Investigation on Dabigatran Etexilate and Worsening of Renal Function in Patients with Atrial fibrillation: The IDEA Study

BACKGROUND AND OBJECTIVES

Warfarin-related nephropathy is an unexplained acute kidney injury, and may occur in patients with supratherapeutic INR, in the absence of overt bleeding. Similar findings have been observed in rats treated with dabigatran etexilate. We conducted a prospective study in dabigatran etexilate-treated patients to assess the incidence of dabigatran-related nephropathy and to investigate the possible correlation between dabigatran plasma concentration (DPC) and worsening renal function.

METHOD

One hundred and seven patients treated long term with dabigatran etexilate for non-valvular atrial fibrillation (NVAF) were followed up for 90 days. DPC, serum creatinine (SCr) and serum cystatin C were prospectively measured. Ninety five patients had complete follow-up data and were evaluable for primary endpoint.

RESULTS

Eleven patients had supratherapeutic DPC, defined as DPC higher than 200 ng/ml at study enrolment, but at the end of follow-up no patient showed a persistent increase in SCr. No patients experienced acute kidney injury.

CONCLUSIONS

Our study shows that no persistent renal detrimental effect is associated with dabigatran treatment. An increase in SCr during dabigatran treatment is reversible and it seems to be unrelated to dabigatran itself.

In Vitro Selection of Specific DNA Aptamers Against the Anti-Coagulant Dabigatran Etexilate

Dabigatran Etexilate (PRADAXA) is a new oral anticoagulant increasingly used for a number of blood thrombosis conditions, prevention of strokes and systemic emboli among patients with atrial fibrillation. It provides safe and adequate anticoagulation for prevention and treatment of thrombus in several clinical settings. However, anticoagulation therapy can be associated with an increased risk of bleeding. There is a lack of specific laboratory tests to determine the level of this drug in blood. This is considered the most important obstacles of using this medication, particularly for patients with trauma, drug toxicity, in urgent need for surgical interventions or uncontrolled bleeding. In this work, we performed Systematic evolution of ligands by exponential enrichment (SELEX) to select specific DNA aptamers against dabigatran etexilate. Following multiple rounds of selection and enrichment with a randomized 60-mer DNA library, specific DNA aptamers for dabigatran were selected. We investigated the affinity and specificity of generated aptamers to the drug showing dissociation constants (Kd) ranging from 46.8-208 nM. The most sensitive aptamer sequence was selected and applied in an electrochemical biosensor to successfully achieve 0. 01 ng/ml level of detection of the target drug. With further improvement of the assay and optimization, these aptamers would replace conventional antibodies for developing detection assays in the near future.

Dabigatran in patients with myocardial injury after non-cardiac surgery (MANAGE): an international, randomised, placebo-controlled trial

BACKGROUND

Myocardial injury after non-cardiac surgery (MINS) increases the risk of cardiovascular events and deaths, which anticoagulation therapy could prevent. Dabigatran prevents perioperative venous thromboembolism, but whether this drug can prevent a broader range of vascular complications in patients with MINS is unknown. The MANAGE trial assessed the potential of dabigatran to prevent major vascular complications among such patients.

METHODS

In this international, randomised, placebo-controlled trial, we recruited patients from 84 hospitals in 19 countries. Eligible patients were aged at least 45 years, had undergone non-cardiac surgery, and were within 35 days of MINS. Patients were randomly assigned (1:1) to receive dabigatran 110 mg orally twice daily or matched placebo for a maximum of 2 years or until termination of the trial and, using a partial 2-by-2 factorial design, patients not taking a proton-pump inhibitor were also randomly assigned (1:1) to omeprazole 20 mg once daily, for which results will be reported elsewhere, or matched placebo to measure its effect on major upper gastrointestinal complications. Research personnel randomised patients through a central 24 h computerised randomisation system using block randomisation, stratified by centre. Patients, health-care providers, data collectors, and outcome adjudicators were masked to treatment allocation. The primary efficacy outcome was the occurrence of a major vascular complication, a composite of vascular mortality and non-fatal myocardial infarction, non-haemorrhagic stroke, peripheral arterial thrombosis, amputation, and symptomatic venous thromboembolism. The primary safety outcome was a composite of life-threatening, major, and critical organ bleeding. Analyses were done according to the intention-to-treat principle. This trial is registered with ClinicalTrials.gov, number NCT01661101.

