The impact of body weight on rivaroxaban pharmacokinetics

Bioequivalence and Food Effect Assessment Between 2 Oral Tablet Formulations of Rivaroxaban 20 mg in Healthy Chinese Subjects

To evaluate the bioequivalence and safety of oral rivaroxaban tablets between a test formulation and a reference formulation in healthy Chinese subjects, a randomized, open, 2-formulation, 4-cycle, complete repeat crossover study was conducted under both fasting and fed states. Thirty-six healthy participants were enrolled separately for the fasting and fed groups, and each subject received a single oral dose of 20 mg of the test or reference formulation of rivaroxaban tablets per cycle. Blood samples were collected at specified intervals, and rivaroxaban was analyzed using liquid chromatography-tandem mass spectrometry. Under fasting and fed conditions, the 90% confidence intervals (CIs) for the geometric mean ratios of the maximum concentration (Cmax), the area under the plasma concentration-time curve from time 0 to the last measurable time point (AUC0-t), and the area under the curve extrapolated to infinity from time 0 (AUC0-∞) all fell within the 80%-125% CI, and the upper limit of the 90% CIs for the test-to-reference ratio of the within-subject variability was <2.5. This indicated that the test formulation of rivaroxaban is bioequivalent to the reference formulation. Compared to the fasted state, the Cmax, AUC0-t, and AUC0-∞ of rivaroxaban increased significantly by factors of 2, 1.6, and 1.5, respectively, following oral administration of 20 mg of rivaroxaban in the fed state. This suggests that a high-fat diet significantly enhances the exposure to rivaroxaban. No serious adverse events were reported under fasting or fed conditions.

Rivaroxaban for Thromboembolism Prophylaxis in Patients with Nephrotic Syndrome: A Single-Arm, Prospective Study

Introduction

Thromboembolism is a recognized complication of nephrotic syndrome (NS). Evidence supporting the use of rivaroxaban to prevent NS-related thrombosis is limited and controversial. This study aimed to explore the impact of NS on rivaroxaban pharmacokinetics and to collect observational data on the efficacy and safety of rivaroxaban as primary thromboprophylaxis in patients with NS.

Methods

This prospective study analyzed 141 patients with NS who received rivaroxaban (10 mg/day) for thromboprophylaxis. High-performance liquid chromatography-tandem mass spectrometry was used to measure the trough and peak plasma concentrations (Ctrough and Cmax) of rivaroxaban. The influence of clinical and genetic factors on these concentrations was examined using multivariate logistic regression.

Results

The median Cmax and Ctrough were 68.5 ng/mL (interquartile range [IQR], 31.7-105.5 ng/mL) and 4.4 ng/mL (IQR, 1.2-11.9 ng/mL), respectively. The incidence of thromboembolic events (TEs) was 12.8%, while that of bleeding events was 14.2%, although all were classified as minor. Albumin level was the most significant factor affecting Cmax (ρ = 0.55; p < 0.001) and was also significantly associated with TEs (0.81; 0.71-0.91 per 1.0 g/dL increase; p = 0.001) and bleeding risks (1.11; 1.03-1.19 per 1.0 g/dL increase; p = 0.008). Single nucleotide polymorphisms in the ABCB1 gene significantly influenced Ctrough but were not associated with clinical outcomes.

Conclusion

Hypoalbuminemia significantly affects the pharmacokinetics of rivaroxaban in NS patients. A dose-adjustment strategy based on rivaroxaban concentrations, accounting for variable albumin levels, may improve the safety and efficacy of thromboprophylaxis in this population.

Establishing a risk prediction model for residual pulmonary vascular obstruction after regular anticoagulant therapy for non-high-risk pulmonary embolism

Background

The incidence of pulmonary embolism (PE) has been on the rise annually. Despite receiving regular sequential anticoagulation therapy, some patients with non-high-risk acute PE (APE) continue to experience residual pulmonary vascular obstruction (RPVO). This study sought to identify the risk factors for RPVO following 3 months of sequential anticoagulation therapy for non-high-risk PE. Machine learning techniques were utilized to construct a clinical prediction model for predicting the occurrence of RPVO.

Methods

A total of 254 acute non-high-risk PE patients were included in this study, all of whom were admitted to the Third People's Hospital of Yunnan Province between 2020 and 2023. After 3 months of regular anticoagulant treatment, computed tomography pulmonary angiography (CTPA) were reviewed to identify the presence of RPVO. Patients were then categorized into either the thrombolysis group or the thrombosis residue group. Throughout the study period, 49 patients were excluded due to missing data, irregular treatment, or loss to follow-up. Clinical symptoms, physical signs, and laboratory results of 205 PE patients were recorded. Correlation and collinearity analyses were conducted on relevant risk factors, and significance tests were performed. Heat maps illustrating the relationships between influencing factors were generated. Predictors were selected using least absolute shrinkage and selection operator (LASSO) regression, followed by multivariate logistic regression analysis to create a predictive model. Internal validation of the model was also carried out.

Results

By searching the literature to understand all the clinical indicators that may affect the efficacy of anticoagulation therapy. A total of 205 patients with non-high-risk acute pulmonary thromboembolism were evaluated for various risk factors. Five independent factors were identified by multivariable analysis-age, chronic obstructive pulmonary disease (COPD), acratia, pulmonary systolic blood pressure (PASP), and major arterial embolism-and their P value, odds ratio (OR) and confidence interval (CI) were as follows: (P=0.012, OR =1.123; 95% CI: 1.026-1.23), (P=0.002, OR =13.30; 95% CI: 2.673-66.188), (P=0.001, OR =14.009; 95% CI: 2.782-70.547), (P=0.003, OR =1.061; 95% CI: 1.020-1.103) and (P<0.001, OR =18.128; 95% CI: 3.853-85.293), which may indicate a poor prognosis after standard anticoagulant therapy. A nomogram was constructed using these variables and internally validated. The receiver operating characteristic (ROC) curves of the model demonstrated strong predictive accuracy, with an area under the curve (AUC) of 0.94 (95% CI: 0.89-0.96) for the training set and 0.93 (95% CI: 0.88-0.95) for the validation set. Calibration curves were utilized to assess the practicality of the nomogram.

Conclusions

A novel predictive model was developed based on a single-center retrospective study to identify patients with RPVO following anticoagulant therapy for acute non-high-risk PE. This model may aid in the early detection of patients, prompt adjustment of treatment, and ultimately lead to a decrease in adverse outcomes.

Pharmacokinetics of single-dose rivaroxaban under fed state in obese vs. non-obese subjects: An open-label controlled clinical trial (RIVOBESE-PK)

The evidence of rivaroxaban's pharmacokinetics in obese compared with non-obese populations remains inconclusive. We aimed to compare the pharmacokinetic profile of rivaroxaban between obese and non-obese populations under fed state. Participants who met the study's eligibility criteria were assigned into one of two groups: obese (body mass index ≥35 kg/m2) or non-obese (body mass index 18.5-24.9 kg/m2). A single dose of rivaroxaban 20 mg was orally administered to each participant. Nine blood samples over 48 h, and multiple urine samples over 18 h were collected and analyzed for rivaroxaban concentration using ultra-performance liquid chromatography coupled with tandem mass detector. Pharmacokinetic parameters were determined using WinNonlin software. Thirty-six participants were recruited into the study. No significant changes were observed between obese and non-obese participants in peak plasma concentration, time to reach peak plasma concentration, area under the plasma concentration-time curve over 48 h or to infinity, elimination rate constant, half-life, apparent volume of distribution, apparent clearance, and fraction of drug excreted unchanged in urine over 18 h. Rivaroxaban's exposure was similar between the obese and non-obese subjects, and there were no significant differences in other pharmacokinetic parameters between the two groups. These results suggest that dose adjustment for rivaroxaban is probably unwarranted in the obese population.

