Modelling and simulation of edoxaban exposure and response relationships in patients with atrial fibrillation

Can edoxaban be used at extremes of bodyweight and in patients with a creatinine clearance ≥95 ml/min? - A population pharmacokinetic analysis

BACKGROUND

Clinical evidence surrounding edoxaban use in patients weighing <50 kg and >120 kg is lacking. The International Society of Thrombosis and Haemostasis Scientific and Standardisation Committee suggests avoiding edoxaban in patients >120 kg. Additionally, concerns exist regarding decreased efficacy in patients prescribed edoxaban for atrial fibrillation with a creatinine clearance (CrCl) >95 ml/min, a finding of the ENGAGE AF-TIMI 48 trial when edoxaban was compared to warfarin.

OBJECTIVE

To derive a population pharmacokinetic (PopPK) model using clinical practice data, to understand the impact of bodyweight and renal function on edoxaban pharmacokinetics.

METHOD

Edoxaban plasma concentrations and patient characteristics were collated from King's College Hospital anticoagulation clinics between 11/2016 and 08/2022. A PopPK model was developed using non-linear mixed effects modelling and used to simulate edoxaban concentrations at the extremes of bodyweight and with varying renal function.

RESULTS

Data from 409 patients (46 < 50 kg, 34 > 120 kg and 123 with a CrCl > 95 ml/min) provided 455 edoxaban plasma concentrations. A one-compartment model with between-subject variability on clearance with a proportional error model best described the data. The most significant covariates impacting on edoxaban exposure were CrCl and bodyweight. Our work suggests that edoxaban exposure in patients weighing up to 140 kg is comparable to those weighing 75 kg. Edoxaban exposure is reduced in patients weighing <50 kg due to the recommended dose reductions. There is also a reduction in AUCss when CrCl > 95 ml/min compared to CrCl 80 ml/min.

CONCLUSIONS

Our population PK model for edoxaban suggests that renal function is a key driver for overall edoxaban exposure. Further clinical outcome data is required to understand clinical effectiveness and adverse outcomes.

Association of direct oral anticoagulant and delayed bleeding with pharmacokinetics after endoscopic submucosal dissection

BACKGROUND AND AIMS

Pharmacokinetic parameters, such as drug plasma level at trough, time to maximum plasma concentration (Tmax), and coagulation factor Xa (FXa) activity generally predict factors for the anticoagulant effects of direct oral anticoagulants (DOACs). Although GI bleeding is a major adverse event after endoscopic submucosal dissection (ESD), little is known about the association between post-ESD bleeding in patients taking DOACs and the pharmacologic parameters. This study aimed to evaluate pharmacologic risk factors for post-ESD bleeding in patients taking DOACs.

METHODS

We prospectively evaluated the incidence of post-ESD bleeding in patients taking DOACs between April 2018 and May 2022 at 21 Japanese institutions and investigated the association with post-ESD bleeding and pharmacologic factors, including plasma concentration and FXa activity at trough and Tmax.

RESULTS

The incidence of post-ESD bleeding was 12.8% (14 of 109; 95% confidence interval [CI], 7.2-20.6). Although plasma DOAC concentration and plasma level/dose ratio at trough and Tmax varied widely among individuals, a significant correlation with plasma concentration and FXa activity was observed (apixaban: correlation coefficient, -0.893; P < .001). On multivariate analysis, risk factors for post-ESD bleeding in patients taking DOACs were higher age (odds ratio [OR], 1.192; 95% CI, 1.020-1.392; P = .027) and high anticoagulant ability analyzed by FXa activity at trough and Tmax (OR, 6.056; 95% CI, 1.094-33.529; P = .039).

CONCLUSIONS

The incidence of post-ESD bleeding in patients taking DOACs was high, especially in older patients and with high anticoagulant effects of DOACs. Measurement of pharmacokinetic parameters of DOACs may be useful in identifying patients at higher risk of post-ESD bleeding.

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.

The impact of renal function on clinical outcomes of patients with cancer-associated isolated distal deep vein thrombosis: Insights from the ONCO DVT study

BACKGROUND

The multicenter, open-label, randomized clinical trial ONCO DVT compared 3-month and 12-month edoxaban treatment regimens for isolated distal deep vein thrombosis (DVT) and suggested potential benefits of prolonged edoxaban treatment in terms of thrombotic risk. However, the risk-benefit balance of prolonged edoxaban treatment in patients with renal function remains unclear.

OBJECTIVES

To compare the safety and efficacy of 3-month and 12-month edoxaban treatment regimens in patients with cancer-associated isolated distal DVT and different renal functions.

METHODS

This pre-specified subgroup analysis of the ONCO DVT study included 601 patients divided into subgroups according to renal function using a 50 mL/min creatinine clearance (Ccr) cutoff. The primary endpoint was symptomatic recurrent venous thromboembolism (VTE) and VTE-related death at 12 months and the major secondary endpoint was major bleeding at 12 months.

RESULTS

Among the 601 patients, 131 (21.8 %) comprised the renal dysfunction subgroup. The primary endpoint occurred in 6 (9.7 %) and 1 (1.4 %) patients in the 3-month and 12-month edoxaban groups in the renal dysfunction subgroup, respectively, and in 16 (6.6 %) and 2 (0.9 %) patients in the no renal dysfunction subgroup, respectively. The major secondary endpoint occurred in 9 (14.5 %) and 7 (10.1 %) patients in the 12-month and 3-month edoxaban groups in the renal dysfunction subgroup, and in 13 (5.3 %) and 21 (9.3 %) patients in the no renal dysfunction subgroup, respectively.

CONCLUSIONS

A 12-month edoxaban regiment was superior to a 3-month treatment in terms of thrombotic risk irrespective of renal function. A higher bleeding risk was not identified in patients with renal dysfunction who received prolonged edoxaban treatment.

Assessment of delayed bleeding after endoscopic submucosal dissection of early-stage gastrointestinal tumors in patients receiving direct oral anticoagulants

Delayed bleeding is a major and serious adverse event of endoscopic submucosal dissection (ESD) for early-stage gastrointestinal tumors. The rate of post-ESD bleeding for gastric cancer is higher (around 5%-8%) than that for esophagus, duodenum and colon cancer (around 2%-4%). Although investigations into the risk factors for post-ESD bleeding have identified several procedure-, lesion-, physician- and patient-related factors, use of antithrombotic drugs, especially anticoagulants [direct oral anticoagulants (DOACs) and warfarin], is thought to be the biggest risk factor for post-ESD bleeding. In fact, the post-ESD bleeding rate in patients receiving DOACs is 8.7%-20.8%, which is higher than that in patients not receiving anticoagulants. However, because clinical guidelines for management of ESD in patients receiving DOACs differ among countries, it is necessary for endoscopists to identify ways to prevent post-ESD delayed bleeding in clinical practice. Given that the pharmacokinetics (e.g., plasma DOAC level at both trough and T_max) and pharmacodynamics (e.g., anti-factor Xa activity) of DOACs are related to risk of major bleeding, plasma DOAC level and anti-FXa activity may be useful parameters for monitoring the anti-coagulate effect and identifying DOAC patients at higher risk of post-ESD bleeding.

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.

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.