FINDINGS

Between Jan 10, 2013, and July 17, 2017, we randomly assigned 1754 patients to receive dabigatran (n=877) or placebo (n=877); 556 patients were also randomised in the omeprazole partial factorial component. Study drug was permanently discontinued in 401 (46%) of 877 patients allocated to dabigatran and 380 (43%) of 877 patients allocated to placebo. The composite primary efficacy outcome occurred in fewer patients randomised to dabigatran than placebo (97 [11%] of 877 patients assigned to dabigatran vs 133 [15%] of 877 patients assigned to placebo; hazard ratio [HR] 0·72, 95% CI 0·55-0·93; p=0·0115). The primary safety composite outcome occurred in 29 patients (3%) randomised to dabigatran and 31 patients (4%) randomised to placebo (HR 0·92, 95% CI 0·55-1·53; p=0·76).

INTERPRETATION

Among patients who had MINS, dabigatran 110 mg twice daily lowered the risk of major vascular complications, with no significant increase in major bleeding. Patients with MINS have a poor prognosis; dabigatran 110 mg twice daily has the potential to help many of the 8 million adults globally who have MINS to reduce their risk of a major vascular complication [corrected].

FUNDING

Boehringer Ingelheim and Canadian Institutes of Health Research.

Anticoagulation efficacy of dabigatran etexilate for left atrial appendage thrombus in patients with atrial fibrillation by transthoracic and transesophageal echocardiography

To evaluate the anticoagulation efficacy of dabigatran etexilate for left atrial appendage (LAA) thrombus resolution in patients with atrial fibrillation by transthoracic echocardiography and transesophageal echocardiography, and to investigate the anticoagulation factors.A total of 58 atrial fibrillation patients with LAA thrombus in our hospital were enrolled. After dabigatran etexilate anticoagulation for 3 months, the patients were divided into the effective group and ineffective group according to dissolution of thrombosis. The baseline data and the left atrial diameter (LAD), left atrial ejection fraction (LAEF), left ventricular ejection fraction, LAA flow velocity (LAA-v), and LAA thrombus size before and after anticoagulation treatment were recorded, and the measurement index were statistically analyzed.After the patients received anticoagulation treatment for 3 months, 15 patients had complete dissolution, thrombus in 21 patients reduced significantly, and the complete dissolution rate was 25.9% (15/58), the effective rate of dissolution was 62.1% (36/58). Compared with the ineffective group, the proportion of persistent atrial fibrillation and LAD in effective group were lower than those in the ineffective group, the LAEF and LAA-v in the effective group were higher than those in the ineffective group, and the differences were statistically significant (P < .05). Multivariate logistic regression analysis on the baseline data and each ultrasound index showed that the type of atrial fibrillation, LAD, LAEF, and LAA-v were independently associated with the efficacy of anticoagulation (P < .05).Dabigatran etexilate is effective in dissolution of LAA thrombus in patients with atrial fibrillation, and the atrial fibrillation type, LAD, LAEF, and LAA-v are significantly related with the efficacy of anticoagulation.

Thrombolytic Therapy in Severe Cardioembolic Stroke After Reversal of Dabigatran with Idarucizumab: Case Report and Literature Review

Whether idarucizumab, an antidote of dabigatran, can be used effectively and safely before thrombolytic therapy with recombinant tissue plasminogen activator (rt-PA) in patients with stroke undergoing treatment with dabigatran remains unknown. We herein describe a 57-year-old man who developed severe cardioembolic stroke with a National Institutes of Health Stroke Scale score of 22 in the left middle cerebral artery territory while undergoing treatment with dabigatran for nonvalvular atrial fibrillation and who was treated with rt-PA after the reversal of dabigatran with idarucizumab. The thrombolytic therapy following the use of idarucizumab significantly improved the patient's neurological symptoms without hemorrhagic complications, although acute arterial occlusion of the right lower limb was found during the clinical course.

Plasma lipids affect dabigatran etexilate anticoagulation in rats with unbalanced diabetes mellitus

BACKGROUND

Dabigatran etexilate (DE) has similar stroke prevention efficacy in patients with and without diabetes mellitus (DM). However, the benefit of reducing major bleeding was not seen in diabetics. Thus, this study investigated anticoagulant responses to DE and the biological predictors of this response in a DM model.

