical practice.

Anticoagulation in Patients with Chronic Kidney Disease

BACKGROUND

Both atrial fibrillation and venous thromboembolism (VTE) are highly prevalent among patients with chronic kidney disease (CKD). Until recently, warfarin was the most commonly prescribed oral anticoagulant. Direct oral anticoagulants (DOACs) have important advantages and have been shown to be noninferior to warfarin with respect to stroke prevention or recurrent VTE in the general population, with lower bleeding rates. This review article will provide available evidence on the use of DOACs in patients with CKD.

SUMMARY

In post hoc analyses of major randomized studies with DOACs for stroke prevention in atrial fibrillation, in the subgroup of participants with moderate CKD, defined as a creatinine clearance (CrCl) of 30-50 mL/min, dabigatran 150 mg and apixaban were associated with lower rates of stroke and systemic embolism, whereas apixaban and edoxaban were associated with lower bleeding and mortality rates, compared with warfarin. In retrospective observational studies in patients with advanced CKD (defined as a CrCl <30 mL/min) and atrial fibrillation, DOACs had similar efficacy with warfarin with numerically lower bleeding rates. All agents warrant dose adjustment in moderate-to-severe CKD. In patients on maintenance dialysis, the VALKYRIE trial, which was designed initially to study the effect of vitamin K on vascular calcification progression, established superiority for rivaroxaban compared with a vitamin K antagonist (VKA) in the extension phase. Two other clinical trials using apixaban (AXADIA and RENAL-AF) in this population were inconclusive due to recruitment challenges and low event rates. In post hoc analyses of randomized studies with DOACs in patients with VTE, in the subgroup of participants with moderate CKD at baseline, edoxaban was associated with lower rates of recurrent VTE, whereas rivaroxaban and dabigatran were associated with lower and higher bleeding rates, respectively, as compared to warfarin.

KEY MESSAGES

DOACs have revolutionized the management of atrial fibrillation and VTE, and they should be preferred over warfarin in patients with moderate-to-severe CKD with appropriate dose adjustment. Therapeutic drug monitoring with a valid technique may be considered to guide clinical management in individualized cases. Current evidence questions the need for oral anticoagulation in patients on maintenance dialysis with atrial fibrillation as both DOACs and VKAs are associated with high rates of major bleeding.

Use of direct oral anticoagulants for venous thromboembolism treatment at extremes of body weight, renal and liver function: an illustrated review

Direct oral anticoagulants (DOACs) have been a welcome addition to clinical practice due to the practical advantages they confer over traditional anticoagulants. In many countries, DOACs are now used as first-line treatment for the management of venous thromboembolism (VTE). Traditional anticoagulants allow for a degree of individualization, either through monitoring the international normalized ratio in the case of vitamin-K antagonists or through dose titration according to bodyweight in the case of low-molecular-weight heparin. However, the use of fixed doses and removal of the need for routine monitoring has created uncertainty in prescribing DOACs for patients at the extremes of bodyweight, renal function, and patients with liver impairment, who were not well represented in the DOAC licensing clinical trials. The discipline of pharmacokinetics is concerned with the movement of drugs through the body. Although the extremes of bodyweight and renal and liver function will influence the pharmacokinetics of DOACs, are these changes significant enough to affect clinical outcomes of bleeding and thrombosis? In other words, can the fixed-dosing strategy of DOACs accommodate these differences in physiology? In this review, we recap key pharmacokinetic principles for drug dosing; review venous thromboembolism trial and real-world data on patients prescribed DOACs at the extremes of bodyweight, renal function, and liver function; relate this to the pharmacokinetic properties of DOACs; and summarize the state of the field and current unknowns.

Effect of the P-glycoprotein inhibitor tamoxifen on edoxaban plasma levels in women with breast cancer

BACKGROUND

Concomitant use of P-glycoprotein inhibitors can reduce clearance of edoxaban and increase its plasma concentration. Caution is advised with simultaneous use of edoxaban and the frequently used P-glycoprotein inhibitor tamoxifen. However, pharmacokinetic data are lacking.

OBJECTIVES

This study aimed to assess the effect of tamoxifen on edoxaban clearance.

METHODS

This was a prospective, self-controlled, pharmacokinetic study in breast cancer participants starting tamoxifen. Edoxaban was given at a dose of 60 mg once daily for 4 consecutive days, first without tamoxifen and later with concomitant tamoxifen in steady-state. On day 4 of both edoxaban sequences, serial blood samples were taken. A population pharmacokinetic model was developed using nonlinear mixed effects modelling in which the effect of tamoxifen on edoxaban clearance was assessed. Additionally, mean area under the curves (AUC) were estimated. Geometric least square means (GLM) ratios were calculated and no interaction was concluded if the 90 % CI was within the 80-125 % no-effect boundaries.

RESULTS

Twenty-four women with breast cancer scheduled for tamoxifen were included. The median age was 56 years (IQR 51-63). The average edoxaban clearance was 32.0 L/h (95 % CI, 11.1-35.0 L/h). There was no effect of tamoxifen on edoxaban clearance, with a fraction of 100 % (95 % CI 92-108) compared to clearance without tamoxifen. The mean AUCs were 1923 ng*h/ml (SD 695) without tamoxifen and 1947 ng*h/ml (SD 595) with tamoxifen (GLM-ratio 100.4; 90 % CI 98.6-102.2).

CONCLUSIONS

Concomitant use of the P-glycoprotein inhibitor tamoxifen does not lead to reduced clearance of edoxaban in patients with breast cancer.