Insights into the Pharmacokinetics and Pharmacodynamics of Direct Oral Anticoagulants in Older Adults with Atrial Fibrillation: A Structured Narrative Review

Older adults, the fastest growing population, represent almost 50% of all users of direct oral anticoagulants (DOACs). Unfortunately, we have very little relevant pharmacological and clinical data on DOACs, especially in older adults with geriatric profiles. This is highly relevant as pharmacokinetics and pharmacodynamics (PK/PD) often differ substantially in this population. Hence, we need to obtain a better understanding of the PK/PD of DOACs in older adults, to ensure appropriate treatment. This review summarises the current insights into PK/PD of DOACs in older adults. A search was undertaken up to October 2022 to identify PK/PD studies of apixaban, dabigatran, edoxaban, and rivaroxaban, that included older adults aged ≥ 75 years. This review identified 44 articles. Older age alone did not influence exposure of edoxaban, rivaroxaban and dabigatran, while apixaban peak concentrations were 40% higher in older adults than in young volunteers. Nevertheless, high interindividual variability in DOAC exposure in older adults was noted, which can be explained by distinctive older patient characteristics, such as kidney function, changes in body composition (especially reduced muscle mass), and co-medication with P-gp inhibitors, which is in line with the current dosing reduction criteria of apixaban, edoxaban, and rivaroxaban. Dabigatran had the largest interindividual variability among all DOACs since its dose adjustment criterion is only age, and thus it is not a preferable option. Additionally, DOAC exposure, which fell outside of on-therapy ranges, was significantly related to stroke and bleeding events. No definite thresholds linked to these outcomes in older adults have been established.

Prediction and Implications of Edoxaban-Associated Bleeding in Patients after Critical Illness

In this retrospective study, we aimed to identify the risk factors for bleeding in patients after critical illness during edoxaban treatment. Data from patients who received edoxaban after critical illness at the Emergency Department at a tertiary care hospital were obtained from the hospital medical records. Multivariate analysis revealed the risk factors for edoxaban-associated bleeding. Additionally, we developed an edoxaban-associated bleeding score (EAB score) based on these results. The derived EAB score was compared with the HAS-BLED score using receiver operating characteristic (ROC) curve analysis. Bleeding was observed in 42 of 114 patients (36.8%). We identified the following bleeding predictors (odds ratios, 95% confidence interval, score points) using multivariate analysis: concomitant use of antiplatelet agents (6.759, 2.047-22.32, 2 points), concomitant use of P-glycoprotein inhibitors (3.825, 1.484-9.856, 1 point), prothrombin time (PT)% following edoxaban administration of <75% and ≥60% (2.507, 0.788-7.970, 1 point), and PT% following edoxaban administration of <60% (11.23, 3.560-35.42, 3 points). The ROC curve analysis revealed an area under the curve of 0.826 for the EAB score and 0.625 for the HAS-BLED score. Under appropriate edoxaban dosing regimens in patients after critical illness, a combination of antiplatelet agents, P-gp inhibitors, and a low PT% following edoxaban administration were identified as strong risk factors for bleeding.

Population Pharmacokinetic Models for Direct Oral Anticoagulants: A Systematic Review and Clinical Appraisal Using Exposure Simulation

Available data have shown an association between direct oral anticoagulant (DOAC) plasma concentration and clinical, particularly bleeding, events. Factors that may influence DOAC plasma concentration are therefore the focus of particular attention. Population pharmacokinetic (PopPK) analyses can help in identifying such factors while providing predictive models. The main aim of the present study was to identify all the PopPK models to date for the four most frequently used DOACs (dabigatran, apixaban, rivaroxaban, and edoxaban). The secondary aim was to use these models to simulate different DOAC plasma concentration–time profiles in relevant clinical scenarios. The results of our model‐based simulations confirm the clinical relevance of the known major factors influencing DOAC exposure and support the current approved dose adaptation, at least for atrial fibrillation. They also highlight how the accumulation of covariates, not currently considered for dose adaptation due to their seemingly minor influence on DOAC exposure, lead to supratherapeutic blood concentrations and could thus enhance the risk of major bleeding. The present results therefore question DOAC dose adaptation in the presence of these covariates, such as drug–drug interaction or genotypes, alongside the known existing covariates. As the overall effect of accumulation of several covariates could be difficult to apprehend for the clinicians, PopPK modeling could represent an interesting approach for informed precision dosing and to improve personalized prescription of DOACs.

Edoxaban versus Warfarin in high-risk patients with atrial fibrillation: A comprehensive analysis of high-risk subgroups

BACKGROUND

To compare the efficacy and safety of edoxaban vs warfarin in high-risk subgroups.

METHODS

ENGAGE AF-TIMI 48 was a multicenter randomized, double-blind, controlled trial in 21,105 patients with atrial fibrillation (AF) within 12 months and CHADS₂ score >2 randomized to higher-dose edoxaban regimen (HDER) 60 mg/reduced 30 mg, lower-dose edoxaban regimen (LDER) 30 mg/reduced 15 mg, or warfarin, and followed for 2.8 years (median). The primary outcome for this analysis was the net clinical outcome (NCO), a composite of stroke/systemic embolism events, major bleeding, or death. Multivariable risk-stratification analysis was used to categorize patients by the number of high-risk features.

RESULTS

The annualized NCO rates in the warfarin arm were highest in patients with malignancy (19.2%), increased fall risk (14.0%), and very-low body weight (13.5%). The NCO rates increased with the numbers of high-risk factors in the warfarin arm: 4.5%, 7.2%, 9.9% and 14.6% in patients with 0 to 1, 2, 3, and >4 risk factors, respectively (P_trend <0.001). Versus warfarin, HDER was associated with significant reductions of NCO in most of the subgroups: elderly, patients with moderate renal dysfunction, prior stroke/TIA, of Asian race, very-low body weight, concomitant single antiplatelet therapy, and VKA-naïve. With more high-risk features (0->4+), the absolute risk reductions favoring edoxaban over warfarin increased: 0.3%->2.0% for HDER; 0.4%->3.4% for LDER vs warfarin (P = .065 and P < .001, respectively).

CONCLUSIONS

While underuse of anticoagulation in high-risk patients with AF remains common, substitution of effective and safer alternatives to warfarin, such as edoxaban, represents an opportunity to improve clinical outcomes.

A Combined Pharmacometrics Analysis of Biomarker Distribution Under Treatment With Standard- or Low-Dose Rivaroxaban in Real-World Chinese Patients With Nonvalvular Atrial Fibrillation

Background: The rivaroxaban dose regimen for patients with nonvalvular atrial fibrillation (NVAF) is complex in Asia. Given the high interindividual variability and the risk of bleeding caused by rivaroxaban in Asians, the influencing factors and the relationship between outlier biomarkers and bleeding events need exploration.

Methods: The integrated pharmacokinetics (PK)/pharmacodynamics (PD) models were characterized based on rich PK/PD data from 304 healthy volunteers and sparse PD [anti-factor Xa activity (anti-Xa) and prothrombin (PT)] data from 223 patients with NVAF. The correlations between PD biomarkers and clinically relevant bleedings in 1 year were explored. The final integrated PK/PD model was used to evaluate the influence of dosage and individual covariates on PD parameters.

Results: A two-compartment, linear model with sequential zero-order and first-order absorption was adopted. The dose-specific relative bioavailability (F₁), diet status, creatinine clearance, and body mass index (BMI) improved the model fit. The apparent systemic clearance was 7.39 L/h, and the central and peripheral volumes were 10.9 and 50.9 L, respectively. The linear direct-effects model with shape factor plus the additive (and/or proportional) error model described the correlation between anti-Xa/PT and plasma concentration. Bodyweight, total cholesterol (TCHO), and diet status were selected as the covariates of the anti-Xa/PT model. Anti-Xa was more sensitive to the increase in rivaroxaban exposure compared with PT. An elevated bleeding tendency was seen with higher peak anti-Xa and PT. For a typical Chinese patient, the peak anti-Xa value (median (5%–95% PI)) of 20 and 15 mg were 309 ng/ml (139–597 ng/ml) and 296 ng/ml (138–604 ng/ml), both median values were within the expected range. For patients with CrCL 30–49 ml/min, the median peak anti-Xa with recommended 10 mg other than 15 mg were within the expected range.

