Direct oral anticoagulants: An update

Central American and Caribbean Consensus Document for the Optimal Management of Oral Anticoagulation in Patients with Non-Valvular Atrial Fibrillation Endorsed by the Central American and Caribbean Society of Arterial Hypertension and Cardiovascular Prevention

Atrial fibrillation (AF) is the most common arrhythmia in adults. Prevention of the ischaemic risk with oral anticoagulants (OACs) is widely recommended, and current clinical guidelines recommend direct oral anticoagulants (DOACs) as preference therapy for stroke prevention. However, there are currently no clinical practice guidelines or recommendation documents on the optimal management of OACs in patients with AF that specifically address and adapt to the Central American and Caribbean context. The aim of this Delphi-like study is to respond to doubts that may arise in the management of OACs in patients with non-valvular AF in this geographical area. A consensus project was performed on the basis of a systematic review of the literature, a recommended ADOLOPMENT-like approach, and the application of a two-round Delphi survey. In the first round, 31 recommendations were evaluated and 30 reached consensus, of which, 10 unanimously agreed. The study assessed expert opinions in a wide variety of contextualized recommendations for the optimal management of DOACs in patients with non-valvular atrial fibrillation (NVAF). There is a broad consensus on the clinical practice guideline (CPG) statements used related to anticoagulation indication, patient follow-up, anticoagulation therapy complications, COVID-19 management and prevention, and cardiac interventions.

Positive Allosteric Modulation of Antithrombin's Inhibitory Activity by RNA Aptamers

The leading cause of death in adults in the United States is cardiovascular disease, with mortality and morbidity mainly attributed to thromboembolism. Heparin is the most common therapy used for treating venous and arterial thrombosis. Heparin effectively accelerates the inhibition of coagulation proteases thrombin and factor Xa through the serine protease inhibitor (serpin) antithrombin (AT). Heparin is an essential therapeutic anticoagulant because of its effectiveness and the availability of protamine sulfate as an antidote. However, heparin therapy has several limitations. Thus, new anticoagulants, including direct thrombin inhibitors (ie, argatroban) and low-molecular-weight heparins (ie, fondaparinux), are used to treat some thromboembolic disorders. We developed and characterized a family of novel RNA-based aptamers that bind AT using two novel selection schemes. One of the aptamers, AT-16, accelerates factor Xa inhibition by AT in the absence of heparin. AT-16's effect on thrombin inhibition by AT is less effective compared to factor Xa. AT-16 induces a conformational change in AT that is different from that induced by heparin. This study demonstrates that an AT-specific RNA aptamer, AT-16, exhibits a positive allosteric modulator effect on AT's inhibition of factor Xa.

Direct-acting oral anticoagulants in antiphospholipid syndrome: A systematic review

The objective of the systematic review is to analyze the efficacy of direct-acting oral anticoagulants (DOAC) in the prophylaxis of thrombosis in antiphospholipid syndrome (APS). We searched for clinical trials, cohort studies and meta-analyses published from January 1, 2012 to September 30, 2022. Articles that analyzed the efficacy of DOAC in the prevention of thrombosis recurrence, with or without comparison with antivitamin K (VKA) drugs, were selected. DOACs, specifically rivaroxaban and apixaban, were significantly less effective than VKAs in preventing recurrence of thrombosis in patients with APS and prior arterial thrombosis or the concomitant presence of two or three different antiphospholipid antibodies. The proportion of patients with severe bleeding as side effect are similar in those treated with DOAC and with VKA. The results argue against the use of DOAC in the treatment of patients with thrombotic APS.

Prescribing Trends of Oral Anticoagulants from 2010 to 2020 in Shanghai, China: A Retrospective Study

Aim

Non-vitamin K antagonist oral anticoagulants (NOACs) were developed as an alternative to warfarin to prevent thromboembolism in patients with atrial fibrillation (AF), prosthetic heart valves, venous thromboembolism (VTE), or other thrombotic disorders. The aim of this study is to explore the trends in prescribing OACs, including warfarin and NOACs, in Shanghai, China.

Methods

Prescription data of OACs were retrospectively collected from Rx Analysis System from 2010 to 2020 in Shanghai, China. Comparisons were made on the trends of each OACs according to different indications, age groups, and hospital grades. The costs and the contribution of individual OACs were also explored.

