ABCG2 polymorphism and rivaroxaban pharmacokinetics in healthy individuals after a single dose.

Rivaroxaban is a direct factor Xa inhibitor. Its interindividual variability is large and may be connected to the occurrence of adverse drug reactions or drug inefficacy. Pharmacogenetics studies concentrating on the reasons underlying rivaroxaban's inadequate response could help explain the differences in treatment results and medication safety profiles. Against this background, this study evaluated whether polymorphisms in the gene encoding the ABCG2 transporter modify the pharmacokinetic characteristics of rivaroxaban. A total of 117 healthy volunteers participated in two bioequivalence experiments with a single oral dose of 20 mg rivaroxaban, with one group fasting and the other being fed. Ultra-high-performance liquid chromatography coupled with mass spectrometry was employed to determine the plasma concentrations of rivaroxaban, and the WinNonlin program was used to calculate the pharmacokinetics parameters. In the fasting group, the rivaroxaban pharmacokinetic parameters of Vd (508.27 vs 334.45 vs 275.59 L) and t1/2 (41.04 vs 16.43 vs 15.47 h) were significantly higher in ABCG2 421 A/A genotype carriers than in ABCG2 421 C/C and 421 C/A genotype carriers (P<0.05). The mean values of Cmax (145.81 vs 176.27 vs 190.19 ng/mL), AUC0-t (1193.81 vs 1374.69 vs 1570.77 ng/mL·h), and Cl (11.82 vs 14.50 vs 13.01 mL/h) for these groups were lower, but this difference was not statistically significant (P>0.05). These findings suggested that the ABCG2 421 A/A genotype may impact rivaroxaban parameters after a single dose in healthy subjects. This finding must be validated before it is applied in clinical practice.

Impact of patient selection in clinical trials: application of ROCKET AF and ARISTOTLE criteria in GARFIELD-AF.

BACKGROUND: The extent to which differences in results from Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) and Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial (ROCKET) atrial fibrillation (AF)-the landmark trials for the approval of apixaban and rivaroxaban, respectively, for non-valvular AF-were influenced by differences in their protocols is debated. The potential influence of selection criteria on trial results was assessed by emulating these trials in data from the Global Anticoagulant Registry in the Field (GARFIELD)-AF registry. METHODS: Vitamin K antagonist (VKA) and non-vitamin K oral antagonist (NOAC) users from GARFIELD-AF were selected according to eligibility for the original ARISTOTLE or ROCKET AF trials. A propensity score overlap weighted Cox model was used to emulate trial randomisation between treatment groups. Adjusted HRs for stroke or systemic embolism (SE) within 2 years of enrolment were calculated for each NOAC versus VKA. RESULTS: Among patients on apixaban, rivaroxaban and VKA, 2570, 3560 and 8005 were eligible for ARISTOTLE, respectively, and 1612, 2005 and 4368, respectively, for ROCKET AF. When selecting for ARISTOTLE criteria, apixaban users had significantly lower stroke/SE risk versus VKA (HR 0.57; 95% CI 0.34 to 0.94) while no reduction was observed with rivaroxaban (HR 0.98; 95% CI 0.68 to 1.40). When selecting for ROCKET AF criteria, safety and efficacy versus VKA were similar across the NOACs. CONCLUSION: Apixaban and rivaroxaban showed similar results versus VKA in high-risk patients selected according to ROCKET AF criteria, whereas differences emerged when selecting for the more inclusive ARISTOTLE criteria. Our results highlight the importance of trial selection criteria in interpreting trial results and underline the problems faced in comparing treatments across rather than within clinical trials.

Clinical guidance for unfractionated heparin dosing and monitoring in critically ill patients.

INTRODUCTION: Unfractionated heparin is a widely used anticoagulant in critically ill patients. It has a well-established safety profile and remains an attractive option for clinicians due to its short half-life and reversibility. Heparin has a unique pharmacokinetic profile, which contributes to significant inter-patient and intra-patient variability in effect. The variability in anticoagulant effect combined with heparin's short half-life mean close monitoring is required for clinical efficacy and preventing adverse effects. To optimize heparin use in critically ill patients, effective monitoring assays and dose adjustment strategies are needed. AREAS COVERED: This paper explores the use of heparin as an anticoagulant and optimal approaches to monitoring in critically ill patients. EXPERT OPINION: Conventional monitoring assays for heparin dosing have significant limitations. Emerging data appear to favor using anti-Xa assay monitoring for heparin anticoagulation, which many centers have successfully adopted as the standard. The anti-Xa assay appears have important benefits relative to the aPTT for heparin monitoring in critically ill patients, and should be considered for broader use.

