Reduced Anticoagulant Effect of Dabigatran in a Patient Receiving Concomitant Phenytoin

Dabigatran, a direct thrombin inhibitor, is an oral anticoagulant indicated for the prevention of stroke in patients with atrial fibrillation (AF) and for the treatment and prevention of deep vein thrombosis and pulmonary embolism. Dabigatran, as well as the other new anticoagulants—rivaroxaban, apixaban, and edoxaban—are substrates for P‐glycoprotein (P‐gp). Although the U.S. labeling for rivaroxaban and apixaban states to avoid concomitant use with phenytoin, a known P‐gp inducer, the U.S. labeling for dabigatran and edoxaban are less clear. We describe the first case report, to our knowledge, documenting a drug interaction between phenytoin and dabigatran by using laboratory measurements of dabigatran serum concentrations. A 45‐year‐old African‐American man was admitted to the inpatient cardiology service following defibrillations from his implantable cardioverter defibrillator. The patient was evaluated and received appropriate antitachycardia pacing for atrial tachyarrhythmias for an episode of ventricular tachycardia (VT), and antiarrhythmic therapy with sotalol was initiated to reduce both his AF and VT burden. On review of the patient's medications for potential interactions, it was discovered that the patient was taking both dabigatran and phenytoin. To determine the magnitude of this drug interaction prior to making a change in his anticoagulation regimen, a dabigatran serum concentration was measured. This concentration was undetectable, indicating that phenytoin had a significant influence on dabigatran's metabolism and that this patient was at high risk for stroke. Clinicians should be aware of this interaction between phenytoin and dabigatran as well as with all other new oral anticoagulants. In patients taking phenytoin who require an anticoagulant, only warfarin should be prescribed to minimize the risk of stroke. In addition, the prescribing information for dabigatran should be updated to include other medications that result in a significant reduction in dabigatran serum concentrations, such as phenytoin.     

房颤合并肝硬化患者的口服抗凝药物选择及抗栓策略研究

目的 探讨房颤合并肝硬化患者临床治疗中口服抗凝药物的选择及安全性。方法 在1例房颤合并乙型肝炎肝硬化患者房间隔修补术后抗栓方案的制定中,通过查阅指南和文献,总结、分析房颤合并肝硬化患者口服抗凝药物的疗效及安全性评价现状。结果 通过综合评估患者情况,停用华法林,予达比加群酯110 mg,bid,联合氯吡格雷75 mg,qd抗栓6个月,之后达比加群酯110 mg,bid长期抗凝治疗。结论 房颤合并肝硬化患者抗栓治疗,应充分评估血栓及出血风险,制定个体化的抗栓策略。房颤合并Child-Pugh A级肝硬化,新型口服抗凝药均可使用;合并Child-Pugh C级肝硬化,口服抗凝剂均不建议使用;合并Child-Pugh B级肝硬化,出血风险高的患者长期抗凝治疗中可选用小剂量达比加群酯。     

Oral anticoagulant adherence and switching in patients with atrial fibrillation: A prospective observational study

BackgroundAdherence to oral anticoagulants (OACs) in patients with atrial fibrillation (AF) is important in preventing stroke. The dominance of retrospective studies using administrative data has led to a lack of data on psychosocial determinants of adherence and prevented comparison of adherence between OAC drug classes. OAC switching is another aspect of adherence that is unexplored.MethodsA prospective design was utilized to measure AF patients’ self-reported adherence and OAC switching, and to identify their clinical, demographic, and psychosocial determinants. Participants were recruited from specialized AF clinics in Canada and followed for up to 2 years. Data were collected via telephone every 3–4 months using a structured survey. Adherence was measured using the Morisky Medication Adherence scale (©MMAS-8).ResultsThe included participants (N = 306) were followed for a median follow up time of 14.1 months and had an average of 3.2(SD 1.4) study visits. The mean self-reported adherence on the ©MMAS-8 was 7.28(SD 0.71) for patients receiving care at specialized AF clinics. Older age, experiencing a bleed, and higher satisfaction with the burden of medications were significantly associated with higher adherence. Drug class did not have any significant impact on adherence. 7.8% of the cohort experienced a switch with most of them being from warfarin to DOAC. Taking warfarin as the index medication, experiencing a bleed and older age were significantly associated with higher odds of switching.ConclusionPatients with AF reported high adherence to their OAC therapy however being on DOAC may not translate to better adherence compared to VKA. Improving satisfaction with the burden of therapy is important in improving adherence.     

