Direct oral anticoagulants: unique properties and practical approaches to management

Rivaroxaban improves vascular response in LPS-induced acute inflammation in experimental models

Rivaroxaban (RVX) was suggested to possess anti-inflammatory and vascular tone modulatory effects. The goal of this study was to investigate whether RVX impacts lipopolysaccharide (LPS)-induced acute vascular inflammatory response. Male rats were treated with 5 mg/kg RVX (oral gavage) followed by 10 mg/kg LPS i.p injection. Circulating levels of IL-6, MCP-1, VCAM-1, and ICAM-1 were measured in plasma 6 and 24 hours after LPS injection, while isolated aorta was used for gene expression analysis, immunohistochemistry, and vascular tone evaluation. RVX pre-treatment significantly reduced LPS mediated increase after 6h and 24h for IL-6 (4.4±2.2 and 2.8±1.7 fold), MCP-1 (1.4±1.5 and 1.3±1.4 fold) VCAM-1 (1.8±2.0 and 1.7±2.1 fold). A similar trend was observed in the aorta for iNOS (5.5±3.3 and 3.3±1.9 folds reduction, P<0.01 and P<0.001, respectively), VCAM-1 (1.3±1.2 and 1.4±1.3 fold reduction, P<0.05), and MCP-1 (3.9±2.2 and 1.9±1.6 fold reduction, P<0.01). Moreover, RVX pre-treatment, improved LPS-induced PE contractile dysfunction in aortic rings (Control vs LPS, Emax reduction = 35.4 and 31.19%, P<0.001; Control vs LPS+RVX, Emax reduction = 10.83 and 11.48%, P>0.05, respectively), resulting in 24.5% and 19.7% change in maximal constriction in LPS and LPS+RVX respectively. These data indicate that RVX pre-treatment attenuates LPS-induced acute vascular inflammation and contractile dysfunction.

Consequences of pre-injury utilization of direct oral anticoagulants in patients with traumatic brain injury: A systematic review and meta-analysis

BACKGROUND

The rapid adoption and widespread use of direct oral anticoagulants (DOACs) has outpaced research efforts to establish their effects in bleeding trauma patients. In patients with complicated traumatic brain injury (TBI) caused by intracranial hemorrhage, DOAC use may be associated with higher bleeding volume and potentially more disastrous sequelae than use of vitamin K antagonists (VKAs). In the current systematic review and meta-analysis we set out to evaluate the literature on the relationship between preinjury DOAC use and course of the intracranial hemorrhage. (ICH), its treatment and mortality rates in TBI patients, and to compare these outcomes to those of patients with preinjury VKA use.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were searched using a search strategy including three main terms: "traumatic brain injury," "direct oral anticoagulants," and "vitamin K antagonists." There were 1,446 abstracts screened, and ultimately, six included articles. Random effects modeling meta-analysis was performed on in-hospital mortality, ICH progression and neurosurgical intervention rate.

RESULTS

All cohorts had similar baseline and emergency department parameters. Within individual studies surgery rate, reversal agents used, ICH progression and in-hospital mortality differed significantly between DOAC and VKA cohorts. Meta-analysis showed no significant difference in in-hospital mortality (odds ratio [OR], 0.98; 95% confidence interval [CI], 0.23-4.06; I = 76%; p = 0.97), neurosurgical interventions (OR, 0.48; 95% CI, 0.14-1.63; p = 0.24), or ICH progression rates (OR, 1.86; 95% CI, 0.32-10.66; p = 0.49) between patients that used preinjury DOACs versus patients that used VKAs.

CONCLUSION

Direct oral anticoagulant-using mild TBI patients do not appear to be at an increased risk of in-hospital mortality, nor of increased ICH progression or surgery rates, compared with those taking VKAs.

LEVEL OF EVIDENCE

Systematic review, level III.

