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

Clinical Benefits of Ibuprofen Arginine: A Narrative Review

Ibuprofen arginine (IBA) combines well-established analgesic and anti-inflammatory properties with enhanced pharmacokinetics. The addition of arginine significantly improves solubility and absorption, leading to a faster onset of action compared to conventional ibuprofen. Clinical studies consistently demonstrate that IBA achieves meaningful pain relief within a shorter timeframe while maintaining a favorable safety profile. IBA's rapid action is particularly valuable in managing acute exacerbations of chronic pain and preventing central sensitization, thus improving patient comfort, adherence, and overall quality of life. By addressing both the inflammatory and nociceptive components of pain, IBA offers an effective and well-tolerated alternative in multimodal pain management strategies. This review explores the clinical benefits of IBA in pain management among various clinical settings.

Effect of Danhong injection on pharmacokinetics and pharmacodynamics of rivaroxaban in rats

BACKGROUND AND OBJECTIVES

Rivaroxaban is often used in combination with DHI to treat thromboembolic disease. Whether the combination causing HDIs is still unknown. The purpose of this study was to evaluate effects of DHI on pharmacokinetics and pharmacodynamics of rivaroxaban in rats and effects on CYP3A2.

METHODS

Plasma concentration of rivaroxaban with or without DHI was determined by HPLC. Pharmacokinetics parameters were calculated. Effect of DHI on pharmacodynamics of rivaroxaban was investigated by APTT, PT, TT, FIB, INR, length of tail thrombosis, vWF, t-PA, PAI-1, IL-1β, TNF-α and histopathological sections. Effect of DHI on CYP3A2 in rats was investigated by probe drug method.

RESULTS

Cmax and AUC of rivaroxaban increased significantly in combination group (P < 0.05). APTT, PT, INR and TT increased (P < 0.05), length of tail thrombosis, FIB, vWF, PAI-1, IL-1β and TNF-α of combination group decreased significantly (P < 0.05) compared with rivaroxaban or DHI alone. Histopathologic section of tail thrombus had significant improvement. Cmax and AUC of dapsone increased (P < 0.05) in DHI group.

CONCLUSION

In summary, DHI is an inhibitor of CYP3A2 and could significantly affect pharmacokinetics and pharmacodynamic of rivaroxaban, enhance anticoagulant and antithrombotic efficacy in rats. However, the combination of rivaroxaban and DHI might lead to potential HDIs. The dosage of rivaroxaban should be adjusted in clinical.

Impact of cytochrome P-450 3A4 enzyme/P-glycoprotein inducing antiseizure medications on direct oral anticoagulant therapy

OBJECTIVES

Concomitant use of cytochrome P-450 and P-glycoprotein (CYP 3A4/P-gp) inducing antiseizure medications and direct oral anticoagulants (DOAC) may result in reduced DOAC effectiveness, but study results are inconsistent and of variable quality. The purpose of this study was to assess the safety of concomitant CYP 3A4/P-gp inducing antiseizure medications and DOAC use.

METHODS

This was a retrospective cohort study of adult patients who were newly, concomitantly receiving a DOAC (apixaban, dabigatran, or rivaroxaban) and either a CYP 3A4/P-gp inducer (carbamazepine, phenytoin, phenobarbital, or primidone) or noninducer (gabapentin). The primary outcome was the occurrence of a thromboembolic complication, defined as the composite of ischemic stroke and systemic embolism (S/SE) and venous thromboembolism (VTE). Secondary outcomes included the components of the primary composite as well as all-cause mortality and clinically relevant bleeding. Adjusted multivariate proportional hazards modeling was used to compare outcomes for each DOAC individually in the inducer and noninducer groups.

RESULTS

There were 1843 and 14 647 patients who received a DOAC plus a CYP3A4/P-gp inducer and noninducer, respectively. Overall, patients were primarily older, white, had atrial fibrillation, and were dispensed dabigatran. After adjustment, there were no statistically significant differences in the primary outcome between the groups ( P  > 0.05); however, concomitant inducer and DOAC use was associated with an increased risk of all-cause mortality ( P  < 0.05).

CONCLUSIONS

No excess risk of thrombosis during concomitant use of DOACs with CYP3A4/P-gp inducing antiseizure medications compared to use with gabapentin was identified. Further research is needed to confirm an association with excess all-cause mortality.

Efficacy, safety, and bleeding risk factor analysis of oral anticoagulants in AF patients ≥ 65 years of age: a multicenter retrospective cohort study

BACKGROUND

Stroke prevention in elderly patients with atrial fibrillation (AF) is challenging and requires a balance between thromboembolic prevention and bleeding. The comparison of novel oral anticoagulants (NOACs) and warfarin in clinical practice in elderly Asian patients has not been well studied. The purpose of this study was to evaluate the efficacy and safety of NOACs versus warfarin in elderly patients with AF in conjunction with data from real-world observational studies.

METHODS

This was a retrospective multicenter cohort study conducted in 4 centers in China, where patient information and clinical events were collected through an average of 15 months of follow-up and case queries. Clinical outcomes included major bleeding, minor bleeding, total bleeding, thrombosis, and all-cause mortality.

RESULTS

A total of 3450 elderly patients with AF were enrolled. 2656 patients were treated with at least 1 NOAC (dabigatran, rivaroxaban, apixaban, or edoxaban), and 794 patients were treated with warfarin. After correcting for confounders, NOACs significantly reduced the risk of minor bleeding [OR 0.70 (95% CL, 0.49-1.01),P = 0.049] and all-cause mortality [OR 0.57( 95% CI, 0.44-0.75),P < 0.001] compared with warfarin, however, major bleeding events [OR 1.51 (95% CL, 0.98-2.42),P = 0.075] and thrombotic events [OR 0.79 (95% CL, 0.57-1.13),P = 0.187] were not significantly different. There was no heterogeneity between clinical outcomes of NOACs and warfarin in subgroup analyses of age (65-74, 75-84, ≥ 85 years), sex (male, female), BMI (≥ 25, < 25), comorbidities (including hypertension, diabetes and no hypertension, no diabetes), except in female subgroup, where NOACs significantly reduced the risk of minor bleeding [OR 0.56 (95% CL, 0.34-0.91),P = 0.018] and increased the risk of major bleeding [OR 2.28 (95% CL, 1.12-5.14),P = 0.032] compared with warfarin.

CONCLUSION

Compared with warfarin, NOACs significantly reduced the risk of minor bleeding, all-cause mortality, and there were no statistically significant differences in major bleeding or thrombotic events. NOACs were not more effective than warfarin in thrombotic and bleeding events, regardless of the subgroup analyses on age, male, BMI and comorbid hypertension and diabetes.

Evaluation of small interfering RNA-dependent knockdowns of drug-metabolizing enzymes in multiwell array culture of primary human hepatocyte spheroids for estimation of fraction metabolized

The determination of the relative contribution of different drug-metabolizing enzymes to the metabolism of slowly metabolized compounds is a challenging task. The quantification of low compound turnover in standard in vitro systems, such as liver microsomes or hepatocyte suspension cultures, can be difficult. Thus, the use of long-term liver models, such as HepatoPac (BioIVT) or liver spheroids, has been suggested. Inhibitors of cytochrome P450 (P450) enzymes, the most important group of drug-metabolizing enzymes, represent the current standard to evaluate the route of drug metabolism. However, a long-term inhibition in systems such as spheroid models may be technically challenging due to limited stability of some of the commonly used inhibitors. Small interfering RNA (siRNA)-dependent knockdown of P450 enzymes in spheroid cultures of primary human hepatocytes represents a novel alternative to the established methods. In the current study, we report the successful attenuation of the CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 isoforms via siRNA on gene expression, as well as on the functional level, for at least 7 days. The analysis revealed that the knockdowns had only minor effects on the overall transcriptome. They also showed acceptable selectivity towards drug-metabolizing enzymes, except for the knockdown of CYP2C19. Applicability of the system for the determination of the fraction metabolized of low clearance substances was examined using 6 compounds metabolized by different P450s. By introducing siRNA-dependent knockdowns in phenotypically relevant primary human hepatocyte spheroid cultures, we hope to provide a novel alternative to standard systems to elucidate clearance pathways in vitro. SIGNIFICANCE STATEMENT: Small interfering RNA-mediated gene knockdowns of different cytochrome P450 enzymes were shown to be effective in long-term primary human hepatocyte spheroid cultures, representing a novel alternative for reaction phenotyping. This method has the potential to improve the assessment of pharmacokinetic variability and victim drug-drug interaction risks due to enzyme polymorphism or inhibition/induction with more confidence, particularly for low clearance drug candidates. Furthermore, minor effects of the small interfering RNA-mediated gene knockdowns for different cytochrome P450 enzymes on cell viability and the transcriptome were observed which implies that this system may be useful in deconvoluting toxicity caused by metabolites.

