A specific antidote for dabigatran: functional and structural characterization

Reversal agents of non-vitamin K dependent anticoagulants: a rapid review of the changing horizon

The newer non-vitamin K dependent anticoagulants (NOACs) have provided a new tool in the armamentarium of physicians treating nonvalvular atrial fibrillation and thromboembolism. Slowly, but steadily, there has been an increased preference of NOACs over vitamin K antagonists. However, the major limiting factor and the concern that precluded their use was lack of reversal in emergent situations. With the advent of reversal agents such as idarucizumab, andexanet alfa and PER977, this gap is also being filled. This will further increase the spectrum of usage of NOACs. In this review we present the detailed information on the completed trials on the reversal agents, the ongoinng trials, and their site of action. The reversal agent idarucizumab is FDA approved and readily available. The others are in clinical trials and are soon expected to be available in clinical practice.

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.

Thrombolysis and thrombectomy in patients treated with dabigatran with acute ischemic stroke: Expert opinion

Systemic thrombolysis with rt-PA is contraindicated in patients with acute ischemic stroke anticoagulated with dabigatran. This expert opinion provides guidance on the use of the specific reversal agent idarucizumab followed by rt-PA and/or thrombectomy in patients with ischemic stroke pre-treated with dabigatran. The use of idarucizumab followed by rt-PA is covered by the label of both drugs.

Prothrombin Complex Concentrates for Bleeding in the Perioperative Setting

Prothrombin complex concentrates (PCCs) contain vitamin K-dependent clotting factors (II, VII, IX, and X) and are marketed as 3 or 4 factor-PCC formulations depending on the concentrations of factor VII. PCCs rapidly restore deficient coagulation factor concentrations to achieve hemostasis, but like with all procoagulants, the effect is balanced against thromboembolic risk. The latter is dependent on both the dose of PCCs and the individual patient prothrombotic predisposition. PCCs are approved by the US Food and Drug Administration for the reversal of vitamin K antagonists in the setting of coagulopathy or bleeding and, therefore, can be administered when urgent surgery is required in patients taking warfarin. However, there is growing experience with the off-label use of PCCs to treat patients with surgical coagulopathic bleeding. Despite their increasing use, there are limited prospective data related to the safety, efficacy, and dosing of PCCs for this indication. PCC administration in the perioperative setting may be tailored to the individual patient based on the laboratory and clinical variables, including point-of-care coagulation testing, to balance hemostatic benefits while minimizing the prothrombotic risk. Importantly, in patients with perioperative bleeding, other considerations should include treating additional sources of coagulopathy such as hypofibrinogenemia, thrombocytopenia, and platelet disorders or surgical sources of bleeding. Thromboembolic risk from excessive PCC dosing may be present well into the postoperative period after hemostasis is achieved owing to the relatively long half-life of prothrombin (factor II, 60-72 hours). The integration of PCCs into comprehensive perioperative coagulation treatment algorithms for refractory bleeding is increasingly reported, but further studies are needed to better evaluate the safe and effective administration of these factor concentrates.

Reversal agents for direct oral anticoagulants: A focused review

For several decades the vitamin K antagonist oral anticoagulants were the only outpatient therapy that existed to reduce the risk of stroke and thromboembolism. When the new direct oral anticoagulants were approved for use and addressed many of the issues associated with oral vitamin K antagonists, a new concern arose-the lack of rapid ability to reverse these agents. Physicians and patients were concerned that in cases of life-threatening bleeding or need for emergent surgery, an antidote to reverse the anticoagulation effect of these agents did not exist. Contemporary research has aimed to produce reversal agents that can be administered to safely neutralize the anticoagulant effect. In this focused review we describe the clinical development as well as mechanisms of action of three agents (idarucizumab, andexanet alpha, and ciraparantag). We review the pharmacokinetics, animal and human study data of these reversal agents and outline the evidence supporting their use. Although questions of safety and appropriate use remain, these reversal agents offer a significant step forward in the widespread use of direct oral anticoagulants and overall management of the anticoagulant effect.