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.

Clinical trial assessing the safety of edoxaban with concomitant chemotherapy in patients with gynecological cancer-associated thrombosis (EGCAT study)

BACKGROUND

Gynecological cancer is one of the highest risk factors for cancer-associated thrombosis (CAT). Although low-molecular-weight heparin (LMWH) is recommended as an anticoagulant for treating CAT, recent studies have shown that direct oral anticoagulants (DOACs) are an acceptable alternative. Patients with cancer require a series of chemotherapies concomitantly with DOAC administration; however, the extent to which these drugs influence DOAC blood concentrations is unknown. In this study, we measured the plasma concentration of edoxaban during chemotherapy for gynecological cancers to determine its safety.

METHODS

Patients histologically diagnosed with ovarian or uterine corpus cancer and CAT were recruited after primary surgery and before the initiation of postoperative adjuvant chemotherapy, including paclitaxel. Patients were administered edoxaban (30 or 60 mg) orally for CAT. The plasma concentrations of edoxaban and active factor Xa were determined and their percentage change before and after chemotherapy was calculated. Additionally, blood coagulation tests were analyzed.

RESULTS

Sixteen patients with gynecological cancer (12 with ovarian cancer and 4 with uterine corpus cancer) were enrolled. Among these, 15 samples were collected one day after chemotherapy initiation. During chemotherapy, the trough concentration of edoxaban changed from 17.6 ± 10.6 to 20.0 ± 15.6 ng/ml, and the mean percentage change in edoxaban concentration was 14.5%. Therefore, the trough concentrations of edoxaban, which represent excretion capacity, were not significantly increased by chemotherapy with paclitaxel. The area under the plasma edoxaban concentration-time curve and the active factor Xa concentration were also unaffected.

CONCLUSION

Patients with CAT and ovarian or uterine corpus cancer administered edoxaban orally showed no significant increase in the trough concentration of edoxaban while undergoing chemotherapy. This suggests the safety of edoxaban use during the treatment of gynecological cancers.

TRIAL REGISTRATION

EGCAT study; Japan Registry of Clinical Trials, jRCTs051190024.

Direct Oral Anticoagulants: An Updated Systematic Review of Their Clinical Pharmacology and Clinical Effectiveness and Safety in Patients With Nonvalvular Atrial Fibrillation

Direct oral anticoagulants have been an increasingly used class of drugs in the setting of nonvalvular atrial fibrillation, defying vitamin K antagonists' monopoly when it comes to anticoagulation due to its several limitations. Direct oral anticoagulants (DOACs) have entered the market as a noninferior and safer option in comparison with vitamin K antagonists, as their respective phase III clinical trials proved. The aim of this article was to update and summarize data on their clinical pharmacology and to review real-world data to know their comparative effectiveness and safety. We performed a systematic review using PubMed, Google Scholar, Embase, and Web of Science as search engines. Regarding pharmacodynamics, there were no substantial changes reported from their original profile. There were many advances in the knowledge about clinical pharmacokinetics of DOACs that have had a direct impact on their clinical use, mainly related to drug-drug interactions. In a real-world setting, DOACs have shown to be noninferior in preventing thromboembolic events compared to vitamin K antagonists. In regards to safety, DOACs have shown a lower bleeding risk relative to warfarin. Comparison between DOACs has demonstrated rivaroxaban to have the highest bleeding risk. Overall, the evidence gathered showed few changes from the original data presented in phase III clinical trials, concluding that their real-world use coincides greatly with them.

Impact of amiodarone on plasma concentration of direct oral anticoagulant in patients with atrial fibrillation

BACKGROUND/PURPOSE

Amiodarone increases exposure of direct oral anticoagulants (DOACs). We aimed to analyze the effects of concurrent amiodarone use on DOAC concentrations and clinical outcomes.

METHODS

Patients who were ≥20 years of age, had atrial fibrillation, and took DOAC were enrolled to provide trough and peak samples for DOAC concentration measurements using ultra-high-performance liquid chromatography-tandem mass spectrometry. The results were compared with concentrations reported in clinical trials to define above, within, or under the expected range. The outcomes of interest were major bleeding and any gastrointestinal bleeding. Multivariate logistic regression and Cox proportional hazards model were used to determine the impact of amiodarone on above-range concentration and clinical outcomes, respectively.

RESULTS

A total of 722 participants (420 men, 58.2%) were enrolled to provide 691 trough samples and 689 peak samples. Among them, 21.3% concurrently used amiodarone. The proportion of patients with above-range trough and peak concentrations was 16.4% and 30.2%, respectively, for amiodarone users, in contrast to 9.4% and 19.8% for amiodarone non-users. The use of amiodarone was associated with above-range trough and peak concentrations (odds ratio [OR] = 2.00 [1.16, 3.47] and 1.82 [1.19, 2.79], respectively). However, amiodarone was not a significant predictor of major bleeding or any gastrointestinal bleeding.

CONCLUSION

Concurrent amiodarone use led to increased DOAC concentration but was not associated with a higher risk of major bleeding or any gastrointestinal bleeding. Therapeutic monitoring of DOAC users concurrently taking amiodarone may be recommended for patients with an additional risk of increased DOAC exposure.

Identification of genetic biomarkers associated with pharmacokinetics and pharmacodynamics of apixaban in Chinese healthy volunteers

BACKGROUND

Apixaban is a superior direct oral anticoagulant exihibiting interindividual variability in concentration and response in the real world. The present study aimed to identify genetic biomarkers associated with pharmacokinetics (PK) and pharmacodynamics (PD) of apixaban in healthy Chinese subjects.