METHODS

Experiments were performed in six control (C), eight DE-treated control (CD), five diabetic (D), and eight DE-treated diabetic (DD) rats. Dabigatran etexilate (50 mg/kg/day) was administered in chow for 12 weeks. At the end of the study, plasma glucose, triglycerides, total cholesterol (TC), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDL-C), and plasma creatinine were measured. Correlations were ascertained with the diluted thrombin time (dTT).

RESULTS

When corrected for similar DE intake, dTT was significantly higher in DD than CD rats (P < 0.001). There was a significant negative correlation between creatinine clearance (CCr) and dTT (r = -0.91, P < 0.01) in DD rats. In addition, dTT was positively correlated with TC (r = 0.96, P < 0.01), LDL-C (r = 0.75, P = 0.04), and glucose (r = 0.83, P = 0.02). In multiple regression analysis, CCr (r = -0.81, P = 0.01), TC (r = 0.93, P < 0.001), and LDL-C (r = 0.74, P < 0.01) remained the only independent predictors of dTT.

CONCLUSIONS

The results show a significantly more intense DE-induced anticoagulation in diabetic rats that does not seem to be solely related to altered kidney function, and demonstrate that plasma cholesterol can significantly affect DE anticoagulation in this setting.

Real-Life Peak and Trough Dabigatran Plasma Measurements over Time in Hospitalized Geriatric Patients with Atrial Fibrillation

BACKGROUND

Few geriatric patients were included in studies on direct oral anticoagulants and data on dabigatran concentration and safety are needed in this population. Our objectives were to evaluate peak and trough dabigatran plasma concentrations over time in a geriatric population and to identify factors associated with dabigatran plasma concentrations and to assess the relationship with bleeding events.

METHODS

Peak and trough dabigatran plasma concentration were performed 4,8,15,30,45 days after inception of dabigatran treatment in 68 consecutive patients ≥75 years old hospitalized in a geriatric hospital with atrial fibrillation. Bleeding events were monitored for 1 year.

RESULTS

Mean age was 85.8(5.1) years old and 76.5% were women. Overall, 541 dabigatran plasma measurements (270 peak, 271 trough) were performed. Mean dabigatran concentrations of the 5 sequential measurements ranged 106-146ng/mL for peak and 66-84ng/mL for trough. Renal failure was associated with high peak and trough dabigatran concentration. Inter- and intra-individual coefficients of variation were 59.5% and 44.7% for peak and 74.5% and 44.6% for trough. Participants in the lower two tertiles of dabigatran concentration at day 8 (D8) remained below the 90th percentile (243.9ng/ml) on the next measurements. Bleeding events were associated with high trough dabigatran concentrations. Trough dabigatran concentration at D8>243.9ng/mL significantly predicted bleeding.

CONCLUSION

In this geriatric population, renal function and low albumin were associated with dabigatran concentrations. Despite large variability, participants in the lower two tertiles of dabigatran concentration at D8 remained below the 90th percentile on the following measurements. D8 dabigatran trough concentration≥243.9ng/mL identified patients at risk of bleeding.

[Goal-directed administration of antidote for reversal of dabigatran anticoagulation]

Goal-directed administration of antidote for reversal of dabigatran anticoagulation Idarucizumab is a monoclonal antibody fragment that acts as an antidote to dabigatran. Idarucizumab is indicated in dabigatran-associated serious bleeds and to reverse dabigatran anticoagulation before acute surgical interventions or invasive medical procedures. The recommended dose of 5 g idarucizumab is sufficient to achieve a lasting restoration of coagulation in most patients. In a number of cases however, notably in deliberate overdoses and in accumulation of dabigatran in renal failure, repeated doses of idarucizumab may be necessary to avoid persisting or rebound anticoagulation. This article gives a brief explanation of the mechanisms responsible for this phenomenon and argues that it should be anticipated. Serial monitoring of APTT or dTT in patients treated with idarucizumab should enable the early detection of treatment failure or rebound anticoagulation and, if clinically indicated, prompt administration of additional doses of antidote.