Apixaban Versus Vitamin K Antagonists in Patients With Antiphospholipid Syndrome: A Cohort Study.

ABSTRACT: Current guidelines recommend that direct anticoagulants should not be used in prevention of recurrent thrombosis in patients with antiphospholipid syndrome (APS). However, except for triple-positive APS and rivaroxaban use, little evidence supports such recommendation. In a real-life cohort study, we evaluated the risk of thromboembolism and bleeding in patients with APS on apixaban versus vitamin K antagonists (VKA). We enrolled 152 patients with APS (aged 44 years [interquartile range 36-56], 83% women), including 66 patients treated with apixaban 5 mg bid and 86 with warfarin (target international normalized ratio [INR] 2-3). During a median follow-up of 53 months, we recorded venous thromboembolism, ischemic stroke, or myocardial infarction, along with major bleeding. We observed 4 thrombotic events (6.1%, 3 venous thromboembolism and 1 ischemic stroke) in patients on apixaban and 12 events (14%, 9 venous thromboembolism, 2 ischemic strokes and 1 myocardial infarction) in VKA patients. Patients with APS on apixaban had similar risk of recurrent thromboembolism compared with those on warfarin (hazard ratio [HR] = 0.327, 95% confidence interval [CI]: 0.104-1.035). Thromboembolic events occurred less commonly in statin users (8% vs. 50%, P = 0.01) and more frequently in triple-positive APS (50% vs. 22.1%, P = 0.028) and in patients with higher D-dimer at baseline ( P = 0.023); the latter difference was present in the apixaban group ( P = 0.02). Patients on apixaban had similar risk of major bleeding compared with warfarin (HR = 0.54, 95% CI: 0.201-1.448). In real-life patients with APS, apixaban appears to be similar to VKA for the prevention of thromboembolism and risk of bleeding, which might suggest that some patients with APS could be treated with apixaban.

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.

Effective application of a direct-acting oral anticoagulants reversal agent in acute type A aortic dissection repair: A case report.

There are insufficient reports on the use of andexanet alfa in cardiac surgery. A 67-year-old man was diagnosed with type A aortic dissection and performed emergent surgery. His medical history included atrial fibrillation treated with Edoxaban. We performed total arch replacement. Despite administration of enough protamine, fresh frozen plasma, and platelet administration, controlling bleeding was difficult. Thus, Andexanet Alfa was initiated after CPB withdrawal. Surgical bleeding was dramatically controlled after its administration. There were no findings suggestive of an embolic event. In conclusion, administration of Andexanet Alfa is safe after cardiopulmonary bypass withdrawal.

[Interference of oral anti-Xa anticoagulants during monitoring of unfractionated heparin treatments: practical and future attitudes]. / Interférence des anticoagulants oraux directs anti-Xa lors de la surveillance des traitements par héparine non-fractionnée : attitudes pratiques et à venir.

Contrary to direct oral anticoagulants (DOAC), unfractionated heparin (UFH) requires daily monitoring when administered at therapeutic dose. At present, UFH monitoring is preferably carried out by measuring plasma anti-Xa activity, however, in patients previously treated with an anti-Xa DOAC and switched to UFH, there is a high risk of DOAC interfering with the measurement of UFH anti-Xa activity. Residual anti-Xa DOAC in the sample can lead to an overestimation of the anticoagulant activity attributed to heparin and thus to incorrect anticoagulation. This risk of interference should not be overlooked because interference may occur even at concentration of DOAC below the hemostatic safety threshold and can last several days. To overcome this issue, several alternatives are being studied. This note provides an update on anti-Xa DOAC interference and different strategies available in current practice. It also underlines the importance of communication between biologists and clinicians on anticoagulant treatments received by patients.

[Is monitoring of anti-factor Xa levels required for low molecular weight heparin prophylaxis of venous thromboembolism in critically ill patients?]

The incidence and mortality of venous thromboembolism (VTE) are high in critically ill patients, and there is still a risk of VTE and bleeding after the use of fixed-dose low molecular weight heparin (LMWH) for prophylaxis. The level of anti-factor Xa is not up to standard after LMWH prophylaxis in patients with surgery or trauma. The condition of critically ill patients is complicated, and the proportion of patients with low antithrombin III is high, which can affect the prophylactic efficacy of LMWH and contribute to VTE occurrence. There is currently no consensus on whether adjusting LMWH dose according to anti-factor Xa levels can reduce VTE occurrence in critically ill patients. High-quality multicenter randomized controlled studies are needed in the future to establish new approaches for precise prevention of VTE in critically ill patients.