METHODS

This multicenter study included 181 healthy Chinese adults taking a single dose of 2.5 mg or 5 mg apixaban and assessed their PK and PD parameters. Genome-wide single nucleotide polymorphism (SNP) genotyping was performed using the Affymetrix Axiom CBC_PMRA Array. Candidate gene association analysis and genome-wide association study were conducted to identify genes with a predictive value for PK and PD parameters of apixaban.

RESULTS

Several ABCG2 variants were associated with C_max and AUC_0-t of apixaban (p < 6.12 × 10^-5) and also presented significant differences of anti-Xa_3h activity and dPT_3h according to different ABCG2 genotypes (p < 0.05). Besides, ABLIM2 variants were found to be associated with PK characteristics and F13A1 and C3 variants were associated with PD characteristics of apixaban (p < 9.46 × 10^-8).

CONCLUSION

ABCG2 variants were found to be ideal genetic biomarkers for both PK and PD characteristics of apixaban. ABLIM2, F13A1 and C3 were identified as potential candidate genes associated with inter-individual variability of apixaban. This study was registered on ClinicalTrials.gov NCT03259399.

Personalizing Direct Oral Anticoagulant Therapy for a Diverse Population: Role of Race, Kidney Function, Drug Interactions, and Pharmacogenetics

Oral anticoagulants (OACs) are commonly used to reduce the risk of venous thromboembolism and the risk of stroke in patients with atrial fibrillation. Endorsed by the American Heart Association, American College of Cardiology, and the European Society of Cardiology, direct oral anticoagulants (DOACs) have displaced warfarin as the OAC of choice for both conditions, due to improved safety profiles, fewer drug-drug and drug-diet interactions, and lack of monitoring requirements. Despite their widespread use and improved safety over warfarin, DOAC-related bleeding remains a major concern for patients. DOACs have stable pharmacokinetics and pharmacodynamics; however, variability in DOAC response is common and may be attributed to numerous factors, including patient-specific factors, concomitant medications, comorbid conditions, and genetics. Although DOAC randomized controlled trials included patients of varying ages and levels of kidney function, they failed to include patients of diverse ancestries. Additionally, current evidence to support DOAC pharmacogenetic associations have primarily been derived from European and Asian individuals. Given differences in genotype frequencies and disease burden among patients of different biogeographic groups, future research must engage diverse populations to assess and quantify the impact of predictors on DOAC response. Current under-representation of patients from diverse racial groups does not allow for proper generalization of the influence of clinical and genetic factors in relation to DOAC variability. Herein, we discuss factors affecting DOAC response, such as age, sex, weight, kidney function, drug interactions, and pharmacogenetics, while offering a new perspective on the need for further research including frequently excluded groups.

Oral anticoagulants in fragile patients with percutaneous endoscopic gastrostomy and atrial fibrillation: the ORIGAMI pilot investigation

BACKGROUND

Extensive data support the superior safety without any trade-off in efficacy of direct oral anticoagulants (DOACs) compared to vitamin K antagonists (VKA) in patients with nonvalvular atrial fibrillation, deep venous thrombosis or pulmonary embolism. Whether DOACs may be successfully used to treat complex and fragile patients with percutaneous endoscopic gastrostomy (PEG) remains to be proven. The purpose of this pilot study was to evaluate the feasibility, anticoagulant effect, and preliminary safety/efficacy profile of edoxaban administered via PEG in patients with an indication for long-term oral anticoagulation.

METHODS

In this prospective, single-arm, pilot study, 12 patients with PEG and guideline-recommended indication for anticoagulation for nonvalvular atrial fibrillation were prospectively enrolled. Crushed edoxaban at approved doses was administered via PEG. Quantitative measures of edoxaban's antifactor Xa activity were performed at steady state. Thromboembolic and bleeding events were assessed at one-month follow-up.

RESULTS

Steady state edoxaban plasma levels were at therapeutic range in all patients; mean plasma concentration was 208.5 (±78.6) ng/mL. At one month follow-up, none had suffered a thromboembolic event; one developed minor bleeding, and one died from non-cardiovascular death, owing to sudden worsening of a pre-existing underlying severe condition.

CONCLUSIONS

In this pilot investigation, we report for the first time that crushed edoxaban, administered at approved doses through PEG in fragile and complex patients, is feasible, results in therapeutic edoxaban concentrations, and is apparently effective and safe.

Frailty as a Marker for the Plasma Concentrations of Direct Oral Anticoagulants in Older Patients: Results of an Exploratory Study

BACKGROUND

Frailty makes older adults vulnerable to adverse health outcomes and can modify pharmacokinetics and drug exposure.

OBJECTIVE

We aimed to explore the relationship between different frailty assessments and trough plasma concentrations of direct oral anticoagulants in older patients.

METHODS

The frailty status of adults aged ≥ 70 years receiving regular direct oral anticoagulant medication was assessed by four different instruments: Fried physical phenotype, Rockwood frailty index, Short Physical Performance Battery, and FRAIL scale. The two performance measures "slow gait speed" and "weak grip strength" were used to build a separate score depending on the number of positive criteria (none, one, two). For each participant, a single steady-state direct oral anticoagulant trough plasma concentration was collected, dose-normalized, and its relationship to the various frailty assessments analyzed.