Impact of Obesity on Atrial Fibrillation Pathogenesis and Treatment Options

Atrial fibrillation (AF) is the most common cardiac arrhythmia. AF increases the risk of stroke, heart failure, dementia, and hospitalization. Obesity significantly increases AF risk, both directly and indirectly, through related conditions, like hypertension, diabetes, and heart failure. Obesity-driven structural and electrical remodeling contribute to AF via several reported mechanisms, including adiposity, inflammation, fibrosis, oxidative stress, ion channel alterations, and autonomic dysfunction. In particular, expanding epicardial adipose tissue during obesity has been suggested as a key driver of AF via paracrine signaling and direct infiltration. Weight loss has been shown to reverse these changes and reduce AF risk and recurrence after ablation. However, studies on how obesity affects pharmacologic or interventional AF treatments are limited. In this review, we discuss mechanisms by which obesity mediates AF and treatment outcomes, aiming to provide insight into obesity-drug interactions and guide personalized treatment for this patient subgroup.

Direct Oral Anticoagulants in Special Patient Populations

Anticoagulants are a cornerstone of treatment in atrial fibrillation. Nowadays, direct oral anticoagulants (DOACs) are extensively used for this condition in developed countries. However, DOAC treatment may be inappropriate in certain patient populations, such as: patients with chronic kidney disease in whom DOAC concentrations may be dangerously elevated; frail elderly patients with an increased risk of falls; patients with significant drug-drug interactions (DDI) affecting either DOAC concentration or effect; patients at the extremes of body mass in whom an "abnormal" volume of distribution may result in inappropriate drug concentrations; patients with recurrent stroke reflecting an unusually high thromboembolic tendency; and, lastly, patients who experience major hemorrhage on an anticoagulant and in whom continued anticoagulation is deemed necessary. Herein we provide a fictional case-based approach to review the recommendations for the use of DOACs in these special patient populations.

Pharmacokinetics, Bioequivalence, and Safety Evaluation of 2 Formulations of 10-mg Rivaroxaban Tablets: A 4-Period Crossover Trial

This study compared the safety, bioequivalence, and pharmacokinetic properties of 2 formulations of 10-mg rivaroxaban tablets in healthy Chinese participants in fasting and fed arms. The trial was an open, randomized, 4-period, replicated crossover scheme, and 36 volunteers were recruited separately for the fasting and fed arms. Volunteers were randomly administered a single dose of the test or reference formulation (10 mg) orally, followed by a 5-day washout period. Rivaroxaban concentrations in the plasma were determined using liquid chromatography-tandem mass spectrometry, and pharmacokinetic parameters were obtained from the concentration-time profiles. The mean values of the test and the reference product for the area under the plasma concentration-time curve from time 0 to the last measurable concentration, area under the plasma concentration-time curve from time 0 to infinity, and maximum plasma concentration were 996 and 1014 ng • h/mL, 1024 and 1055 ng • h/mL, and 150 and 152 ng/mL in the fasting arm, respectively; the values were 1155 and 1167 ng • h/mL, 1160 and 1172 ng • h/mL, and 202 and 193 ng/mL in the fed arm, respectively. All the parameters were within acceptable limits in terms of bioequivalence. No serious adverse events were observed. This study demonstrated that the 2 rivaroxaban tablets were bioequivalent in healthy Chinese participants under fasting and fed conditions.

Direct oral anticoagulant drugs for the management of venous thromboembolism

ABSTRACT

Direct oral anticoagulants (DOACs) are effective for both prevention and treatment of venous thromboembolism (VTE) and have favorable safety in comparison with warfarin. Although drug-drug interactions with DOACs are not as frequent as with warfarin, certain drugs can interfere with DOAC metabolism, affect DOAC efficacy, and potentially cause adverse reactions when used in combination with DOACs. The NP must determine which agent is most beneficial for the individual patient with VTE based on a number of factors. A knowledge of periprocedural management of DOACs will assist the NP in providing a smooth transition for patients undergoing minor and major procedures and surgeries.

Transferability of Published Population Pharmacokinetic Models for Apixaban and Rivaroxaban to Subjects with Obesity Treated for Venous Thromboembolism: A Systematic Review and External Evaluations

Apixaban and rivaroxaban have first-line use for many patients needing anticoagulation for venous thromboembolism (VTE). The pharmacokinetics of these drugs in non-obese subjects have been extensively studied, and, while changes in pharmacokinetics have been documented in obese patients, data remain scarce for these anticoagulants. The aim of this study was to perform an external validation of published population pharmacokinetic (PPK) models of apixaban and rivaroxaban in a cohort of obese patients with VTE. A literature search was conducted in the PubMed/MEDLINE, Scopus, and Embase databases following the PRISMA statement. External validation was performed using MonolixSuite software, using prediction-based and simulation-based diagnostics. An external validation dataset from the university hospitals of Brest and Rennes, France, included 116 apixaban pharmacokinetic samples from 69 patients and 121 rivaroxaban samples from 81 patients. Five PPK models of apixaban and 16 models of rivaroxaban were included, according to the inclusion criteria of the study. Two of the apixaban PPK models presented acceptable performances, whereas no rivaroxaban PPK model did. This study identified two published models of apixaban applicable to apixaban in obese patients with VTE. However, none of the rivaroxaban models evaluated were applicable. Dedicated studies appear necessary to elucidate rivaroxaban pharmacokinetics in this population.

Is a Lower Dose of Rivaroxaban Required for Asians? A Systematic Review of a Population Pharmacokinetics and Pharmacodynamics Analysis of Rivaroxaban

Rivaroxaban has been widely used to prevent and treat various thromboembolic diseases for more than a decade. However, whether a lower dose of rivaroxaban is required for Asians is still debatable. This review aimed to explore the potential ethnic difference in pharmacokinetic/pharmacodynamic (PK/PD) characteristics between Asians and Caucasians. A systematic search was conducted and twenty-four studies were identified, of which 10 were conducted on Asian adults, 11 on predominantly Caucasian adults, and 3 on Caucasian pediatrics. The apparent clearance (CL/F) of rivaroxaban in Caucasian adults with non-valvular atrial fibrillation (6.45-7.64 L/h) was about 31-43% higher than that in Asians (4.46-5.98 L/h) taking 10~20 mg rivaroxaban every 24 h. Moreover, there was no obvious difference in CL/F among Japanese, Chinese, Thai, and Irani people. Regarding PK/PD relationship, prothrombin time was linked to rivaroxaban concentration in a linear or near-linear manner, and Factor Xa activity was linked with the E_max model. The exposure-response relationship was comparable between Asians and Caucasians. Renal function has a significant influence on CL/F, and no covariate was recognized for exposure-response relationship. In conclusion, a lower dose of rivaroxaban might be required for Asians, and further studies are warranted to verify this ethnic difference to facilitate optimal dosing regimens.