Beyond Routine Monitoring: A Comprehensive Review of Direct Oral Anticoagulants and the Role of Coagulation Profiles in Their Management

Direct oral anticoagulants (DOACs) have revolutionized anticoagulation therapy, providing effective and safe management of thrombosis and related conditions. As their use continues to grow, accurately monitoring their effects is essential to achieve optimal patient outcomes. Traditional coagulation tests, such as prothrombin time (PT) and activated partial thromboplastin time, have long been used to evaluate clotting function and bleeding risk in patients on anticoagulants. However, these standard tests often fall short with DOACs due to complex interactions between the drugs and the assays. While PT offers some insight into coagulation, its reliability for drugs like apixaban, one of the most commonly prescribed DOACs, remains debated. This limitation underscores the need for alternative monitoring strategies, such as the modified diluted PT, which shows promise in providing more accurate assessments of DOAC levels. This review discusses the pharmacokinetics of DOACs, their impact on standard coagulation tests, and various factors - such as liver disease and drug interactions - that complicate these assessments. Additionally, it highlights the importance of incorporating specific assays, including anti-factor Xa activity and dilute thrombin time, for precise anticoagulation management. By synthesizing current evidence, this review aims to identify improved methods for monitoring DOAC therapy, guide clinicians in optimizing anticoagulation treatment, and ultimately enhance patient outcomes.

Why patients fail to seek information on OTC product interactions with a direct-acting oral anticoagulant: perspectives on information-seeking

BACKGROUND

Many patients taking direct-acting oral anticoagulants (DOACs) also consume over-the-counter (OTC) products (dietary supplements and OTC medications), yet many lack knowledge of potential interactions that may increase or decrease DOAC efficacy and may not seek information about OTC products. The objective of this study was to describe patient attitudes and beliefs that inhibited information seeking about potential apixaban-OTC product interactions.

METHODS

Participants included English-, Spanish-, Mandarin-, and Cantonese-speaking adults from two large academic medical centers who reported taking apixaban (a frequently prescribed DOAC) in the past month. Thematic analysis was performed on semi-structured interviews.

RESULTS

Sixty patients aged 24-93 years (mean = 65.3; SD = 15.6) were interviewed; 55% were women. Participants took a total of 236 OTC products. Those with potential interactions with apixaban warranting consideration for therapy modification included: ibuprofen (n = 14; 5.9%), aspirin (n = 8; 3.4%), and naproxen (n = 3; 1.3%). Interviews revealed 5 major themes related to a lack of information-seeking about OTC products: (1) patients lack awareness of the potential for interactions; (2) patients believe that OTC products are safe and/or regulated (largely because they were familiar with the products, had previously taken them, or assumed that dietary supplements were regulated by the Food and Drug Administration); (3) patients believe that providers are responsible for alerting patients about potential interactions (as patients assumed that providers were aware of their OTC product use); (4) patients had prior knowledge of and/or used OTC products infrequently; and (5) obtaining information can be inconvenient. Inquiries regarding preferred information sources revealed 59 (98.3%) patients most frequently sought or would seek information from physicians and 34 (56.7%) from the internet.

CONCLUSIONS

Patients taking apixaban raised reasons for not seeking information about potential OTC product interactions that included poor awareness, perceptions regarding the safety of OTC products, and beliefs in provider responsibility for informing them about interactions. Greater patient education is needed regarding the potential for OTC product-DOAC interactions and the regulation of OTC products, particularly dietary supplements.

Managing drug-drug interactions with mavacamten: A focus on combined use of antiarrhythmic drugs and anticoagulants

Mavacamten is a selective, allosteric, and reversible cardiac myosin inhibitor, representing the first disease-specific treatment for obstructive hypertrophic cardiomyopathy (HCM) that targets the core pathophysiological mechanism of this condition. Clinical evidence supports its efficacy in improving symptoms, cardiac function, and remodeling, thereby supplementing established treatment regimens. However, mavacamten is extensively metabolized by hepatic cytochromes, and its half-life is contingent upon CYP2C19 phenotype. Consequently, coadministered medications that inhibit or induce these enzymes may significantly alter mavacamten pharmacokinetics, potentially leading to reversible systolic dysfunction or diminished therapeutic efficacy. This paper provides a comprehensive analysis of mavacamten pharmacokinetics and its potential interactions with antithrombotic and antiarrhythmic agents, which are the cornerstones of atrial fibrillation management in HCM population. Our aim is to offer clinicians practical guidance on safely administering mavacamten in conjunction with these medications, discuss the role of pharmacogenomics, and outline rigorous patient safety monitoring strategies to ensure effective and individualized treatment.

Drug-Drug Interactions Between DAAs and Anticoagulants or Antiplatelets: A Position Paper of the Italian Anticoagulation Clinics

The natural history of chronic hepatitis C virus (HCV) infection has changed after the introduction of direct-acting antiviral agents (DAAs). Screening programs have been ongoing to reach the World Health Organisation's goal of HCV elimination by 2030, and most infected people are eligible for treatment. Given the increased cardiovascular risk in people with HCV infection and the metabolic pathways of DAAs, it is not uncommon to face the issue of drug-drug interactions (DDIs) with antiplatelet or anticoagulant drugs. In the absence of clinical trials, we offer suggestions to deal with DDIs in case of treatment of patients with DAAs who are also receiving antiplatelet or anticoagulant drugs, based on the best available evidence from pharmacodynamics and pharmacokinetics studies in conjunction with clinical experience in the field of haemostasis and thrombosis.

Understanding Drug Interactions in Antiplatelet Therapy for Atherosclerotic Vascular Disease: A Systematic Review

BACKGROUND

Antiplatelet drugs are a cornerstone in managing atherosclerotic vascular disease (ASVD). However, their interactions with other medications present significant challenges to treatment efficacy and safety. Patients with ASVD often require multiple treatment regimens due to complex comorbidities, which increases the risk of drug-drug interactions (DDIs). These interactions can lead to drug resistance, reduced therapeutic outcomes, or adverse effects. A thorough understanding of DDIs is crucial for optimizing patient care.

AIMS

This review aims to explore the clinical significance. mechanisms, and implications of DDIs in antiplatelet therapy Additionally, it seeks to identify future research directions to advance personalized treatment strategies and improve therapeutic outcomes.

MATERIALS AND METHODS

A systematic literature review was conducted using key databases, focusing on clinical studies, mechanistic research, and guidelines related to antiplatelet therapy and DDIs. Findings were analyzed to identify common interaction patterns, associated risks, and management strategies.

RESULTS

The review identifies common DDIs involving antiplatelet drugs, particularly with anticoagulants, nonsteroidal anti-inflammatory drugs, and proton pump inhibitors. These interactions primarily occur through pharmacokinetic mechanisms, such as alterations in drug metabolism via cytochrome P450 enzymes, and pharmacodynamic mechanisms, including synergistic or antagonistic effects on platelet inhibition. Clinically, DDIs can increase bleeding risk, reduce antiplatelet efficacy, and contribute to adverse cardiovascular outcomes. Strategies to mitigate these risks include individualized drug selection, dose adjustments, genetic testing, and therapeutic drug monitoring.

DISCUSSION

Effective management of DDIs in antiplatelet therapy is essential to improve clinical outcomes. A patient-specific approach, considering comorbidities, genetic predispositions, and concurrent medications, is crucial. The review categorizes DDIs based on clinical settings and underscores the need for further research on predictive biomarkers, pharmacogenomics, and advanced monitoring techniques.

CONCLUSION

DDIs significantly impact the effectiveness and safety of antiplatelet therapy, necessitating a comprehensive understanding of their mechanisms and clinical implications. Future research should focus on developing personalized treatment approaches, integrating genetic testing, and optimizing pharmacological monitoring to minimize risks and improve therapeutic outcomes. This review provides a foundation for advancing clinical practice and enhancing the management of patients with ASVD.

Potential interactions between antimicrobials and direct oral anticoagulants: Population-based cohort and case-crossover study

BACKGROUND

Although drug interactions between clarithromycin/erythromycin/fluconazole and direct oral anticoagulants (DOACs) are mechanistically plausible, it is uncertain whether they are clinically relevant.

OBJECTIVE

This study aims to investigate the association among coprescribed DOACs and antimicrobials and bleeding, cardiovascular disease and mortality.

METHODS

We identified DOAC users in the Clinical Practice Research Datalink Aurum from January 1, 2011 to March 29, 2021. We used a cohort design to estimate hazard ratios (HRs) for bleeding outcomes (intracranial bleeding, gastrointestinal bleeding, other bleeding), comparing DOACs + clarithromycin/erythromycin/fluconazole users with DOACs users not receiving these antimicrobials. Cardiovascular outcomes were ischaemic stroke, myocardial infarction, venous thromboembolism, cardiovascular mortality, and all-cause mortality. A 6-parameter case-crossover design comparing odds of exposure with different drug initiation patterns for all outcomes in hazard window vs referent window within an individual was also conducted.