RESULTS

Forty-two participants completed the study, with most using apixaban (n = 22). Dose-normalized apixaban trough concentrations were 2.48-fold higher in frail participants (Fried phenotype) than in robust participants (p = 0.009) and correlated positively with Fried physical phenotype (r_s = 0.535, p = 0.010) and negatively with Short Physical Performance Battery (r_s = - 0.434, p = 0.044). Compared with participants who met none of the criteria "slow gait speed" and "weak grip strength", apixaban trough concentrations were approximately 1.9-fold higher in participants who were positive for one (p = 0.018) or two (p = 0.013) of these measures.

CONCLUSIONS

In this exploratory study, higher levels of frailty on performance-based frailty assessments were associated with higher apixaban exposure in older adults.

CLINICAL TRIAL REGISTRATION

German Clinical Trials Register DRKS00016741; registered 20 February, 2019.

Anti-factor Xa activity, prothrombin time, and activated partial thromboplastin time in patients treated with factor Xa inhibitors

The regimens for factor Xa (FXa) inhibitors (apixaban, edoxaban, and rivaroxaban) vary with venous thromboembolism (VTE) or non-valvular atrial fibrillation (NVAF). The dosage and duration of FXa inhibitor therapy also differ. However, the distribution of anti-factor Xa activity (AXA) values, prothrombin time (PT), and activated partial thromboplastin time (APTT) in patients administered each FXa inhibitor has not fully been assessed. Trough and peak AXA values, PT, and APTT were measured in 85 patients taking apixaban, 105 patients taking edoxaban, and 27 patients taking rivaroxaban. The patients were further divided into three groups based on the dosage. Each FXa inhibitor showed various ranges of AXA values, and twice-daily use resulted in higher absolute AXA values than once-daily use. AXA values and PT for 20 mg apixaban at both trough and peak times were significantly higher than those for 5 mg or 10 mg. AXA values for 60 mg edoxaban at peak time were significantly higher than those for 15 mg or 30 mg. AXA values for 30 mg of rivaroxaban at both trough and peak times were significantly higher than those for 10 mg or 15 mg. In a nonlinear regression model of the relationship between AXA and PT or APTT, PT was positively correlated with AXA values for each FXa inhibitor. This study obtained trough and peak levels of AXA, PT, and APTT in patients with VTE or NVAF who were administered apixaban, edoxaban, and rivaroxaban.

Atrial fibrillation and stroke

INTRODUCTION

Stroke is one of the leading causes of mortality and morbidity globally. Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. It is set to reach epidemic proportions. AF is associated with a five-fold increase in risk of stroke. Strokes caused by AF more often are fatal or result in severe disability. Even though the incidence of stroke has been significantly reduced by oral anticoagulation, AF is thought to account for a significant proportion of cryptogenic strokes where no etiology is identified.

AREAS COVERED

This article reviews the literature related to AF and stroke, pathophysiological insights, diagnosis of AF in stroke patients, and its management (Graphical Abstract).

EXPERT OPINION

The pathophysiology of thrombogenesis that links AF and stroke is not well understood and is an area of active research to identify new therapeutic targets to prevent AF and stroke. As the nature of AF and stroke is multifaceted, an integrated care approach to managing AF and stroke is increasingly essential.

Feasibility, effectiveness, and safety of edoxaban administration through percutaneous endoscopic gastrostomy: 12-months follow up of the ORIGAMI study

Background and aims

Edoxaban proved to be safe and effective also in fragile patients, but its administration through percutaneous endoscopic gastrostomy (PEG) has not been previously investigated. The purpose of this study was to evaluate the feasibility and the preliminary safety and efficacy profiles of edoxaban administered via PEG in patients with an indication for long-term oral anticoagulation.

Methods

ORIGAMI was a prospective, single-arm, observational study (NCT04271293). Patients with PEG and an indication for long-term anticoagulation were prospectively enrolled. Crushed edoxaban at approved doses was administered via PEG. The primary endpoint was the composite of cardio-embolic events consisting of ischemic stroke, systemic embolism, or symptomatic deep venous thrombosis/pulmonary embolism (DVT/PE). Secondary endpoints were the number of bleeding events and edoxaban plasma concentrations at steady state. We here report the 12-month results.

Results

A total of 12 patients were enrolled. The main indication for PEG implantation was amyotrophic lateral sclerosis (10/12). The primary endpoint of cardio-embolic events did not occur in any patients at 12 months. All patients were in the therapeutic range of steady-state edoxaban plasma levels. Three minor bleedings were observed, while no major bleedings occurred during the observational period. A total of five patients died. All deaths were from non-cardiovascular causes and were consistent with the natural history of the pre-existing severe disease.

Conclusion

Our study suggests that edoxaban administration via PEG is feasible and appears safe and effective in fragile, comorbid patients, resulting in therapeutic plasma concentrations of edoxaban.

Clinical trial registration

[ClinicalTrials.gov], identifier [NCT04271293].

The non-vitamin K antagonist oral anticoagulants in atrial fibrillation patients with high-normal renal function - A systematic review

Non-vitamin K antagonist oral anticoagulants (NOACs) have revolutionized treatment of atrial fibrillation. Although benefits of anticoagulation therapy are clear, a minority of patients still experience treatment inefficacy or harm. All NOACs have varying degree of renal clearance, which may significantly affect plasma concentrations. Pivotal clinical trials have explored the effects of dose reduction in patients with chronic renal disease. None of these have, however, specifically addressed the need for a dose up-titration in patients with renal hyperfiltration, in whom lower drug plasma levels are to be expected. A signal for lower efficacy in this patient subset has recently emerged. We systematically assessed the peer-reviewed scientific literature on this topic, including a recently reported randomized pharmacokinetic study in renal hyperfiltrators also reporting on ischemic and bleeding events. We conclude that the reduction in NOAC plasma levels in AF patients with renal hyperfiltration is limited in extent and, does not translate into a clinically meaningful reduction in efficacy for NOACs as compared to vitamin K antagonists (VKAs) in such patients. At the current state of knowledge, NOAC current dosing should not be altered in patients with high-normal renal function.