Pharmacokinetics and Dosing Regimens of Direct Oral Anticoagulants in Morbidly Obese Patients: An Updated Literature Review

Data on the impact of morbid obesity (body mass index [BMI] ≥ 40 kg/m²) on the pharmacokinetics (PK), pharmacodynamics (PD) of direct oral anticoagulants (DOACs) are relatively limited, making it difficult to design optimal dosing regimens in morbidly obese patients.To review literature on PK/PD profile, efficacy, and safety of DOACs in venous thromboembolism (VTE) and nonvalvular atrial fibrillation (AF) patients with morbid obesity and make recommendations regarding optimal dosing regimens in these patient populations.A detailed literature search was conducted (from inception to June 22, 2022) for relevant articles involving PK/PD and clinical data on DOACs use in morbidly obese patients with VTE or AF, or healthy volunteers.A total of 28 studies were identified. DOAC-specific PK variations and clinical outcomes have been observed. Obesity may have a modest effect on PK/PD of dabigatran, apixaban, or rivaroxaban. Dabigatran was effective in AF patients with morbid obesity but might increase the risk of gastrointestinal bleeding. Standard dosing of apixaban or rivaroxaban is effective and safe for VTE and AF patients with morbid obesity. Trough edoxaban concentration and anti-Xa activity were similar in different BMI groups (18.5 to >40 kg/m²), and standard dosing of edoxaban may be effective and safe for AF patients.Current evidence suggests dabigatran should be used with caution in patients with AF as it might increase the risk of gastrointestinal bleeding; Standard dosing of apixaban or rivaroxaban can be used in VTE or AF patients; Standard dosing of edoxaban may be considered in AF patients.

Management of venous thromboembolism in morbidly obese patients: a 10-year review

Obesity is a known risk factor for venous thromboembolism (VTE) and poses a unique set of challenges in anticoagulation management. We report a 10-year experience of VTE management in morbidly obese patients. We conducted a retrospective analysis of VTE presentations to Northern Health, Victoria, Australia, from January 2011 to December 2020, with median follow-up of 44 months. Morbidly obese patients (defined as weighing > 120 kg) were compared to those ≤ 120 kg. Patients with active malignancy were excluded. 194 VTE cases with weight > 120 kg were compared to 2168 cases weighing ≤ 120 kg. Patients > 120 kg were more likely to present with unprovoked VTE (59.3% vs. 45.2%, p < 0.001) and major VTE (74.7% vs. 67.4%, p = 0.028). Overall, patients > 120 kg were more likely to develop VTE recurrence after anticoagulation cessation (7.80 vs. 3.92 per 100-patient-years, HR 1.97, 95%CI 1.29-3.00), while there were no significant differences in major bleeding or 30-day all-cause mortality. There were no significant differences in outcomes in patients > 120 kg treated with warfarin compared to direct oral anticoagulants (DOAC), or when comparing those treated with an uncapped (1 mg/kg BD) vs. capped (< 1 mg/kg) enoxaparin dosing regimen. Morbid obesity is associated with increased clot burden at presentation and VTE recurrence following anticoagulation cessation, without significant differences in bleeding compared to those ≤ 120 kg. There were no significant differences in morbidly obese patients' outcomes when treated with warfarin or DOAC, or when treated with an uncapped or capped enoxaparin dosing strategy. Larger randomised controlled trials evaluating the safety of DOACs and different enoxaparin dosing strategies in patients > 120 kg are warranted.

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

BACKGROUND

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

AIMS

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

MATERIALS & METHODS

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

RESULTS

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

CONCLUSION

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

PROSPERO

CRD42020202636.

Population Pharmacokinetics and Dose Optimization Based on Renal Function of Rivaroxaban in Thai Patients with Non-Valvular Atrial Fibrillation

Low-dose rivaroxaban has been used in Asian patients with direct oral anticoagulants (DOACs) eligible for atrial fibrillation (AF). However, there are few pharmacokinetic (PK) data in Thai patients to support precise dosing. This study aimed to develop a population PK model and determine the optimal rivaroxaban doses in Thai patients. A total of 240 Anti-Xa levels of rivaroxaban from 60 Thai patients were analyzed. A population PK model was established using the nonlinear mixed-effect modeling approach. Monte Carlo simulations were used to predict drug exposures at a steady state for various dosages. Proportions of patients having rivaroxaban exposure within typical exposure ranges were determined. A one-compartment model with first-order absorption best described the data. Creatinine clearance (CrCl) and body weight significantly affected CL/F and V/F, respectively. Regardless of body weight, a higher proportion of patients with CrCl < 50 mL/min receiving the 10-mg once-daily dose had rivaroxaban exposures within the typical exposure ranges. In contrast, a higher proportion of patients with CrCl ≥ 50 mL/min receiving the 15-mg once-daily dose had rivaroxaban exposures within the typical exposure ranges. The study’s findings suggested that low-dose rivaroxaban would be better suited for Thai patients and suggested adjusting the medication’s dose in accordance with renal function.

Prescribing direct-acting oral anticoagulants - mind the evidence gap

Direct-acting oral anticoagulants (DOACs) are licensed for the prevention of thromboembolism in non-valvular atrial fibrillation amongst other indications. Prescribers use information derived from the summary of product characteristics which is based on the key trials supporting the DOAC's market authorisation. However, prescribers may not be aware of the limitations within these trials regarding underrepresentation of patient populations commonly encountered in clinical practice and how this may adversely impact them. This review highlights the gaps in the licensing evidence using 4 clinical vignettes that explore prescribing challenges in older adults, female patients, patients with obesity and patients from non-Europid ethnic backgrounds.

Rivaroxaban population pharmacokinetic and pharmacodynamic modeling in Iranian patients

WHAT IS KNOWN AND OBJECTIVE

Although predictable pharmacokinetic and pharmacodynamic of rivaroxaban allow fixed dosing regimens without routine coagulation monitoring, there is still the necessity to monitor and predict the effects of rivaroxaban in specific conditions and different populations. The current study was designed and conducted to analyze the rivaroxaban population pharmacokinetics in Iranian patients and establish a pharmacokinetic/pharmacodynamic model to predict the relationship between rivaroxaban concentration and its anticoagulant activity.

METHODS

A sequential nonlinear mixed effect pharmacokinetic/pharmacodynamic modeling method was used to establish the relation between rivaroxaban concentration and anti-factor Xa activity, prothrombin time, and activated partial thromboplastin time (aPTT) as pharmacodynamic biomarkers in a population of sixty-nine Iranian patients under treatment with oral rivaroxaban. Rivaroxaban plasma concentration was quantified by a validated high-performance liquid chromatography-tandem mass spectrometry.

RESULTS AND DISCUSSION

The typical population values (inter-individual variability%) of the oral volume of distribution and clearance for a one-compartment model were 61.2 L (21%) and 3.68 L·h^-1 (61%), respectively. Creatinine clearance and Child-Turcotte-Pugh score were found to affect the clearance. A direct link linear structural model best fitted the data for both prothrombin time and aPTT. The baseline estimates of aPTT and prothrombin time in the population were 35.0 (15%) and 12.6 (2%) seconds, respectively. The slope of the relationship between apTT, prothrombin time, and rivaroxaban concentration was 0.033 (28%) and 0.018 (54%) s·ml·ng^-1 , respectively. The selected model for anti-factor Xa activity consisted of a direct link inhibitory E_max model with Hill coefficient. The maximum level of inhibition (E_max ) was 4 IU·ml^-1 . The concentration of rivaroxaban producing 50% of the maximum inhibitory effect (EC₅₀ ) was 180 (24%) ng·ml^-1 , and Hill coefficient (γ) was 1.44 (108%). No covariates showed a statistically significant effect on PT and activated partial thromboplastin time prolonging properties and anti-factor Xa activity.