Results

Growing trends in overall prescriptions for OACs were observed. The prescriptions of NOACs were significantly increased since 2016, while the prescriptions of warfarin kept decreasing since 2017. A highly statistically significant increase in prescriptions of Rivaroxaban was observed from 2016 to 2020 (P < .001). Despite the price reduction of rivaroxaban in 2018, the total cost of rivaroxaban continued to rise (P < .001). Rivaroxaban emerged as a preferred NOAC in both indications of AF and VTE, and accounted for more than three-quarters of the total costs for OACs since 2019. Compared with rivaroxaban, the prescription numbers of dabigatran and apixaban were much smaller, and the growth of prescriptions were much slower. Differences in prescribing patterns in different indications, age groups, and grades of hospitals were also founded.

Conclusion

There has been a rapid increase in the use of OAC over the last 11 years in Shanghai, China. NOACs have been adopted rapidly, and have been gradually replacing warfarin. Warfarin remains the top choice for certain patients with valvular heart disease. Future studies are warranted considering changes in the OAC use in a larger scale, as well as the rationality and its influence factors on OAC use.

Direct oral anticoagulants toxicity in children: an overview and practical guide

INTRODUCTION

By increasing use of direct oral anticoagulants (DOACs) in adults and children, gradual increase in the number of intentional or unintentional DOAC poisonings among children is suspected in the near future. Hence, clinicians and pharmacists need to be familiar with the clinical features and management of DOAC-toxicity among pediatric population.

AREAS COVERED

This article provides an overview and practical guide to DOAC-toxicity in pediatrics according to the available clinical evidence.

EXPERT OPINION

Based on limited available data, accidental pediatric ingestion of DOACs can be managed by supportive care in most cases. However, serious toxicity may occur following massive overdose, in presence of underlying disorders (renal or hepatic dysfunction) and concurrent anticoagulant therapy. Activated charcoal is recommended for known recent ingestion of DOACs (within 2-4 hours) to reduce the gastrointestinal absorption. Supportive interventions including local hemostatic measures and volume resuscitation are the cornerstone of management of bleeding. Vitamin K and fresh frozen plasma are ineffective for DOAC reversal and thus are not recommended. Currently, safety and efficacy data regarding the use of specific reversal agents (including idarucizumab and andexanet alfa) and 3-factor or 4-factor prothrombin complex concentrate (PCC) or activated PCC (aPCC) among children with DOAC-associated bleeding are lacking.

Factor XI Inhibitors for Prevention and Treatment of Venous Thromboembolism: A Review on the Rationale and Update on Current Evidence

Although anticoagulation therapy has evolved from non-specific drugs (i.e., heparins and vitamin K antagonists) to agents that directly target specific coagulation factors (i.e., direct oral anticoagulants, argatroban, fondaparinux), thrombosis remains a leading cause of death worldwide. Direct oral anticoagulants (i.e., factor IIa- and factor Xa-inhibitors) now dominate clinical practice because of their favorable pharmacological profile and ease of use, particularly in venous thromboembolism (VTE) treatment and stroke prevention in atrial fibrillation. However, despite having a better safety profile than vitamin K antagonists, their bleeding risk is not insignificant. This is true for all currently available anticoagulants, and a high bleeding risk is considered a contraindication to anticoagulation. As a result, ongoing research focuses on developing future anticoagulants with an improved safety profile. Several promising approaches to reduce the bleeding risk involve targeting the intrinsic (or contact activation) pathway of coagulation, with the ultimate goal of preventing thrombosis without impairing hemostasis. Based on epidemiological data on hereditary factor deficiencies and preclinical studies factor XI (FXI) emerged as the most promising candidate target. In this review, we highlight unmet clinical needs of anticoagulation therapy, outlay the rationale and evidence for inhibiting FXI, discuss FXI inhibitors in current clinical trials, conduct an exploratory meta-analysis on their efficacy and safety, and provide an outlook on the potential clinical application of these novel anticoagulants.

Safety and efficacy of direct oral anticoagulants in comparison with warfarin across different BMI ranges: A systematic review and meta-analysis

Background

Many publications have compared various outcomes defining safety and efficacy of DOACs across different BMI ranges. Our meta-analysis compares warfarin and DOACs for its treatment effects over different BMI ranges.

Methods

A systematic search was conducted from inception to May 2021 on PubMed, Scopus and Embase databases. The data was extracted and pooled using a random effects model. Our study consisted of patients being treated for VTE and AF, across different BMI categories. For the comparison of DOAC, risk ratios (RR) with 95% confidence intervals (CIs) were used, whilst for the second comparison between warfarin and DOACs odds ratios (OR) were used.