某院口服抗凝药使用现状及安全性评价

目的 为临床合理使用口服抗凝药(OAC)提供参考。方法 通过医院信息系统收集2016年至2018年开具OAC患者的病历资料,了解OAC中华法林与口服非维生素K拮抗剂抗凝药(NOAC,包括利伐沙班、达比加群酯)的使用现状,对各OAC使用人次、金额、用药适应证等信息进行统计,计算再入院率及不良事件发生率,以评估OAC安全性。结果 该院服用OAC的患者逐年增加,服用NOAC的患者构成比逐年增加,但未超过华法林;与NOAC相比,华法林平均费用较低,但所致再入院率及大出血事件发生率较高。结论 综合考虑成本与效用,华法林仍是大多数服用OAC患者的首选,但不良事件风险较高,总体安全性不如NOAC。     

Challenges and Treatment for Stroke Prophylaxis in Patients with Atrial Fibrillation in Mexico: A Review

Atrial fibrillation (AF) is associated with an increased risk of stroke. AF-related strokes cause greater disability and mortality than those in patients without AF, and are associated with a significant clinical and economic burden in Mexico. Antithrombotic therapy reduces stroke risk in patients with AF and is recommended for all patients except those classified as having a low stroke risk. However, its use is suboptimal all around the world; one study showed that only 4 % of Mexican patients with AF who presented with ischemic stroke were in the therapeutic range for anticoagulation. Vitamin K antagonists (VKAs) such as warfarin or acenocoumarin have long been the only oral anticoagulants for stroke prevention in AF. Although effective, VKAs have disadvantages, including the need for regular coagulation monitoring and dose adjustment. Interactions with numerous common medications and foods contribute to the risk of serious bleeding and thrombotic events in VKA-treated patients. Thus novel oral anticoagulants (NOACs), more properly called direct oral anticoagulants (DOACs), such as dabigatran etexilate, rivaroxaban, apixaban, and edoxaban (not available in Mexico), have been developed. These offer the convenience of fixed-dose treatment without the need for monitoring, and have few drug or food interactions. Pivotal phase III trials have demonstrated that these agents are at least as effective as warfarin in preventing stroke and are associated with a reduced risk of intracranial hemorrhage. With apixaban approved in Mexico in April 2013, clinicians now have the choice of three novel DOACs as alternatives to warfarin. However, it is yet to be established which of these agents should be the first choice, and treatment decisions are likely to depend on the individual patient’s characteristics.     

Management of Dabigatran‐Associated Bleeding with Two Doses of Idarucizumab Plus Hemodialysis

Vitamin K antagonists have been a mainstay of treatment for patients requiring anticoagulation for atrial fibrillation, but direct oral anticoagulants, such as dabigatran, have become increasingly prescribed. Compared with warfarin, dabigatran has a significantly lower risk of life‐threatening bleeding; however, bleeding events can still occur, supporting the need for effective reversal strategies. Idarucizumab was recently approved by the U.S. Food and Drug Administration to reverse the anticoagulant effects of dabigatran when life‐threatening bleeding occurs or an urgent need for an invasive medical procedure exists. Before idarucizumab's approval, reversal strategies included hemodialysis, coagulation factor replacement, and, in the setting of acute ingestion, activated charcoal. We describe the case of a 58‐year‐old, obese woman with a history of atrial fibrillation who developed acute kidney injury while taking dabigatran 150 mg twice/day, resulting in coagulopathy. Despite receiving idarucizumab 5 g and hemodialysis, there was a rebound increase in prothrombin time (PT) and activated partial thromboplastin time (aPTT) values, prompting administration of an additional 5‐g dose of idarucizumab and continued hemodialysis, with subsequent PT and aPTT values remaining within their appropriate ranges. To our knowledge, this is the first case report to describe the successful use of repeat dosing of idarucizumab with hemodialysis to reverse the anticoagulant effects of dabigatran. Although two doses of idarucizumab were given to our patient, this dosing regimen is not the current standard of practice. Administration of idarucizumab and the use of additional reversal strategies should involve an assessment of each individual patient's severity of bleeding and subsequent risk of thrombosis. Due to the recent availability of idarucizumab and varying success with alternative reversal strategies, additional knowledge is needed for the optimal reversal of anticoagulation from dabigatran.     