WHAT IS NEW AND CONCLUSION

Our results confirmed that pharmacokinetic/pharmacodynamic models similar to those of the other studies describe the relationship between the rivaroxaban concentration and its anticoagulant effect in Iranian patients. However, considerable differences were observed in the parameters of the pharmacodynamics-pharmacokinetic models with the results of other reports that can explain the unpredictable effects of rivaroxaban in some patients.

Management of Venous Thromboembolism in Morbid Obesity With Rivaroxaban or Warfarin

BACKGROUND

Rivaroxaban is a first-line option for the management of venous thromboembolism (VTE). However, limited data are available regarding its effectiveness in morbidly obese patients.

OBJECTIVE

To evaluate rates of thrombosis and bleeding in morbidly obese patients receiving rivaroxaban or warfarin for VTE.

METHODS

A multicenter, retrospective cohort study was conducted to compare rates of bleeding and thrombosis in patients receiving rivaroxaban versus warfarin for acute VTE. Patients were included if they were older than 18 years and had a body mass index (BMI) greater than 40 kg/m² or weight greater than 120 kg. The primary effectiveness outcome was hazard of VTE recurrence; the primary safety outcome was hazard of major bleeding. Patients were followed for up to 12 months.

RESULTS

A total of 1281 patients were identified for acute VTE and were included in this study with 487 patients receiving rivaroxaban and 785 receiving warfarin. The average cohort age was 57.6 ± 14.6 years, and the average weight was 136.4 ± 27.2 kg. After controlling for confounding factors, the use of rivaroxaban was not associated with an increased hazard of VTE events when compared with warfarin (hazard ratio [HR] = 0.69, 95% confidence interval [CI]: 0.42-1.08, P = 0.12) or major bleeding (HR = 1.29, 95% CI: 0.66-2.30, P = 0.52).

CONCLUSION AND RELEVANCE

No difference was observed in obese patients with weight >120 kg or BMI >40 kg/m² receiving rivaroxaban or warfarin for VTE treatment in hazard of VTE or major bleeding. Either agent may be considered an appropriate treatment option in this population.

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.

Inter- and intra-individual concentrations of direct oral anticoagulants: The KIDOAC study

BACKGROUND

Direct oral anticoagulants (DOACs) do not require concentration monitoring. However, whether DOAC concentrations are stable and their variation between and within patients is not well studied.

METHODS

Patients on vitamin K antagonists (VKA) who switched to rivaroxaban, apixaban, or dabigatran were included between 2018 and 2020. Blood was drawn at DOAC trough and peak concentrations at week 0, 2, and 8. Plasma drug concentrations were determined by anti-factor Xa concentrations (rivaroxaban, apixaban) or diluted thrombin time (dabigatran). Inter- and intra-individual variability was assessed by calculating the coefficient of variation (CV). Linear regression models were employed to evaluate associations between DOAC trough concentrations and previous VKA dosage, creatinine clearance, and body mass index (BMI).

RESULTS

One hundred fifty-two patients were included, of whom 96 (63%) were male and with a mean age of 73.9 ± 8.4 years. For the inter-individual variability, the CV ranged between 48% and 81% for trough values and between 25% and 69% for peak values among patients using the recommended DOAC dose. Intra-individual variability was substantially lower, as here the CV ranged between 18% and 33% for trough values and between 15% and 29% for peak values among patients using the recommended DOAC dose. Previous VKA dosage and creatinine clearance were inversely associated with DOAC trough concentrations. No association was found between BMI and DOAC trough concentrations.

CONCLUSION

Inter-individual variability of DOAC concentrations was higher than intra-individual variability. Lower previous VKA dosage and creatinine clearance were associated with higher DOAC trough concentrations. These findings support further study into an optimal target range, in which the risks of both bleeding and thrombosis are minimal.

Rivaroxaban Pharmacokinetics in Obese Subjects: A Systematic Review

INTRODUCTION

Venous thromboembolism (VTE) is a leading cause of morbidity and mortality globally. The direct oral anticoagulants, including rivaroxaban, are relatively novel therapeutic options in the treatment and prevention of VTE. There is a conflicting and inconclusive evidence surrounding the pharmacokinetics (PK) of rivaroxaban in patients with VTE who are obese.

OBJECTIVES

We conducted a systematic review to provide an overview, and to synthesize the available evidence in the current literature pertaining to rivaroxaban PK in obese subjects who are healthy or diseased.

METHODS

The PubMed, Embase, ScienceDirect, Rayyan, and Cochrane Library databases were systematically searched from 1 May 2021 through 28 February 2022. Studies investigating rivaroxaban PK in adult obese subjects were included in the review. Pertinent data, including anthropometric parameters, rivaroxaban dosage regimen, PK parameters, PK model, and outcome measures were extracted. Reference values of rivaroxaban PK parameters in the general population were used for comparison purposes. The review protocol was registered in the PROSPERO database (CRD42020177770).

RESULTS

In the 11 studies included in this systematic review, over 7140 healthy or diseased subjects received rivaroxaban therapy, with varying clinical indications in the diseased population. The reported PK parameters of rivaroxaban in obese subjects compared with reference values in the general population were variable. The reported values of the volume of distribution (V_d) among obese subjects (73.4-82.8 L) fell within the range of values reported/calculated for the general population (59.4-104 L), assuming complete bioavailability. However, some of the reported values of clearance (CL) in obese subjects (7.86-16.8 L.h^-1) do not fall within the range of values reported/calculated for the general population (5.57-11.3 L.h^-1). The reported maximum plasma concentrations in obese subjects versus the general population following a 10 mg dose were 149 vs. 143-180 µg.L^-1, and following a 20 mg dose were 214-305 vs. 299-360 µg.L^-1, respectively. The area under the plasma concentration versus time curves (AUC) over different intervals in obese subjects versus the general population following a 10 mg dose were 1155 (AUC from time zero to infinity [AUC_∞]) vs. 1029 (AUC_∞) µg.h.L^-1; and 1204-2800 (AUC from time zero to 24 h [AUC₂₄]) vs. 3200 (AUC₂₄) µg.h.L^-1, respectively, following a 20 mg dose. The reported values of half-life and time to reach the maximum plasma concentration in obese subjects versus the general population were not consistent across studies.

CONCLUSION

Variable changes and inconsistencies in different rivaroxaban PK parameters were reported in obese subjects. Further well-designed studies are warranted to better characterize the PK and clinical outcomes of rivaroxaban in subjects with obesity.

Apixaban and rivaroxaban use for atrial fibrillation in patients with obesity and BMI ≥50 kg/m2

BACKGROUND

Apixaban and rivaroxaban are increasingly used for thromboembolism prophylaxis in patients with non-valvular atrial fibrillation (NVAF) and commonly in patients with obesity and body mass index (BMI) ≥50 kg/m² despite the limited data.

OBJECTIVES

This study aimed to establish the effectiveness and safety of apixaban and rivaroxaban in patients with NVAF and BMI ≥50 kg/m² .