Results

In our first comparison, 12 studies (n = 254,908 patients) were included. For our second comparison, six studies (n = 109,609 patients) were included. Major bleeding events in the underweight group were higher than normal weight [RR: 1.89 (1.10, 3.23); P = 0.02; I² = 0%]. Overweight patients were related with reduced rates of VTE than in patients with normal BMI [RR: 0.86 (0.76, 0.97); P = 0.02; I² = 0%]. In comparison with patients receiving warfarin, DOACs had significantly reduced risk of major bleeding in normal weight, overweight and obese [OR: 0.64 (0.49, 0.83); P = 0.0007 I² = 90%].

Conclusion

The risk of VTE reduces with an increasing BMI, hence there could be a possible obesity paradox in patients with anticoagulation therapy. In comparison to warfarin, DOACs proved to be the safer option by having a reduced risk of bleeding across all BMI categories.

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Warfarin therapy and its effectiveness for prevention of thromboembolism.

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Effect of warfarin and DOACs over different BMI ranges.

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Safety and efficacy of DOACs across different BMI ranges.

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Lower risk of bleeding in normal weight, overweight, and obese patients with DOACs.

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Warfarin and DOACs across different BMI categories in VTE and AF patients.

Factor Xa Inhibitors for Patients after Mechanical Heart Valve Replacement?

Patients with a mechanical heart valve need a lifelong anticoagulation due to the increased risk of valve thrombosis and thrombo-embolism. Currently, vitamin K antagonists (VKA) are the only approved class of oral anticoagulants, but relevant interactions and side effects lead to a large number of patients not achieving the optimal therapeutic target international normalized ration (INR). Therefore, steady measurements of the INR are imperative to ensure potent anticoagulation within a distinctive range. Direct oral anticoagulants (DOACs) with newer agents could serve as a possible alternative to VKAs in this patient cohort. DOACs are approved for several indications, e.g., atrial fibrillation (AF). They only have a minor interaction potential, which is why monitoring is not needed. Thereby, DOACs improve the livability of patients in need of chronical anticoagulation compared with VKAs. In contrast to dual platelet inhibition using aspirin in combination with an ADP receptor antagonist and the direct thrombin inhibitor dabigatran, the oral factor Xa inhibitors apixaban and rivaroxaban show promising results according to current evidence. In small-scale studies, factor Xa inhibitors were able to prevent thrombosis and thrombo-embolic events in patients with mechanical heart valves. Finally, DOACs seem to represent a feasible treatment option in patients with mechanical heart valves, but further studies are needed to evaluate clinical safety. In addition to the ongoing PROACT Xa trial with apixaban in patients after aortic On-X valve implantation, studies in an all-comer collective with rivaroxaban could be promising.

Direct oral anticoagulant safety during breastfeeding: a narrative review

PURPOSE

There are limited data regarding the safety of direct oral anticoagulants (DOACs) during breastfeeding. The aim of the present study is to investigate the extent of excretion of DOACs into human milk according to the available clinical and experimental studies.

METHODS

On 16th January 2021, we systematically searched PubMed, Scopus, Embase, and Web of Science for all studies which investigated DOACs in breastfeeding without any time frame and language limitation. Search keywords were [breastfeeding, breast feeding, breastfed, lactation, milk secretion OR milk] AND [apixaban OR Eliquist OR rivaroxaban OR Xarelto OR edoxaban OR Savaysa OR dabigatran OR Pradaxa OR dabigatran etexilate OR dabigatran etexilate mesylate OR direct oral anticoagulant OR DOAC OR new oral anticoagulant OR NOAC]. Finally, we identified six articles which reported DOAC use during breastfeeding or lactation.

RESULTS AND CONCLUSION

According to the available limited data, dabigatran has the least excretion in human breast milk. Rivaroxaban and dabigatran both have acceptable milk excretion cutoffs, whereas apixaban milk excretion is greater than the maximum allowed range. Further well-designed studies with larger sample sizes are required to generate consistent comparable data and clarify benefits and risks of each DOAC during breastfeeding.