Novel oral anticoagulants: focus on the direct factor Xa inhibitor darexaban

INTRODUCTION: Inhibition of the pathways of anticoagulation is widely used for the prevention and treatment of arterial and venous thrombosis. Vitamin K antagonists (VKAs) have been the mainstay of oral anticoagulation for more than 60 years. Their safety and effectiveness have been established in multiple clinical trials, for a variety of clinical indications. However, there are several limitations to the use of VKAs including delayed onset of action and dosage titration, numerous food and drug interactions and need for regular laboratory monitoring. To overcome some of the limitations of traditional agents, new oral anticoagulants (OACs) have been developed and evaluated. AREAS COVERED: In the present review article, the pharmacokinetic properties of darexaban are presented, along with the available preliminary clinical data. The performance of darexaban in respect to safety and efficacy compared with its competitors is further discussed. EXPERT OPINION: Darexaban is a potent direct factor Xa inhibitor that demonstrated impressive pharmacokinetic properties in pre-clinical studies. It was further successfully evaluated in the ONYX program for the prevention of venous thromboembolism in patients undergoing hip replacement. Finally, in the Phase II RUBY-1 trial, darexaban was tested on the top of standard antiplatelet therapy for the prevention of ischemic events in acute coronary syndrome (ACS) patients. Despite the fact that darexaban had a relatively uneventful clinical evaluation program, its further development was recently discontinued. This decision could probably reflect the non-favorite results in commercially attractive indications, such as secondary prevention post-ACS and the increased competition for less common or short-term indications such stroke prevention in AF or VTE prophylaxis respectively.     

Timing of Initiation of Oral Anticoagulation after Acute Ischemic Stroke in Patients with Atrial Fibrillation

Patients with atrial fibrillation (AF) who suffer an acute ischemic stroke are at risk for both hemorrhagic transformation and recurrent ischemic stroke in the acute post-stroke period. Oral anticoagulants are recommended for secondary stroke prevention in patients with AF. The optimal time to initiate anticoagulant therapy after acute ischemic stroke in patients with AF is uncertain. There is concern that early initiation increases the risk of hemorrhagic transformation, whereas delayed initiation leaves the patient at risk for recurrent ischemic stroke. In this article, we provide a review of the risk of hemorrhagic transformation of acute ischemic stroke as well as review the literature and major guidelines addressing the timing of anticoagulation initiation after an acute ischemic stroke in patients with AF. Relevant articles published from 1990 to the present were identified using the PubMed and Embase databases. The majority of available literature is observational data. Large ischemic lesions, cerebral microbleeds, thrombolytic therapy, and other clinical factors may increase the risk of hemorrhagic transformation of an acute ischemic stroke. Parenteral anticoagulation within 48 hours is associated with an increased risk of hemorrhagic transformation and is not recommended. Insufficient data exist to support the safety of routine oral anticoagulant (direct oral anticoagulants or warfarin) initiation within 48 hours of an acute ischemic stroke. Direct oral anticoagulant initiation within 2 days of an acute ischemic stroke is associated with a 5% rate of hemorrhagic transformation. Infarct size and presence of hemorrhage are important factors in identifying the optimal time to initiation and should guide decisions when available. A recommended framework for patient decision making is provided. Randomized controlled trials in this area are needed to identify the optimal timing of anticoagulation initiation, and such trials are under way.     

Novel oral anticoagulants: focus on the direct factor Xa inhibitor darexaban

Introduction: Inhibition of the pathways of anticoagulation is widely used for the prevention and treatment of arterial and venous thrombosis. Vitamin K antagonists (VKAs) have been the mainstay of oral anticoagulation for more than 60 years. Their safety and effectiveness have been established in multiple clinical trials, for a variety of clinical indications. However, there are several limitations to the use of VKAs including delayed onset of action and dosage titration, numerous food and drug interactions and need for regular laboratory monitoring. To overcome some of the limitations of traditional agents, new oral anticoagulants (OACs) have been developed and evaluated.