METHODS

A single health-system, retrospective cohort study evaluated the effectiveness and safety of apixaban and rivaroxaban initiated in adult patients (≥18 years of age) with BMI ≥50 kg/m² and NVAF. Outcomes of ischemic stroke, systemic embolic events, and bleeding were compared to a cohort of patients with BMI 18 to 30 kg/m² .

RESULTS

After 1619 patient-years worth of follow-up in 595 patients, the primary endpoint of incidence of ischemic stroke was numerically similar in both groups, 1.3 per 100 patient-years in the BMI ≥50 kg/m²  group, compared to 2.0 per 100 patient-years in the BMI <30 kg/m²  group (RR 0.65, 95% CI 0.38-1.82, p = 0.544). Incidence of major bleeding and clinically relevant non-major bleeding was also numerically similar between the two groups.

CONCLUSIONS

This study demonstrated that apixaban and rivaroxaban in patients with a BMI ≥50 kg/m² for treatment of NVAF may be safe and effective at preventing thromboembolic events and had no increased risk of bleeding. Although, findings should be interpreted with caution and confirmed with additional studies. This study contributes to the growing body of evidence that direct oral anticoagulants (DOACs) may be effective and safe to use for the treatment of NVAF in patients with BMI ≥50 kg/m² .

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.

Use of direct oral anticoagulants in patients with obesity for treatment and prevention of venous thromboembolism: Updated communication from the ISTH SSC Subcommittee on Control of Anticoagulation

Although direct-acting oral anticoagulants (DOACs) have widespread first-line use for treatment and prevention of venous thromboembolism (VTE), uncertainty remains regarding their efficacy and safety in patients with obesity. We reviewed available data for use of DOACs for VTE treatment and prevention in patients with obesity, including phase 3, phase 4, meta-analyses, and pharmacokinetic and pharmacodynamics studies. In addition, we reviewed available data regarding DOACs in bariatric surgery. We provide updated guidance recommendations on using DOACs in patients with obesity for treatment and prevention of VTE, as well as following bariatric surgery.

Comparative Effectiveness and Safety of Rivaroxaban and Warfarin Among Nonvalvular Atrial Fibrillation (NVAF) Patients with Obesity and Polypharmacy in the United States (US)

Introduction

Current evidence indicates that rivaroxaban may be a safe and effective alternative to warfarin among patients with nonvalvular atrial fibrillation (NVAF) and obesity. However, evidence regarding the impact of polypharmacy is limited in this population. The present study evaluated the effectiveness and safety of rivaroxaban versus warfarin among NVAF patients with obesity and polypharmacy in the US.

Methods

De-identified health insurance claims data from the IQVIA PharMetrics^® Plus data (01/2010–09/2019) were used to identify NVAF patients with obesity (BMI ≥ 30 kg/m²) and polypharmacy (≥ 5 medications) initiated on rivaroxaban or warfarin. Inverse probability of treatment weighting (IPTW) was used to adjust for imbalances between groups. Study outcomes were evaluated up to 36 months post-treatment initiation and included the composite of stroke or systemic embolism (stroke/SE) and major bleeding. Subgroup analyses were conducted stratified by polypharmacy category (5–9 or ≥ 10 medications). Outcomes were assessed using Cox proportional hazards regression models with hazard ratios (HR) and 95% confidence intervals (CIs).

Results

A total of 7000 and 3920 NVAF patients with obesity and polypharmacy were initiated on rivaroxaban and warfarin, respectively. At 36 months of follow-up, rivaroxaban was associated with a 29% lower risk of stroke/SE relative to warfarin (HR 0.71, 95% CI 0.57, 0.90). Major bleeding risk was not significantly different among rivaroxaban- compared to warfarin-treated patients (HR 0.85, 95% CI 0.70, 1.03). Subgroup analyses yielded results that were largely consistent with the overall polypharmacy analysis.

Conclusions

These results suggest that rivaroxaban is an effective and safe treatment option among NVAF patients with obesity and polypharmacy in a commercially-insured US population.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01746-2.

[Actual use of direct oral anticoagulants in venous thromboembolic disease]

Direct oral anticoagulants recently became the first-line choice for anticoagulation in venous thromboembolic disease. Many studies have shown its non-inferiority regarding the risk of thromboembolic recurrence compared to anti-vitamin K without increasing the risk of bleeding in the general population. However, specific populations such as patients with cancer, patients with kidney failure, patients with constitutional thrombophilia, elderly patients, or patients with extreme weight are at risk of intolerance to the use of direct oral anticoagulants. Precautions in use may be necessary as discussed in recently published guidelines about antiphospholipid syndrome. This review aims to list the main clinical trials investigating direct oral anticoagulants in venous thromboembolic disease in the general population and populations at risk, as well as to provide an update on current international and French guidelines.

The Pharmacology, Efficacy, and Safety of Rivaroxaban in Obese Patient Populations

Cardiovascular disease (CVD) remains the leading cause of death in the USA. Several risk factors have been identified, and obesity has become one of prominent concern. Excessive weight is considered a risk factor for CVD based on evidence linking it to a hypercoagulable state. Considering the prevalence of CVD and obesity in the USA, along with the increased risk for thrombus-related events, anticoagulation plays a significant role in prevention and treatment. Direct oral anticoagulants have taken the place of many traditional anticoagulants. Considering the recently approved indications and continued postmarketing studies conducted with rivaroxaban, this updated review provides data on the overall impact of obesity on this compound. This includes data obtained from both healthy obese volunteers and obese patients with various CVD conditions enrolled in rivaroxaban clinical trials, along with data obtained from postmarketing real-world evidence studies. Assessment of the clinical pharmacology and population pharmacokinetics in obese individuals revealed no clinically relevant effects of increased weight. Additionally, subgroup analyses from each of the pivotal phase III trials supporting the current approved labeling also demonstrated consistent efficacy and safety results in obese patients. Lastly, these findings are further supported by several recent real-world evidence studies assessing the continued effectiveness and safety of rivaroxaban. In conclusion, rivaroxaban's overall pharmacological and clinical profile remained consistent in obese adults when assessed in both drug development and postmarketing studies, supporting the premise that higher weight does not necessitate adjustment in either dose strength or regimen.

Risk factors for ecchymosis in patients receiving rivaroxaban for thromboprophylaxis after total knee arthroplasty: a retrospective cohort study

WHAT IS KNOWN AND OBJECTIVE

Ecchymosis of the limb is commonly seen after total knee arthroplasty (TKA) when using anticoagulants for thromboprophylaxis, but it is unknown which factors may predispose patients to an increased risk. The aim of this study was to evaluate risk factors for ecchymosis in patients receiving rivaroxaban after TKA.

METHODS

A retrospective, single-centre cohort analysis was conducted. The electronic medical records of patients admitted to the Department of Orthopedics during January 2018 to December 2019 and who received rivaroxaban 10 mg daily after TKA were reviewed for documentation of ecchymosis. Baseline demographics, laboratory values and surgical information were included for analysing their relationship with ecchymosis.