RESULTS

Of 483,815 DOAC users, we identified 21,701 coprescribed clarithromycin, 4532 coprescribed erythromycin, and 4840 coprescribed fluconazole. We observed an increased risk of gastrointestinal bleeding over 7 days following coprescription of DOAC + erythromycin vs DOAC alone (HR 3.66; 99% confidence interval [CI] 1.27-10.51), with wide CIs in case-crossover analysis. No evidence of increased risk of bleeding outcomes was seen for DOAC + clarithromycin/fluconazole in cohort and case-crossover analyses. For cardiovascular outcomes, compared with DOAC alone, an increased risk of cardiovascular mortality with DOAC + clarithromycin (HR 3.36; 99% CI 1.73-6.52) and increased risk of all-cause mortality with DOAC + clarithromycin/erythromycin/fluconazole were observed in cohort analysis. However, similar risks were found when initiating erythromycin/fluconazole with and without DOACs.

CONCLUSION

We found no strong evidence of increased risks of bleeding and cardiovascular outcomes in DOACs + clarithromycin/fluconazole/erythromycin users except a possible short-term increased risk of gastrointestinal bleeding in DOACs + erythromycin users.

UGT2B15 single nucleotide polymorphism reduces dabigatran acylglucuronide formation in humans

Background

Dabigatran etexilate (DABE), a prodrug of dabigatran (DAB), is a direct thrombin inhibitor used to prevent ischemic stroke and thromboembolism during atrial fibrillation. The effect of genetic polymorphisms on its metabolism, particularly UGT2B15, has not been extensively explored in humans. This study aimed to investigate the effects of UGT2B15, ABCB1, and CES1 polymorphisms on the pharmacokinetics of DAB and its acylglucuronide metabolites in healthy subjects.

Methods

A total of 124 healthy males were genotyped for UGT2B15, ABCB1, and CES1 polymorphisms. After a single 150 mg dose of DABE, plasma concentrations of total and free DAB, as well as dabigatran acylglucuronide (DABG) were measured using LC-MS/MS. Pharmacokinetic parameters were analyzed using non-compartmental methods, and statistical comparisons were conducted between the genotype groups.

Results

UGT2B15 c.253G>T significantly affected free DAB pharmacokinetics, with a lower Tmax and oral clearance in TT genotype (n = 28, p < 0.05). For DABG, Cmax was significantly higher in GG genotypes (n = 32, 42.3 ± 16.3 ng/mL) compared to that in GT (n = 64, 32.4 ± 20.5 ng/mL) and TT (29.7 ± 17.1 ng/mL) genotypes. Similarly, the AUCall of DABG was highest in GG genotypes (327 ± 148.3 ng h·mL-1), followed by GT (238.7 ± 166.5 ng h·mL-1) and TT (223.3 ± 165.4 ng h·mL-1) genotypes (p < 0.05). The metabolite-to-parent ratios (m/p ratios) for Cmax and AUCall were significantly higher in GG and GT genotypes than that in TT genotype. ABCB1 and CES1 polymorphisms had no significant impact on the pharmacokinetics of DAB or DABG.

Conclusion

UGT2B15 polymorphisms were associated with difference in DAB glucuronidation and pharmacokinetics in healthy male participants.

Multimorbidity and Venous Thromboembolism: Epidemiological Evidence, Pathophysiology, Prophylactic and Therapeutic Anticoagulation Efficacy, Safety, and Difficulties. A Review

Multimorbidity defined as the co-occurrence of two or more chronic comorbidities, is becoming increasingly burdensome and is a big challenge for healthcare systems all over the world. Venous thromboembolism (VTE) is a potentially lethal disease and is the third most common cardiovascular disease. Multimorbidity is closely associated with VTE, and the VTE risk is approximately fourfold higher in individuals with multimorbidity compared to those without. Notable and consistent evidences show a significant association between multimorbidity and VTE. Plausible mechanisms for the observed associations between multimorbidity and VTE have been outlined, including higher prevalence of identified VTE risk factors, organ function and coagulation function disorders, reduced physical activity, older age, low cognitive level of VTE, and complications following the multimorbidity. Worse therapeutic and prophylactic anticoagulation efficacy, and safety are suggested by the studies, and the VTE recurrence and bleeding risk are higher in patients with multimorbidity compared to those without. Management of the therapeutic and prophylactic anticoagulation for VTE in patients with multimorbidity is difficult, and a balanced and detailed evaluation of the risks of VTE and bleeding is needed, and antiplatelet medications, increased doses or alternative direct oral anticoagulants (DOACs), thromboelastography (TEG), and physical activity may be helpful.

Safety and efficacy of direct oral anticoagulants in kidney transplant recipients: A systematic review and meta-analysis

INTRODUCTION

Direct-acting oral anticoagulants (DOACs) have recently shown potential efficacy for many conditions without the need for regular monitoring. However, their use in kidney transplant recipients (KTRs) is controversial, with no clear consensus on how they compare to vitamin K antagonists (VKAs), which have traditionally been used as preferred anticoagulation therapy in these patients.

METHODS

PubMed, Cochrane Central, and Embase databases were systematically searched up to December 2023 for studies comparing DOACs versus VKAs in KTRs. The main outcomes of interest included venous thromboembolism (VTE), major bleeding, graft failure, mortality, and changes in estimated glomerular filtration rate (eGFR). Statistical analyses were performed using RStudio 4.1.2 software.

PROSPERO ID

CRD42024498423.

RESULTS

Five studies with a total of 959 participants were included. Of these, 433 (45.15 %) participants were treated with DOACs. The mean age of participants was 60.05 years, and 65.9 % were male. The use of DOACs in KTRs was associated with a significant reduction in major bleeding (RR 0.56; 95 % CI 0.35 to 0.90; p = 0.02; I2 = 0 %) and mortality (RR 0.49; 95 % CI 0.33 to 0.74; p = 0.0006; I2 = 0 %). No significant differences were found between groups in VTE (RR 0.82; 95 % CI 0.47 to 1.43; p = 0.48; I2 = 12 %), graft failure (RR 0.43; 95 % CI 0.14 to 1.27; p = 0.13; I2 = 52 %), and eGFR (MD 3.72 mL/Kg/1.73 m2; 95 % CI -1.58 to 9.03; p = 0.17; I2 = 0 %). Evidence quality for some outcomes remains low to moderate, limiting the confidence in these conclusions.

CONCLUSION

Our meta-analysis suggests that DOACs represent an effective anticoagulation strategy in KTR, with a significant reduction in major bleeding and mortality relative to VKA.

Characteristics of Gastrointestinal Bleeding While Taking Direct Oral Anticoagulants in Patients with Nonvalvular Atrial Fibrillation and Differences Among Drugs-A Single-Center Retrospective Cohort Study

Introduction: Direct oral anticoagulants (DOACs) are frequently used to prevent embolism in atrial fibrillation. Gastrointestinal bleeding is frequent, but its drug-specific characteristics remain unclear. This study examined the frequency and characteristics of gastrointestinal bleeding in patients with nonvalvular atrial fibrillation for different DOACs. Methods: The present study included 978 patients receiving treatment with DOACs for nonvalvular atrial fibrillation between 2011 and 2018 and examined the frequencies of clinically significant events including major cardiovascular and cerebrovascular events, hemorrhagic events, or death during the first 5 years of prescription. Gastrointestinal bleeding was evaluated for the frequency, source and severity of gastrointestinal bleeding by DOAC type. Results: The median age of subjects was 73 years (interquartile range, 65-80 years), and 622 (64%) were male. The overall observation period was 2499 person-years. During this period, 102 (4.1/100 person-years) major cardiovascular events and 107 (4.3/100 person-years) clinically significant bleeding were reported, including 60 cases (2.4/100 person-years) of gastrointestinal bleeding and 37 cases (1.5/100 person-years) of all-cause mortality. Gastrointestinal bleeding accounted for more than half of all bleeding events among DOAC users, and bleeding from the lower gastrointestinal tract was more common than that from the upper gastrointestinal tract, particularly with dabigatran. No significant difference was seen in the rate of gastrointestinal bleeding by drug type. Peptic ulcer accounted for half of the events of upper gastrointestinal bleeding, all of which were severe. Conclusions: Gastrointestinal bleeding is frequent among patients taking DOACs, especially from the lower alimentary tract. The tendency was more pronounced with dabigatran. In the upper gastrointestinal tract, severe peptic ulcer bleeding is common and requires caution.

DOACs: role of anti-Xa and drug level monitoring

Direct oral anticoagulants (DOACs) do not require routine monitoring of anticoagulant effect, but measuring DOAC activity may be desirable in specific circumstances to detect whether clinically significant DOAC levels are present (eg, prior to urgent surgery) or to assess whether drug levels are excessively high or excessively low in at-risk patients (eg, after malabsorptive gastrointestinal surgery). Routine coagulation tests, including the international normalized ratio (INR) or activated partial thromboplastin time (aPTT), cannot accurately quantify drug levels but may provide a qualitative assessment of DOAC activity when considering the estimated time to drug clearance based on timing of last drug ingestion and renal and hepatic function. Drug-specific chromogenic and clot-based assays can quantify drug levels but they are not universally available and do not have established therapeutic ranges. In this review, we discuss our approach to measuring DOAC drug levels, including patient selection, interpretation of coagulation testing, and how measurement may inform clinical decision-making in specific scenarios.