Areas covered: In the present review article, the pharmacokinetic properties of darexaban are presented, along with the available preliminary clinical data. The performance of darexaban in respect to safety and efficacy compared with its competitors is further discussed.

Expert opinion: Darexaban is a potent direct factor Xa inhibitor that demonstrated impressive pharmacokinetic properties in pre-clinical studies. It was further successfully evaluated in the ONYX program for the prevention of venous thromboembolism in patients undergoing hip replacement. Finally, in the Phase II RUBY-1 trial, darexaban was tested on the top of standard antiplatelet therapy for the prevention of ischemic events in acute coronary syndrome (ACS) patients. Despite the fact that darexaban had a relatively uneventful clinical evaluation program, its further development was recently discontinued. This decision could probably reflect the non-favorite results in commercially attractive indications, such as secondary prevention post-ACS and the increased competition for less common or short-term indications such stroke prevention in AF or VTE prophylaxis respectively.     

Suboptimal Use of Oral Anticoagulants in Atrial Fibrillation: Has the Introduction of Direct Oral Anticoagulants Improved Prescribing Practices?

Background and Objectives

Atrial fibrillation (AF) and the associated risk of stroke are emerging epidemics throughout the world. Suboptimal use of oral anticoagulants for stroke prevention has been widely reported from observational studies. In recent years, direct oral anticoagulants (DOACs) have been introduced for thromboprophylaxis. We conducted a systematic literature review to evaluate current practices of anticoagulation in AF, pharmacologic features and adoption patterns of DOACs, their impacts on proportion of eligible patients with AF who receive oral anticoagulants, persisting challenges and future prospects for optimal anticoagulation.

Literature Source and Selection Criteria

In conducting this review, we considered the results of relevant prospective and retrospective observational studies from real-world practice settings. PubMed (MEDLINE), Scopus (RIS), Google Scholar, EMBASE and Web of Science were used to source relevant literature. There were no date limitations, while language was limited to English. Selection was limited to articles from peer reviewed journals and related to our topic.

Results

Most studies identified in this review indicated suboptimal use of anticoagulants is a persisting challenge despite the availability of DOACs. Underuse of oral anticoagulants is apparent particularly in patients with a high risk of stroke. DOAC adoption trends are quite variable, with slow integration into clinical practice reported in most countries; there has been limited impact to date on prescribing practice.

Conclusion

Available data from clinical practice suggest that suboptimal oral anticoagulant use in patients with AF and poor compliance with guidelines still remain commonplace despite transition to a new era of anticoagulation featuring DOACs.

     

The safety and efficacy of the use of oral anticoagulant medications in patients with diabetes mellitus: A systematic review

AimsDiabetes mellitus (DM) and atrial fibrillation (AF) commonly co-exist. Oral anticoagulants (OACs) are widely used in patients with DM. This review aims to summarise the available literature on the safety (hypoglycaemia or bleeding) and efficacy (stroke or systemic embolism) of the use of OACs in patients with DM.MethodsWe searched the Medline, the Excerpta Medica dataBASE (Embase) and Cochrane databases up to the 10th of December 2020. The search strategy was conducted using both keywords and MeSH terms. We included randomised controlled trials (RCTs) and observational studies that reported on the safety and efficacy of the use of OACs in patients with diabetes from all age groups. Study selection, data extraction and quality assessment were conducted independently by two reviewers.ResultsA total of 3,976 articles were identified through the search process, of which seven studies met the inclusion criteria of the systematic review: four observational studies and three studies that were randomised controlled trials, with a total of 703,855 patients. Two observational studies reported that the use of warfarin was associated with a higher risk of hypoglycaemic events, specifically with sulfonylurea. One observational study and three randomised controlled trials reported that the use of warfarin compared to other oral anticoagulants was associated with a higher risk of bleeding. In addition, three randomised controlled trials reported that the use of warfarin compared to other oral anticoagulants was associated with a lower risk of stroke or systemic embolism.ConclusionsThis systematic review found that DOACs had a better efficacy outcome and safer clinical outcomes in comparison to warfarin in patients with diabetes.     