RESULTS AND DISCUSSION

A total of 227 patients were included in the study. Among them, 54 patients (23.8%) developed ecchymosis, and 173 did not. The ecchymosis group had a higher proportion of patients with a body weight >60 kg [83.33% vs. 50.00%, p = 0.0004] and hypertension [61.11% vs 41.46%, p = 0.0304]. The ecchymosis group also had a higher BMI [26.04 ± 2.71 kg/m² vs 24.52 ± 3.18 kg/m² , p = 0.0066] mean arterial pressure (MAP) recorded from post-operation day 1 to day 3 [105.21 mmHg vs 91.52 mmHg, p = 0.0003]. However, serum albumin concentrations before surgery [3.85 g/dL vs. 4.20 g/dL, p = 0.0225] and on post-operation day 3 [3.50 g/dL vs. 3.91 g/dL, p = 0.0370] were lower in the ecchymosis group. Serum haemoglobin on post-operation day 3 was also lower [10.07 g/dL vs. 11.57 g/dL, p = 0.0459]. Five risk factors for ecchymosis were identified by binary logistic regression: mean MAP (from POD1 to POD3) (OR=2.901, 95% CI: 2.522-3.293, p < 0.001), BMI (OR=2.513, 95% CI: 1.929-3.011, p < 0.001), history of hypertension (OR=2.661, 95% CI: 1.272-4.535, p = 0.032), post-surgery serum albumin level (OR=0.848, 95% CI: 0.735-0.977, p = 0.023) and post-surgery serum haemoglobin level (OR=0.943; 95% CI: 0.898-0.990, p = 0.018).

WHAT IS NEW AND CONCLUSION

The present analyses identified that BMI, history of hypertension, mean MAP (POD1 to POD3), post-surgery serum albumin level and post-surgery serum haemoglobin level were independent risk factors for rivaroxaban-related ecchymosis in patients who underwent TKA. These factors should be considered and optimized before starting rivaroxaban therapy.

Direct Oral Anticoagulants Plasma Levels Measurement: Clinical Usefulness from Trials and Real-World Data

Measurement of direct oral anticoagulants (DOACs) activity is not routinely necessary. Indeed, evaluation of DOACs plasmatic concentration is discouraged for the majority of patients, due to the lack of outcome data supporting this approach. Nevertheless, DOAC measurements may be useful in emergency situations such as serious bleeding events, need for urgent invasive procedures, and acute ischemic stroke or in managing anticoagulation in "special populations" not adequately studied in clinical trials, for example the very elderly or those at the extremes of body weight. The aim of this review is to describe and summarize the methods for DOACs activity evaluation and the settings in which their plasma level measurement may be indicated, analyzing indications from scientific societies and evidence from clinical trials, as well as real world data on the usefulness of DOACs plasma levels "monitoring."

Direct Oral Anticoagulants in the Treatment of Venous Thromboembolism: Use in Patients with Advanced Renal Impairment, Obesity, or Other Weight-Related Special Populations

There are currently more than 7 million patients taking a direct oral anticoagulant (DOAC), with more new prescriptions per year than warfarin. Despite impressive efficacy and safety data for the treatment of venous thromboembolism, patients with obesity or advanced renal impairment represented a small portion of the patients enrolled in the phase 3 clinical trials. Therefore, to evaluate the potential use of DOACs in these special populations, clinicians need to have an understanding of the pharmacokinetics and pharmacodynamics of these agents in these settings. Since data from randomized controlled trials are limited, data from observational trials are helpful in gaining comfort with the use of DOACs in these special populations. Selecting the appropriate dose for each agent is imperative in achieving optimal patient outcomes. We provide an extensive review of the pharmacokinetics, pharmacodynamics, phase 3 clinical trials, and observational studies on the use of DOACs in patients with advanced renal impairment, obesity, or other weight-related special populations to provide clinicians with a comprehensive understanding of the data for optimal drug and dose selection.

Healthcare resource utilization and costs of rivaroxaban versus warfarin among non-valvular atrial fibrillation (NVAF) patients with obesity in a US population

AIM

To assess the real-world healthcare resource utilization (HRU) and costs of patients with non-valvular atrial fibrillation (NVAF) and obesity newly initiated on rivaroxaban or warfarin in the US.

METHODS

This retrospective study used IQVIA PharMetrics Plus data (01/2010-09/2019) to evaluate patients (≥18 years) with NVAF and obesity (body mass index ≥30 kg/m²) initiated on rivaroxaban or warfarin (on or after 01/2013). Inverse probability of treatment weighting (IPTW) was used to adjust for confounding between cohorts. HRU and costs were assessed post-treatment initiation. Weighted cohorts were compared using Poisson regression models and cost differences, with 95% confidence intervals (CIs) and p values generated using non-parametric bootstrap procedures.

RESULTS

After IPTW, 10,555 and 5,080 patients were initiated on rivaroxaban and warfarin, respectively (mean age: 59 years). At 12 months follow-up, the rivaroxaban cohort had lower all-cause HRU, including fewer hospitalizations (rate ratio [RR]: 0.80, 95% CI: 0.74, 0.87), emergency room visits (RR: 0.89, 95% CI: 0.83, 0.97), and outpatient visits (RR: 0.72, 95% CI: 0.69, 0.77; all p < .05). Medical costs were also reduced in the rivaroxaban cohort (mean difference: -$6,759, 95% CI: -$9,814, -$3,311) due to reduced hospitalization costs (mean difference: -$5,967, 95% CI: -$8,721, -$3,327), resulting in lower total all-cause healthcare costs compared to the warfarin cohort (mean difference: -$4,579, 95% CI: -$7,609, -$1,052; all p < .05). The rivaroxaban cohort also had lower NVAF-related HRU and medical costs driven by lower hospitalization at 12 months post-treatment initiation. HRU and cost reductions associated with rivaroxaban persisted up to 36 months of follow-up.

LIMITATIONS

Claims data may have contained inaccuracies and obesity was classified based on ICD diagnosis codes given that patient BMI values were not available.

CONCLUSIONS

Rivaroxaban was associated with reduced HRU and costs compared to warfarin among NVAF patients with obesity in a real-world US setting.

Use of direct-acting oral anticoagulants in solid organ transplantation: A systematic review

The use of direct-acting oral anticoagulants (DOACs) has increased secondary to the mounting evidence for comparable efficacy and potentially superior safety to vitamin K antagonists (VKAs) in the general population. However, insufficient data regarding DOAC use in solid organ transplant (SOT) recipients and numerous pharmacokinetic and pharmacodynamic considerations limit their use in this highly selected patient population. A systematic review of recent clinical evidence on the safety and efficacy of DOACs compared to VKAs in SOT recipients was conducted. Additional considerations including transplant-specific strategies for DOAC reversal and common pharmacokinetic/pharmacodynamic concerns were also reviewed. Although current evidence is limited to single-center retrospective analyses, DOACs, especially apixaban, appear to be a safe and effective alternative to VKAs for SOT recipients with stable graft function and without drug-drug interactions. Reliable data on DOAC reversal at the time of transplant surgery are lacking, and clinicians should consider idarucizumab, andexanet alfa, and other non-specific reversal agents on an individual patient basis. There is no evidence supporting deviations from the Food and Drug Administration labeling recommendations for DOAC dosing in the setting of drug-drug interactions, obesity, and renal function, especially in patients on hemodialysis.