Effects of preinjury oral anticoagulants on the outcomes of traumatic brain injury in elderly patients: a systematic review and meta-analysis

BACKGROUND

With the increasing cases of TBI cases in the elderly population taking anticoagulants for comorbidities, there is a need to better understand the safety of new anticoagulants and how to manage anticoagulated TBI patients.

METHODS

A meta-analysis using a random-effect model was conducted to compare the effect of preinjury use of DOACs and VKAs on the outcomes following TBI.

RESULTS

From 1951 studies, 49 studies with a total sample size of 15,180 met our inclusion criteria. Our meta-analysis showed no difference between preinjury use of DOACs or VKAs on ICH progression, in-hospital delayed ICH, delayed ICH at follow-up, and in-hospital mortality, but using DOACs was associated with a lower risk of immediate ICH (OR = 0.58; 95% CI = [0.42; 0.79]; p < 0.01) and neurosurgical interventions (OR = 0.59; 95% CI = [0.42; 0.82]; p < 0.01) compared to VKAs. Moreover, patients on DOACs experienced shorter length of stay in the hospital than those on VKAs (OR = -0.42; 95% CI = [-0.78; -0.07]; p = 0.02).

CONCLUSION

We found a lower risk of immediate ICH and surgical interventions as well as a shorter hospital stay in patients receiving DOACs compared to VKA users before the head injury.

Coccidiomycosis: ankle septic arthritis with an extended incubation period requiring aggressive multidisciplinary surgical intervention

Coccidiomycosis is a regional disease with global importance, with both an expanding endemic area and population, as well as increasing travel. Although unusual, it should be considered in patients with a travel history to endemic areas, even when immunocompetent and outside the usual incubation period. We present a case of isolated ankle septic arthritis which required an aggressive multidisciplinary surgical approach as well as antibiotic therapy.

Evaluation of Drug-Drug Interactions Between Clarithromycin and Direct Oral Anticoagulants Using Physiologically Based Pharmacokinetic Models

Objective: This study assessed the pharmacokinetic (PK) interactions between clarithromycin (a P-glycoprotein [P-gp] inhibitor) and four direct oral anticoagulants (DOACs) (P-gp substrates) using physiologically based PK (PBPK) models to elucidate the influence of P-gp in the interaction between them. Methods: PBPK models for clarithromycin, DABE-dabigatran (DAB), rivaroxaban, apixaban, and edoxaban were constructed using GastroPlus™ (version 9.9), based on physicochemical data and PK parameters from the literature. The models were optimized and validated in healthy subjects. We evaluated the predictive performance of the established model and further assessed the impact of P-gp on the PK of the four DOACs. Successfully validated models were then used to evaluate potential drug-drug interactions (DDIs) between clarithromycin and the DOACs. Results: The established PBPK models accurately described the PK of clarithromycin, DABE-DAB, rivaroxaban, apixaban, and edoxaban. The predicted PK parameters (Cmax, Tmax, AUC0-t) were within 0.5-2 times the observed values. A sensitivity analysis of P-gp parameters indicated that an increase in P-gp expression was reduced by in vivo exposure to DOACs. The models demonstrated good predictive ability for DDIs between clarithromycin and the anticoagulants, and the ratio of the predicted values to the observed values of Cmax and the area under the curve (AUC) in the DDI state was within the range of 0.5-2. Conclusions: Comprehensive PBPK models for clarithromycin, DABE-DAB, rivaroxaban, apixaban, and edoxaban were developed, which can effectively predict DDIs mediated by P-gp's function. These models provide theoretical support for clinical dose adjustments and serve as a foundation for future PBPK model development for DOACs under specific pathological conditions.

Tailoring oral anticoagulant treatment in the era of multi-drug therapies for PAH and CTEPH

The use of oral anticoagulants in the management of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) presents distinct therapeutic challenges and benefits. In PAH, the benefits of oral anticoagulation are uncertain, with studies yielding mixed results on their efficacy and safety. Conversely, oral anticoagulants are a cornerstone in the treatment of CTEPH, where their use is consistently recommended to prevent recurrent thromboembolic events. The choice between vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs) remains a significant clinical question, as each type presents advantages and potential drawbacks. Furthermore, drug-drug interactions (DDIs) with concomitant PAH and CTEPH treatments complicate anticoagulant management, necessitating careful consideration of individual patient regimens. This review examines the current evidence on oral anticoagulant use in PAH and CTEPH and discusses the implications of DDIs within a context of multi-drug treatments, including targeted drugs in PAH.

Impact of elevated direct factor Xa inhibitor plasma levels on perioperative blood loss in patients undergoing urgent surgery

INTRODUCTION

Data on the perioperative bleeding risk associated with elevated plasma levels of direct factor Xa inhibitors (FXa inhibitors) are limited. This study examines perioperative red blood cell (RBC) loss in patients undergoing urgent surgery with a residual FXa inhibitor level exceeding 100 mcg/L and without preoperative FXa inhibitor reversal.

METHODS

This retrospective analysis includes data from 32 patients who underwent urgent noncardiac surgery between 2018 and 2022. This study aims to analyze perioperative RBC loss in patients undergoing urgent surgery with a residual FXa inhibitor level exceeding 100 mcg/L and without preoperative FXa inhibitor antidote-based reversal or unspecific treatment with 4-factor prothrombin complex concentrate (PCC). All patients were managed using a watch-and-wait strategy.

RESULTS

The last determination of FXa inhibitor plasma concentration prior to surgery showed a median of 245 mcg/L (IQR 144-345), with a median time interval of 3.8 h (IQR 2.4-7.2) before incision. Median RBC loss during surgery was 49 mL (IQR 0-253), 189 mL (IQR 104-217) until POD1 and 254 mL (IQR 58-265) until POD3. Only one patient required intraoperative treatment with 4-factor-PCC and none required reversal with andexanet alfa. Linear regression models found no significant influence of FXa inhibitor plasma levels on intraoperative RBC loss. Rivaroxaban was associated with higher RBC loss until postoperative Day 1 compared with apixaban. No thromboembolic events were observed.

CONCLUSION

Despite markedly elevated plasma concentrations of residual direct FXa inhibitors, perioperative RBC loss was limited in patients undergoing urgent noncardiac surgery. The intraoperative watch-and-wait strategy with selective intraoperative FXa inhibitor reversal or treatment only when required appears to be an appropriate approach.

Analysis of hemorrhagic drug-drug interactions between P-gp inhibitors and direct oral anticoagulants from the FDA Adverse Event Reporting System

BACKGROUND

Limited understanding exists regarding the hemorrhagic risk resulting from potential interactions between P-glycoprotein (P-gp) inhibitors and direct oral anticoagulants (DOACs). Utilizing the Food and Drug Administration Adverse Event Reporting System (FAERS) data, we analyzed hemorrhagic adverse events (AEs) linked with the co-administration of P-gp inhibitors and DOACs, aiming to offer guidance for their safe and rational use.

METHODS

Hemorrhagic events associated with P-gp inhibitors in combination with DOACs were scrutinized from the FAERS database. Hemorrhagic signals mining was performed by estimating the reported odds ratios (RORs), corroborated by additive and multiplicative models and a combination risk ratio (PRR) model.

RESULTS

Our analysis covered 4,417,195 cases, revealing 11,967 bleeding events associated with P-gp inhibitors. We observed a significantly higher risk of bleeding with the combination of apixaban and felodipine (ROR 118.84, 95% CI 78.12-180.79, additive model 0.545, multiplicative model 1.253, PRR 22.896 (2450.141)). Moreover, consistent associations were found in the co-administration analyzes of rivaroxaban with dronedarone and diltiazem, and apixaban with losartan, telmisartan, and simvastatin.

CONCLUSION

Our FAERS data analysis unveils varying degrees of bleeding risk associated with the co-administration of P-gp inhibitors and DOACs, underscoring the importance of vigilance about them in clinical practice.

Bempedoic Acid, the First-in-Class Oral ATP Citrate Lyase Inhibitor with Hypocholesterolemic Activity: Clinical Pharmacology and Drug-Drug Interactions

Bempedoic acid is a new drug that improves the control of cholesterol levels, either as monotherapy or in combination with existing lipid-lowering therapies, and shows clinical efficacy in cardiovascular disease patients. Thus, patients with comorbidities and under multiple therapies may be eligible for bempedoic acid, thus facing the potential problem of drug-drug interactions (DDIs). Bempedoic acid is a prodrug administered orally at a fixed daily dose of 180 mg. The dicarboxylic acid is enzymatically activated by conjugation with coenzyme A (CoA) to form the pharmacologically active thioester (bempedoic acid-CoA). This process is catalyzed by very-long-chain acyl-CoA synthetase 1 (ACSVL1), expressed almost exclusively at the hepatic level. Bempedoic acid-CoA is a potent and selective inhibitor of ATP citrate lyase (ACL), a key enzyme in the biosynthetic pathway of cholesterol and fatty acids. The drug reduces low-density lipoprotein-cholesterol (LDL-C) (20-25%), non-high-density lipoprotein-cholesterol (HDL-C) (19%), apolipoprotein B (apoB) (15%), and total cholesterol (16%) in patients with hypercholesterolemia or mixed dyslipidemia. The drug has a favorable pharmacokinetics profile. Bempedoic acid and its metabolites are not substrates or inhibitors/inducers of cytochrome P450 (CYP450) involved in drug metabolism. On the other hand, bempedoic acid-glucuronide is a substrate for organic anion transporter 3 (OAT3). Bempedoic acid and its glucuronide are weak inhibitors of the OAT2, OAT3, and organic anion-transporting polypeptide 1B1 (OATP1B1) and 1B3 (OATP1B3). Thus, bempedoic acid could inhibit (perpetrator) the hepatic uptake of OATP1B1/3 substrate drugs and the renal elimination of OAT2 and OAT3 substrates and could suffer (victim) the effect of OAT3 transporter inhibitors, reducing its renal elimination. Based on these pharmacological characteristics, here, we describe the potential DDIs of bempedoic acid with concomitant medications and the possible clinical implications.