Idarucizumab: A Review as a Reversal Agent for Dabigatran

Idarucizumab (Praxbind(®)), a humanized monoclonal antibody, is a specific reversal agent for the direct oral thrombin inhibitor dabigatran, available as its prodrug dabigatran etexilate (Pradaxa(®)). Idarucizumab is approved in several countries (including the USA, the EU, Canada and Australia) for use in adult patients on dabigatran when the reversal of its anticoagulant effects is required for emergency surgery/procedures or in the event of life-threatening or uncontrolled bleeding. In the ongoing pivotal RE-VERSE AD trial in these populations (n = 90), intravenous idarucizumab 5 g reversed dabigatran-induced prolongation of dilute thrombin time (dTT) and ecarin clotting time (ECT) within minutes. The median maximum percentage reversal was 100 % for both assays (primary endpoint). Idarucizumab normalized dTT and ECT in 88-98 % of patients who had elevated levels at baseline. After idarucizumab administration, bleeding stopped in 97 % of evaluable patients in the bleeding cohort within 24 h (median time to cessation of bleeding was 11.4 h), and the rate of normal intraoperative haemostasis was 92 % in the surgical cohort. Idarucizumab was generally well tolerated. In conclusion, idarucizumab is a unique and specific treatment option for the reversal of the anticoagulant effects of dabigatran in adult patients requiring emergency procedures or in the event of life-threatening or uncontrolled bleeding.

A rapid pro-hemostatic approach to overcome direct oral anticoagulants

Direct inhibitors of coagulation factor Xa (FXa) or thrombin are promising oral anticoagulants that are becoming widely adopted. The ability to reverse their anticoagulant effects is important when serious bleeding occurs or urgent medical procedures are needed. Here, using experimental mouse models of hemostasis, we show that a variant coagulation factor, FXa(I16L), rapidly restores hemostasis in the presence of the anticoagulant effects of these inhibitors. The ability of FXa(I16L) to reverse the anticoagulant effects of FXa inhibitor depends, at least in part, on the ability of the active site inhibitor to hinder antithrombin-dependent FXa inactivation, paradoxically allowing uninhibited FXa to persist in plasma. Because of its inherent catalytic activity, FXa(I16L) is more potent (by >50-fold) in the hemostasis models tested than a noncatalytic antidote that is currently in clinical development. FXa(I16L) also reduces the anticoagulant-associated bleeding in vivo that is induced by the thrombin inhibitor dabigatran. FXa(I16L) may be able to fill an important unmet clinical need for a rapid, pro-hemostatic agent to reverse the effects of several new anticoagulants.

Idarucizumab for Reversal of Dabigatran-Associated Anticoagulation

Objective: To review clinical data on idarucizumab for the reversal of dabigatran-associated anticoagulation. Data Sources: Articles for this review were identified via PubMed using the MeSH term dabigatran combined with the keyword idarucizumab. Additional online searches via PubMed and Google Scholar were conducted for both prescribing and cost information. Study Selection and Data Extraction: English-language clinical trials published between 1946 and May 2016 were included for review. Bibliographies of selected articles were also manually reviewed for relevant publications that focused on reversal strategies for dabigatran-associated anticoagulation. Data Synthesis: The safety and tolerability of idarucizumab has been evaluated in 3 phase I clinical trials. The use of idarucizumab for reversing dabigatran-associated anticoagulation is also being evaluated in the phase III RE-VERSE AD study. Interim results of the RE-VERSE AD study have been published. Conclusions: Idarucizumab rapidly neutralizes the anticoagulant effect of dabigatran in healthy volunteers, in patients with life-threatening bleeding, and in patients requiring urgent surgery that cannot be delayed. These observations are largely based on laboratory assessments rather than clinical outcomes. Idarucizumab is well tolerated, and it does not appear to induce procoagulant or immunogenic adverse effects.

Reversal agents for NOACs: Connecting the dots

OBJECTIVE

The objective of this review is to provide an overview on the current development of the specific reversal agents for Non-vitamin K Oral Anticoagulants (NOACs).

METHODS

We conducted a systematic literature search strategy to identify potential studies on Medline, Embase, and the Cochrane register.

CONCLUSIONS

These new reversal agents for NOACs, will help address the unmet need for the management of major or life threatening bleeds, and the management of emergency surgical procedures in patients taking NOACs. It will increase confidence in the use of NOACs; thereby extending treatment to a wider range of patients.

Reversal of Dabigatran with Idarucizumab

INTRODUCTION

The use of novel oral anticoagulants such as dabigatran has been increasing over the last five years. Indicated for use in the prevention of thromboembolic complications from non-valvular atrial fibrillation and for the treatment and prevention of venous thromboembolic disease, dabigatran is increasingly encountered clinically. Lack of an efficacious reversal agent has been a challenge for increased clinical 10 adoption, and for management of patients with bleeding complications while taking dabigatran, or those requiring urgent procedures while taking dabigatran. Idarucizumab, a monoclonal antibody fragment, has recently been approved for use to reverse anticoagulation with dabigatran in patients with serious bleeding.