Conclusion: Fixed doses of rivaroxaban could be prescribed for patients with NVAF without adjustment for bodyweight, BMI, and TCHO. Randomized studies should be performed to evaluate the efficacy and safety of low-dose rivaroxaban in Chinese patients with NVAF.

Evaluating pharmacokinetic drug-drug interactions of direct oral anticoagulants in patients with renal dysfunction

INTRODUCTION

Drug transporters, metabolic enzymes, and renal clearance play significant roles in the pharmacokinetics of direct oral anticoagulants (DOACs). Recommendations for DOAC drug-drug interactions (DDIs) by the product labeling are limited to selected CYP3A4 and P-glycoprotein inhibitors and lack considerations for concomitant renal dysfunction.

AREAS COVERED

This review focuses on: 1) current recommendations for the management of pharmacokinetic DOAC DDIs and the evidence used to support them; 2) alterations in DOAC exposure in the setting of concomitant DDIs and mild, moderate, and severe renal impairment; 3) clinical outcomes associated with this combination; and 4) expert recommendations for the management of pharmacokinetic DOAC DDIs. English-language, full-text articles on apixaban, dabigatran, rivaroxaban, and edoxaban with a publication date up to 30 September 2021 were retrieved from PubMed.

EXPERT OPINION

Given the lack of supporting clinical data, empiric dose adjustments based on pharmacokinetic data alone should be avoided. When a considerable increase in a DOAC exposure is anticipated, it may be advisable to use an alternative DOAC or anticoagulant from a different class. Future research on identification of DOAC therapeutic ranges and target patient populations is needed to inform clinical utility of DOAC level monitoring to guide the management of DDIs.

Andexanet Alfa for Specific Anticoagulation Reversal in Patients with Acute Bleeding during Treatment with Edoxaban

Background  Andexanet alfa (andexanet) is approved for specific anticoagulation reversal in patients with life-threatening or uncontrolled bleeding during treatment with rivaroxaban or apixaban. There is limited experience with andexanet in patients with acute bleeding on edoxaban.

Methods  Patients with acute major bleeding within 18 hours of edoxaban intake were prospectively enrolled. Patients received a bolus and 2-hour follow-on infusion of andexanet. The co-primary efficacy outcomes were change in antifactor Xa activity and the percentage of patients achieving excellent or good hemostasis, 12 hours after andexanet treatment. Efficacy was analyzed in patients with confirmed major bleeding and baseline antifactor Xa activity ≥40 ng/mL. Safety was analyzed in all patients.

Results  Thirty-six patients (mean age: 82 years, 61.1% male and 91.7% with atrial fibrillation) with acute major bleeding on edoxaban received andexanet. The primary site of bleeding was intracranial in 29 patients (80.6%). In the efficacy population ( n  = 28), median antifactor Xa activity decreased from 121.1 (interquartile range [IQR]: 70.3–202.4) ng/mL at baseline to 24.0 (IQR: 77.7–83.7) ng/mL at the end of andexanet bolus (median decrease: 68.9%, 95% confidence interval [CI]: 56.1–77.7%). Excellent or good hemostasis at 12 hours was achieved in 78.6% (95% CI: 59.0–91.7%) of patients. Within 30 days, four patients (11.1%) experienced a thrombotic event and four others (11.1%) died.

Conclusion  In patients with acute major bleeding on edoxaban, andexanet significantly decreased antifactor Xa activity. Hemostatic efficacy was similar to that observed in patients with bleeding on rivaroxaban or apixaban. Thrombotic events occurred at a rate expected in such patients.

Efficacy and safety of edoxaban tosylate hydrate 15 mg in the prevention of venous thromboembolism in patients with impaired renal function after orthopedic surgery of the lower extremities

Background

Although not indicated in the USA, edoxaban tosylate hydrate 15 mg is used for venous thromboembolism (VTE) prophylaxis after orthopedic surgery of the lower extremities in Japan. However, its efficacy and safety in patients with impaired renal function have not been fully evaluated. We aimed to investigate the intervention’s effectiveness in these patients.

Methods

From 2018 to 2020, patients who underwent total hip arthroplasty, total knee arthroplasty, hip fracture surgery, or knee arthroplasty single granule replacement and with renal dysfunction were evaluated. Safety was evaluated according to bleeding occurrence during edoxaban treatment and liver function endpoints. Patients were divided into the 15- and 30-mg oral groups, including 23 patients with impaired renal function and 209 with normal renal function, respectively.

Results

VTE incidence in the 15- and 30-mg groups was 8.7% and 8.6%, respectively; the intergroup difference was insignificant (odds ratio [OR] 0.99; 95% confidence interval [CI] 0.22–4.56; p = 1.00). Bleeding did not occur in the 15-mg group and was noted in 9 patients in the 30-mg group during treatment with edoxaban; the intergroup difference was insignificant (p = 1.00). The increase in aspartate aminotransferase and alanine aminotransferase levels was 30% in the 15-mg group and 19% in the 30-mg group, with no difference between the groups (p = 0.27). Multivariate analysis showed that the dose of edoxaban was not a significant factor associated with the incidence of VTE (adjusted OR 2.31; 95% CI 0.39–13.8; p = 0.36).

Conclusions

Edoxaban 15 mg in patients with impaired renal function may be as effective as edoxaban 30 mg in patients with normal renal function. However, the number of cases included in this study was small and the power was insufficient; therefore, a study with a larger sample size is desirable.

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.

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

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

Edoxaban versus warfarin in patients with atrial fibrillation in relation to the risk of stroke: A secondary analysis of the ENGAGE AF-TIMI 48 study

INTRODUCTION

The efficacy and safety of the oral factor Xa inhibitor edoxaban compared to warfarin stratified by CHA₂DS₂VASc scores have not been described.

METHODS

The ENGAGE AF-TIMI 48 trial randomized patients with atrial fibrillation to once-daily edoxaban or warfarin. We classified patients based on CHA₂DS₂VASc score and compared pharmacokinetics (edoxaban concentration), pharmacodynamics (anti-factor Xa [FXa] with edoxaban, time-in-therapeutic range for warfarin), efficacy (stroke or systemic embolism [SSE]), safety (major bleeding [MB], intracranial hemorrhage), and cardiovascular mortality, for the approved edoxaban regimen vs warfarin.

RESULTS

The distribution CHA₂DS₂VASc score were:≤3, N = 4159 (29.6%); 4, N = 4066 (28.9%); 5, N = 3165 (22.5%); and ≥6, N = 2681 (19.1%). Increasing rates of SSE (1.05 to 2.99%/year) and MB (2.27 to 4.66%/year) were observed in the warfarin arm as the CHA₂DS₂VASc score increased. The hazard ratios per unit increase of CHA₂DS₂VASc score were 1.29 (1.21-1.38) and 1.26 (1.17-1.36) for SSE, and 1.20 (1.13-1.27) and 1.19 (1.12-1.27) for MB, with warfarin and edoxaban, respectively. Time-in-therapeutic range in warfarin-treated patients was similar and high (median 68%-69%) across CHA₂DS₂VASc scores, whereas edoxaban trough concentration, exogenous anti-FXa activity and %inhibition of endogenous FXa were higher at increasing CHA₂DS₂VASc scores. Edoxaban reduced SSE, MB, intracranial hemorrhage, and cardiovascular mortality vs warfarin to a similar degree across the range of CHA₂DS₂VASc scores (P-int = 0.90, 0.96, 0.21, and 0.37, respectively). Because of higher event rates the number of events prevented with edoxaban tended to be greater in patients with higher CHA₂DS₂VASc scores.

CONCLUSION

The benefit and safety of edoxaban versus warfarin is maintained across CHA₂DS₂VASc scores. While the relative risk reductions remain similar, edoxaban provides incrementally larger absolute reductions in outcomes over warfarin in patients with higher CHA₂DS₂VASc scores.