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

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

Safety of Sofosbuvir-Based Direct-Acting Antivirals for Hepatitis C Virus Infection and Direct Oral Anticoagulant Co-Administration

Background: Direct oral anticoagulants (DOACs) are recommended for the management of thrombosis prophylaxis, especially in patients with atrial fibrillation. As substrates of cytochrome P450 (CYP) 3A4 and/or P-glycoprotein, they are implicated in potential drug-drug interactions. NS5A/NS5B inhibitors are direct-acting agents (DAAs) against the Hepatitis C Virus (HCV) infection that exert a mild inhibition of P-glycoprotein without effects on CYP3A4. A DOAC and NS5A/NS5B inhibitor co-administration may lead to an increased risk of bleeding. Real-world data on the concomitant use of DOACs and DAAs are scarce. On this purpose, we perform a retrospective analysis on the risk of vascular adverse events (bleeding and thrombosis) among HCV patients under DOAC/DAA therapy, even in advanced liver disease. Methods: Between May 2015 and April 2023, patients treated with sofosbuvir-based DAA regimens and DOACs were consecutively included in this study from 12 Italian medical centers. Baseline characteristics, especially concerning bleeding risk and liver function, were collected. The occurrence of bleeding events, classified as major and minor, was the primary endpoint. Secondary endpoints were the rate of any thrombotic events and/or the need for discontinuation of one or both treatments. Moreover, a cohort of patients, matched by demographic characteristics (age and sex), that switched to vitamin K antagonists (VKAs) during the antiviral treatment was compared with the DOAC/DAA group. Results: A total of 104 patients were included. Thirty-eight of them (36.5%) were cirrhotic. Atrial fibrillation was an indication for anticoagulation in almost all cases (76%). Rivaroxaban (35.6%) was the most used DOAC, followed by apixaban (26.9%), dabigatran (19.2%) and edoxaban (18.3%). Sofosbuvir/velpatasvir (78.8%) was the most prescribed DAA, and all patients were already on anticoagulant therapy before the start of DAAs. During concomitant DOAC/DAA treatment, no major bleeding events were recorded, while four minor bleeding events occurred, but none resulted in DAA or DOAC discontinuation. At univariate analysis, the only additional risk factor statistically related to bleeding events was the anticoagulant therapy (hazard ratio [HR]: 13.2, 95% confidence interval 1,6-109). Performing an evaluation by a LOGIT binomial analysis with demographic characteristics, the antiplatelet therapy remained statistically associated to bleeding events. No significant differences were found in the rate of clinically relevant bleeding when the main population was compared with the VKA-switched cohort. A single major bleeding event leading to anticoagulation and DAA discontinuation was reported in VKA-switched matched cohort. Conclusions: In our study, the concomitant use of NS5A/NS5B inhibitors with DOAC showed good safety, and the only risk factor associated with bleeding events was the concomitant antiplatelet therapy. These findings support the use of DOACs during sofosbuvir-based HCV treatment, even in advanced liver disease. Replacing DOACs with VKAs does not appear to be of clinical benefit.

Perioperative Management of Patients Taking Direct Oral Anticoagulants: A Review

Importance

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

Observations

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

Conclusions and Relevance

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

To stop or not to stop novel oral anticoagulants prior to performing joint interventional maneuvers? Evidence from a prospective study that the therapy can be maintained

Anticoagulation is common in patients undergoing routine musculoskeletal interventional maneuvers. Previous retrospective studies have established the safety of continuing anticoagulation with novel oral anticoagulants (NOACs) when performing this kind of interventions. Indeed, ultrasound (US)-guided interventional maneuvers have shown a superior safety profile compared to blind anatomical maneuvers. To evaluate prospectively the periprocedural bleeding events in NOAC-anticoagulated patients undergoing interventional articular or periarticular procedures. Consecutive patients diagnosed with inflammatory or degenerative rheumatologic pathology requiring interventional maneuvers were prospectively recruited. Group 1 was treated with NOACs, group 2 was treated with vitamin K antagonists, and group 3 was not anticoagulated. Prior to the international maneuver, NOAC therapy was continuously administered, in regimens dictated by the underlying anticoagulation indication. Demographics, comorbidities, laboratory parameters, locally administered medication (corticosteroids or viscosupplementation), interventional maneuver location, needle size, and local bleeding events were recorded. Post-procedural control was performed at 30 min, 48 h, and 7 days. No articular/periarticular bleeding event occurred in patients treated with NOACs, regardless of their type and dosage, locally administered medication, needle size, location, and number of interventions per individual. Several patients in all groups developed small superficial ecchymoses at the injection site. Our results suggest that NOACs are safe to be used in a continuous regimen prior to US-guided injections, even as dual antithrombotic therapy (in combination with aspirin). The use of lower gauge needles, chosen for viscosupplementation therapy, was not burdened with adverse effects on the procedural outcome. Key Points • Currently, no prospective studies have been performed to establish the safety of continuous NOAC anticoagulation when performing routine intra- or periarticular interventional maneuvers. • The study offers an extensive view on a wide spectrum of intra- and periarticular interventional maneuvers including anatomic targets and needle sizes that were not previously assessed. • The study offers a perspective into performing repetitive maneuvers in the same patient, both over a short time and at longer intervals. • The zero periprocedural bleeding risk observed in our study may reassure practitioners and suggest that US-guided interventional therapeutic interventions are safe in patients treated with a continuous regimen of different NOACs.

Application of a Novel UPLC-MS/MS Method for Analysis of Rivaroxaban Concentrations in Dried Blood Spot and Plasma Samples Collected from Patients with Venous Thrombosis

Despite a higher safety profile compared to vitamin K antagonists, rivaroxaban therapy is still connected with multiple adverse effects, such as a high risk of bleeding. Thus, therapeutic drug monitoring (TDM) of rivaroxaban concentrations is suggested. An alternative to plasma samples can be dried blood spots (DBS), which minimize the cost of sample storage and transport. In this study, we developed a UPLC-MS/MS method for the analysis of rivaroxaban in DBS and plasma samples. Chromatographic separation was achieved on a Zorbax Eclipse Plus C18 column (2.1 × 100 mm; 3.5 µm, Agilent Technologies Inc., Santa Clara, CA, USA) with a mobile phase consisting of water and acetonitrile, both containing 0.1% formic acid. The analytes were detected using a positive ionization mode by multiple reaction monitoring. We validated the method according to ICH guidelines. The precision and accuracy were satisfactory. Extraction recovery was approximately 57% and 66% for DBS and plasma samples, respectively. A high correlation between rivaroxaban concentrations in plasma and DBS samples collected from patients was confirmed with Deming regression. The suitability of both sampling techniques for the rivaroxaban TDM was also verified by Bland-Altman plots based on DBS-predicted and observed plasma concentrations. In addition, we found a significant relationship between rivaroxaban concentrations and coagulation parameters, including prothrombin time (PT) and international normalized ratio (INR).

Effects of the antitumor drugs adagrasib and asciminib on apixaban metabolism in vitro and in vivo

Apixaban is an oral anticoagulant that directly inhibits the target Factor Xa (FXa). In this study, we focused on the in vivo and in vitro effects of adagrasib and asciminib on apixaban metabolism, to discover potential drug-drug interactions (DDI) and explore their inhibitory mechanisms. The levels of apixaban and its metabolite, O-desmethyl-apixaban (M2), were determined by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). In vitro evaluation, the maximum half inhibitory concentration (IC50) of adagrasib in rat liver microsomes (RLM) and human liver microsomes (HLM) against apixaban was 7.99 μM and 117.40 μM, respectively. The IC50 value of asciminib against apixaban in RLM and HLM was 4.28 μM and 18.42 μM, respectively. The results of the analysis on inhibition mechanisms showed that adagrasib inhibited the metabolism of apixaban through a non-competitive mechanism, while asciminib inhibited the metabolism of apixaban through a mixed mechanism. Moreover, the interaction of apixaban with adagrasib and asciminib in Sprague-Dawley (SD) rats was also investigated. It was found that the pharmacokinetic characteristics of apixaban were significantly changed when combined with these two antitumor drugs, where AUC(0-t), AUC(0-∞), t1/2, Tmax, and Cmax were increased, while CLz/F was significantly decreased. But both drugs did not appear to affect the metabolism of M2 in a significant way. Consistent results from in vitro and in vivo demonstrated that both adagrasib and asciminib inhibited the metabolism of apixaban. It provided reference data for the future clinical individualization of apixaban.