AREAS COVERED

Herein we discuss the development and early clinical data evaluating the use of idarucizumab for dabigatran reversal. Expert commentary: Idarucizumab has been shown to be an efficacious reversal agent for patients receiving dabigatran. The drug provides a novel and clinically useful agent for patients with significant bleeding while receiving dabigatran, or those needing urgent invasive procedures.

Intravenous Thrombolysis With Recombinant Tissue-Type Plasminogen Activator in a Stroke Patient Receiving Dabigatran Anticoagulant After Antagonization With Idarucizumab

Background and Purpose—

Therapeutic options for acute ischemic stroke patients presenting on effective anticoagulation are limited. Idarucizumab, a humanized, monoclonal antibody fragment for immediate reversal of dabigatran, may allow this subgroup of orally anticoagulated patients to regain eligibility for thrombolysis.

Methods—

We report the first successful acute antagonization of dabigatran by idarucizumab before intravenous thrombolysis with recombinant tissue-type plasminogen activator.

Results—

Idarucizumab was given to a 76-year-old male patient on dabigatran ≈3.5 hours after his last dose. Neurological status on admission was NIHSS (National Institutes of Health Stroke Scale) 11. Recombinant tissue-type plasminogen activator was initiated immediately after dabigatran reversal. The patient was discharged with a favorable outcome of NHISS 1 on day 7. No complications were observed.

Conclusions—

This case represents a new therapeutic paradigm. It is further supported by in vitro data showing no nonspecific interactions of idarucizumab with recombinant tissue-type plasminogen activator–induced thrombolysis. Thus, patients effectively anticoagulated with dabigatran who were previously contraindicated for thrombolytic therapy in this situation may now receive treatment because of the ability to rapidly reverse the anticoagulant activity of dabigatran with idarucizumab.

Update on atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia with a substantial effect on individual morbidity and mortality as well as healthcare expenditure. The management of AF is complex and fraught with many uncertain and contentious issues. We have seen substantial progress in AF management in the last two decades including better understanding of the epidemiology, genomics, monitoring, drug and non-pharmacological treatment of the arrhythmia, its complications and stroke risk reduction. In this review, we present a comprehensive discussion on AF with emphasis on most recent updates.

Unraveling the pharmacokinetic interaction of ticagrelor and MEDI2452 (Ticagrelor antidote) by mathematical modeling

The investigational ticagrelor‐neutralizing antibody fragment, MEDI2452, is developed to rapidly and specifically reverse the antiplatelet effects of ticagrelor. However, the dynamic interaction of ticagrelor, the ticagrelor active metabolite (TAM), and MEDI2452, makes pharmacokinetic (PK) analysis nontrivial and mathematical modeling becomes essential to unravel the complex behavior of this system. We propose a mechanistic PK model, including a special observation model for post‐sampling equilibration, which is validated and refined using mouse in vivo data from four studies of combined ticagrelor‐MEDI2452 treatment. Model predictions of free ticagrelor and TAM plasma concentrations are subsequently used to drive a pharmacodynamic (PD) model that successfully describes platelet aggregation data. Furthermore, the model indicates that MEDI2452‐bound ticagrelor is primarily eliminated together with MEDI2452 in the kidneys, and not recycled to the plasma, thereby providing a possible scenario for the extrapolation to humans. We anticipate the modeling work to improve PK and PD understanding, experimental design, and translational confidence.

Structure-guided residence time optimization of a dabigatran reversal agent

Novel oral anticoagulants are effective and safe alternatives to vitamin-K antagonists for anticoagulation therapy. However, anticoagulation therapy in general is associated with an elevated risk of bleeding. Idarucizumab is a reversal agent for the direct thrombin inhibitor, dabigatran etexilate (Pradaxa®) and is currently in Phase 3 studies. Here, we report data on the antibody fragment aDabi-Fab2, a putative backup molecule for idarucizumab. Although aDabi-Fab2 completely reversed effects of dabigatran in a rat model in vivo, we observed significantly reduced duration of action compared to idarucizumab. Rational protein engineering, based on the X-ray structure of aDabi-Fab2, led to the identification of mutant Y103W. The mutant had optimized shape complementarity to dabigatran while maintaining an energetically favored hydrogen bond. It displayed increased affinity for dabigatran, mainly driven by a slower off-rate. Interestingly, the increased residence time translated into longer duration of action in vivo. It was thus possible to further enhance the efficacy of aDabi-Fab2 based on rational design, giving it the potential to serve as a back-up candidate for idarucizumab.