Randomized, Double-Blind Comparison of Half-Dose Versus Full-Dose Edoxaban in 14,014 Patients With Atrial Fibrillation

BACKGROUND

In the ENGAGE AF-TIMI 48 (Effective Anticoagulation with Factor Xa Next Generation in Atrial Fibrillation-Thrombolysis In Myocardial Infarction 48) trial, the lower dose edoxaban regimen (LDER) and the higher dose edoxaban regimen (HDER) were noninferior to well-managed warfarin for stroke prevention in atrial fibrillation.

OBJECTIVES

The objective of the present analysis of the ENGAGE AF TIMI-48 trial was to comprehensively compare the net clinical outcome (NCO) of LDER (30 mg once daily, dose reduced to 15 mg in selective patients) versus HDER (60 mg once daily, dose reduced to 30 mg in selective patients).

METHODS

This study performed a pre-specified analysis of the ENGAGE AF-TIMI 48 trial, comparing patients on LDER versus HDER.

RESULTS

The pre-defined primary NCO (stroke/systemic embolism [SEE], major bleeding, death) was less frequent with LDER (7.26% vs. 8.01%; hazard ratio: 0.90; 95% confidence interval: 0.84 to 0.98; p = 0.014). The secondary (disabling stroke, life-threatening bleeding, or all-cause mortality) and tertiary pre-defined NCOs (stroke, SEE, life-threatening bleeding, or all-cause mortality) were similar between the 2 dosing regimens. Patients randomized to LDER versus HDER had a significantly higher risk of stroke/SEE (2.04% vs. 1.56%; hazard ratio: 1.31; 95% confidence interval: 1.12 to 1.52; p < 0.001). Conversely, major bleeding, intracranial hemorrhage, major gastrointestinal bleeding, and life-threatening bleeding occurred significantly less frequently with LDER compared with those of HDER. These findings were supported by multiple pharmacokinetic findings.

CONCLUSIONS

In the ENGAGE AF-TIMI 48 trial, the primary NCO was reduced with LDER versus HDER, whereas the secondary and tertiary NCOs were similar between the 2 dosing regimens. These results may aid physicians in evidence-based individualization of edoxaban dosing. However, the approved HDER remains the standard therapy among the available edoxaban dosing regimens for stroke prevention in atrial fibrillation. (Effective Anticoagulation with Factor Xa Next Generation in Atrial Fibrillation-Thrombolysis In Myocardial Infarction 48 [ENGAGE AF-TIMI 48]; NCT00781391).

Muscle Mass and Direct Oral Anticoagulant Activity in Older Adults With Atrial Fibrillation

BACKGROUND

Direct oral anticoagulants (DOAC) are hydrophilic drugs with plasma levels inversely proportional to lean body mass. Sarcopenic patients with low muscle mass may be at risk for supra-therapeutic DOAC levels and bleeding complications. We therefore sought to examine the influence of lean body mass on DOAC levels in older adults with atrial fibrillation (AF).

METHODS

A prospective cohort study was conducted with patients 65 years of age or more receiving rivaroxaban or apixaban for AF. Appendicular lean mass (ALM) was measured using a bioimpedance device and a dual X-ray absorptiometry scanner. DOAC levels were measured using a standardized anti-Xa assay 4 hours after (peak) and 1 hour before (trough) ingestion.

RESULTS

The cohort consisted of 62 patients (47% female, 77.0 ± 6.1 years). The prescribed DOACs were apixaban 2.5 mg (21%), apixaban 5 mg (53%), and rivaroxaban 20 mg (26%). Overall, 16% had supra-therapeutic DOAC levels at trough and 25% at peak. In the multivariable logistic regression model, lower ALM was independently associated with supra-therapeutic DOAC levels at trough (odds ratio per ↓ 1-kg 1.23, 95% confidence interval 1.02 to 1.49) and peak (odds ratio per ↓ 1-kg 1.18, 95% confidence interval 1.02 to 1.37). Addition of ALM to a model consisting of age, total body weight, and renal function resulted in improved discrimination for supra-therapeutic DOAC levels.

CONCLUSION

Our proof-of-concept study has identified an association between ALM and DOAC levels in older adults with AF. Further research is needed to determine the impact of ALM on bleeding complications and the potential role of ALM-guided dosing for sarcopenic patients.

Safety and efficacy of dronedarone from clinical trials to real-world evidence: implications for its use in atrial fibrillation

Efficacy and safety of dronedarone was shown in the ATHENA trial for paroxysmal or persistent atrial fibrillation (AF) patients. Further trials revealed safety concerns in patients with heart failure and permanent AF. This review summarizes insights from recent real-world studies and meta-analyses, including reports on efficacy, with focus on liver safety, mortality risk in patients with paroxysmal/persistent AF, and interactions of dronedarone with direct oral anticoagulants. Reports of rapidly progressing liver failure in dronedarone-prescribed patients in 2011 led to regulatory cautions about potential liver toxicity. Recent real-world evidence suggests dronedarone liver safety profile is similar to other antiarrhythmics and liver toxicity could be equally common with many Class III antiarrhythmics. Dronedarone safety concerns (increased mortality in patients with permanent AF) were raised based on randomized controlled trials (RCT) (ANDROMEDA and PALLAS), but comedication with digoxin may have increased the mortality rates in PALLAS, considering the dronedarone-digoxin pharmacokinetic (PK) interaction. Real-world data on apixaban-dronedarone interactions and edoxaban RCT observations suggest no significant safety risks for these drug combinations. Median trough plasma concentrations of dabigatran 110 mg during concomitant use with dronedarone are at acceptable levels, while PK data on the rivaroxaban-dronedarone interaction are unavailable. In RCTs and real-world studies, dronedarone significantly reduces AF burden and cardiovascular hospitalizations, and demonstrates a low risk for proarrhythmia in patients with paroxysmal or persistent AF. The concerns on liver safety must be balanced against the significant reduction in hospitalizations in patients with non-permanent AF and low risk for proarrhythmias following dronedarone treatment.

Non-Vitamin K Antagonist Oral Anticoagulants and Factors Influencing the Ischemic and Bleeding Risk in Elderly Patients With Atrial Fibrillation: A Review of Current Evidence

ABSTRACT

Non-vitamin K antagonist oral anticoagulants (NOACs) are a widely prescribed treatment to prevent stroke in patients with nonvalvular atrial fibrillation, and a therapy and preventative measure to prevent recurrences following venous thromboembolism. Optimal use of NOACs requires a thorough knowledge of the pharmacology of these drugs, as well as an understanding of patient factors affecting their use. The 4 NOACs-dabigatran, apixaban, edoxaban, and rivaroxaban are available in a range of doses suitable for differing indications and with a variety of dose reduction criteria. Identification of the correct dose is one of the key challenges in the individualization of treatment. Elderly patients with atrial fibrillation are at a greater risk of both ischemic and bleeding events than younger patients. Consequently, it is essential to achieve balance in anticoagulation strategies. Medication adherence to NOACs is important for safe and effective treatment, particularly in elderly populations. A growing body of evidence shows that once-daily dosing improves adherence and persistence to therapy, without having an impact on bleeding risk.