Chronic kidney disease and anticoagulation: from vitamin K antagonists and heparins to direct oral anticoagulant agents

Anticoagulation in patients with impaired kidney function can be challenging since drugs' pharmacokinetics and bioavailability are altered in this setting. Patients with chronic kidney disease (CKD) treated with conventional anticoagulant agents [vitamin K antagonist (VKA), low-molecular weight heparin (LMWH) or unfractionated heparin (UFH)] are at high risk of bleeding events (both non-major and major clinically relevant bleeding). While anticoagulation reduces the risk of thromboembolic events, the co-existing bleeding risk and the fact that the most commonly used anticoagulation agents are eliminated via the kidneys pose additional challenges. More recently, two classes of direct oral anticoagulant agents (DOACs) have been investigated for the prevention and management of venous thromboembolic events: the direct factor Xa inhibitors rivaroxaban, apixaban and edoxaban, and the direct thrombin inhibitor dabigatran. In this review, we discuss the complex challenges and the practical considerations associated with the management of anticoagulation treatment in patients with CKD, with a special focus on DOACs.

Is it reasonable to use a lower DOACs dose in some patients with VTE? Yes

In the Hokusai-VTE trial, 733 patients were treated with the reduced dose edoxaban regimen, which maintained efficacy and safety compared with the 60 mg dose, and was safer than warfarin. The prophylactic doses of apixaban and rivaroxaban reduced the risk of recurrent venous thromboembolism (VTE) in the extended treatment trials. Dabigatran 110 mg was approved by the European Medicine Agency for VTE treatment. Further data from registries and real-world studies will help to clarify whether patients, with other specific characteristics, can benefit from the reduced dose of direct oral anticoagulants.

Anticoagulant Reversal and Anesthetic Considerations

Bleeding complications are a common concern with the use of anticoagulant agents. In many situations, reversing of neutralizing their effects may be warranted. Prothrombin complex concentrate replaces coagulation factors lowered by warfarin, as does fresh frozen plasma, but in a more concentrated form. Protamine negates the effect of heparin and combines chemically with heparin molecules to form an inactive salt. It also partially reverses the effects of low-molecular-weight heparin. Recombinant activated factor VII is a nonspecific procoagulant that activates the extrinsic clotting pathway, resulting in thrombin generation, but does not directly neutralize the activity of any of the new oral anticoagulants.

Italian intersociety consensus on DOAC use in internal medicine

The direct oral anticoagulants (DOACs) are drugs used in clinical practice since 2009 for the prevention of stroke or systemic embolism in non-valvular atrial fibrillation, and for the treatment and secondary prevention of venous thromboembolism. The four DOACs, including the three factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) and one direct thrombin inhibitor (dabigatran) provide oral anticoagulation therapy alternatives to Vitamin K antagonists (VKAs). Despite their clear advantages, the DOACs require on the part of the internist a thorough knowledge of their pharmacokinetic and pharmacodynamic characteristics to ensure their correct use, laboratory monitoring and the appropriate management of adverse events. This document represents a consensus paper on the use of DOACs by representatives of three Italian scientific societies: the Italian Society of Internal Medicine (SIMI), the Federation of the Associations of Hospital Managers (FADOI), and the Society for the Study of Haemostasis and Thrombosis (SISET). This document formulates expert opinion guidance for pragmatic managing, monitoring and reversing the anticoagulant effect of DOACs in both chronic and emergency settings. This practical guidance may help the internist to create adequate protocols for patients hospitalized ion internal medicine wards, where patients are often elderly subjects affected by poly-morbidities and renal insufficiency, and, thus, require particular attention to drug-drug interactions and peri-procedural protocols.

Fibrin(ogen) drives repair after acetaminophen-induced liver injury via leukocyte αMβ2 integrin-dependent upregulation of Mmp12

BACKGROUND & AIMS

Acetaminophen (APAP)-induced liver injury is coupled with activation of the blood coagulation cascade and fibrin(ogen) accumulation within APAP-injured livers of experimental mice. We sought to define the role of fibrin(ogen) deposition in APAP-induced liver injury and repair.

METHODS

Wild-type, fibrinogen-deficient mice, mutant mice with fibrin(ogen) incapable of binding leukocyte αMβ2 integrin (Fibγ390-396A mice) and matrix metalloproteinase 12 (Mmp12)-deficient mice were fasted, injected with 300mg/kg APAP i.p. and evaluated at a range of time-points. Plasma and liver tissue were analyzed. Rescue of Fibγ390-396A mice was carried out with exogenous Mmp12. To examine the effect of the allosteric leukocyte integrin αMβ2 activator leukadherin-1 (LA-1), APAP-treated mice were injected with LA-1.