Practical guide to choosing dabigatran 150 mg twice daily or apixaban 5 mg twice daily for patients with atrial fibrillation

Based on previous reports, we propose a practical guide to choose dabigatran 150 mg twice daily or apixaban 5 mg twice daily for patients with atrial fibrillation. We recommend the use of dabigatran 150 mg twice daily for patients with atrial fibrillation who have a high risk of embolism (e.g., ischemic stroke on other oral anticoagulants, presence of left atrial appendage thrombus) and a low risk of bleeding. However, the prevalence of such patients with atrial fibrillation is considered low because patients with atrial fibrillation with a high risk of embolism usually have a high risk of bleeding. In most other patients with atrial fibrillation, the use of apixaban 5 mg twice daily should be considered.

Insight into the perioperative management of direct oral anticoagulants: concerns and considerations

INTRODUCTION

Direct oral anticoagulants (DOACs) have gained momentum in recent years in patients requiring anticoagulation for the prevention and management of venous thromboembolism and thromboembolic events caused by atrial fibrillation. The use of these agents involves potential bleeding complications, particularly during invasive procedures. With increasing use of DOACs, adequate knowledge regarding the perioperative management of patients on DOACs has become indispensable.

AREAS COVERED

This review covers the indications, mechanism of action, and pharmacokinetics of DOACs and their management in different perioperative settings based on various current guidelines and practices. The role of bridging therapy with heparin and the recently developed reversal agents are also discussed.

EXPERT OPINION

The perioperative management of DOACs is influenced by drug pharmacokinetics, potential comorbidities of the patient and perioperative thrombotic and bleeding risk. In low bleeding risk and minor procedures, continuing DOACs seems to be safe. Interrupting DOACs in high-risk procedures might be necessary and should be based on the elimination half-life of the drug and renal function of the patient. Further research is needed to better clarify the role of recently developed reversal agents in the perioperative setting and to identify specific laboratory tests to guide the perioperative management of DOACs.

Coagulation, Microenvironment and Liver Fibrosis

Fibrosis is the main consequence of any kind of chronic liver damage. Coagulation and thrombin generation are crucial in the physiological response to tissue injury; however, the inappropriate and uncontrolled activation of coagulation cascade may lead to fibrosis development due to the involvement of several cellular types and biochemical pathways in response to thrombin generation. In the liver, hepatic stellate cells and sinusoidal endothelial cells orchestrate fibrogenic response to chronic damage. Thrombin interacts with these cytotypes mainly through protease-activated receptors (PARs), which are expressed by endothelium, platelets and hepatic stellate cells. This review focuses on the impact of coagulation in liver fibrogenesis, describes receptors and pathways involved and explores the potential antifibrotic properties of drugs active in hemostasis in studies with cells, animal models of liver damage and humans.

Reversal Strategies for Intracranial Hemorrhage Related to Direct Oral Anticoagulant Medications

Direct oral anticoagulants (DOACs) are a new class of anticoagulants that directly inhibit either thrombin or factor Xa in the coagulation cascade. They are being increasingly used instead of warfarin or other vitamin K antagonists (VKAs). Adverse side effects of DOACs may result in hemorrhagic complications, including life-threatening intracranial hemorrhage (ICH), though to a much lesser degree than VKAs. Currently there are relatively limited indications for DOACS but their usage is certain to expand with the availability of their respective specific reversal agents. Currently, only idarucizumab (antidote for dabigatran) has been United States Food and Drug Administration- (FDA-) approved, but others (andexanet-α and ciraparantag) may be approved in near future, and the development and availability of such reversal agents have the potential to dramatically change the current anticoagulant use by providing reversal of multiple oral anticoagulants. Until all the DOACs have FDA-approved reversal agents, the treatment of the dreaded side effects of bleeding is challenging. This article is an attempt to provide an overview of the management of hemorrhage, especially ICH, related to DOAC use.

Diagnosis and management of patients with atrial fibrillation

Atrial fibrillation is a common cardiac arrhythmia and is the most frequent arrhythmia experienced by older people. It is caused by chaotic electrical activity in the atria, leading to an irregular and often rapid heart rate. Atrial fibrillation is associated with an increased risk of ischaemic stroke, resulting from the turbulent blood flow in the atria. This article details the presentation of, and risk factors associated with, developing atrial fibrillation, the importance of reducing the risk of adverse events such as stroke, and the treatment options available. It also outlines the nursing role in the care of patients with the condition, as part of a multidisciplinary team approach.