A simple and sensitive HILIC-based UHPLC-MS/MS method for quantifying of rivaroxaban in dried blood spots: Application in comparison with the plasma sample method

Rivaroxaban, indicated for the treatment of atrial fibrillation, deep vein thrombosis, pulmonary embolism, and coronary or peripheral artery disease, is one of the most frequently used direct oral anticoagulants. Therapeutic drug monitoring [TDM] is essential to minimize bleeding and thrombosis during personalized rivaroxaban treatment. An efficient and reliable analytical technique is required to quatify the rivaroxaban during its therapeutic indication. Dried blood spots (DBSs) sampling is a convenient bioanalytical method with minimal invasive blood drawing, long-term stability, and low shipment and storage costs. Therfore, DBS sampling technique is growing rapidly for TDM of drugs in medical care. This study developed an ultra high performance liquid chromatography-tandem mass spectrometry method of quantitating rivaroxaban in DBSs samples using the isotopic labeled analog (rivaroxaban-d4) as an internal standard (IS). Rivaroxaban and IS were separated on an Acquity HILIC column and eluted with a mobile-phase composition of acetonitrile and 20 mM ammonium acetate in the ratio of 95:5 at a flow rate of 0.3 mL/min. The precursor-to-product ion transitions of 436.03 ˃ 144.9 for rivaroxaban and 440.04 ˃ 144.9 for IS were used to quantify in multiple reaction monitoring mode. The method was accurate and precise in the 2.06-1000 ng/mL calibration range without hematocrit and blood spot volume effects. Rivaroxaban was stable in DBSs samples under different anticipated storage and temperature conditions. We observed good correlation between the plasma concentration and the DBSs concentration, indicating that the proposed DBSs method is suitable for monitoring the rivaroxaban concentration using a simple and convenient sample collection procedure.

Advanced delivery strategies facilitating oral absorption of heparins

Heparins show great anticoagulant effect with few side effects, and are administered by subcutaneous or intravenous route in clinics. To improve patient compliance, oral administration is an alternative route. Nonetheless, oral administration of heparins still faces enormous challenges due to the multiple obstacles. This review briefly analyzes a series of barriers ranging from poorly physicochemical properties of heparins, to harsh biological barriers including gastrointestinal degradation and pre-systemic metabolism. Moreover, several approaches have been developed to overcome these obstacles, such as improving stability of heparins in the gastrointestinal tract, enhancing the intestinal epithelia permeability and facilitating lymphatic delivery of heparins. Overall, this review aims to provide insights concerning advanced delivery strategies facilitating oral absorption of heparins.

Prophylaxis of venous thromboembolism in medical patients

Venous thromboembolism (VTE) is a prevalent and serious complication in hospitalized medical patients. Pulmonary embolism is the most common preventable cause of hospital death. VTE extends hospitalization, with a higher resource consumption and an increase in healthcare costs. Risk factors for VTE include intrinsic factors and those related to hospitalization. It is important to know and to identify these factors at the moment of hospital admission and during the course of disease. VTE prophylaxis has demonstrated to be an efficient and effective action. Its implementation reduces life-threatening pulmonary embolism, symptomatic deep vein thrombosis and death rate three months after discharge. An individual and detailed assessment of prophylaxis risk-benefit is a priority. In our country, low molecular weight heparins are still the first option for VTE pharmacological prophylaxis. In those patients at high risk of bleeding or in whom anticoagulation is contraindicated mechanical methods could be used.

Antithrombotic Therapy of a Young Adult with Giant Left Main Coronary Artery Aneurysm

Giant coronary artery aneurysm (CAA) is a rare disorder, defined as coronary artery dilatation, in which the diameter of the coronary artery exceeds more than 1.5 times of its normal size. The most common cause of CAA is coronary atherosclerosis for adults and Kawasaki disease (KD) for children and adolescents (especially for the giant CAA that occurred in adolescence). CAA complications include thrombus, acute myocardial infarction (AMI), vasospasm, rupture, ischemia, heart failure, and arrhythmia. So, antithrombotic therapy is crucial for patients with giant CAA.Although giant CAA has been reported in some cases before, few of these cases described antithrombotic therapy particularly, let alone informed direct oral anticoagulant (DOAC) use in these patients. Here, we report a case of a young patient with acute coronary artery disease caused by huge CAA. Rivaroxaban combined with clopidogrel was used for his antithrombotic therapy. Moreover, we reviewed the existing reports to provide an overview of antithrombotic treatment in patients with giant CAA.