An Algorithmic Approach to Management of Venous Thromboembolism

Venous thromboembolism (VTE) is associated with significant morbidity and mortality. Factors such as the presence of transient risk factors for VTE, risk of bleeding, and location of deep vein thrombosis (DVT) determine the duration of anticoagulation. Extended anticoagulation is offered to patients with unprovoked pulmonary embolism (PE) or proximal DVT and a low risk of bleeding. Anticoagulation for 3 months is advised in patients with provoked DVT or PE, high risk of bleeding, and isolated distal or upper extremity DVT. In patients with unprovoked PE or proximal DVT and a low risk of bleeding, who want to stop anticoagulation after 3 months, further risk stratification is necessary. Clinical scoring system, and thrombophilia testing otherwise not routinely performed, may be considered to measure risk of annual recurrence in such cases. Short-term anticoagulation may be considered in subsegmental PE and superficial vein thrombosis, particularly if patients are at low risk of bleeding and have persistent risk factors for recurrent VTE. In cases of catheter-associated thrombosis, the catheter need not be removed routinely, and the patient may be anticoagulated for 3 months or longer if the catheter is maintained in patients with cancer. Extensive screening for occult cancer in cases of unprovoked VTE is not beneficial. New oral anticoagulants such as apixaban, rivaroxaban, or dabigatran may be preferred to vitamin K antagonists in patients without cancer or renal failure, more so after the development of reversal agents such as idarucizumab and andexanet alfa.

Reversing the Effect of Oral Anticoagulant Drugs: Established and Newer Options

The vitamin K antagonists (VKAs) have been the standard (and only) oral anticoagulants used for the long-term treatment or prevention of venous thromboembolism or stroke in patients with atrial fibrillation. The coagulopathy induced by VKAs can be reversed with vitamin K, and in urgent situations, the vitamin K-dependent coagulation factors can be replaced by transfusion. In the last decade, a new class of oral anticoagulants has been developed, direct oral anticoagulants that bind to a specific coagulation factor and neutralize it. These compounds were shown to be effective and safe compared with the VKAs and were licensed for specific indications, but without a specific reversal agent. The absence of a reversal agent is a barrier to more widespread use of these agents. Currently, for the management of major life-threatening bleeding with the direct oral anticoagulants, most authorities recommend the use of four factor prothrombin complex concentrates. There are now three reversal agents in development and poised to enter the market. Idarucizumab is a specific antidote targeted to reverse the direct thrombin inhibitor, dabigatran, which was recently approved for use in the USA. Andexanet alfa is an antidote targeted to reverse the oral direct factor Xa inhibitors as well as the indirect inhibitor enoxaparin. Ciraparantag is an antidote targeted to reverse the direct thrombin and factor Xa inhibitors as well as the indirect inhibitor enoxaparin.

Update on Anticoagulation: What the Interventional Radiologist Needs to Know

The novel oral anticoagulants (NOACs) represent a major advance in the treatment of patients with nonvalvular atrial fibrillation and venous thromboembolism (VTE). They have several advantages over vitamin-K antagonists such as warfarin, including more predictable pharmacokinetics and improved safety, particularly with fatal bleeding and intracranial hemorrhage. However, several issues remain surrounding the use of NOACs in certain subpopulations and with the approach to reversal. The periprocedural management of anticoagulation with these relatively new agents can also present several challenges. This article reviews the basic pharmacology, efficacy, and safety of these drugs. Several populations at higher risk for complications with use of NOACs are discussed, including those undergoing procedures. Finally, several target-specific reversal agents have either received FDA approval or likely will be approved in the near future; these agents and their roles in the approach to anticoagulation reversal will also be discussed.

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.

Newer Oral Anticoagulants: Stroke Prevention and Pitfalls

Warfarin is very effective in preventing stroke in patients with atrial fibrillation. However, its use is limited due to fear of hemorrhagic complications, unpredictable anticoagulant effects related to multiple drug interactions and dietary restrictions, a narrow therapeutic window, frequent difficulty maintaining the anticoagulant effect within a narrow therapeutic window, and the need for inconvenient monitoring. Several newer oral anticoagulants have been approved for primary and secondary prevention of stroke in patients with non-valvular atrial fibrillation. These agents have several advantages relative to warfarin therapy. As a group, these direct oral anticoagulants (DOAC), which include the direct thrombin inhibitor, dabigatran, and the factor Xa inhibitors (rivaroxaban, apixaban, and edoxaban), are more effective than dose adjusted warfarin for prevention of all-cause stroke (including both ischemic and hemorrhagic stroke), and have an overall more favorable safety profile. Nevertheless, an increased risk of gastrointestinal bleeding (with the exception of apixaban), increased risk for thrombotic complication with sudden discontinuation, and inability to accurately assess and reverse anticoagulant effect require consideration prior to therapy initiation, and pose a challenge for decision making in acute stroke therapy.