Effect of drug interactions with non-vitamin-K oral anticoagulants on thromboembolic events in patients with nonvalvular atrial fibrillation.

Introduction: Few real-world studies have investigated drug-drug interactions (DDIs) involving non-vitamin-K antagonist oral anticoagulants (NOACs) in patients with nonvalvular atrial fibrillation (NVAF). The interactions encompass drugs inducing or inhibiting cytochrome P450 3A4 and permeability glycoprotein. These agents potentially modulate the breakdown and elimination of NOACs. This study investigated the impact of DDIs on thromboembolism in this clinical scenario. Method: Patients who had NVAF and were treated with NOACs were selected as the study cohort from the National Health Insurance Research Database of Taiwan. Cases were defined as patients hospitalised for a thromboembolic event and who underwent a relevant imaging study within 7 days before hospitalisa-tion or during hospitalisation. Each case was matched with up to 4 controls by using the incidence density sampling method. The concurrent use of a cytochrome P450 3A4/permeability glycoprotein inducer or inhibitor or both with NOACs was identified. The effects of these interactions on the risk of thromboembolic events were examined with univariate and multivariate conditional logistic regressions. Results: The study cohort comprised 60,726 eligible patients. Among them, 1288 patients with a thromboembolic event and 5144 matched control patients were selected for analysis. The concurrent use of a cytochrome P450 3A4/permeability glycoprotein inducer resulted in a higher risk of thromboembolic events (adjusted odds ratio [AOR] 1.23, 95% confidence interval [CI] 1.004-1.51). Conclusion: For patients with NVAF receiving NOACs, the concurrent use of cytochrome P450 3A4/ permeability glycoprotein inducers increases the risk of thromboembolic events.

Evaluation of the safety and efficacy of direct oral anticoagulants compared with vitamin-k antagonists in the treatment of left ventricular thrombosis. A systematic review and meta-analysis.

BACKGROUND: Since the introduction of direct oral anticoagulants (DOACs) and their comparison with vitamin K antagonists (VKAs), conflicting results have been reported regarding the optimal treatment for left ventricular thrombosis (LVT). OBJECTIVES: In this meta-analysis, we intend to comprehensively evaluate the safety and efficacy of these treatments. METHODS: All clinical trials and cohorts that compared the efficacy or safety of VKAs with DOACs in the treatment of LVTs were systematically searched until April 15, 2023. RESULTS: The results of 32 studies with a pooled sample size of 4213 patients were extracted for meta-analysis. DOACs, especially rivaroxaban and apixaban, cause faster resolution, lower mortality, and fewer complications (SSE and bleeding events) than VKAs in the management of LVTs. CONCLUSION: Compared with VKAs, DOACs result in significantly faster (only rivaroxaban) and safer resolution of left ventricular thrombosis.

Efficacy and Safety of Direct Oral Anticoagulants for Acute Treatment of Venous Thromboembolism in Older Adults: A Network Meta-Analysis of Randomised Controlled Trials.

OBJECTIVE: This systematic review and network meta-analysis aimed to evaluate the efficacy and safety of direct oral anticoagulants (DOACs) in adults aged 75 and over undergoing acute venous thromboembolism (VTE) treatment. METHODS: PubMed, Embase and the CENTRAL were searched up to 25 December 2023. The incidence of VTE recurrence and bleeding events was assessed. Employing a frequentist network meta-analysis approach, interventions not directly compared could be indirectly assessed through the 95% confidence interval (CI), enhancing the interpretability of the search results. The surface under the cumulative ranking curves (SUCRA) was utilized to generate the relative ranking probabilities for each group. RESULTS: Our study, analysing 6 randomised controlled trials with 3665 patients, compares direct oral anticoagulants (DOACs) and vitamin K antagonists (VKAs) in adults aged 75 and over with acute venous thromboembolism. Edoxaban reduces VTE recurrence risk compared with VKAs (risk ratio [RR] .50, 95% CI 0.27 - .95), while apixaban significantly decreases bleeding risk compared with VKAs (RR .23, 95% CI 0.08 - .69), edoxaban (RR .28, 95% CI 0.09 - .86) and rivaroxaban (RR .28, 95% CI 0.09 - .86). Despite low overall evidence quality, apixaban consistently ranks highest for both efficacy and safety. Findings underscore the nuanced efficacy-safety balance in this population, emphasizing cautious interpretation due to evidence limitations. CONCLUSION: Apixaban emerges as a favourable choice for acute VTE treatment in the elderly, displaying reduced bleeding risk compared to other treatments while maintaining comparable efficacy. Future studies should explore diverse anticoagulants efficacy and safety in older populations. Additionally, clinical prediction models tailored to geriatric cohorts are crucial for guiding treatment duration decisions.