RESULTS

In wild-type mice, APAP overdose increased intrahepatic levels of high molecular weight cross-linked fibrin(ogen). Anticoagulation reduced early APAP hepatotoxicity (6h), but increased hepatic injury at 24h, implying a protective role for coagulation at the onset of repair. Complete fibrin(ogen) deficiency delayed liver repair after APAP overdose, evidenced by a reduction of proliferating hepatocytes (24h) and unresolved hepatocellular necrosis (48 and 72h). Fibγ390-396A mice had decreased hepatocyte proliferation and increased multiple indices of liver injury, suggesting a mechanism related to fibrin(ogen)-leukocyte interaction. Induction of Mmp12, was dramatically reduced in APAP-treated Fibγ390-396A mice. Mice lacking Mmp12 displayed exacerbated APAP-induced liver injury, resembling Fibγ390-396A mice. In contrast, administration of LA-1 enhanced hepatic Mmp12 mRNA and reduced necrosis in APAP-treated mice. Further, administration of recombinant Mmp12 protein to APAP-treated Fibγ390-396A mice restored hepatocyte proliferation.

CONCLUSIONS

These studies highlight a novel pathway of liver repair after APAP overdose, mediated by fibrin(ogen)-αMβ2 integrin engagement, and demonstrate a protective role of Mmp12 expression after APAP overdose.

LAY SUMMARY

Acetaminophen overdose leads to activation of coagulation cascade and deposition of high molecular weight cross-linked fibrin(ogen) species in the liver. Fibrin(ogen) is required for stimulating liver repair after acetaminophen overdose. The mechanism whereby fibrin(ogen) drives liver repair after acetaminophen overdose requires engagement of leukocyte αMβ2 integrin and subsequent induction of matrix metalloproteinase 12.

Laboratory determination of old and new targeted anticoagulant agents for prevention of bleeding and thrombotic events in cancer patients

A two-fold prolongation of activated partial thromboplastin time (APTT) is established as therapeutic range for therapy with unfractionated heparin, hirudin and argatroban. The international normalized ratio (INR) of 2 to 3 is required to maintain anticoagulation in the therapeutic range of vitamin K antagonists. The therapeutic range of anti-factor Xa activity during therapy with low-molecular weight heparins and danaparoid are less well and of direct oral anticoagulants (DOAC) poorly defined. The relation of aPTT and INR values to thrombotic and bleeding events are well established despite a large variation of values in affected patients. The relation of coagulation values of the other anticoagulants to clinical events is open. The value of determination in cancer patients is higher because of the increased risk for thrombotic and bleeding events of this patient group. Several activities are currently undertaken to certify methods for in vitro diagnostic testing for DAOCs.

Use of Oral Anticoagulation in the Management of Atrial Fibrillation in Patients with ESRD: Pro

Warfarin has had a thin margin of benefit over risk for the prevention of stroke and systemic embolism in patients with ESRD because of higher bleeding risks and complications of therapy. The successful use of warfarin has been dependent on the selection of patients with nonvalvular atrial fibrillation at relatively high risk of stroke and systemic embolism and lower risks of bleeding over the course of therapy. Without such selection strategies, broad use of warfarin has not proven to be beneficial to the broad population of patients with ESRD and nonvalvular atrial fibrillation. In a recent meta-analysis of use of warfarin in patients with nonvalvular atrial fibrillation and ESRD, warfarin had no effect on the risks of stroke (hazard ratio, 1.12; 95% confidence interval, 0.69 to 1.82; P=0.65) or mortality (hazard ratio, 0.96; 95% confidence interval, 0.81 to 1.13; P=0.60) but was associated with increased risk of major bleeding (hazard ratio, 1.30; 95% confidence interval, 1.08 to 1.56; P<0.01). In pivotal trials, novel oral anticoagulants were generally at least equal to warfarin for efficacy and safety in nonvalvular atrial fibrillation and mild to moderate renal impairment. Clinical data for ESRD are limited, because pivotal trials excluded such patients. Given the very high risk of stroke and systemic embolism and the early evidence of acceptable safety profiles of novel oral anticoagulants, we think that patients with ESRD should be considered for treatment with chronic anticoagulation provided that there is an acceptable bleeding profile. Apixaban is currently indicated in ESRD for this application and may be preferable to warfarin given the body of evidence for warfarin and its difficulty of use and attendant adverse events.