Bioequivalence and Pharmacokinetic Study of 2 Edoxaban Tablets in Healthy Chinese Subjects

The aim was to investigate the bioequivalence of 2 orally administered edoxaban 60-mg tablets and the food effects on the pharmacokinetics of edoxaban. Sixty-four healthy Chinese subjects participated in this open-label, randomized, 2-sequence, 4-period, crossover study. All subjects randomly received 60-mg generic (test) or branded (reference) edoxaban tablet in each period. Plasma edoxaban concentrations were determined using liquid chromatography-tandem mass spectrometry. The pharmacokinetic parameters maximum concentration (C_max ) and area under the concentration-time curve (AUC) were compared to assess bioequivalence. The geometric least-squares mean ratios for C_max , AUC from time 0 to the last measurable time point (AUC_0-t ), and AUC from time 0 extrapolated to infinity (AUC_0-∞ ) were 97.0%, 95.4%, and 96.1%, respectively, in the fasting test, and 98.6%, 100.0%, and 99.8%, respectively, in the fed test. Food increased exposure and prolonged the time to maximum concentration of edoxaban. Both formulations displayed comparable safety profiles, with no serious adverse events reported. The 2 products of edoxaban tablets are bioequivalent and safe in healthy Chinese volunteers. Food may have a modest effect on the pharmacokinetic properties of edoxaban.

Laboratory Test Predictors for Major Bleeding in Elderly (≥80 Years) Patients With Nonvalvular Atrial Fibrillation Treated With Edoxaban 15 mg: Sub-Analysis of the ELDERCARE-AF Trial

Background

We investigated the predictors related to major bleeding events during treatment with edoxaban 15 mg in patients aged ≥80 years with nonvalvular atrial fibrillation and high bleeding risk, for whom standard oral anticoagulants are inappropriate, focusing on standard laboratory tests related to bleeding.

Methods and Results

This was a prespecified subanalysis of the on‐treatment analysis set of the ELDERCARE‐AF (Edoxaban Low‐Dose for Elder Care Atrial Fibrillation Patients) trial. Major bleeding was the primary safety end point. The event rates were calculated according to prespecified characteristics at baseline. A total of 984 Japanese patients were randomly assigned to edoxaban 15 mg or placebo (n=492, each). During the study period, 20 and 11 major bleeding events occurred in the edoxaban and placebo groups, respectively. The adjusted analysis revealed that hemoglobin <12.3 g/dL (adjusted hazard ratio [aHR], 3.57 [95% CI, 1.10–11.55]) and prothrombin time ≥12.7 seconds; (aHR, 2.89 [95% CI, 1.05–8.02]) independently predicted major bleeding, while creatinine clearance <30 mL/min showed a tendency towards an increase in major bleeding (aHR, 2.68; 95% CI, 0.96–7.46). In patients treated with edoxaban lacking these 3 risk factors, no major bleeding occurred; major bleeding event rates increased with each risk factor. Patients with 3 risk factors were significantly more likely to have a major bleeding event at 11.05%/year (HR, 7.15 [95% CI, 1.92–26.71]).

Conclusions

In elderly patients with nonvalvular atrial fibrillation with high bleeding risk, baseline hemoglobin <12.3 g/dL, prothrombin time ≥12.7 seconds, and creatinine clearance <30 mL/min may predict major bleeding during treatment with edoxaban 15 mg.

Registration

URL: ELDERCARE‐AF https://www.clinicaltrials.gov; Unique number: NCT02801669.

Thromboembolic Events While Taking Direct Oral Anticoagulants: An Analysis of Post-market WHO Database Reports from 2012 to 2020

BACKGROUND AND OBJECTIVE

Several cases of venous thromboembolism in patients treated with direct oral anticoagulants (DOACs) have been reported in the literature, but a quantative analysis of postmarketing reports is lacking. The objective of this study was to determine the post-marketing odds ratio (OR) and reporting odds ratio (ROR) of venous thromboembolism in patients receiving DOACs compared among each other and to vitamin K antagonists (VKAs).

METHODS

The OR and ROR were used to determine the ratio of reports for deep vein thrombosis and pulmonary embolism between 1 January, 2012 and 15 November, 2020 using the World Health Organization VigiLyze database. This was performed using all venous thromboembolism events in which a DOAC or a VKA was the suspected medication. The OR and ROR including 95% confidence intervals were calculated for each DOAC drug in comparison to all VKAs as a group.

RESULTS

The OR of deep vein thrombosis was highest for rivaroxaban compared with dabigatran and apixaban [2.63 (2.41-2.89); 1.84 (1.72-1.97)]. The OR of deep vein thrombosis was lowest for edoxaban compared with dabigatran, apixaban and rivaroxaban [0.44 (0.32-0.61); 0.31 (0.22-0.42); 0.17 (0.12-0.23)]. The OR of pulmonary embolism was also highest for rivaroxaban compared with dabigatran and apixaban [2.59 (2.37-2.83); 1.79 (1.68-1.92)]. The OR of pulmonary embolism was also lowest for edoxaban compared with dabigatran, apixaban and rivaroxaban [0.77 (0.60-0.97); 0.59 (0.41-0.67); 0.30 (0.23-0.37)]. Comparing RORs of various DOACs with VKAs, rivaroxaban had the highest RORs for deep vein thrombosis/pulmonary embolism, in comparison to apixaban, dabigatran and edoxaban.