Glass bead-activated clotting time (gb-ACT) for monitoring the anticoagulation effects in elderly patients with high risk of venous thromboembolism (VTE).

BACKGROUND: To find a new bedside method to monitor the anticoagulation effects of low-molecular-weight heparins (LMWHs) in patients with a high risk of venous thromboembolism (VTE). RESEARCH DESIGN AND METHODS: A total of 32 hospitalized patients (aged ≥60 years) who were at high risk of VTE were assigned to receive subcutaneous LMWH for 5 to 14 days. Plasma anti-factor Xa (anti-Xa) activity was conducted by a chromogenic method, and the glass bead-activated whole blood clotting time (gb-ACT) value was obtained by a Sonoclot Analyzer. RESULTS: A correlation between the gb-ACT values and the anti-Xa levels was suggested (R = 0.447, p = 0.002), and it was stronger in the older group aged 80 years above (R = 0.467, p = 0.008) and in the group of patients with an eGFR of 30 ~ 60 mL/min (R = 0.565, p = 0.005). The area under the curve (AUC) for gb-ACT by receiver operating characteristic (ROC) curve evaluation was 0.725 (p = 0.011), and the gb-ACT >282.5s provided a sensitivity of 60% and specificity of 74% for anti-Xa >0.800 IU/ml. CONCLUSIONS: The gb-ACT values detected by a Sonoclot Analyzer could act as a novel bedside method in the monitoring of LMWH anticoagulation.

Perioperative Management in Patients with Atrial Fibrillation Treated with Non-Vitamin K Antagonist Oral Anticoagulants Undergoing Minor Bleeding Risk Procedure: Rationale and Protocol for the PERIXa Study.

Background: While treatment interruption of non-vitamin K antagonist oral anticoagulants (NOACs) for elective surgery or procedures among patients with atrial fibrillation (AF) is becoming more prevalent, there remains insufficient evidence regarding the optimal perioperative management of NOACs, particularly procedures with minor bleeding risks. Objective: This study aims to evaluate the safety and effectiveness of a simplified, standardized protocol for perioperative management of direct factor Xa inhibitors in patients, with AF undergoing procedures associated with minor bleeding risk. Methods: This multicenter, prospective single-arm registry study plans to enroll patients undergoing procedures with minor bleeding risk who were prescribed direct factor Xa inhibitors for AF. The procedures with minor bleeding risk will include gastrointestinal endoscopy for diagnostic purposes, selected dental procedures, and ocular surgery for cataracts or glaucoma. For apixaban, patients will withhold the last evening dose and resume either from the evening dose of the procedure day or the following morning, depending on the bleeding risk of the patient. For edoxaban or rivaroxaban, patients will withhold only a single dose on the procedure day. The primary outcome is the occurrence of major bleeding events within 30 days. Secondary outcomes include systemic thromboembolism, all-cause mortality, and a composite of major and clinically relevant non-major bleeding events. Conclusion: This study has the potential to generate evidence regarding the safety of perioperative management for patients, with AF undergoing procedures associated with minor bleeding risk. Trial Registration: Clinicaltrials.gov: NCT05801068.

Development of immediate-release formulation with reliable absorption of rivaroxaban in various meal regimes.

The bioavailability of rivaroxaban at the higher doses (15 and 20 mg) is considerably reduced when the drug is administered on an empty stomach. This can lead to inadequate anticoagulant effect, and therefore, it is recommended to use the higher doses at fed state. However, proper posology may represent a barrier for some patients. Therefore, the aim of this study was to evaluate innovative rivaroxaban-containing formulations designed to eliminate the food effect to ensure reliable absorption and thus to improve patient adherence with the treatment. Three prototypes (Cocrystal, HPMCP and Kollidon) with rivaroxaban were developed and their bioavailability and food effect in comparison to the reference product was tested in open label, randomized, single oral dose, crossover studies, where test products were administered under fasting and fed conditions and the reference product was administered under fed conditions. Comparable bioavailability for all tested prototypes both under fed and fasting conditions was demonstrated as the 90% confidence intervals of the geometric mean ratios for area under the concentration-time curve remained within the standard acceptance range of 80.00%-125.00%. An innovative immediate release form of rivaroxaban with no food effect on drug bioavailability has been developed, which may represent an important step toward increasing adherence, improving treatment outcome and reducing health care costs.