Dabigatran antagonizes growth, cell-cycle progression, migration, and endothelial tube formation induced by thrombin in breast and glioblastoma cell lines

Thrombin activates its G-coupled seven transmembrane protease-activated receptor (PAR-1) by cleaving the receptor's N-terminal end. In several human cancers, PAR1 expression and activation correlates with tumor progression and metastatization. This provides compelling evidence for the effectiveness of an appropriate antithrombin agent for the adjuvant treatment of patients with cancer. Dabigatran is a selective direct thrombin inhibitor that reversibly binds to thrombin. In this study, we aimed to explore if dabigatran may affect mechanisms favoring tumor growth by interfering with thrombin-induced PAR-1 activation. We confirmed that exposure of tumor cells to thrombin significantly increased cell proliferation and this was coupled with downregulation of p27 and concomitant induction of cyclin D1. Dabigatran was consistently effective in antagonizing thrombin-induced proliferation as well as it restored the baseline pattern of cell cycle protein expression. Thrombin significantly upregulated the expression of proangiogenetic proteins like Twist and GRO-α in human umbilical vascular endothelial cells (HUVEC) cells and their expression was significantly brought down to control levels when dabigatran was added to culture. We also found that the chemoattractant effect of thrombin on tumor cells was lost in the presence of dabigatran, and that the thrombin antagonist was effective in dampening vascular tube formation induced by thrombin. Our data support a role of thrombin in inducing the proliferation, migration, and proangiogenetic effects of tumor cells in vitro. Dabigatran has activity in antagonizing all these effects, thereby impairing tumor growth and progression. In vivo models may help to understand the relevance of this pathway.

Safety ad efficacy of direct oral anticoagulants for extended treatment of venous thromboembolism

Currently available anticoagulants have limitations for long-term treatment of venous thromboembolism (VTE). We have evaluated the efficacy and safety of direct oral anticoagulants (DOACs) for extended treatment of VTE. Four randomized controlled trials (RCTs) comparing DOACs (apixaban, rivaroxaban, and dabigatran) with placebo or warfarin for extended treatment of VTE were published. Primary efficacy outcome was recurrent VTE or VTE-related death, and primary safety outcome was major bleeding. DOACs significantly lower the risk of recurrent VTE or VTE-related death compared to placebo/warfarin, as well as all-cause mortality. Risk of major bleeding is not different with DOACs compared to placebo/warfarin. However, DOACs are associated with a significantly higher rate of the composite of major and clinically relevant bleeding compared to placebo. In conclusion, DOACs are effective and safe for the extended treatment of VTE, and may reduce the risk of all-cause mortality.

An open-label study of the pharmacokinetics and pharmacodynamics of dabigatran etexilate 150mg once daily in Caucasian patients with moderate renal impairment undergoing primary unilateral elective total knee or hip replacement surgery

BACKGROUND

In adults with moderate renal impairment (creatinine clearance [CrCl] 30-50mL/min) undergoing total hip or knee replacement (THR/TKR), the recommended dose of dabigatran etexilate is 150mg once daily (qd). We investigated the steady state pharmacokinetics, pharmacodynamics and safety in these patients.

METHODS

Single-arm, open-label phase 4 study (NCT01184989) in Caucasian patients receiving dabigatran etexilate 75mg 1-4h after surgery and 150mg qd on days 2-10 (TKR) or days 2-35 (THR). Plasma total dabigatran concentrations (day 6±1) were determined by high-performance liquid chromatography tandem mass spectrometry and indirectly using the commercially available diluted thrombin time (dTT) assay (Hemoclot® Thrombin Inhibitors).

RESULTS

Of 112 patients (mean CrCl 42.5mL/min, age 79.1years, 69.6% female), 100 completed the study. Geometric mean trough and peak dabigatran concentrations were 47.5ng/mL (10th-90th percentile 19.7-120) and 166ng/mL (49.1-364), respectively. There were four major bleeding events and no venous thromboembolic events. Dabigatran concentrations determined from dTT (and falling within the assay range of 50-500ng/mL) underestimated actual values by 7.6% (90% confidence interval 5.3, 9.9), which is within the acceptance limits of ±15%.

CONCLUSIONS

These findings in Caucasians with moderate renal impairment undergoing THR or TKR support the use of the 150mg qd dose of dabigatran etexilate. With adequate set-up, calibration and quality control the dTT assay might be appropriate for situations, such as serious bleeding or a need for urgent surgery, where determination of dabigatran levels would be helpful.