CONCLUSIONS

Our findings may indicate a higher association between rivaroxaban therapy and venous thromboembolism as compared with apixaban, dabigatran and edoxaban. These findings are uncertain owing to the reliability of a post-marketing registration system that is negatively influenced by a high level of under-reporting. However, based on pharmacodynamics, we cannot exclude the possibility that there is a real effect that may be driven by non-adherence.

Efficacy and Safety Considerations With Dose-Reduced Direct Oral Anticoagulants: A Review

Importance

Dose-reduced regimens of direct oral anticoagulants (DOACs) may be used for 2 main purposes: dose-adjusted treatment intended as full-intensity anticoagulation (eg, for stroke prevention in atrial fibrillation [AF] in patients requiring dose reduction) or low-intensity treatment (eg, extended-duration treatment of venous thromboembolism [VTE]). We reviewed randomized clinical trials (RCTs) to understand the scenarios in which dose-adjusted or low-intensity DOACs were tested and reviewed the labeled indications by regulatory authorities, using data from large registries to assess whether the use of dose-reduced DOACs in routine practice aligned with the findings of RCTs.

Observations

Among 4191 screened publications, 35 RCTs that used dose-adjusted DOACs were identified for dabigatran, apixaban, rivaroxaban, and edoxaban. Of these 35 RCTs, 29 were related to stroke prevention in AF. Efficacy and safety results for dose-adjusted DOACs in large RCTs of AF were similar to those found for full-dose DOACs. To our knowledge, dabigatran, apixaban, and rivaroxaban have not been studied as dose-adjusted therapy for acute VTE treatment. Low-intensity DOACs were identified in 37 RCTs. Low-intensity DOACs may be used for extended-duration treatment of VTE (apixaban and rivaroxaban), primary prevention in orthopedic surgeries (dabigatran, apixaban, and rivaroxaban), primary prevention in ambulatory high-risk cancer patients (apixaban and rivaroxaban) or (postdischarge) high-risk medical patients (rivaroxaban), in stable atherosclerotic vascular disease, or after a recent revascularization for peripheral artery disease in conjunction with aspirin (rivaroxaban). Minor variations exist between regulatory authorities in different regions regarding criteria for dose adjustment of DOACs. Data from large registries indicated that dose-reduced DOACs were used occasionally with doses or for clinical scenarios different from those studied in RCTs or recommended by regulatory authorities.

Conclusions and Relevance

Dose adjustment and low-intensity treatment are 2 different forms of dose-reduced DOACs. Dose adjustment is mostly relevant for AF and should be done based on the approved criteria. Dose adjustment of DOACs should not be used for acute VTE treatment in most cases. In contrast, low-intensity DOACs may be used for primary or secondary VTE prevention for studied and approved indications. Attention should be given to routine practice patterns to align the daily clinical practice with existing evidence of safety and efficacy.

Drug-Drug Interactions of Direct Oral Anticoagulants (DOACs): From Pharmacological to Clinical Practice

The direct oral anticoagulants (DOACs), dabigatran, rivaroxaban, apixaban, and edoxaban, are becoming the most commonly prescribed drugs for preventing ischemic stroke in patients with non-valvular atrial fibrillation (NVAF) and for the treatment and prevention of venous thromboembolism (VTE). Rivaroxaban was also recently approved for the treatment of patients with a recent acute coronary syndrome (ACS). Their use demonstrated to have a favorable risk-benefit profile, with significant reductions in stroke, intracranial hemorrhage, and mortality compared to warfarin, but with increased gastrointestinal bleeding. Nevertheless, their safety profile is compromised in multimorbidity patients requiring contemporary administration of several drugs. Comorbidity and polypharmacy have a high prevalence in elderly patients, who are also more susceptible to bleeding events. The combination of multiple treatments can cause relevant drug–drug interactions (DDIs) by affecting the exposure or the pharmacological activities of DOACs. Although important differences of the pharmacokinetic (PK) properties can be observed between DOACs, all of them are substrate of P-glycoprotein (P-gp) and thus may interact with strong inducers or inhibitors of this drug transporter. On the contrary, rivaroxaban and, to a lower extent, apixaban, are also susceptible to drugs altering the cytochrome P450 isoenzyme (CYP) activities. In the present review, we summarize the potential DDI of DOACs with several classes of drugs that have been reported or have characteristics that may predict clinically significant DDIs when administered together with DOACs. Possible strategies, including dosage reduction, avoiding concomitant administration, or different time of treatment, will be also discussed to reduce the incidence of DDI with DOACs. Considering the available data from specific clinical trials or registries analysis, the use of DOACs is associated with fewer clinically relevant DDIs than warfarin, and their use represents an acceptable clinical choice. Nevertheless, DDIs can be significant in certain patient conditions so a careful evaluation should be made before prescribing a specific DOAC.

The edoxaban‐M4 metabolite and measurement of edoxaban by chromogenic assays in human plasma

Introduction

Edoxaban is the only anti-Xa inhibitor metabolized in pharmacologically active moiety that could interfere with chromogenic anti-Xa assays, especially in case of drug-drug interactions or physiological disorders.