Facing real-life with direct oral anticoagulants in patients with nonvalvular atrial fibrillation: outcomes from the first observational and prospective study in a Spanish population

Aim: To analyze the effectiveness and safety of direct oral anticoagulants (DOACs) in atrial fibrillation (AF) patients attended in clinical practice. Methods: Observational and prospective study of AF patients that started treatment with DOACs. Results: 1443 patients (age 77.2 ± 9.7 years, CHA2DS2-VASc = 4.1 ± 1.5) were included. 46.0% were taking rivaroxaban, 24.4% dabigatran, 22.5% apixaban and 7.1% edoxaban. Patients taking dabigatran were younger, had lower CHA2DS2-VASc and lesser renal insufficiency. Patients taking apixaban had higher CHA2DS2-VASc and more renal insufficiency. Rates of stroke/major bleeding/intracranial bleeding were 0.7/1.3/0.2 events/100 patient-years, respectively. Conclusion: This was the first prospective study that analyzed the use of all DOACs in AF patients in Spain, showing a good profile in terms of safety and effectiveness in accordance with pivotal studies.

Pharmacogenomics of Novel Direct Oral Anticoagulants: Newly Identified Genes and Genetic Variants

Direct oral anticoagulants (DOAC) have shown an upward prescribing trend in recent years due to favorable pharmacokinetics and pharmacodynamics without requirement for routine coagulation monitoring. However, recent studies have documented inter-individual variability in plasma drug levels of DOACs. Pharmacogenomics of DOACs is a relatively new area of research. There is a need to understand the role of pharmacogenomics in the interpatient variability of the four most commonly prescribed DOACs, namely dabigatran, rivaroxaban, apixaban, and edoxaban. We performed an extensive search of recently published research articles including clinical trials and in-vitro studies in PubMed, particularly those focusing on genetic loci, single nucleotide polymorphisms (SNPs), and DNA polymorphisms, and their effect on inter-individual variation of DOACs. Additionally, we also focused on commonly associated drug-drug interactions of DOACs. CES1 and ABCB1 SNPs are the most common documented genetic variants that contribute to alteration in peak and trough levels of dabigatran with demonstrated clinical impact. ABCB1 SNPs are implicated in alteration of plasma drug levels of rivaroxaban and apixaban. Studies conducted with factor Xa, ABCB1, SLCOB1, CYP2C9, and VKORC1 genetic variants did not reveal any significant association with plasma drug levels of edoxaban. Pharmacokinetic drug-drug interactions of dabigatran are mainly mediated by p-glycoprotein. Strong inhibitors and inducers of CYP3A4 and p-glycoprotein should be avoided in patients treated with rivaroxaban, apixaban, and edoxaban. We conclude that some of the inter-individual variability of DOACs can be attributed to alteration of genetic variants of gene loci and drug-drug interactions. Future research should be focused on exploring new genetic variants, their effect, and molecular mechanisms that contribute to alteration of plasma levels of DOACs.

Multidisciplinary approach to the management of patients with pulmonary embolism and deep vein thrombosis: a consensus on diagnosis, traditional therapy and therapy with rivaroxaban

Despite the availability of updated guidelines for the diagnosis and treatment of venous thromboembolism (VTE), the management of this disorder in clinical practice is often not standardized, given the different degree of compliance with official recommendations by the various involved specialists. The aim of this consensus paper, as a result of a board of experts in thromboembolism, is to define strategies to improve the quality of patients' care and the efficiency of healthcare resources utilization, by means of: (a) analysis of the guidelines for diagnosis and treatment of VTE; (b) analysis of diagnostic and therapeutic algorithms currently used in clinical practice by different specialists; (c) agreement on a common algorithm for diagnosis and treatment of VTE in different clinical settings; (d) definition of the possible role of the new oral anticoagulant agents (NOAC), such as rivaroxaban, based on their potential benefits for both acute and chronic therapy. The so-called "single drug approach" (as opposed to the traditional heparin/VKA combination), which can be adopted with these drugs, makes anticoagulation more convenient for both patients and healthcare providers, without the need for a close monitoring of the hemocoagulative status, and with a concomitant reduction of length of hospitalization and treatment costs. Among NOACs, in this paper we focused on rivaroxaban only because it was the unique available NOAC in Italy for the treatment of VTE at the time the manuscript was written. Concerning rivaroxaban, the results of two phase III, randomized and controlled trials confirm the non-inferiority of this drug compared to standard therapy (enoxaparin/warfarin) for the treatment of patients with pulmonary embolism (EINSTEIN PE Study) or deep vein thrombosis (EINSTEIN DVT Study) in terms of both efficacy and safety, supporting its use as an effective therapeutic option for these disorders.