Comparative Assessment of the Anticoagulant Activity of Rivaroxaban and Dabigatran in Patients With Nonvalvular Atrial Fibrillation: A Noninterventional Study

There is a shortage of data in everyday clinical practice about the anticoagulant effects caused by the new oral anticoagulants (NOAs). Our aim was to estimate the intensity of anticoagulant activity induced by rivaroxaban 20 mg qd and dabigatran 110 mg bid among patients with nonvalvular atrial fibrillation (NV-AF).We studied 20 patients with NV-AF treated with dabigatran, and 20 patients treated with rivaroxaban. We performed conventional coagulation tests, thrombin generation (TG) test, thromboelastometry (ROTEM), and epinephrine-induced light transmission aggregometry (LTA) in all 40 patients and 20 controls. Hemoclot Thrombin Inhibitors (HTI) and Factor Xa Direct Inhibitor (DiXaI) assay were used to measure dabigatran and rivaroxaban plasma levels, respectively.Measurements of all assays estimating anticoagulant activity across the 2 patient groups were similar, except for aPTT. Patients on dabigatran exhibited statistically significantly prolonged aPTT values (P < 0.001). In LTA, patients on dabigatran also showed decreased aggregation compared to those on rivaroxaban (P = 0.045). Regarding the TG test, there was no association between endogenous thrombin potential (ETP) and rivaroxaban plasma levels (P = 0.33) as opposed to dabigatran levels (P < 0.001), but significant correlations were observed between rivaroxaban plasma concentrations and kinetic parameters of TG assay (Tlag, P = 0.045; Tmax, P = 0.016; and Cmax, P = 0.003).Based on ROTEM and TG assays, the anticoagulant effects induced by the 2 drugs given in the specific dose regimens in real-world patients were comparable. Only platelet aggregation was found to be more affected by dabigatran as compared to rivaroxaban.

Idarucizumab: Clinical Role of a Novel Reversal Agent for Dabigatran

Atrial fibrillation (AF), a common cardiac arrhythmia associated with increased risk of heart failure, thromboembolic phenomena and death, is a leading cause of hospitalization of adults. A major complication of AF is an increased risk of ischemic stroke leading to long-term disability and in severe cases, death. Historically, Coumadin has been the drug of choice for chronic anticoagulation and stroke prevention in AF patients however, given the need for constant monitoring and multiple drug interactions, newer anticoagulants have been developed. One such drug is dabigatran, with the promise of less frequent monitoring and decreased bleeding tendencies as compared to Coumadin. The main disadvantage of dabigatran has been the lack of a reversal agent in case of severe bleeding or emergent surgical intervention. This was until the recent The Food and Drug Administration approval of idarucizumab, a potential reversal agent for dabigatran. In this article, we discuss the evidence addressing idarucizumab safety, tolerability and its efficacy for reversing effect of dabigatran.

The addition of idarucizumab to plasma samples containing dabigatran allows the use of routine coagulation assays for the diagnosis of hemostasis disorders

BACKGROUND

The anticoagulant effect of dabigatran can be approximated by its prolongation of routine coagulation assays. Consequently, dabigatran also interferes with thrombophilia screening or with diagnosing hemostasis disorders that have developed after the initiation of anticoagulant treatment, such as vitamin K deficiency or acquired hemophilia A.

OBJECTIVES

This study was carried out to determine whether idarucizumab, a humanized antibody fragment that binds dabigatran, could fully neutralize dabigatran in routine diagnostic coagulation assays conducted in vitro, thereby preventing false-positive or false-negative diagnostic readouts.

METHODS

Preliminary experiments identified coagulation assays that were sensitive to dabigatran, and identified a concentration of idarucizumab that neutralized the effects of dabigatran. These assays were then carried out with patient and control plasma samples spiked with dabigatran, with or without a molar excess of idarucizumab.

RESULTS

Dabigatran altered the prothrombin time, activated partial thromboplastin time and thrombin time, and the measurement of intrinsic and extrinsic factor levels. Screening and confirmation tests used for lupus anticoagulant detection were prolonged by dabigatran, falsely suggesting the presence of lupus anticoagulant. Conversely, the addition of dabigatran falsely corrected an abnormal activated protein C resistance ratio. Addition of idarucizumab completely normalized these measurements, and allowed the correct identification of normal and abnormal samples with these assays.

CONCLUSIONS

In vitro addition of idarucizumab to plasma samples containing dabigatran fully neutralizes the drug, and facilitates the use of routine coagulation assays to allow the diagnosis of hemostasis disorders that may be concurrently present in patients taking dabigatran.