The 2018 European Heart Rhythm Association Practical Guide on the use of non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation

The current manuscript is the second update of the original Practical Guide, published in 2013 [Heidbuchel et al. European Heart Rhythm Association Practical Guide on the use of new oral anticoagulants in patients with non-valvular atrial fibrillation. Europace 2013;15:625-651; Heidbuchel et al. Updated European Heart Rhythm Association Practical Guide on the use of non-vitamin K antagonist anticoagulants in patients with non-valvular atrial fibrillation. Europace 2015;17:1467-1507]. Non-vitamin K antagonist oral anticoagulants (NOACs) are an alternative for vitamin K antagonists (VKAs) to prevent stroke in patients with atrial fibrillation (AF) and have emerged as the preferred choice, particularly in patients newly started on anticoagulation. Both physicians and patients are becoming more accustomed to the use of these drugs in clinical practice. However, many unresolved questions on how to optimally use these agents in specific clinical situations remain. The European Heart Rhythm Association (EHRA) set out to coordinate a unified way of informing physicians on the use of the different NOACs. A writing group identified 20 topics of concrete clinical scenarios for which practical answers were formulated, based on available evidence. The 20 topics are as follows i.e., (1) Eligibility for NOACs; (2) Practical start-up and follow-up scheme for patients on NOACs; (3) Ensuring adherence to prescribed oral anticoagulant intake; (4) Switching between anticoagulant regimens; (5) Pharmacokinetics and drug-drug interactions of NOACs; (6) NOACs in patients with chronic kidney or advanced liver disease; (7) How to measure the anticoagulant effect of NOACs; (8) NOAC plasma level measurement: rare indications, precautions, and potential pitfalls; (9) How to deal with dosing errors; (10) What to do if there is a (suspected) overdose without bleeding, or a clotting test is indicating a potential risk of bleeding; (11) Management of bleeding under NOAC therapy; (12) Patients undergoing a planned invasive procedure, surgery or ablation; (13) Patients requiring an urgent surgical intervention; (14) Patients with AF and coronary artery disease; (15) Avoiding confusion with NOAC dosing across indications; (16) Cardioversion in a NOAC-treated patient; (17) AF patients presenting with acute stroke while on NOACs; (18) NOACs in special situations; (19) Anticoagulation in AF patients with a malignancy; and (20) Optimizing dose adjustments of VKA. Additional information and downloads of the text and anticoagulation cards in different languages can be found on an EHRA website (www.NOACforAF.eu).

Management of Hemorrhage Related to Direct Action Oral Anticoagulant Medication

Introduction: Direct Oral Anticoagulant – DOACs) are a new class of anticoagulant that directly inhibit the trombine (dabigatran) or Xa factor (rivaroxabane , edoxabane and apixabane) in the coagulation cascade. These medications are being more frequently used for the treatment and prevention of thrombolytic events, mainly in patients with atrial fibrillation, in substitute to varfrine or other vitamin K antagonists (VKAs). Although the incidence of hemorrhage is higher in AVKs than in DOACs, these events may also occur in this group, even in the form of intracranial hemorrhage (ICH), with risk of death. Nowadays, DOACs indications have progressively enhanced and the availability of their specific reverse agents certainly will enhance the safety of their usage. Idarucizumab, reverse agent of dabigatrane, and alpha andexanet, reverse agent of Xa factor, have been approved by the Food and Drug Administration in the United States and ciraparantag may be approved in a near future. Objective: To review the literature on the manage of hemorrhage related to the use of DOACs. Methods: Review of literature that used articles from 1998 to 2017, from several platforms and journals. Conclusion: DOACs constitute a great advance in prophylaxis and treatment of thrombolytic diseases, which presents elevated morbidymortality, and hemorrhages are the main adverse events related to their usage, being rarely necessary the immediate reverse of the anticoagulation. However, the existence of DOACs specific reverse agents enhance the safety of patients, whose anticoagulation may be rapidly reversed if necessary.

Manejo das Hemorragias Relacionadas aos Anticoagulantes Orais de Ação Direta

Introdução: Os anticoagulantes orais diretos (direct oral anticoagulant – DOACs) são uma nova classe de anticoagulantes que inibem diretamente a trombina (dabigatrana) ou o fator Xa (rivaroxabana, edoxabana e apixabana) na cascata da coagulação. Esses estão sendo cada vez mais utilizados para tratamento e prevenção de eventos tromboembólicos, principalmente em pacientes com fibrilação atrial, em substituição à varfarina ou outros antagonistas de vitamina K (AVKs). Embora a incidência de hemorragias seja maior nos AVKs do que nos DOACs, elas também podem ocorrer nesse grupo, até mesmo na forma de hemorragia intracraniana (HIC) com risco de morte. Atualmente as indicações dos DOACs vêm aumentando progressivamente, e a disponibilização de seus agentes reversores específicos certamente aumentará a segurança e, consequentemente, sua utilização. O idarucizumab, reversor da dabigatrana, e o andexanet alfa, reversor dos inibidores do fator Xa, foram aprovados pelo Food and Drug Administration (FDA) dos Estados Unidos e o ciraparantag poderá ser aprovado em um futuro próximo. Objetivo: Revisar a literatura sobre o manejo da hemorragia relacionada ao uso dos DOACs. Métodos: Revisão da literatura que utilizou artigos de 1998 a 2017, de diversas plataformas e revistas. Conclusão: Os DOACs constituem um grande avanço na profilaxia e tratamento da doença tromboembólica, que cursa com elevada morbimortalidade, e as hemorragias são os principais eventos adversos relacionados ao seu uso, sendo raramente necessária a reversão imediata da anticoagulação. No entanto, a existência dos reversores específicos dos DOAcs aumenta a segurança dos pacientes, que poderão ter sua anticoagulação revertida rapidamente, se necessário.

Non-Vitamin K Antagonist Oral Anticoagulants in Asian Patients With Supranormal Renal Function

Background and Purpose- In clinical trials, the reduced efficacy of non-vitamin K antagonist oral anticoagulants (NOACs) for stroke prevention was reported for patients with nonvalvular atrial fibrillation with a creatinine clearance (CrCl) >95 mL/min compared with that of warfarin. We examined the effectiveness, safety, and net clinical benefit of NOACs compared with warfarin in Asian patients with atrial fibrillation and supranormal renal function. Methods- Using data from the Korean National Health Insurance Service database from January 2014 to December 2016, we included patients with nonvalvular atrial fibrillation with CrCl >80 mL/min. Among these incident oral anticoagulant users with rivaroxaban (n=6297), dabigatran (n=4241), apixaban (n=3395), edoxaban (n=1187), and warfarin (n=9884) were analyzed. Propensity score weighting was used to balance covariates across study groups. Hazard ratios for ischemic stroke, intracranial hemorrhage, gastrointestinal bleeding, major bleeding, all-cause death, and the composite outcome defined as ischemic stroke+intracranial hemorrhage+gastrointestinal bleeding+all-cause death were analyzed using Cox regression analysis with warfarin as the reference. Results- Baseline characteristics were well balanced among all groups (mean age, 66±11 years; 63% were men; mean CHA₂DS₂-VASc score, 3.0±1.8). Forty-five percent of the patients had CrCl >95 mL/min. Pooled NOACs yielded lower risks of ischemic stroke (hazard ratio, 0.51; 95% CI, 0.43-0.60) and the composite outcome (hazard ratio, 0.64; 95% CI, 0.58-0.70) than warfarin in patients with CrCl >80 mL/min. These benefits were consistent in those with CrCl >95 mL/min. All 4 NOACs reduced the risks of ischemic stroke and the composite outcome in both patients with CrCl >80 mL/min and >95 mL/min. Conclusions- The NOACs showed better effectiveness and safety than warfarin in the patients with atrial fibrillation and supranormal renal function; this was consistently observed for all 4 NOACs and in patients with CrCl >95 mL/min.