Cardiovascular Drug Interactions with Nirmatrelvir/Ritonavir for COVID-19: Considerations for Daily Practice

Cardiovascular disease is associated with progression to severe COVID-19 and patients with the condition are among those in whom early antiviral therapy should be warranted. The combination of nirmatrelvir/ritonavir (Paxlovid®) has been approved for clinical use by the Food and Drug Administration and European Medicines Agency. Because patients with cardiovascular disease are often on polypharmacy, physicians need to be aware of potential drug-drug interactions (DDIs) when treating COVID-19 with nirmatrelvir/ritonavir. Guidance is given for avoiding DDIs, emphasising that preventing and managing potential DDIs with nirmatrelvir/ritonavir requires thorough assessment and knowledge. The present review summarises the clinical pharmacology of nirmatrelvir/ritonavir and provides details on potential DDIs with a focus on daily practice in patients with cardiovascular disease. Particular attention is needed for drugs that are predominantly metabolised by cytochrome P450 3A4, are substrates of P-glycoprotein and have a narrow therapeutic index. Proper management of potential DDIs must balance the benefit of nirmatrelvir/ ritonavir to prevent severe disease with the risk of serious adverse events.

Efficacy and safety of dabigatran and rivaroxaban in atrial fibrillation patients with impaired liver function: a multicenter retrospective cohort study

BACKGROUND

The efficacy and safety of direct oral anticoagulants (DOACs) in atrial fibrillation (AF) patients with impaired liver function (ILF) have not been sufficiently studied. The aim of this study was to evaluate the efficacy and safety of DOACs for stroke prevention in patients with AF and ILF.

METHOD

This study was based on data from 15 centers in China, including 4,982 AF patients. The patients were divided into 2 subgroups based on their liver function status: patients with normal liver function (NLF)(n = 4213) and patients with ILF (n = 769). Logistic regression analysis was used to investigate the risk of total bleeding, major bleeding, thromboembolism, and all-cause deaths in AF patients with NLF and ILF after taking dabigatran or rivaroxaban, respectively.

RESULTS

Among AF patients treated with dabigatran or rivaroxaban, patients with ILF were associated with significantly higher major bleeding, compared with NLF patients (aOR: 4.797; 95% CI: 2.224-10.256; P < 0.001). In patients with NLF, dabigatran (n = 2011) had considerably lower risk of total bleeding than rivaroxaban (n = 2202) (aOR: 1.23; 95% CI: 1.002-1.513; P = 0.049). In patients with ILF, dabigatran (n = 321) significantly favored lower risks of major bleeding compared with rivaroxaban(n = 448) (aOR: 5.484; 95% CI: 1.508-35.269; P = 0.026).

CONCLUSION

After using dabigatran or rivaroxaban, patients with ILF had remarkably increased risk of major bleeding compared with patients with NLF. In AF patients with NLF, dabigatran had the distinct strength of significantly reduced risk of total bleeding compared with rivaroxaban. In patients with AF and ILF, dabigatran use was associated with lower risk for major bleeding compared with rivaroxaban.

New Perspectives on Risk Assessment and Anticoagulation in Elective Spine Surgery Patients: The Impact of Ultra-Minimally Invasive Endoscopic Surgery Techniques on Patients with Cardiac Disease

The advent of ultra-minimally invasive endoscopic spine surgery, characterized by significantly reduced surgery times, minimal blood loss, and minimal tissue trauma, has precipitated a paradigm shift in the preoperative management of patients with cardiac disease undergoing elective spine procedures. This perspective article explores how these advancements have influenced the requirements for preoperative cardiac workups and the protocols surrounding the cessation of anticoagulation and antiplatelet therapies. Traditionally, extensive cardiac evaluations and the need to stop anticoagulation and antiplatelet agents have posed challenges, increasing the risk of cardiac events and delaying surgical interventions. However, the reduced invasiveness of endoscopic spine surgery presents a safer profile for patients with cardiac comorbidities, potentially minimizing the necessity for rigorous cardiac clearance and allowing for more flexible anticoagulation management. This perspective article synthesizes current research and clinical practices to provide a comprehensive overview of these evolving protocols. It also discusses the implications of these changes for patient safety, surgical outcomes, and overall healthcare efficiency. Finally, the article suggests directions for future research, emphasizing the need for updated guidelines that reflect the reduced perioperative risk associated with these innovative surgical techniques. This discussion is pivotal for primary care physicians, surgeons, cardiologists, and the broader medical community in optimizing care for this high-risk patient population.

Incidence of intracranial bleeding in mild traumatic brain injury patients taking oral anticoagulants: a systematic review and meta-analysis

BACKGROUND

Traumatic brain injury (TBI) is one of the leading causes of disability and death worldwide. Most TBI cases occur in older people, because they are at a higher risk of accidental falling. As the population ages, the use of anticoagulants is increasing. Some serious complications of TBI, such as intracranial hemorrhage (ICH), may occur even in mild cases. According to the current guidelines regarding managing mild TBI patients, a CT head scan is recommended for all patients receiving anticoagulation. We aim to assess the incidence of ICH in patients with mild TBI taking oral anticoagulants.

METHODS

Our systematic review and meta-analysis were performed using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) checklist. The protocol was registered in PROSPERO (CRD42024503086). Twenty-eight studies evaluating patients with a mild TBI from ten countries with a total sample size of 11,172, 5671 on DOACs, and 5501 on VKAs were included in our meta-analysis.

RESULTS

The random-effects overall incidence of ICH among oral anticoagulated patients with mild TBI was calculated to be 9.4% [95% CI 7.2-12.1%, I2 = 89%]. The rates of immediate ICH for patients taking DOACs and VKAs were 6.4% and 10.5%, respectively. The overall rate of immediate ICH in anticoagulated mild TBI patients was 8.5% [95% CI 6.6-10.9%], with a high heterogeneity between studies (I2 = 88%). Furthermore, the rates of delayed ICH in patients with mild TBI taking DOACs and VKAs were 1.6% and 1.9%, respectively. The overall incidence of delayed ICH among oral anticoagulated mild TBI patients was 1.7% [95% CI 1-2.8%, I2 = 79%]. The overall rate of ICH among mild TBI patients taking DOAC was calculated to be 7.3% [95% CI 5.2-10.3%], with significant heterogeneity between studies (I2 = 79%). However, the overall ICH rate is higher in patients who take only VKAs 11.3% [95% CI 8.6-14.7%, I2 = 83%]. Patients on DOACs were at lower risk of ICH after mild TBI compared to patients on VKAs (OR = 0.64, 95% CI 0.48-0.86, p < 0.01, I2 = 28%).

CONCLUSION

Our meta-analysis confirms the need for performing brain CT scan in patients with mild TBI patients who receive oral anticoagulants before injury. Due to limited data, further multi-center, prospective studies are warranted to confirm the true incidence of traumatic ICH in patients on anticoagulants.

Common P-glycoprotein (ABCB1) polymorphisms do not seem to be associated with the risk of rivaroxaban-related bleeding events: Preliminary data

INTRODUCTION

Considering conflicting previous reports, we aimed to evaluate whether the common ABCB1 polymorphisms (rs1128503, rs2032582, rs1045642, rs4148738) affected the risk of bleeding in rivaroxaban-treated patients.

MATERIALS AND METHODS

We report preliminary data from a larger nested case-control study. Consecutive adults started on rivaroxaban for any indication requiring > 6 months of treatment were followed-up to one year. Patients who experienced major or non-major clinically relevant bleeding during the initial 6 months were considered cases, whereas subjects free of bleeding over > 6 months were controls. The polymorphisms of interest (rs1128503, rs2032582, rs1045642, rs4148738) were in a strong linkage disequilibrium, hence patients were classified regarding the "load" of variant alleles: 0-2, 3-5 or 6-8. The three subsets were balanced regarding a range of demographic, comorbidity, comedication and genetic characteristics. A logistic model was fitted to probability of bleeding.

RESULTS

There were 60 cases and 220 controls. Raw proportions of cases were similar across the subsets with increasing number of ABCB1 variant alleles (0-2, N = 85; 3-6, N = 133; 6-8, N = 62): 22.4%, 21.8%, and 19.4%, respectively. Fully adjusted probabilities of bleeding were also similar across the subsets: 22.9%, 27.5% and 17.7%, respectively. No trend was observed (linear, t = -0.63, df = 273, P = 0.529; quadratic, t = -1.10, df = 273, P = 0.272). Of the 15 identified haplotypes, the completely variant (c.1236T_c.2677T(A)_c.3435T_c.2482-2236A) (40.7%) and completely wild-type (C_G_C_G) (39.5%) haplotypes prevailed, and had a closely similar prevalence of cases: 21.1% vs. 23.1%, respectively.

CONCLUSIONS

The evaluated common ABCB1 polymorphisms do not seem to affect the risk of early bleeding in patients started on rivaroxaban.