Outcome of Patients Receiving Thrombolytic Therapy While on Rivaroxaban for Nonvalvular Atrial Fibrillation (from Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation)

The safety of intravenous thrombolysis in patients taking rivaroxaban has not been well established. We retrospectively analyzed the outcomes of all patients who received thrombolytic therapy in the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF). A review of medical and adverse event records for patients receiving thrombolytic therapy while enrolled in ROCKET AF was performed to determine their baseline characteristics, indications for thrombolysis, and type of agent used. Safety end points were 30-day post-thrombolytic rates of stroke, bleeding, and mortality. A total of 28 patients in ROCKET AF received thrombolytic therapy, with 19 patients on rivaroxaban and 9 patients on warfarin. Ischemic stroke was the most common indication for thrombolysis (n = 10), and alteplase was the most commonly used fibrinolytic agent (n = 14). Of the 19 patients in the rivaroxaban group, there were 2 nonfatal bleeding events and 2 deaths, mostly occurring when thrombolytic therapy was administered within 48 hours of the last rivaroxaban dose. Of the 9 patients in the warfarin group, there was 1 nonfatal bleeding event and 3 deaths, most occurring when thrombolytic therapy was administered outside of 48 hours from the last warfarin dose. In conclusion, these observations suggest that careful assessment of the time since the last dose may be of clinical significance in patients on novel oral anticoagulants who require emergent thrombolysis.

Paramagnetic micro-particles as a tool for rapid quantification of apixaban, dabigatran, edoxaban and rivaroxaban in human plasma by UHPLC-MS/MS

Background:

Assessment of the anticoagulant activity of direct oral anticoagulants (DOACs) is justified in special clinical situations. Here, we evaluated two independent extraction methods and developed a multi-analyte ultra-high performance liquid chromatography tandem mass (UHPLC-MS/MS) method for the quantification of apixaban, dabigatran, edoxaban and rivaroxaban in human plasma.

Methods:

Routine extraction based on protein precipitation with acetonitrile and subsequent centrifugation was compared to sample clean-up using commercial paramagnetic micro-particles and subsequent magnetic depletion. Stable isotope-labeled analogs of all analytes were employed as internal standards. The method was validated according to international guidelines in terms of linearity, precision, trueness, sensitivity, recovery and matrix effects. The performances of both extraction methods were assessed in clinical samples obtained from patients treated with either apixaban or rivaroxaban. Additionally, we report on a patient with nonadherence to rivaroxaban treatment and fulminant pulmonary embolism.

Results:

The method was linear from 2 to 500 ng/mL for all analytes, and quantification of DOACs was established within a run time of 2.0 min. Based on MS/MS analyte responses, relative matrix effects were better controlled for dabigatran after extraction with paramagnetic micro-particles. Internal standards fully compensated for recovery and matrix effects in all assays, yielding equivalent results for both methods. Apixaban and rivaroxaban concentrations determined in clinical samples after extraction with both methods were in good agreement (R

Conclusions:

A rapid and accurate multi-component UHPLC-MS/MS method for the quantification of four DOACs in human plasma was established. Paramagnetic micro-particles appear suitable for clean-up of plasma samples for LC-MS/MS-based therapeutic drug monitoring purposes.

New Oral Anticoagulants and Their Reversal Agents

OPINION STATEMENT

Direct oral anticoagulants (DOAC) are an attractive therapeutic option for anticoagulant treatment in the setting of venous thromboembolism or non-valvular atrial fibrillation. These drugs overall appear to have a lower risk of life-threatening hemorrhage than the vitamin K antagonists. In addition, they demonstrate more predictable and stable pharmacokinetics. Measurement of the degree of anticoagulation is desirable in patients with DOAC-associated hemorrhage, but commonly available coagulation assays show poor sensitivity for degree of DOAC effect. DOAC-specific tests are time consuming and not widely available. All coagulation tests should be interpreted considering the timing of last intake and renal function. When life-threatening bleeding occurs, hemostasis should be restored as rapidly as possible. Non-specific prohemostatic drugs may have a role in DOAC reversal, and specific antidotes are at different stages of development. In this review, we provide a summary of DOAC characteristics and an overview of the different therapeutic options available for DOAC reversal.