Materials and methods

We evaluated the contribution of the main metabolite of edoxaban, edoxaban-M4 (M4), in 79 plasma samples from patients taking edoxaban. The total anti-Xa activity was evaluated on three different chromogenic factor Xa-based assays. Results were compared with a validated ultra-high-performance liquid chromatography coupled with a tandem mass spectrometry measurement. Edoxaban and its active M4 metabolite have also been spiked separately in normal pooled plasma to assess the sensitivity of chromogenic anti-Xa assays to both molecules individually.

Results

Spiked edoxaban or M4 provided different slopes of linear regression models between chromogenic and chromatographic measurement (from 0.97 for STA Liquid Anti-Xa to 1.10 for Biophen Heparin LRT Low with edoxaban and from 0.70 for Biophen DiXaI High to 0.83 for Biophen Heparin LRT High, respectively). A positive correlation is observed between the increase of the ratio M4/edoxaban with the difference between chromogenic and chromatographic measurements.

Conclusion

Edoxaban and M4 do not similarly impact chromogenic assays, leading to biased chromogenic estimations of ponderal concentrations. In patient samples, this impact is even more important at low concentrations or in the case of an increase in the M4/edoxaban ratio because of hepatic or renal impairments or in case of drug interactions. This study highlights the limitations and risks of error of expressing results in ponderal concentrations instead of global activity anti-Xa.

Biopharmaceutics considerations for direct oral anticoagulants

Vitamin K antagonists (VKA) and direct oral anticoagulants (DOACs) have been clinically used in the treatment of coagulation disorders. There are four DOACs approved since 2010 (dabigatran etexilate, rivaroxaban, apixaban, and edoxaban), and they were designed to overcome the practical limitations of VKA. This review summarized biopharmaceutics considerations about DOACs, which are critically discussed, applying risk analyses to subside the further classification of these drugs according to the Biopharmaceutics Classification System (BCS). These discussions included data compiled about physicochemical properties, equilibrium solubility, permeability, and drug dissolution of DOACs. From the biopharmaceutics characteristics is possible to identify critical variables related to the absorption process, which can help in the design of new formulations. The data were compared with the criteria recommended by regulatory agencies for the biopharmaceutics classification according to the BCS. From that, these data may be used to discuss the approval of generic medicines by the BCS-based biowaiver, and the clinical risks arising from novel formulations with DOACs. However, although there are indications of biopharmaceutics classifications for DOACs, conclusive information to classify these compounds according to the BCS is lacking, requiring more experimental studies to achieve this aim. Conclusive information is essential for a safe decision about the biowaiver, as well as to guide the development of new formulations containing the DOACs.

Use of Apixaban in Atrial Fibrillation With Ritonavir-Boosted Antiretroviral Therapy: A Case Report

PURPOSE

Direct oral anticoagulants (DOACs) pose a challenge when given with potent CYP3A4 and P-gp inhibitors, such as the commonly prescribed pharmacokinetic booster ritonavir. As per the manufacturer, apixaban offers a dose reduction when administered concurrently with ritonavir; thus, we explore the clinical indication and safety of apixaban when given with ritonavir-boosted highly active antiretroviral therapy (HAART) in an HIV patient.

SUMMARY

We describe a 73-year-old male with extensive cardiac history, including a past medical history of resolved left ventricular thrombus, newly diagnosed non-valvular atrial fibrillation treated with warfarin, and HIV infection treated with ritonavir-boosted HAART. The patient presented to the emergency department with bleeding from multiple sites, necessitating the use of vitamin K. Consequently, his hospital course was complicated by episodes of minor bleeding and labile INR. Due to the complicated nature of his condition and the potential for drug-drug interactions (DDIs), he was transitioned from warfarin to apixaban. Since there is little readily available data to support the use of rivaroxaban and dabigatran with ritonavir, our patient was safely started on dose-reduced apixaban for stroke prophylaxis in atrial fibrillation due to the predictable nature of apixaban pharmacokinetics and proven superiority regarding adverse effects, as compared to other DOACs.

CONCLUSION

Dose-reduced apixaban is a safe and viable choice in patients with atrial fibrillation warranting stroke prophylaxis while concurrently receiving ritonavir-boosted HAART.

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.

A Scoping Review of Alternative Anticoagulation Strategies for Hemodialysis Patients with a Mechanical Heart Valve

INTRODUCTION

Patients with end-stage renal disease (ESRD) have high rates of cardiac valvulopathy but can develop contraindications for vitamin K antagonist (VKA) therapy. We explored the evidence for alternative anticoagulation strategies in patients with ESRD with a contraindication for VKA therapy.

METHODS

A scoping review was completed, searching MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Web of Science, and Conference abstracts from inception to March 30, 2021. The study population was patients with ESRD who were on VKA therapy and developed a contraindication to VKA therapy use. All data regarding studies, patient characteristics, anticoagulation strategy, and clinical outcomes were summarized.

RESULTS

Twenty-three articles met inclusion criteria. These articles included 57 patients. Contraindications to VKA therapy included calcific uremic arteriolopathy (CUA) (n = 55) and warfarin-induced skin necrosis (n = 2). All studies were either case reports or case series. There were 10 anticoagulation strategies identified. Continuation of VKA therapy was associated with increased death and decreased rates of CUA resolution (80.0% and 10.0%, respectively), compared to apixaban (24.0% and 70.8%), subcutaneous (SC) low-molecular-weight heparin (LMWH) (14.3%, 85.7%), and SC unfractionated heparin (0.0%, 100.0%). While only 5 patient cases were reported with mechanical heart valves, SC LMWH use has been reported in this context with good outcomes.