Influence of Renal Function on the Pharmacokinetics, Pharmacodynamics, Efficacy, and Safety of Non-Vitamin K Antagonist Oral Anticoagulants

With the growing integration of non-vitamin K antagonist oral anticoagulants (NOACs) into clinical practice, questions have arisen regarding their use in special populations, including groups that may have been underrepresented in clinical trials. Patients with renal impairment, particularly in the lower echelons of renal function, are one such group. In an effort to elucidate the current evidence regarding the use of NOACs in patients with renal impairment, a systematic assessment of the literature was performed. The MEDLINE database was interrogated for studies and analyses evaluating the influence of renal function on the pharmacokinetics, pharmacodynamics, efficacy, and safety of NOACs published from January 1, 2000, through August 2, 2017. The 82 relevant publications retrieved highlight the diversity in the NOAC class regarding the impact of renal function on drug clearance, drug exposures, and clinical trial outcomes. In several large clinical trials, subgroup analyses revealed no significant differences when patients were stratified by creatinine clearance as a measure of renal function. Efficacy findings, in particular, were largely aligned with the overall population in the included studies. However, relative risks of bleeding were shown to vary, sometimes driven by changes in bleeding event rates in the comparator arm (eg, warfarin, enoxaparin). With few exceptions, minimal influence of mild renal impairment was observed on the relative efficacy and safety of NOACs. Taken together, the evidence suggests that the presence of renal impairment merits careful consideration of anticoagulant choice but should not deter physicians from appropriate use of NOACs.

Non-Vitamin K Antagonist Oral Anticoagulants in Patients With Atrial Fibrillation and End-Stage Renal Disease

Over the past decade, there have been tremendous advancements in anticoagulation therapies for stroke prevention in patients with atrial fibrillation (AF). Although the non-vitamin K antagonist oral anticoagulants (NOACs) demonstrated favorable clinical outcomes compared with warfarin overall, the decision to anticoagulate and the choice of appropriate agent in patients with AF and concomitant chronic kidney disease (CKD) or end-stage renal disease (ESRD) are a particularly complex issue. CKD and ESRD increase both the risk of stroke and bleeding, and since all of the NOACs undergo various levels of renal clearance, renal dysfunction inevitably affects the pharmacokinetics of the drug in each patient. Furthermore, the randomized controlled clinical trials of each NOAC versus warfarin often did not include patients with advanced CKD or ESRD. In this focused review, we describe the available evidence supporting the use of NOACs for prevention of stroke in patients with AF with concomitant advanced CKD or ESRD. Although questions of safety and appropriate use of these new agents in CKD and ESRD remain, NOACs offer a significant step forward in the anticoagulation management of at-risk patients with AF.

Update on Direct Oral AntiCoagulants (DOACs)

Recent findings require an update of previous recommendations for the perioperative use of Direct Oral AntiCoagulants (DOACs). A break in preoperative treatment of 24-96 hours is recommended based on the pharmacokinetic profiles of DOACs and depends on individual patient characteristics, their renal and possibly liver function, and their surgery-related risk of bleeding. In cases of renal or hepatic insufficiency, whether to extend the preoperative interruption of IIa- and Xa-inhibitors is a clinical decision that must be reached on an individual patient basis. In cases of epidural or spinal anaesthesia, more conservative pausing-intervals are recommended due to the risk of persistent neurologic deficits (e.g., paraplegia) following the development of spinal subdural and epidural haematomas. Elective surgery should be postponed according to these recommendations. Preoperative "bridging" with LMWH (more precisely referred to as "switching") should be omitted due to a significantly increased risk of bleeding. In addition, the incidence of perioperative thromboembolic risks, such as DVT, PE, and stroke, are no different whether interruption or "switching" is undertaken. Postoperatively, the DOACs can be reinstituted within the first 24 hours. In cases of major surgery or if there is a higher risk of bleeding, resumption of DOACS should only begin after 24-72 hours. In patients with an elevated thromboembolic risk, transient postoperative LMWH administration can be recommended during this period.Interaction of DOACs with other drugs usually occurs during the absorption, transport and elimination of these drugs. Therefore, substance- specific restrictions and recommendations should be observed during these times. In everyday clinical practice, webbased, independent information portals on drug-interactions are very helpful in providing safe and rapid information about potential interactions when DOACs are used in combination with other drugs, especially during perioperative management.Non-adherence to medications is a worldwide problem that has dangerous and costly consequences. Present data suggest that persistence is the primary factor that supports adherence. Despite the adherence data presented in the DOACS approval studies (e.g., persistence in the treatment of acute venous thromboembolism has been reported to be between 94-99%), the first registries and meta-analyses provide sobering results regarding the incidence of persistence and the success rate of interventions designed to improve adherence with DOACs in cases of long-term usage.

Pharmacokinetics, safety, and tolerability of edoxaban in end-stage renal disease subjects undergoing haemodialysis

Edoxaban is an oral, direct, once-daily, factor Xa inhibitor developed for stroke prevention in patients with atrial fibrillation and for the treatment and secondary prevention of recurrent thromboembolism in patients with acute symptomatic venous thromboembolism. Among elderly patients who require anticoagulation therapies, some may have end-stage renal disease (ESRD). This open-label, phase 1, randomised, two-way crossover study was conducted to evaluate the pharmacokinetics of edoxaban in 10 subjects on haemodialysis. Eligible subjects with ESRD on chronic haemodialysis received a single, oraldose of edoxaban 15 mg 2 hours (h) prior to (on-dialysis) or in between (off-dialysis) haemodialysis sessions. Haemodialysis resulted in a minor decrease in mean total exposure (AUC0-∞; 676.2 ng⋅h/ml) as compared with that observed in subjects off-dialysis (691.7 ng⋅h/ml). Mean maximum observed plasma concentration (Cmax) values were comparable between on-dialysis and off-dialysis treatments (53.3 vs 56.3 ng/ml, respectively). Mean apparent total body clearance (CL/F) values were 24.1 and 22.5 l/h during the on-dialysis and off-dialysis treatment periods, respectively. Dialyser clearance was 5.7 l/h and haemodialysis clearance was 6.1 l/h. Haemodialysis clearance was only 6.1 l/h, suggesting that it only accounts for one-fourth of the total clearance in these subjects. A single, oral dose of 15 mg of edoxaban was well tolerated by subjects with ESRD. In conclusion, based on these single-dose PK data, a supplementary dose of edoxaban may not be required following a haemodialysis session. Importantly, haemodialysis is not an effective mechanism for removal of edoxaban from the blood.

Incorporating edoxaban into the choice of anticoagulants for atrial fibrillation

The non-vitamin K antagonist oral anticoagulants (NOACs) are replacing warfarin for stroke prevention in many patients with nonvalvular atrial fibrillation. Edoxaban, an oral factor Xa inhibitor, is the newest entrant in this class. Results of the Effective Anticoagulation with Factor Xa Next Generation in Atrial Fibrillation (ENGAGE AF) study demonstrate that edoxaban is noninferior to warfarin for prevention of stroke and systemic embolic events, and is associated with significantly less major bleeding, including intracranial bleeding, and reduced cardiovascular mortality. With a net clinical benefit over warfarin, edoxaban is well positioned as a choice among the NOACs, which include dabigatran, rivaroxaban, and apixaban. But how will clinicians choose amongst them? The purpose of this paper is to (a) place the ENGAGE AF trial results into context with results of the studies with the other NOACs, and (b) aid clinicians in selection of the right anticoagulant for the right atrial fibrillation patient.