Spontaneous Hemopericardium Associated With Apixaban Use With Newly Diagnosed Malignancy and Acute Kidney Injury: A Case Report

Direct oral anticoagulants have simplified the use of anticoagulation for patients and clinicians. These medications now have indications for non-valvular atrial fibrillation and venous thromboembolism and carry a lower risk of bleeding than warfarin. While bleeding complications are common amongst all anticoagulants, spontaneous hemopericardium is a rarely reported side effect of direct oral anticoagulants, previously reported in patients with concomitant malignancy or kidney injury. We present a case of a patient with recently diagnosed renal malignancy and atrial fibrillation on apixaban who developed a spontaneous hemopericardium that required a pericardial window.

[Translation into French and republication of: "Anticoagulant treatment of cancer-associated thromboembolism"]

Venous thromboembolism (VTE) is a frequent and potentially fatal complication in patients with cancer. During the initial period after the thromboembolic event, a patient receiving anticoagulant treatment is exposed both to a risk of VTE recurrence and also to an elevated bleeding risk conferred by the treatment. For this reason, the choice of anticoagulant is critical. The choice should take into account patient-related factors (such as functional status, age, body mass index, platelet count and renal function), VTE-related factors (such as severity or site), cancer-related factors (such as activity and progression) and treatment related factors (such as drug-drug interactions), which all potentially influence bleeding risk, and patient preference. These should be evaluated carefully for each patient during a multidisciplinary team meeting. For most patients, apixaban or a low molecular-weight heparin is the most appropriate initial choice for anticoagulant treatment. Such treatment should be offered to all patients with active cancer for at least 6months. The patient and treatment should be re-evaluated regularly, and anticoagulant treatment changed when necessary. Continued anticoagulant treatment beyond 6months is justified if the cancer remains active or if the patient experienced recurrence of VTE in the first 6months. In other cases, the interest of continued anticoagulant treatment may be considered on an individual patient basis in collaboration with oncologists.

Direct oral anticoagulants and venous malformations: literature review and retrospective study of 29 patients

Background

Venous malformations (VMs) are commonly associated with localized intravascular coagulopathy leading to elevated D-dimer and risks of hemorrhagic and thromboembolic events, particularly in extensive lesions. While low-molecular-weight heparin (LMWH) has been effective in managing coagulopathy and pain, direct oral anticoagulants (DOACs) emerge as a promising alternative.

Objectives

This study aims to evaluate the efficacy and safety of DOACs in treating VMs associated with localized intravascular coagulopathy, offering a comparative perspective to LMWH.

Methods

A retrospective study was conducted on 29 patients with VMs and secondary localized intravascular coagulopathy treated with DOACs between 2013 and 2023 in a single tertiary center specialized in vascular anomalies. Data were collected from February 24, 2023, to September 1, 2023.

Results

Patients' median age was 40 years (range, 22-76 years), with a female predominance of 66%. Descriptive statistical analysis showed that 85% of patients experienced pain improvement, and 86% showed a reduction in D-dimer by at least 25%, with a mean reduction of 57% (SD, ±32%; IQR, [38-81%]). Additionally, 37% of patients reported a bleeding event, mostly minor.

Conclusion

The study findings suggests that DOACs may serve as an alternative to LMWH for patients with VMs associated with pain management and reduced D-dimer, alongside a low observed risk of major bleeding. Tailored dosing considering the location of the malformation, bleeding and thrombotic tendencies, and laboratory abnormalities is recommended. Future studies with larger cohorts and extended follow-up are necessary for more conclusive evidence on DOACs' role in this patient population.

Drug-Drug Interaction Studies of Esmethadone (REL-1017) Involving CYP3A4- and CYP2D6-Mediated Metabolism

BACKGROUND AND OBJECTIVE

Esmethadone (dextromethadone; d-methadone; S-methadone (+)-methadone; REL-1017) is the opioid inactive dextro-isomer of racemic methadone. Esmethadone is a low potency N-methyl-D-aspartate (NMDA) receptor channel blocker with higher affinity for GluN2D subtypes. Esmethadone showed robust, rapid, and sustained antidepressant effects in patients with major depressive disorder (MDD) with inadequate response to ongoing serotonergic antidepressant treatment.

METHODS

Here we described the results of in vitro and phase 1 clinical trials aimed at investigating the esmethadone metabolism and possible drug-drug interactions.

RESULTS

Esmethadone is primarily metabolized to EDDP (2-ethylene-1,5-dimethyl-3,3-diphenylpyrrolidine) by multiple enzymes, including CYP3A4/5 and CYP2B6. In vitro studies showed that esmethadone inhibits CYP2D6 with IC50 of 9.6 μM and is an inducer of CYP3A4/5. The clinical relevance of the inhibition of CYP2D6 and the induction of CYP3A4 were investigated by co-administering esmethadone and dextromethorphan (a substrate for CYP2D6) or midazolam (a substrate for CYP3A4) in healthy volunteers. The administration of esmethadone at the dosage of 75 mg (which is the loading dose administered to patients in MDD clinical trials) significantly increased the exposure (AUC) of both dextromethorphan and its metabolite dextrorphan by 2.71 and 3.11-fold, respectively. Esmethadone did not modify the pharmacokinetic profile of midazolam, while it increased Cmax and AUC of its metabolite 1'-hydroxymidazolam by 2.4- and 3.8-fold, respectively. A second study evaluated the effect of the CYP3A4 inhibitor cobicistat on the pharmacokinetics of esmethadone. Cobicistat slightly increase (+32%) the total exposure (AUC0-inf) of esmethadone.

CONCLUSIONS

In summary, esmethadone demonstrated a negligible effect on CYP3A4 induction and its metabolism was not meaningfully affected by strong CYP3A4 inhibitors while it increased exposure of CYP2D6-metabolized drugs.

Low-Density Lipoprotein Cholesterol-Lowering Drugs: A Narrative Review

The modern history of cholesterol-lowering drugs started in 1972 when Dr. Akira Endo identified an active compound (compactin) that inhibited cholesterol biosynthesis from the culture broth of blue-green mold (Penicillium citrinum Pen-51). Since 1987, statins have represented the milestone for the treatment of atherosclerotic cardiovascular disease. A new therapy for the treatment of hypercholesterolemia since the discovery of statins is ezetimibe, the first and only agent inhibiting intestinal cholesterol absorption. Ezetimibe was approved by the FDA in October 2002. A year later, the association between gain-of-function PCSK9 genetic mutations and hypercholesterolemia was reported, and this discovery opened a new era in lipid-lowering therapies. Monoclonal antibodies and small-interfering RNA approaches to reduce PCSK9 were developed and approved for clinical use in 2015 and 2022, respectively. Finally, the newly approved bempedoic acid, an oral adenosine triphosphate citrate lyase inhibitor that lowers LDL-C, is able to reduce major adverse cardiovascular events in both primary and secondary prevention. In the present narrative review, we summarize the pharmacological properties and the clinical efficacy of all these agents currently used for a tailored therapy of hypercholesterolemia in patients with atherosclerotic cardiovascular disease.

Novel Thiourea and Oxime Ether Isosteviol-Based Anticoagulants: MD Simulation and ADMET Prediction

Activated blood coagulation factor X (FXa) plays a critical initiation step of the blood-coagulation pathway and is considered a desirable target for anticoagulant drug development. It is reversibly inhibited by nonvitamin K antagonist oral anticoagulants (NOACs) such as apixaban, betrixaban, edoxaban, and rivaroxaban. Thrombosis is extremely common and is one of the leading causes of death in developed countries. In previous studies, novel thiourea and oxime ether isosteviol derivatives as FXa inhibitors were designed through a combination of QSAR studies and molecular docking. In the present contribution, molecular dynamics (MD) simulations were performed for 100 ns to assess binding structures previously predicted by docking and furnish additional information. Moreover, three thiourea- and six oxime ether-designed isosteviol analogs were then examined for their drug-like and ADMET properties. MD simulations demonstrated that four out of the nine investigated isosteviol derivatives, i.e., one thiourea and three oxime ether ISV analogs, form stable complexes with FXa. These derivatives interact with FXa in a manner similar to Food and Drug Administration (FDA)-approved drugs like edoxaban and betrixaban, indicating their potential to inhibit factor Xa activity. One of these derivatives, E24, displays favorable pharmacokinetic properties, positioning it as the most promising drug candidate. This, along with the other three derivatives, can undergo further chemical synthesis and bioassessment.

Anticoagulant treatment of cancer-associated thromboembolism

Venous thromboembolism (VTE) is a frequent and potentially fatal complication in patients with cancer. During the initial period after the thromboembolic event, a patient receiving anticoagulant treatment is exposed both to a risk of VTE recurrence and also to an elevated bleeding risk conferred by the treatment. For this reason, the choice of anticoagulant is critical. The choice should take into account patient-related factors (such as functional status, age, body mass index, platelet count and renal function), VTE-related factors (such as severity or site), cancer-related factors (such as activity and progression) and treatment-related factors (such as drug-drug interactions), which all potentially influence bleeding risk, and patient preference. These should be evaluated carefully for each patient during a multidisciplinary team meeting. For most patients, apixaban or a low molecular-weight heparin is the most appropriate initial choice for anticoagulant treatment. Such treatment should be offered to all patients with active cancer for at least six months. The patient and treatment should be re-evaluated regularly and anticoagulant treatment changed when necessary. Continued anticoagulant treatment beyond six months is justified if the cancer remains active or if the patient experienced recurrence of VTE in the first six months. In other cases, the interest of continued anticoagulant treatment may be considered on an individual patient basis in collaboration with oncologists.