CONCLUSIONS

In patients with ESRD who develop a contraindication to VKA therapy, several alternative anticoagulation strategies have been reported with superior outcomes to VKA continuation. While outcomes appear superior to continuation of VKA therapy, more data are required before definitive recommendations can be made for the patient with ESRD and a mechanical heart valve.

Inhaled Edoxaban dry powder inhaler formulations: Development, characterization and their effects on the coagulopathy associated with COVID-19 infection

Herein, we demonstrated the development and characterization of a dry powder inhaler (DPI) formulation of edoxaban (EDX); and investigated the in-vitro anticoagulation effect for the management of pulmonary or cerebral coagulopathy associated with COVID-19 infection. The formulations were prepared by mixing the inhalable micronized drug with a large carrier lactose and dispersibility enhancers, leucine, and magnesium stearate. The drug-excipient interaction was studied using X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) methods. The drug and excipients showed no physical inter particulate interaction. The in-vitro drug aerosolization from the developed formulation was determined by a Twin Stage Impinger (TSI) at a flow rate of 60 ± 5 L /min. The amount of drug deposition was quantified by an established HPLC-UV method. The fine particle fraction (FPF) of EDX API from drug alone formulation was 7%, whereas the formulations with excipients increased dramatically to almost 7-folds up to 47%. The developed DPI formulation of EDX showed a promising in-vitro anticoagulation effect at a very low concentration. This novel DPI formulation of EDX could be a potential and effective inhalation therapy for managing pulmonary venous thromboembolism (VTE) associated with COVID-19 infection. Further studies are warranted to investigate the toxicity and clinical application of the inhaled EDX DPI formulation.

Edoxaban for the treatment of pulmonary embolism in hospitalized COVID-19 patients

PURPOSE

We aimed to investigate the clinical performance of edoxaban for the treatment of pulmonary embolism (PE) in hospitalized COVID-19 patients.

METHODS

We conducted a retrospective analysis selecting hospitalized patients with COVID-19 admitted to our Institution from 20 May 2020 to 20 November 2020 with computer tomography (CT) detected PE at admission, treated with edoxaban after initial parenteral therapy. Clinical outcomes were compared between patients with and without ARDS at admission and between those with and without CT confirmed PE resolution.

RESULTS

50 patients were included. Mean follow-up was 42.5 ± 10 days. No baseline differences were found between patients with ARDS (30%) and those without ARDS at admission. Patients with PE resolution (84%) were younger (P = 0.03), had a shorter duration of fondaparinux therapy (9.9 ± 3.8 vs 15.8 ± 7.5 days; P = 0.0015) and length of hospitalization (36 ± 8 vs 46 ± 9 days: P = 0.0023) compared with those without PE resolution. 2 patients experienced major bleedings. At multivariate analysis the time to edoxaban switch was the only predictor of the PE resolution (HR: 0.92; 95% C.I. 0.86 to 0.99).

CONCLUSION

Edoxaban was an effective and safe treatment for acute PE in COVID-19 setting.

Factors Associated With Edoxaban Concentration Among Patients With Atrial Fibrillation

Background and Purpose: Edoxaban exposure varies across different ethnicities. The purpose of our study was to examine the risk factors associated with high or low edoxaban concentrations in Asian populations.

Methods: Participants with atrial fibrillation who were undergoing edoxaban therapy were enrolled. Peak (1–4 h after edoxaban administration) and trough (24 ± 4 h from the last edoxaban dose) blood samples were collected to measure edoxaban concentrations using ultrahigh-performance liquid chromatography with tandem mass spectrometry. The edoxaban concentrations were compared to those observed in clinical trials to define a higher- or lower-than-expected range. Multivariate logistic regression was used to analyze the risk factors associated with high or low edoxaban concentrations.

Results: Eighty participants (49 men, 61.3%) were enrolled and provided 78 trough and 76 peak samples. Twenty participants (25.6%) were determined to have low trough concentrations, which was associated with higher creatinine clearance and the use of the 30 mg regimen (odds ratio [OR] and 95% confidence interval [CI], 1.06 [1.01, 1.11], p = 0.01 and 5.77 [1.34, 24.75], p = 0.02, respectively). In contrast, 21 participants (27.6%) had high peak concentrations, which was associated with an off-label overdosing regimen (OR = 4.68 [1.23, 17.70], p = 0.02).

Conclusion: Our study identified factors associated with increased or decreased edoxaban exposure. The measurement of edoxaban concentration may be recommended for patients with selected characteristics.

Direct Oral Anticoagulants in Patients with Obesity and Atrial Fibrillation: Position Paper of Italian National Association of Hospital Cardiologists (ANMCO)

The use of the direct oral anticoagulants dabigatran, rivaroxaban, apixaban and edoxaban (DOACs) offers some major advantages over warfarin and other vitamin K antagonists (VKAs). One advantage is the possibility to use a fixed dose in normal-weight patients, overweight patients and patients with obesity. However, the "one size fits all" strategy raised a concern regarding the possibility to undertreat patients with a high body mass index. No randomized controlled trials (RCTs) have ever compared VKAs and DOACs in this population. We analyzed data from the literature on DOAC pharmacokinetics and pharmacodynamics, results from the four pivotal phase III trials on non-valvular atrial fibrillation, retrospective observational studies and metanalyses. While we are aware of the limitation imposed by the absence of specific RCTs, we propose the position of the Italian Association of Hospital Cardiologists (ANMCO) on the use of DOACs in patients with obesity based on the existing evidence.