Comparison of apixaban versus aspirin for the prevention of latent bioprosthetic aortic valve thrombosis: study protocol for a prospective randomized trial.

BACKGROUND: The optimal antithrombotic strategy early after aortic valve replacement surgery with a biological valve remains controversial due to lack of high-quality evidence. Either oral anticoagulants or acetylsalicylic acid should be considered for the first 3 months. Hypo-attenuated leaflet thickening on cardiac computed tomography has been associated with latent bioprosthetic valve thrombosis and may be prevented with anticoagulation. We hypothesize that anticoagulation with apixaban is superior to single antiplatelet therapy with acetylsalicylic acid in reducing hypo-attenuated leaflet thickening of bioprosthetic aortic valve prostheses. METHODS: In this prospective, open-label, randomized trial, patients undergoing isolated aortic valve replacement surgery with rapid deployment bioprosthetic valves will be randomized. The treatment group will receive 5 mg of apixaban twice a day for the first 3 months and 100 mg of acetylsalicylic acid thereafter. The control group will be administered 100 mg of acetylsalicylic acid once a day, indefinitely. After the 3-month treatment period, a contrast-enhanced electrocardiogram-gated cardiac computed tomography will be performed to identify hypo-attenuated leaflet thickening of the bioprosthetic valve. The primary objective of the study is to assess the impact of apixaban on the prevention of hypo-attenuated leaflet thickening at 3 months. The secondary and exploratory endpoints will be clinical outcomes and safety profiles of the two strategies. DISCUSSION: Antithrombotic therapy after aortic valve replacement is used to prevent valve thrombosis and systemic thromboembolism. Latent bioprosthetic valve thrombosis is a precursor of clinically significant prosthetic valve dysfunction or thromboembolic events. The hallmark feature of latent bioprosthetic valve thrombosis is hypo-attenuated leaflet thickening on cardiac computed tomography. Subclinical leaflet thrombosis occurs frequently in bioprosthetic aortic valves, more commonly in transcatheter than in surgical valves. There is no evidence on the effect of direct oral anticoagulants on the incidence of hypo-attenuated leaflet thickening after surgical aortic valve replacement with rapid deployment bioprostheses. TRIAL REGISTRATION: ClinicalTrials.gov NCT06184113. Registered on December 28, 2023.

Assessment of Days Alive Out of Hospital as a Possible End Point in Trials of Stroke Prevention for Atrial Fibrillation: A ROCKET AF Analysis.

BACKGROUND: Days alive out of hospital (DAOH) is an objective and patient-centered net benefit end point. There are no assessments of DAOH in clinical trials of interventions for atrial fibrillation (AF), and it is not known whether this end point is of clinical utility in these populations. METHODS AND RESULTS: ROCKET AF (Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation) was an international double-blind, double-dummy randomized clinical trial that compared rivaroxaban with warfarin in patients with atrial fibrillation at increased risk for stroke. We assessed DAOH using investigator-reported event data for up to 12 months after randomization in ROCKET AF. We assessed DAOH overall, by treatment group, and by subgroup, including age, sex, and comorbidities, using Poisson regression. The mean±SD number of days dead was 7.3±41.2, days hospitalized was 1.2±7.2, and mean DAOH was 350.7±56.2, with notable left skew. Patients with comorbidities had fewer DAOH overall. There were no differences in DAOH by treatment arm, with mean DAOH of 350.6±56.5 for those randomized to rivaroxaban and 350.7±55.8 for those randomized to warfarin (P=0.86). A sensitivity analysis found no difference in DAOH not disabled with rivaroxaban versus warfarin (DAOH not disabled, 349.2±59.5 days and 349.1 days±59.3 days, respectively, P=0.88). CONCLUSIONS: DAOH did not identify a treatment difference between patients randomized to rivaroxaban versus warfarin. This may be driven in part by the low overall event rates in atrial fibrillation anticoagulation trials, which leads to substantial left skew in measures of DAOH.

Direct Oral Anticoagulation in Lung Transplant Recipients.