Spotlight on idarucizumab and its potential for the reversal of anticoagulant effects of dabigatran

Idarucizumab is the first targeted antidote of dabigatran, a direct oral anticoagulant used for prevention and treatment of venous thromboembolism and prevention of stroke in atrial fibrillation. Idarucizumab is a humanized fragment of a monoclonal antibody, which binds dabigatran reversibly with high affinity and, when administered intravenously, immediately neutralizes its anticoagulant effect. It is rapidly cleared by the kidney with captured dabigatran. In Phase I and II trials, no significant adverse events have been reported. Specifically, idarucizumab has no anticoagulant or procoagulant effect by itself. Idarucizumab is currently being evaluated in an ongoing Phase III trial, in patients treated with dabigatran presenting with severe active bleeding or requiring emergency surgery or an invasive procedure and are at high risk of bleeding. The results of the interim analysis confirm the ability of idarucizumab to neutralize dabigatran instantaneously, without rebound effect, except in rare patients with very high baseline levels of anticoagulant. Although not definitely proving clinical efficacy, due to the noncontrolled design of the trial and the heterogeneity of patient conditions, these promising results on an intermediate criterion with strong rationale have led to the approval of idarucizumab for these indications. However, several questions are unresolved. First, activity measurement of dabigatran in blood, useless in current practice, could be useful to guide the treatment and avoid over- or underutilization of the antidote; but so far, it has not been largely available in real time. Second, the translation of anticoagulant neutralization to an effect on mortality and better outcome is highly dependent on the global management of these patients, especially rapid diagnosis, supportive care, and easy access to antidote administration. Although idarucizumab represents a remarkable achievement in drug design and development, whether it will be an important step toward improved safety of patients treated with dabigatran in the real world will have to be demonstrated in the postmarketing phase.

Are Some Anticoagulants More Equal Than Others? - Evaluating the Role of Novel Oral Anticoagulants in AF Ablation

Left atrial ablation strategies are being increasingly performed as a Class 1 therapeutic indication for drug refractory paroxysmal atrial fibrillation (AF). Traditionally AF ablation has been performed with patients on uninterrupted warfarin therapy, however over the last few years, novel oral anticoagulants (NOACs) have emerged as attractive alternatives to warfarin in order to reduce stroke risk due to AF. NOACs are therefore increasingly being used instead of warfarin in the management of AF. There is also mounting evidence mainly in the form of small randomised studies and meta-analysis that have demonstrated that the use of NOACs for AF ablation is efficacious, safe and convenient. However the peri-procedural dosing protocols used in various studies especially in terms of whether NOAC use is interrupted or uninterrupted during AF ablation, have significant inter-operator and inter-institution variability. Currently there is also a lack of randomised controlled trials to validate the data obtained from meta-analyses. There is also evidence that use of NOACs may increase the requirement of unfractionated heparin during the procedure. This review article shall examine the currently available evidence-base, appraise the gaps in the current evidence and also underscore the need for larger randomised clinical trials in this rapidly developing field.

Emergent Bleeding in Patients Receiving Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) offer clinical advantages over warfarin, such as minimal medication and food interactions and fixed dosing without the need for routine monitoring of coagulation status. As with all anticoagulants, bleeding, either spontaneous or provoked, is the most common complication. The long-term use of these drugs is increasing, and there is a crucial need for emergency medicine service professionals to understand the optimal management of associated bleeding. This review aims to describe the indications and pharmacokinetics of available DOACs; to discuss the risk of bleeding; to provide a treatment algorithm to manage DOAC-associated emergency bleeding; and to discuss future directions in bleeding management, including the role of specific reversal agents, such as the recently approved idarucizumab for reversal of the direct thrombin inhibitor dabigatran. Because air medical personnel are increasingly likely to encounter patients receiving DOACs, it is important that they have an understanding of how to manage patients with emergent bleeding.

Management of novel oral anticoagulants in emergency and trauma surgery

BACKGROUND

The compelling safety, efficacy and predictable effect of novel oral anticoagulants (NOACs) is driving a rapid expansion in their therapeutic indications. Management of the increasing number of patients on those new agents in the setting of emergency or trauma surgery can be challenging and the absence of specific reversal agents has been a matter of concern. This review summarises the key principles that underpin the management of those patients with a particular emphasis on the recent development of specific antidotes.