心房颤动合并慢性肾脏病患者口服抗凝药物治疗的研究进展

慢性肾病与心房颤动(房颤)密切相关并常常共存.慢性肾病和房颤均是血栓发生的危险因素,因此房颤合并慢性肾病人群其缺血性卒中及体循环栓塞的风险显著增加.对于普通的房颤人群,口服抗凝药物治疗是预防缺血性卒中和体循环栓塞发生的有效干预手段,并且慢性肾病还会增加出血风险,因此合并慢性肾病的房颤人群进行口服抗凝药物治疗可能并不具有...     

The hidden costs of anticoagulation in hospitalized patients with non-valvular atrial fibrillation

Introduction: Non-valvular atrial fibrillation (NVAF) and ischemic stroke are collectively associated with annual hospital costs of tens of billions of dollars in the USA. Oral anticoagulant (OAC) treatment with warfarin reduces the risk of stroke in patients with NVAF. Unfortunately, because of the complexity of warfarin therapy and potential for adverse events (AEs), many patients who might benefit go untreated or receive suboptimal therapy, increasing their stroke and/or bleeding risk.

Areas covered: This review explores current hospital costs and resource utilization for NVAF patients on warfarin therapy and the potential impact of newer OACs in this area.

Expert opinion: Many ischemic strokes could be prevented through wider use of OACs. Further, admissions due to anticoagulant-associated AEs could be reduced by optimizing OAC therapy. In the hospital, specialized anticoagulation services can decrease costs by improving the effectiveness of warfarin management, empowering patients through education and optimizing care transitions. With fewer interactions and no dose titration or monitoring required, the novel OACs (NOACs) have the potential to further decrease inpatient resource utilization and costs. It is important that, as data become available, inpatient costs are included in cost–benefit comparisons between warfarin and the NOACs.     

Anticoagulation in atrial fibrillation: the trials and tribulations of keeping within therapeutic range

Atrial fibrillation (AF) is a growing epidemic in the developed world that has attracted much attention due to the associated risk of stroke and thromboembolism. This article discusses the application of oral anticoagulation (OAC) therapy with vitamin K antagonists (VKA) in order to reduce these risks. The article provides an overview of OAC management and highlights the need for greater efforts to increase time within therapeutic range.     

Consensus in cardiology on non-vitamin-K oral anticoagulants for patients with atrial fibrillation

Introduction: Non-vitamin-K oral anticoagulants (NOACs) are known to have advantages over vitamin K antagonists (VKAs) for patients with atrial fibrillation (AF). However, more than half of patients are still treated with VKAs. The absence of direct comparisons amongst NOACs and the insufficient evidence in some clinical situations could explain, at least in part, this predominance of VKAs. The aims of our study were: 1) to analyze the opinion of an expert panel on the role of NOACs in different clinical scenarios; 2) to elaborate specific consensus recommendations for the management of NOACs for each one of these situations.

Patients and methods: An online survey was created covering distinct aspects of the use of oral anticoagulants in various clinical settings. A two-round modified Delphi approach was used.

Results: Forty-eight experts responded to the survey. Consensus was reached on 58% (48/83) of the items. The panelists concluded that the term non-valvular AF should be avoided. In most clinical settings NOACs were preferred over VKAs. Once daily NOACs were preferred in elderly patients to improve therapeutic compliance and, in those over the age of 85, edoxaban could be the best choice. Edoxaban and apixaban were the favorites for patients with AF and moderate chronic kidney disease (CKD). In the case of patients on triple antithrombotic therapy due to AF and acute coronary syndrome (ACS) the lowest effective NOAC dose should be used.

Conclusion: Our study emphasizes that there are several clinical circumstances in patients with AF requiring complex decisions about anticoagulation treatment and offers some recommendations based on the consensus reached by an expert panel.     

Anticoagulation in atrial fibrillation: the trials and tribulations of keeping within therapeutic range

ABSTRACT

Atrial fibrillation (AF) is a growing epidemic in the developed world that has attracted much attention due to the associated risk of stroke and thromboembolism. This article discusses the application of oral anticoagulation (OAC) therapy with vitamin K antagonists (VKA) in order to reduce these risks. The article provides an overview of OAC management and highlights the need for greater efforts to increase time within therapeutic range.