Dose reduction of edoxaban preserves efficacy and safety for the treatment of venous thromboembolism

Direct oral anticoagulants simplify venous thromboembolism (VTE) treatment by obviating the need for coagulation monitoring. Nonetheless, renal function, body weight and P-glycoprotein inhibitors influence drug levels. The objective of this analysis was to determine whether reduction in edoxaban dose based on clinical criteria avoids excess drug exposure and preserves efficacy and safety in the Hokusai-VTE study. After initial heparin, patients received edoxaban or warfarin for 3-12 months. Edoxaban was given once daily at a dose of 60 mg, which was reduced to 30 mg in patients with a creatinine clearance of 30–50 ml/minute, body weight ≤60 kg or receiving certain P-glycoprotein inhibitors. The primary efficacy outcome was recurrent VTE and the principal safety outcome was major or clinically relevant non-major bleeding. A total of 8292 patients with acute VTE were randomised, 733 and 719 patients in the edoxaban and warfarin groups met the criteria for dose reduction. These patients were older, more often female or Asian and had more extensive VTE. Edoxaban levels were lower in the 30 mg edoxaban group. Rates of recurrent VTE and bleeding with the 30 mg and 60 mg edoxaban dose were comparable: VTE rates were 3.0 % and 3.2 % and clinically relevant bleeding rates were 7.9 % and 8.6 %, respectively. Rates of recurrent VTE and bleeding in the warfarin-treated patients meeting the criteria for dose reduction were 4.2 % and 12.8 %, respectively. The reduced dose edoxaban regimen maintained efficacy and safety compared with the 60 mg dose but was safer than warfarin in patients meeting the criteria for dose reduction.

Supplementary Material to this article is available online at www.thrombosis-online.com.

Direct oral anticoagulants versus warfarin for preventing stroke and systemic embolic events among atrial fibrillation patients with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is an independent risk factor for atrial fibrillation (AF), which is more prevalent among CKD patients than the general population. AF causes stroke or systemic embolism, leading to increased mortality. The conventional antithrombotic prophylaxis agent warfarin is often prescribed for the prevention of stroke, but risk of bleeding necessitates regular therapeutic monitoring. Recently developed direct oral anticoagulants (DOAC) are expected to be useful as alternatives to warfarin.

OBJECTIVES

To assess the efficacy and safety of DOAC including apixaban, dabigatran, edoxaban, and rivaroxaban versus warfarin among AF patients with CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register (up to 1 August 2017) through contact with the Information Specialist using search terms relevant to this review. Studies in the Specialised Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) which directly compared the efficacy and safety of direct oral anticoagulants (direct thrombin inhibitors or factor Xa inhibitors) with dose-adjusted warfarin for preventing stroke and systemic embolic events in non-valvular AF patients with CKD, defined as creatinine clearance (CrCl) or eGFR between 15 and 60 mL/min (CKD stage G3 and G4).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed quality, and extracted data. We calculated the risk ratio (RR) and 95% confidence intervals (95% CI) for the association between anticoagulant therapy and all strokes and systemic embolic events as the primary efficacy outcome and major bleeding events as the primary safety outcome. Confidence in the evidence was assessing using GRADE.

MAIN RESULTS

Our review included 12,545 AF participants with CKD from five studies. All participants were randomised to either DOAC (apixaban, dabigatran, edoxaban, and rivaroxaban) or dose-adjusted warfarin. Four studies used a central, interactive, automated response system for allocation concealment while the other did not specify concealment methods. Four studies were blinded while the other was partially open-label. However, given that all studies involved blinded evaluation of outcome events, we considered the risk of bias to be low. We were unable to create funnel plots due to the small number of studies, thwarting assessment of publication bias. Study duration ranged from 1.8 to 2.8 years. The large majority of participants included in this study were CKD stage G3 (12,155), and a small number were stage G4 (390). Of 12,545 participants from five studies, a total of 321 cases (2.56%) of the primary efficacy outcome occurred per year. Further, of 12,521 participants from five studies, a total of 617 cases (4.93%) of the primary safety outcome occurred per year. DOAC appeared to probably reduce the incidence of stroke and systemic embolism events (5 studies, 12,545 participants: RR 0.81, 95% CI 0.65 to 1.00; moderate certainty evidence) and to slightly reduce the incidence of major bleeding events (5 studies, 12,521 participants: RR 0.79, 95% CI 0.59 to 1.04; low certainty evidence) in comparison with warfarin.

AUTHORS' CONCLUSIONS

Our findings indicate that DOAC are as likely as warfarin to prevent all strokes and systemic embolic events without increasing risk of major bleeding events among AF patients with kidney impairment. These findings should encourage physicians to prescribe DOAC in AF patients with CKD without fear of bleeding. The major limitation is that the results of this study chiefly reflect CKD stage G3. Application of the results to CKD stage G4 patients requires additional investigation. Furthermore, we could not assess CKD stage G5 patients. Future reviews should assess participants at more advanced CKD stages. Additionally, we could not conduct detailed analyses of subgroups and sensitivity analyses due to lack of data.

Population Pharmacokinetics of Edoxaban in Patients with Non-Valvular Atrial Fibrillation in the ENGAGE AF-TIMI 48 Study, a Phase III Clinical Trial

INTRODUCTION

Edoxaban is a novel factor Xa inhibitor. This study characterizes the population pharmacokinetics of edoxaban in patients with non-valvular atrial fibrillation (NVAF) included in the phase III ENGAGE AF-TIMI 48 study, evaluates covariates for the dose-exposure relationship in this population, and assesses the impact of protocol-specified dose reductions on exposure using simulations.

METHODS

Model development was performed using NONMEM(®) and based on sparse data from the ENGAGE AF-TIMI 48 study augmented with dense data from 13 phase I studies to inform and stabilize the model. The influence of body weight (WT), creatinine clearance (CLCR), concomitant P-glycoprotein (P-gp) inhibitors, age, sex, race, and NVAF on pharmacokinetic parameters was evaluated based on statistical significance and clinical relevance.

RESULTS

A two-compartment model with first-order elimination and first-order absorption after an absorption lag-time best described the data. Apparent volume and clearance terms increased with increasing WT. Apparent renal clearance increased with increasing CLCR. Apparent non-renal, renal, and inter-compartmental clearance terms differed between phase I volunteers and NVAF patients. Asian patients were found to have increased apparent central volume of distribution, bioavailability, and total apparent clearance. Concomitant P-gp inhibitors increased the bioavailability statistically significantly, but this did not reach clinical relevance.

CONCLUSION

Edoxaban disposition and the variability in this disposition, including influence of covariates, after oral administration were adequately characterized in patients with NVAF. The 50 % dose reduction in patients with low WT (≤60 kg), moderate renal impairment (CLCR ≤50 mL/min), or concomitant P-gp inhibitors led to 30 % lower exposure than in the other patients.

Dissociation between the pharmacokinetics and pharmacodynamics of once-daily rivaroxaban and twice-daily apixaban: a randomized crossover study

Essentials In this crossover study the anticoagulant effects of rivaroxaban and apixaban were compared. Healthy volunteers received rivaroxaban 20 mg once daily or apixaban 5 mg twice daily. Rivaroxaban was associated with more prolonged inhibition of thrombin generation than apixaban. Rivaroxaban induced a clear prolongation of prothrombin time and activated partial thromboplastin time.

SUMMARY

Background The anticoagulant actions of the oral direct activated factor Xa inhibitors, rivaroxaban and apixaban, have not previously been directly compared. Objectives To compare directly the steady-state pharmacokinetics and anticoagulant effects of rivaroxaban and apixaban at doses approved for stroke prevention in patients with non-valvular atrial fibrillation. Methods Twenty-four healthy Caucasian male volunteers were included in this open-label, two-period crossover, phase 1 study (EudraCT number: 2015-002612-32). Volunteers were randomized to receive rivaroxaban 20 mg once daily or apixaban 5 mg twice daily for 7 days, followed by a washout period of at least 7 days before they received the other treatment. Plasma concentrations and anticoagulant effects were measured at steady state and after drug discontinuation. Results Overall exposure was similar for both drugs: the geometric mean area under the plasma concentration-time curve for the 0-24-h interval was 1830 μg h L-1 for rivaroxaban and 1860 μg h L-1 for apixaban. Rivaroxaban was associated with greater inhibition of endogenous thrombin potential (geometric mean area under the curve relative to baseline during the 0-24-h interval: 15.5 h versus 17.5 h) and a more pronounced maximal prolongation relative to baseline of prothrombin time (PT) (1.66-fold versus 1.14-fold) and activated partial thromboplastin time (APTT) (1.43-fold versus 1.16-fold) at steady state than apixaban. Conclusions Despite similar exposure to both drugs, rivaroxaban 20 mg once daily was associated with greater and more sustained inhibition of thrombin generation than apixaban 5 mg twice daily. Sensitive PT and APTT assays can be used to estimate the anticoagulant effects of rivaroxaban.