FINDINGS

As of 2015, a new line of antidotes, specific for these drugs, are at different stages of their development with their release imminent. However, as NOACs are innately reversible due to their short half-life, the use of reversal agents will probably be restricted to a few exceptional cases. Post-marketing surveillance will be paramount to better clarify the role of these promising drugs.

CONCLUSIONS

Management of patients on NOACs in the context of emergency or trauma surgery relies on best supportive care in combination with the blood products and/or specific antidotes as required. Familiarity with the new reversal agents is essential but further evidence on their indications, safety and efficacy as well as consensus guidelines are warranted prior to widespread adoption.

The European guideline on management of major bleeding and coagulopathy following trauma: fourth edition

BACKGROUND

Severe trauma continues to represent a global public health issue and mortality and morbidity in trauma patients remains substantial. A number of initiatives have aimed to provide guidance on the management of trauma patients. This document focuses on the management of major bleeding and coagulopathy following trauma and encourages adaptation of the guiding principles to each local situation and implementation within each institution.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004 and included representatives of six relevant European professional societies. The group used a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were reconsidered and revised based on new scientific evidence and observed shifts in clinical practice; new recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated. This guideline represents the fourth edition of a document first published in 2007 and updated in 2010 and 2013.

RESULTS

The guideline now recommends that patients be transferred directly to an appropriate trauma treatment centre and encourages use of a restricted volume replacement strategy during initial resuscitation. Best-practice use of blood products during further resuscitation continues to evolve and should be guided by a goal-directed strategy. The identification and management of patients pre-treated with anticoagulant agents continues to pose a real challenge, despite accumulating experience and awareness. The present guideline should be viewed as an educational aid to improve and standardise the care of the bleeding trauma patients across Europe and beyond. This document may also serve as a basis for local implementation. Furthermore, local quality and safety management systems need to be established to specifically assess key measures of bleeding control and outcome.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. The implementation of locally adapted treatment algorithms should strive to achieve measureable improvements in patient outcome.

The Real-World Treatment of Hemorrhages Associated With Dabigatran and Rivaroxaban: A Multicenter Evaluation

PURPOSE

Adoption of the target-specific oral anticoagulants (TSOACs) has been slow; accordingly, lack of guidance for emergent reversal confounded by the need for "direct" reversal agents has contributed significantly to warfarin entrenchment in the medical community. The purpose of this analysis is to provide real-world experiences regarding the management of the hemorrhaging patient secondary to dabigatran and rivaroxaban.

METHODS

Retrospective review of patients admitted with a hemorrhage secondary to dabigatran or rivaroxaban were evaluated. Descriptive statistics were utilized for analysis.

RESULTS

Four hundred forty-four patients were screened for inclusion into the study; notably, 419 (94%) of the patients were excluded because the bleed was secondary to warfarin therapy. Of those included in this analysis (n = 25), gastrointestinal bleeding accounted for 21 events (84%), followed by intracranial (n = 2; 8%) and epistaxis (n = 2; 8%). Two patients (8%) expired during admission and 6 patients (24%) expired within 6 months after discharge from the hospital. Three (12%) minor bleeds, 7 (28%) major bleeds, and 15 (60%) life-threatening bleeds were identified. Minor bleeds required careful monitoring, supportive care, and cessation of anticoagulation therapy, whereas increasing severity required multiple interventions with prothrombin complex concentrate, recombinant activated factor 7, fresh frozen plasma, packed red blood cells, cryoprecipitate, and platelets.

CONCLUSION

The approach to the management of bleeding events borne from TSOACs has proven to be very heterogeneous. In the midst of this observation period, these facilities developed protocols, which created a stratification of bleeds and a more regimented approach to managing them. Although bleeding is less with new agents, the creation of pathways/algorithms for the management of TSOACs and education regarding clinical decision-making may be beneficial for the expeditious and appropriate management when these events arise.