OBJECTIVES: Presently, the management of direct oral anticoagulants lacks specific guidelines for patients before and after transplant, particularly for lung transplant recipients. We aimed to consolidate the existing literature on direct oral anticoagulants and explore their implications in lung transplant recipients. MATERIALS AND METHODS: We conducted a comprehensive search in PubMed and Google Scholar databases for studies published between January 2000 and December 2022, using specific search terms. We only included studies involving lung transplant recipients and focusing on direct oral anticoagulants. RESULTS: Five relevant publications were identified, providing varied insights. None of the studies specifically addressed bleeding complications associated with direct oral anticoagulants in lung transplant recipients. Limited details were available on the type of solid-organ transplant or the specific direct oral anticoagulant used in these studies. CONCLUSIONS: Varied bleeding complications associated with direct oral anticoagulants in lung transplant recipients were reported, but studies lacked specificity on transplant type and direct oral anticoagulant variations. Notably, the incidence of venous thrombotic embolism in lung transplant recipients was comparatively higher than in other solid-organ transplant recipients, potentially linked to factors such as corticosteroid therapy, calcineurin inhibitors, and cytomegalovirus infections. Our synthesis on findings of use of direct oral anticoagulant in lung transplant recipients emphasized challenges of managing these medications in urgent transplant situations. Recommendations from experts suggested caution in initiation of direct oral anticoagulants posttransplant until stability in renal and hepatic function is achieved. The limited evidence on safety of direct oral anticoagulants in lung transplant recipients underscores the need for further research and guidance in this specific patient population.

Physiologically based absorption modeling to predict the bioequivalence of two apixaban formulations.

The equivalence of absorption rates and extents between generic drugs and their reference formulations is crucial for ensuring therapeutic comparability. Bioequivalence (BE) studies are widely utilized and play a pivotal role in substantiating the approval and promotional efforts for generic drugs. Virtual BE simulation is a valuable tool for mitigating risks and guiding clinical BE studies, thereby minimizing redundant in vivo BE assessments. Herein, we successfully developed a physiologically based absorption model for virtual BE simulations, which precisely predicts the BE of the apixaban test and reference formulations. The modeling results confirm that the test and reference formulations were bioequivalent under both fasted and fed conditions, consistent with clinical studies. This highlights the efficacy of physiologically based absorption modeling as a powerful tool for formulation screening and can be adopted as a methodological and risk assessment strategy to detect potential clinical BE risks.

Safety and Efficacy of Direct Oral Anticoagulants vs Warfarin in Patients With Obesity and Venous Thromboembolism: A Retrospective Analysis.

BACKGROUND: Current venous thromboembolism guidelines recommend using direct oral anticoagulants (DOACs) over warfarin regardless of obesity status; however, evidence remains limited for the safety and efficacy of DOAC use in patients with obesity. This retrospective analysis sought to demonstrate the safety and efficacy of DOACs compared with warfarin in a diverse population of patients with obesity in light of current prescribing practices. METHODS: A retrospective cohort study was conducted at a large academic health system between July 2014 and September 2019. Adults with an admission diagnosis of deep vein thrombosis (DVT) or pulmonary embolism, with weight greater than 120 kg or a body mass index greater than 40, and who were discharged on an oral anticoagulant were included. Outcomes included occurrence of a thromboembolic event (DVT, pulmonary embolism, or ischemic stroke), bleeding event requiring hospitalization, and all-cause mortality within 12 months following index admission. RESULTS: Out of 787 patients included, 520 were in the DOAC group and 267 were in the warfarin group. Within 12 months of index hospitalization, thromboembolic events occurred in 4.23% of patients in the DOAC group vs 7.12% of patients in the warfarin group (hazard ratio, 0.6 [95% CI, 0.32-1.1]; P = .082). Bleeding events requiring hospitalization occurred in 8.85% of DOAC patients vs 10.1% of warfarin patients (hazard ratio, 0.93 [95% CI, 0.57-1.5]; P = .82). A DVT occurred in 1.7% and 4.9% of patients in the DOAC and warfarin groups, respectively (hazard ratio, 0.35 [95% CI, 0.15-0.84]; P = .046). CONCLUSION: No significant differences could be determined between DOACs and warfarin for cumulative thromboembolic or bleeding events, pulmonary embolism, ischemic stroke, or all-cause mortality. The risk of DVT was lower with apixaban and rivaroxaban. Regardless of patient weight or body mass index, physicians prescribed DOACs more commonly than warfarin.