Diagnosis and management of acute lower gastrointestinal bleeding

PURPOSE OF REVIEW

We review and summarize the most recent literature, including evidence-based guidelines, on the evaluation and management of acute lower gastrointestinal bleeding (LGIB).

RECENT FINDINGS

LGIB primarily presents in the elderly, often on the background of comorbidities, and constitutes a significant healthcare and economic burden worldwide. Therefore, acute LGIB requires rapid evaluation, informed decision-making, and evidence-based management decisions. LGIB management involves withholding and possibly reversing precipitating medications and concurrently addressing risk factors, with definitive diagnosis and therapy for the source of bleeding usually performed by endoscopic or radiological means. Recent advancements in LGIB diagnosis and management, including risk stratification tools and novel endoscopic therapeutic techniques have improved LGIB management and patient outcomes. In recent years, the various society guidelines on acute lower gastrointestinal bleeding have been revised and updated accordingly.

SUMMARY

By integrating the most recently published high-quality clinical studies and society guidelines, we provide clinicians with an up-to-date and comprehensive overview on acute LGIB diagnosis and management.

Effectiveness and Safety of Different Oral Anticoagulants with P-glycoprotein/ CYP3A4 Inhibitors: A Network Meta-analysis

BACKGROUND

Metabolism of oral anticoagulants (OAC) is affected by P-glycoprotein (P-gp)/ CYP3A4 enzyme. However, the P-gp/CYP3A4 inhibitors are unavoidably used with OACs.

METHODS

Medline, Cochrane, and Embase were systematically searched for randomized controlled trials and cohort studies from inception till 23rd November, 2022 to assess the safety and effectiveness of OACs when concomitantly used with P-gp/CYP3A4 inhibitors. The primary outcomes were major bleeding and gastrointestinal (GI) bleeding. Secondary outcomes were stroke/systemic embolism (SE), all-cause mortality, any bleeding as well as intracranial hemorrhage (ICH). We estimated summary odds ratios (OR) with 95% credible intervals (CI) using pairwise and network meta-analysis with random effects.

RESULTS

A total of 11 studies involving 37,973 patients were included. When concomitantly used with P-pg/ CYP3A4 inhibitors, network meta-analysis indicated that dabigatran, apixaban, and edoxaban were associated with significantly lower risk of major bleeding compared to rivaroxaban, with ORs of 0.56, 0.51 and 0.48, respectively. Rivaroxaban and dabigatran were associated with a significantly increased risk of GI bleeding than warfarin, apixaban and edoxaban. Dabigatran and apixaban were linked with significantly lower risk of any bleeding compared with warfarin (ORs were 0.75 and 0.68, respectively) or rivaroxaban (ORs were 0.67 and 0.60, respectively). Apixaban (OR 0.32) and edoxaban (OR 0.35) were associated with a lower risk of ICH compared with warfarin. There was no difference between any OACs in terms of stroke/SE or all-cause mortality.

CONCLUSION

When concomitantly used with P-gp/CYP3A4 inhibitors, apixaban and edoxaban were associated with a lower risk of bleeding, though no significant difference in effectiveness was observed among all OACs.

DOAC plasma concentration upon hospital admission in a cohort of trauma patients. An observational real-life study

PURPOSE

Due to a better safety profile, direct oral anticoagulants (DOACs) are increasingly prescribed for prevention of thromboembolic events. However, little is known about DOAC plasma concentrations in trauma patients upon hospital admission. Thus, we investigated the frequency and extent of DOAC possible over- and underdosing in trauma patients upon hospital admission.

METHODS

In this single-center retrospective study, DOAC plasma concentrations of adult trauma patients were analyzed with specific calibrated anti-IIa (dabigatran) and anti-Xa (apixaban, edoxaban and rivaroxaban) tests within 4 h after hospital admission.

RESULTS

A total of 210 trauma patients, admitted between 2019 and 2022, were included in the analyses. Low DOAC levels < 30 ng/mL were detected in 13.3% of the patients. In 7.1% of the patients, DOAC plasma levels ranged between 300-399 ng/mL and further 7.1% exhibited plasma concentrations > 400 ng/mL. The highest incidence of high to very high DOAC plasma concentration was observed for patients on rivaroxaban and dabigatran. A moderate correlation was observed between dabigatran plasma concentration and estimated glomerular filtration rate (rho = - 0.5338, p = 0.0003). For rivaroxaban no clear association between plasma concentration and liver or renal function could be detected. Patients on statins had significantly higher DOAC concentration in comparison with those not taking statins (153 (76-274) vs 108 (51-217) ng/mL, p = 0.046).

CONCLUSION

The current study revealed that patients on dabigatran and rivaroxaban were prone to higher DOAC plasma levels upon hospital admission in comparison with apixaban and edoxaban. DOAC plasma level measurement in trauma patients might be warranted due to unpredictively low or high plasma concentrations. However, the clinical impact of altered plasma levels on both, bleeding and thromboembolic events, remains to be determined by future studies.

Anticoagulation in Patients with Chronic Kidney Disease

BACKGROUND

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

SUMMARY

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

KEY MESSAGES

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

Construction of a risk scoring system using clinical factors and RYR2 polymorphisms for bleeding complications in patients on direct oral anticoagulants

Introduction: Bleeding is one of the most undesirable complications of direct oral anticoagulants (DOACs). While the ryanodine receptor (RYR2) has been related to cardiac diseases, research on bleeding complications is lacking. This study aimed to elucidate the association between RYR2 and bleeding risk to develop the risk scoring system in patients treated with DOACs. Methods: This study was a retrospective analysis of prospectively collected samples. We selected ten SNPs within the RYR2 gene, and two models were constructed (Model I: demographic factors only, Model II: demographic and genetic factors) in multivariable analysis. Independent risk factors for bleeding were used to develop a risk scoring system. Results: A total of 447 patients were included, and 49 experienced either major bleeding or clinically relevant non-major bleeding. In Model I, patients using rivaroxaban and experiencing anemia exhibited an increased bleeding risk after adjusting for covariates. Upon incorporating genetic factors into Model I, a significant association with bleeding was also observed in cases of overdosing on DOACs and in patients with a creatinine clearance (CrCl) < 30 mL/min, in addition to rivaroxaban and anemia (Model II). Among genetic factors, RYR2 rs12594 GG, rs17682073 AA, rs3766871 GG, and rs6678625 T alleles were associated with bleeding complications. The area under the receiver operating characteristic curve (AUROC) of Model I was 0.670, whereas that of Model II increased to 0.803, demonstrating better performance with the inclusion of genetic factors. Using the significant variables in Model II, a risk scoring system was constructed. The predicted bleeding risks for scores of 0, 1-2, 3-4, 5-6, 7-8, and 9-10 points were 0%, 1.2%, 4.6%, 15.7%, 41.7%, and 73.3%, respectively. Conclusion: This study revealed an association between RYR2 and bleeding complications among patients taking DOACs and established a risk scoring system to support individualized DOAC treatment for these patients.

Effective Prevention of Arterial Thrombosis with Albumin-Thrombin Inhibitor Conjugates

Thromboprophylaxis is indicated in patients at an elevated risk of developing thrombotic disorders, typically using direct oral anticoagulants or low-molecular-weight heparins. We postulated that transient thromboprophylaxis (days-weeks) could be provided by a single dose of an anticoagulant engineered for prolonged pharmacokinetics. In the present work, d-phenylalanyl-l-prolyl-l-arginine chloromethyl ketone (PPACK) was used as a model anticoagulant to test the hypothesis that conjugation of thrombin inhibitors to the surface of albumin would provide durable protection against thrombotic insults. Covalent conjugates were formed between albumin and PPACK using click chemistry, and they were tested in vitro using a thrombin activity assay and a clot formation assay. Thromboprophylactic efficacy was tested in mouse models of arterial thrombosis, both chemically induced (FeCl3) and following ischemia-reperfusion (transient middle cerebral artery occlusion; tMCAO). Albumin-PPACK conjugates were shown to have nanomolar potency in both in vitro assays, and following intravenous injection had prolonged circulation. Conjugates did not impact hemostasis (tail clipping) or systemic coagulation parameters in normal mice. Intravenous injection of conjugates prior to FeCl3-induced thrombosis provided significant protection against occlusion of the middle cerebral and common carotid arteries, and injection immediately following ischemia-reperfusion reduced stroke volume measured 3 days after injury by ∼40% in the tMCAO model. The data presented here provide support for the use of albumin-linked anticoagulants as an injectable, long-circulating, safe thromboprophylactic agent. In particular, albumin-PPACK provides significant protection against thrombosis induced by multiple mechanisms, without adversely affecting hemostasis.