Management of new oral anticoagulants related life threatening or major bleedings in real life: a brief report

Although new oral anticoagulants (NOAs) have been marketed in many countries, concern exists about the management of bleedings related to these drugs due to the lack of specific antidotes. The aim of our study was to report on real life management of NOAs-related life-threatening or major bleedings. We report data from consecutive cases of NOAs related major bleedings admitted to 4 hospitals since NOAs became marketed in Italy. We treated 8 patients, 4 males, with mean age 84 ± 7 years, 7 of whom were on dabigatran and one on rivaroxaban. The indication for NOA was atrial fibrillation. All bleedings were spontaneous and involving the gastro-intestinal tract. At the time of bleeding all patients had a drop in hemoglobin levels over 20 g/L. Creatinine clearance was ≤30 mL/min in 4 patients. All patients received general supportive measures, 4 of 8 patients were transfused with packed red cells and one patient received platelet transfusion. Three patients were treated with tranexamic acid and one patient on dabigatran received 4-factor prothrombin complex concentrate (PCC) with bleeding cessation, although coagulation parameters were not corrected. The median time for normalization of coagulation parameters was 3 days (range 1-6 days). All patients were discharged alive and NOAs were discontinued. In NOAs related major gastro-intestinal bleeding general supportive measures seem to be effective for the majority of patients. Despite promoting bleeding cessation, 4-factor PCC does not reverse abnormal coagulation parameters.

The current approach of atrial fibrillation management

Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice. Aging populations coupled with improved outcomes for many chronic medical conditions has led to increases in AF diagnoses. AF is also known to be associated with an increased risk of adverse events such as transient ischemic attack, ischemic stroke, systemic embolism, and death. This association is enhanced in select populations with preexisting comorbid conditions such as chronic heart failure. The aim of this review is to highlight the advances in the field of cardiology in the management of AF in both acute and long-term settings. We will also review the evolution of anticoagulation management over the past few years and landmark trials in the development of novel oral anticoagulants (NOACs), reversal agents for new NOACs, nonpharmacological options to anticoagulation therapy, and the role of implantable loop recorder in AF management.

Reversal of novel oral anticoagulants

The development of a new generation of non-vitamin K oral anticoagulants represents a potential breakthrough in the management of patients with thrombotic diseases, disorders and conditions. While a large and growing body of evidence from large-scale clinical trials and registries supports a favorable safety profile, having a means to rapidly reverse their anticoagulant effects represents an unmet need among practicing clinicians. Several targeted reversal agents are currently in development and the early results are promising. Idarucizumab is a monoclonal antibody that can immediately and specifically reverse dabigatran. Andexanet alfa is a recombinant modified factor Xa that can bind and reverse oral and parenteral factor Xa inhibitors, including rivaroxaban, apixaban and edoxaban, and low molecular weight heparin. Aripazine is a small molecule that can reverse the action of factor Xa inhibitors and possibly dabigatran as well through non-covalent binding and charge-charge interactions.

Contemporary management of acute and chronic deep venous thrombosis

INTRODUCTION

This review aims to provide an update on the management of deep vein thrombosis (DVT).

SOURCES OF DATA

A systematic search of PubMed, Google Scholar and Cochrane databases was carried out.

AREAS OF AGREEMENT

Direct oral anticoagulants (DOACs) are as effective and easier to use than vitamin K antagonists for the treatment of DVT. Catheter-directed thrombolysis can reduce post thrombotic syndrome in patients with iliofemoral DVT. Compression bandaging can help heal a venous ulcer.

AREAS OF CONTROVERSY

Compression hosiery to prevent post thrombotic syndrome. Long-term evidence to show clinical benefit of using endovenous therapies to restore deep vein patency.

GROWING POINTS

Developing imaging methods to identify patients who would benefit from venous thrombolysis. The evolution of dedicated venous stents.

AREAS TIMELY FOR DEVELOPING RESEARCH

Understanding the mechanisms that lead to stent occlusion and investigation into the appropriate treatments that could prevent in-stent thrombosis is required.

Idarucizumab

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, contact Wolters Kluwer customer service at 866-397-3433. The March 2016 monograph topics are necitumumab, talimogene laherparepvec, asfotase alfa, trabectedin, and osimertinib. The Safety MUE is on patiromer.

Management of Venous Thromboembolism: Recent Advances in Oral Anticoagulation Therapy

OBJECTIVE

To review clinical data on direct oral anticoagulants (DOACs) used in the acute treatment of venous thromboembolism (VTE) as well as practical considerations when using these products.

DATA SOURCES

Searches of PubMed and Google Scholar for VTE, deep vein thrombosis, pulmonary embolism, and relevant drug international nonproprietary names were conducted. Additional online searches were conducted for prescribing information.

STUDY SELECTION AND DATA EXTRACTION

Relevant articles on dabigatran, rivaroxaban, apixaban, and edoxaban for the management of VTE compared with oral vitamin K antagonists (VKAs; published between 1966 and December 2015) were reviewed and summarized, together with information on dosing, pharmacokinetics/pharmacodynamics, and drug-drug interactions.