Clinical Performance of Nonvitamin K Antagonist Oral Anticoagulants in Real-World Obese Patients with Atrial Fibrillation

The prevalence of both atrial fibrillation (AF) and obesity has steadily increased. Nonvitamin K antagonist oral anticoagulants (NOACs) have been shown to be more effective and safer than vitamin K antagonists (VKAs) for long-term stroke prevention in patients with nonvalvular AF. There are still limited data in the literature regarding performance of NOACs in obese patients with AF in the “real world.” The aim of our study was to compare the safety and effectiveness of NOACs versus well-controlled VKA therapy in obese AF patients in a “real-world” setting. Here, we have considered patients with AF and obesity (body mass index [BMI] > 30 kg/m2) on NOAC or VKA therapy included in the multicenter Atrial Fibrillation Research Database (NCT03760874). The occurrence of major bleedings (MBs) and thromboembolic events (composite of ischemic stroke, transient ischemic attack, and systemic embolism) was respectively considered primary safety and effectiveness outcomes. We identified 1,047 AF patients with obesity who received NOAC (n = 272) or VKA (n = 775) treatment. After propensity score matching analysis, 248 NOAC and 496 VKA recipients with similar clinical characteristics, including BMI (34.8 ± 3.4 in NOAC vs. 35.1 ± 3.8 in the VKA group; p = 0.50), were evaluated. The mean follow-up was 39 ± 7 months. The incidence rate of thromboembolic events was 1.10 per 100 person-years (0.67 in NOAC vs. 1.28 in the VKA group; hazard ratio [HR]: 0.52; 95% confidence interval [CI]: 0.22–1.22; p = 0.19). The incidence rate of MB was 1.9 per 100 person-years (1.1 in NOAC vs. 2.28 in the VKA group; HR: 0.46; 95% CI: 0.24–0.88; p = 0.04). The incidence rate of intracranial hemorrhage was 0.4 per 100 person-years (0.27 in NOAC vs. 0.47 in the VKA group; HR: 0.57; 95% CI: 0.12–2.73; p = 0.48). A positive net clinical benefit (NCB) of NOACs over VKAs was found (+0.91). Presence of anemia (HR: 1.75; p = 0.003) and concomitant use of antiplatelet drugs (HR: 2.41; p = 0.001) were found to be independent predictors of MB; moreover, age (HR: 1.65; p = 0.003) was an independent predictor of thromboembolic events. Our data support the hypothesis of safe and effective use of NOACs in patients with AF and obesity, justified by a statistically significant lower incidence of MB and a favorable NCB over VKAs.

How I treat obese patients with oral anticoagulants

Obesity has become a major threat to health worldwide. The prevalence of obesity is rapidly increasing, so much so that the World Health Organization has declared obesity as a global epidemic. Obesity is associated with multiple health problems, including venous thromboembolism and atrial fibrillation, both of which are treated with anticoagulation. However, obesity and treatments for obesity such as bariatric surgery can influence absorption, excretion, pharmacokinetics, and pharmacodynamics of various anticoagulants. This results in uncertainty regarding the best antithrombotic strategies in this population, particularly in the morbidly obese. In the recent years, several studies have attempted to investigate anticoagulation use in this population and provided more insight. Herein, we present 4 cases of anticoagulant use in the obese to illustrate the common challenges faced by clinicians and discuss our approach. Whenever possible, we provide a review of the literature and base our recommendations on the best available evidence.

Fixed dose rivaroxaban can be used in extremes of bodyweight: A population pharmacokinetic analysis

BACKGROUND

Emerging safety and efficacy data for rivaroxaban suggest traditional therapy and rivaroxaban are comparable in the morbidly obese. However, real-world data that indicate pharmacokinetic (PK) parameters are comparable at the extremes of body size are lacking. The International Society of Thrombosis and Haemostasis Scientific and Standardisation Committee (ISTH SSC) suggests avoiding the use of direct oral anticoagulants (DOACs) in patients weighing >120 kg or with a body mass index >40 kg/m2 and gives no recommendation on the use of DOACs in those <50 kg.

OBJECTIVES

To generate a population PK model to understand the influence of bodyweight on rivaroxaban exposure from clinical practice data.

METHOD

Rivaroxaban plasma concentrations and patient characteristics were collated between 2013 and 2018 at King's College Hospital anticoagulation clinic. A population PK model was developed using a nonlinear mixed effects approach and then used to simulate rivaroxaban concentrations at the extremes of bodyweight.

RESULTS

A robust population PK model derived from 913 patients weighing between 39 kg and 172 kg was developed. The model included data from n = 86 >120 kg, n = 74 BMI >40 kg/m2 , and n = 30 <50 kg. A one-compartment model with between-subject variability on clearance and a proportional error model best described the data. Creatinine clearance calculated by Cockcroft-Gault, with lean bodyweight as the weight descriptor in this equation, was the most significant covariate influencing rivaroxaban exposure.

CONCLUSIONS

Our work demonstrates rivaroxaban can be used at extremes of bodyweight provided renal function is satisfactory. We recommend that the ISTH SSC revises the current guidance with respect to rivaroxaban at extremes of body size.

Warden B. Direct Oral Anticoagulant Use: A Practical Guide to Common Clinical Challenges

Direct oral anticoagulants ( DOAC s) have quickly become attractive alternatives to the long‐standing standard of care in anticoagulation, vitamin K antagonist. DOAC s are indicated for prevention and treatment of several cardiovascular conditions. Since the first approval in 2010, DOAC s have emerged as leading therapeutic alternatives that provide both clinicians and patients with more effective, safe, and convenient treatment options in thromboembolic settings. With the expanding role of DOAC s, clinicians are faced with increasingly complex decisions relating to appropriate agent, duration of treatment, and use in special populations. This review will provide an overview of DOAC s and act as a practical reference for clinicians to optimize DOAC use among common challenging scenarios. Topics addressed include (1) appropriate indications; (2) use in patients with specific comorbidities; (3) monitoring parameters; (4) transitioning between anticoagulant regimens; (5) major drug interactions; and (6) cost considerations.

Warden B. Direct Oral Anticoagulant Use: A Practical Guide to Common Clinical Challenges

Direct oral anticoagulants (DOACs) have quickly become attractive alternatives to the long-standing standard of care in anticoagulation, vitamin K antagonist. DOACs are indicated for prevention and treatment of several cardiovascular conditions. Since the first approval in 2010, DOACs have emerged as leading therapeutic alternatives that provide both clinicians and patients with more effective, safe, and convenient treatment options in thromboembolic settings. With the expanding role of DOACs, clinicians are faced with increasingly complex decisions relating to appropriate agent, duration of treatment, and use in special populations. This review will provide an overview of DOACs and act as a practical reference for clinicians to optimize DOAC use among common challenging scenarios. Topics addressed include (1) appropriate indications; (2) use in patients with specific comorbidities; (3) monitoring parameters; (4) transitioning between anticoagulant regimens; (5) major drug interactions; and (6) cost considerations.

Direct Oral Anticoagulants in Obesity: An Updated Literature Review

OBJECTIVE

To review literature on the use of direct-acting oral anticoagulants (DOACs) in patients with high body weight (BW) and/or high body mass index (BMI) and to make recommendations regarding use in this patient population.

DATA SOURCES

A search using PubMed was conducted (inception to April 13, 2020) using the term DOAC AND the terms obesity OR body weight. A separate search was also conducted with individual DOACs (dabigatran, apixaban, rivaroxaban, edoxaban) and the aforementioned terms.

STUDY SELECTION AND DATA EXTRACTION

Studies included examined the effect of BW and/or BMI on DOAC pharmacokinetics, efficacy, or safety. Included studies had DOAC indications of prevention of stroke in nonvalvular atrial fibrillation, or treatment or long-term prevention of venous thromboembolism.