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

Edoxaban, a once daily non-vitamin K antagonist oral anticoagulant, is a direct, selective, reversible inhibitor of factor Xa (FXa). In healthy subjects, single oral doses of edoxaban result in peak plasma concentrations within 1.0–2.0 h of administration, followed by a biphasic decline. Exposure is approximately dose proportional for once daily doses of 15–150 mg. Edoxaban is predominantly absorbed from the upper gastrointestinal tract, and oral bioavailability is approximately 62 %. Food does not affect total exposure to edoxaban. The terminal elimination half-life in healthy subjects ranges from 10 to 14 h, with minimal accumulation upon repeat once daily dosing up to doses of 120 mg. The steady-state volume of distribution is approximately 107 L, and total clearance is approximately 22 L/h; renal clearance accounts for approximately 50 % of total clearance, while metabolism and biliary secretion account for the remaining 50 %. Intrinsic factors, such as age, sex and race, do not affect edoxaban pharmacokinetics after renal function is taken into account. Oral administration of edoxaban results in rapid changes in anticoagulatory biomarkers, with peak effects on anticoagulation markers (such as anti-FXa), the prothrombin time and the activated partial thromboplastin time occurring within 1–2 h of dosing.

Once- versus twice-daily direct oral anticoagulants in non-valvular atrial fibrillation

INTRODUCTION

Direct oral anticoagulants (DOACs) have emerged as alternatives to vitamin K antagonists for the prevention of stroke in patients with non-valvular atrial fibrillation (NVAF). Four DOACs: dabigatran, rivaroxaban, apixaban and edoxaban, are currently available. In the absence of head-to-head clinical comparisons of DOACs, dosing regimen may influence drug choice. Areas covered: Edoxaban and rivaroxaban are administered once daily, dabigatran and apixaban twice daily. The selection of these dosage regimens is largely based on studies for the prevention or treatment of venous thromboembolism or acute coronary syndrome. Edoxaban is the only DOAC in which once and twice-daily regimens were compared in patients with NVAF; bleeding rates were higher in the twice-daily groups. Once-daily versus twice-daily regimens have a number of practical implications. Missing a once-daily dose would have a greater impact on anticoagulation. Some real world and retrospective studies found that a once-daily dosing regimen leads to better adherence and persistence to therapy, an important consideration for maintaining optimum anticoagulation. However, other studies have not found increased adherence among once daily regimens. Expert opinion: Prescription of DOACs should be tailored to the individual patient and dosing regimen is only one of the variables that should be taken into account.

Evolving Treatments for Arterial and Venous Thrombosis: Role of the Direct Oral Anticoagulants

The direct oral anticoagulants (DOACs) represent a major advance in oral anticoagulant therapy and have replaced the vitamin K antagonists as the preferred treatment for many indications. By simplifying long-term anticoagulant therapy and improving its safety, the DOACs have the potential to reduce the global burden of thrombosis. Postmarketing studies suggest that the favorable results achieved with DOACs in the randomized controlled trials can be readily translated into practice, but highlight the need for appropriate patient, drug and dose selection, and careful follow-up. Leveraging on their success to date, ongoing studies are assessing the utility of DOACs for the prevention of thrombosis in patients with embolic stroke of unknown source, heart failure, coronary artery disease, peripheral artery disease, antiphospholipid syndrome, and cancer. The purpose of this article is to (1) review the pharmacology of the DOACs, (2) describe the advantages of the DOACs over vitamin K antagonists, (3) summarize the experience with the DOACs in established indications, (4) highlight current challenges and limitations, (5) highlight potential new indications; and (6) identify future directions for anticoagulant therapy.

Population Pharmacokinetics of Edoxaban in Japanese Atrial Fibrillation Patients With Severe Renal Impairment

This is a population pharmacokinetic (PopPK) analysis to predict PK of edoxaban, a direct-acting oral anticoagulant, in nonvalvular atrial fibrillation (NVAF) patients with severe renal impairment (SRI; creatinine clearance [CL_cr ] <30 mL/min). Data from a phase 3 study recently conducted in Japanese NVAF patients (n = 90), including patients with SRI, were used to update the ENGAGE PopPK model that had been developed based on pooled data from the phase 3 ENGAGE AF-TIMI 48 study and 13 phase 1 PK studies, which included few patients with SRI. The final model indicated that the ENGAGE PopPK model was applicable to Japanese patients in that the model-simulated and study-observed concentration-time profiles were in agreement. Estimated model parameters after the addition of Japanese SRI data were consistent with those derived from the original ENGAGE PopPK data set. The model-predicted exposure in NVAF patients with SRI who received edoxaban at a 15-mg, once-daily dose was similar to that in patients with normal renal function or with mild renal impairment receiving a 30-mg dose. This suggests that efficacy and safety data from the ENGAGE AF study can be used to support dose setting for NVAF patients with SRI.

Direct oral anticoagulant considerations in solid organ transplantation: A review

For more than 60 years, warfarin was the only oral anticoagulation agent available for use in the United States. In many recent clinical trials, several direct oral anticoagulants (DOACs) demonstrated similar efficacy with an equal or superior safety profile, with some other notable benefits. The DOACs have lower inter- and intrapatient variability, much shorter half-lives, and less known drug-drug and drug-food interactions as compared to warfarin. Despite these demonstrated benefits, the use of DOACs has not gained uniform acceptance because of lack of supportive data in special patient populations, including recipients of solid organ transplants maintained on immunosuppression. This review describes the properties of several novel DOACs including their pharmacology and mechanisms of action as they relate to use among solid organ transplant recipients. We have particularly focused on (i) dosing in patients with impaired renal and hepatic function; (ii) considerations for drug-drug interactions with immunosuppressive medications; and (iii) management of the anticoagulated patients at the time of unplanned surgery. The risks and benefits of the use of DOACs in solid organ transplant recipients should be carefully evaluated prior to the introduction of these agents in this highly distinct patient population.

An integrated pharmacokinetic/pharmacogenomic analysis of ABCB1 and SLCO1B1 polymorphisms on edoxaban exposure

Edoxaban and its low-abundance, active metabolite M4 are substrates of P-glycoprotein (P-gp; MDR1) and organic anion transporter protein 1B1 (OATP1B1), respectively, and pharmacological inhibitors of P-gp and OATP1B1 can affect edoxaban and M4 pharmacokinetics (PK). In this integrated pharmacogenomic analysis, genotype and concentration-time data from 458 healthy volunteers in 14 completed phase 1 studies were pooled to examine the impact on edoxaban PK parameters of allelic variants of ABCB1 (rs1045642: C3435T) and SLCO1B1 (rs4149056: T521C), which encode for P-gp and OATP1B1. Although some pharmacologic inhibitors of P-gp and OATP1B1 increase edoxaban exposure, neither the ABCB1 C3435T nor the SLCO1B1 T521C polymorphism affected edoxaban PK. A slight elevation in M4 exposure was observed among SLCO1B1 C-allele carriers; however, this elevation is unlikely to be clinically significant as plasma M4 concentrations comprise <10% of total edoxaban levels.