DATA SYNTHESIS

The DOACs have the potential to circumvent many of the disadvantages of VKAs. At a minimum, they greatly increase the available therapeutic options, thus providing a greater opportunity for clinicians to select a management option that best fits the needs of individual patients. Despite the significant advance that DOACs represent, they are not without risk and require careful consideration of a number of clinical issues to optimize safety and efficacy.

CONCLUSIONS

The emergence of DOACs for the management of thromboembolic disorders represents a paradigm shift from oral VKAs. The DOACs provide similar efficacy and improved safety in selected patients as compared with VKAs. Clinicians treating VTE need to be familiar with the intricacies involved in using these agents, including the appropriate dose selection for the relevant indication, avoidance of drug-drug and drug-disease interactions, and consideration of dose adjustments in specific clinical situations, such as organ dysfunction.

Reversing anticoagulant effects of novel oral anticoagulants: role of ciraparantag, andexanet alfa, and idarucizumab

Novel oral anticoagulants (NOACs) are increasingly used in clinical practice, but lack of commercially available reversal agents is a major barrier for mainstream use of these therapies. Specific antidotes to NOACs are under development. Idarucizumab (aDabi-Fab, BI 655075) is a novel humanized mouse monoclonal antibody that binds dabigatran and reverses its anticoagulant effect. In a recent Phase III study (Reversal Effects of Idarucizumab on Active Dabigatran), a 5 g intravenous infusion of idarucizumab resulted in the normalization of dilute thrombin time in 98% and 93% of the two groups studied, with normalization of ecarin-clotting time in 89% and 88% patients. Two other antidotes, andexanet alfa (PRT064445) and ciraparantag (PER977) are also under development for reversal of NOACs. In this review, we discuss commonly encountered management issues with NOACs such as periprocedural management, laboratory monitoring of anticoagulation, and management of bleeding. We review currently available data regarding specific antidotes to NOACs with respect to pharmacology and clinical trials.

Considerations for long-term anticoagulant therapy in patients with venous thromboembolism in the novel oral anticoagulant era

Background

Patients who have had a venous thromboembolic event are generally advised to receive anticoagulant treatment for 3 months or longer to prevent a recurrent episode. Current guidelines recommend initial heparin and an oral vitamin K antagonist (VKA) for long-term anticoagulation. However, because of the well-described disadvantages of VKAs, including extensive food and drug interactions and the need for regular anticoagulation monitoring, novel oral anticoagulants (NOACs) have become an attractive option in recent years. These agents are given at fixed doses and do not require routine coagulation-time monitoring. The NOACs are discussed in this review with regard to the needs of patients on long-term anticoagulation.

Methods

Current guidelines from Europe and North America that refer to the treatment of deep vein thrombosis and/or pulmonary embolism are included, as well as published randomized Phase III clinical trials of NOACs. PubMed searches were used for sourcing case studies of long-term anticoagulant treatment, and results were filtered for human application and screened for relevance.

Conclusion

NOAC-based therapy showed a similar efficacy and safety profile to heparins/VKAs but without the need for regular anticoagulation monitoring or dietary adjustments, and can be taken as a fixed-dose regimen once or twice daily. This represents a significant step forward in facilitating the management of long-term anticoagulation therapy. Furthermore, in the EINSTEIN studies, improved patient satisfaction was documented with the NOAC rivaroxaban, which may result in better adherence to therapy and an overall reduction in the incidence of recurrent venous thromboembolism.

Recent advances in anticoagulant drug delivery

INTRODUCTION

Anticoagulants have been prescribed to patients to prevent deep vein thrombosis or pulmonary embolism. However, because of several problems in anticoagulant therapy, much attention has been directed at developing an ideal anticoagulant, and numerous attempts have been made to develop new anticoagulant delivery systems in recent years.

AREAS COVERED

This review discusses the challenges associated with the recent development of anticoagulants and their delivery systems. Various delivery methods have been developed to improve the use of anticoagulants. Recent advances in anticoagulant delivery and antidote development are also discussed in the context of their current progression states.

EXPERT OPINION

There have been many different approaches to developing the delivery system of anticoagulants. One approach has been to expand the use of new oral agents and develop their antidotes. Reducing the size of heparins to use smaller heparins for delivery, and developing oral or topical heparins are also some of the approaches used. Various physical formulations or chemical modifications are other ways that have enhanced the therapeutic potential of anticoagulant agents. On the whole, recent advances have contributed to increasing the efficacy and safety of anticoagulant clinically and have benefited the field of anticoagulant delivery.