DATA SYNTHESIS

The efficacy and safety of DOACs in patients with high BW/BMI has not yet been elucidated by randomized trials; however, 2016 international guidelines suggest avoiding their use in patients with a BW >120 kg or BMI >40 kg/m². Since 2016, several studies have been published examining use of DOACs in this patient population.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review thoroughly discusses the literature on DOACs in patients with a BW >120 kg or BMI >40 kg/m² pre-2016 and post-2016 guidelines.

CONCLUSIONS

Evidence indicates that each DOAC may have differences in outcomes when used in patients with a high BW/BMI. Currently, low-quality data are available that support avoiding dabigatran and considering apixaban or rivaroxaban; lack of sufficient data preclude a recommendation for edoxaban use in this patient population.

Rivaroxaban Precision Dosing Strategy for Real-World Atrial Fibrillation Patients

Rivaroxaban is a direct-acting oral anticoagulant approved to prevent strokes in patients with atrial fibrillation. Dosage recommendations are approved for all adult patients to receive either 15 mg or 20 mg once daily depending upon renal function. There are a number of reasons to believe rivaroxaban dosing could be more effective and/or safer for more patients if increased dosing precision is available. Because real-world patients are more diverse than those studied in phase III clinical trials, we evaluated the extremes of creatinine clearance (CrCl) on rivaroxaban clearance using a published population pharmacokinetic model and applying exposure variation limits (±20%) based on published literature. The proposed dosing recommendations are 10 mg once daily (CrCl 15-29 ml/min), 15 mg once daily (CrCl 30-69 ml/min), 10 mg twice daily (CrCl 70-159 ml/min), and 15 mg twice daily (CrCl 160-250 ml/min). These new dosing recommendations should be prospectively tested for predictive accuracy and to assess the impact on AF patient efficacy and safety.

Use of Direct Oral Anticoagulants in Morbidly Obese Patients

In 2016, the International Society on Thrombosis and Haemostasis (ISTH) published guidelines advising caution when using direct oral anticoagulants (DOACs) in patients with morbid obesity due to limited clinical efficacy and safety data supporting their use in this patient population. In this review, we analyzed published articles in the MEDLINE database (from inception through May 29, 2019), and the Cochrane Library, Google Scholar, and EMBASE databases (from inception through April 26, 2019) that evaluated morbidly obese patients with atrial fibrillation (AF) or venous thromboembolism (VTE) who received DOACs. A total of 19 studies, which included pharmacokinetic studies, original phase III trials for the DOACs, post hoc analyses of phase III trials, and retrospective cohort studies, were evaluated. Although currently available data do not indicate that using DOACs in the morbidly obese is problematic, DOAC-specific pharmacokinetic variations have been observed. Additionally, less data evaluating DOAC efficacy and safety exist for VTE treatment compared with the data for stroke prevention in patients with AF. The overall quality of the studies included in this review was low due to limited prospective randomized trial data, limiting the ability to form definitive judgments on efficacy and safety DOACs in the morbidly obese. Continued caution is recommended when considering DOAC use in the morbidly obese, particularly for those requiring anticoagulation for VTE treatment, until additional higher-quality data become available.

Peak plasma concentration of direct oral anticoagulants in obese patients weighing over 120 kilograms: A retrospective study

BACKGROUND

Due to a paucity of data on the efficacy and safety of direct oral anticoagulants (DOACs) in patients with a body mass index >40 kg/m2 or a weight >120 kg, the use of DOACs in this group is not recommended.

OBJECTIVES

To determine the proportion of obese patients with body weight >120 kg with a peak plasma concentration of DOACs lower than the expected median trough level derived from population pharmacokinetic studies for each DOAC.

METHODS

Patients with body weight >120 kg taking DOACs for any indication underwent a peak drug concentration measurement at steady state.

RESULTS

38 patients were included in the analysis. The mean age was 64 ± 11 years, and 30 (79%) were males. The median body weight was 132.5 kg (interquartile range [IQR] 127-146.5). The median peak concentrations (IQR) were 148 ng/mL (138-240), 138 ng/mL (123-156.5), 215 ng/mL (181-249) for apixaban, dabigatran, and rivaroxaban, respectively. Two patients (5%, 95% confidence interval [CI]: 0.5%-18%) had a peak plasma concentration lower than the median trough and eight (21%, 95% CI: 11%-37%) had a peak plasma concentration below the fifth percentile (10th percentile for dabigatran) peak concentration.

CONCLUSIONS

Most patients in our study had peak plasma concentration higher than the median trough level for each of the three DOACs. However, 21% had a peak plasma concentration that was below the usual on-therapy range of peak concentration for the corresponding DOAC.

Anticoagulation at the extremes of body weight: choices and dosing

INTRODUCTION

The landscape of therapeutic anticoagulation has changed dramatically over the past decade, with availability of direct oral anticoagulants (DOACs), which inhibit factor Xa or thrombin. However, the optimal anticoagulant agent and dosing strategy for patients at both extremes of body weight has not been established for any anticoagulant, including DOACs, vitamin K antagonists (VKA), and the various heparin options. Areas covered: This paper reviews available evidence to assist clinicians in prescribing of anticoagulation therapy at the extremes of body weight. Expert commentary: There are limited data to guide prescribing of all available anticoagulants at the extremes of weight and further research regarding efficacy and safety outcomes in these groups is required. Laboratory monitoring to guide dosing of traditional anticoagulants provides reassurance of 'predictable' efficacy. In contrast agents that are not routinely monitored by laboratory testing provide greater challenges. For example, underweight patients are at risk of receiving higher drug exposures of DOACs, whereas the use of fixed dose DOACs in obese patients may be associated with lower drug exposures.

Use of direct oral anticoagulants in antiphospholipid syndrome

The direct oral anticoagulants (DOACs) are therapeutic alternatives to warfarin and other vitamin K antagonists (VKAs), and constitute the standard of care for many indications. VKAs constitute the conventional therapy for the treatment and secondary thromboprophylaxis of thrombotic antiphospholipid syndrome (APS), but are often problematic, owing to the variable sensitivity of thromboplastins to lupus anticoagulant. Thus, the International Normalized Ratio may not accurately reflect anticoagulation intensity, or be clinically effective. Definition of the current role of DOACs in the treatment of APS is based on limited clinical trial data and information from other sources, including manufacturers' data, case series or cohort studies, and expert consensus. The Rivaroxaban in Antiphospholipid Syndrome (RAPS) randomized controlled trial (RCT), which had a laboratory surrogate primary outcome measure, suggests that rivaroxaban has the potential to be an effective and convenient alternative to warfarin in thrombotic APS patients with a single venous thromboembolism event requiring standard-intensity anticoagulation. However, further studies, in particular to provide better long-term efficacy and safety data, are needed before it can be widely recommended. APS patients are clinically heterogeneous, with the risk of recurrent thrombosis and the intensity of anticoagulation being influenced by their clinical phenotype and risk profile. DOAC trials involving homogeneous thrombotic APS populations, with the antiphospholipid antibody status well defined, will help to optimize the appropriate treatment in APS patient subgroups. Ongoing and emerging DOAC RCTs should provide further information to guide the use of DOACs in APS patients. Optimal identification of APS patients is a key step in working towards improved therapeutic strategies in these individuals.