Dabigatran Concentrations Research Articles

An optimized dRVVT-based assay to estimate the intensity of anticoagulation in patients treated with direct oral anticoagulants

BackgroundThe dilute Russell's viper venom time (dRVVT) has been suggested for the assessment of the intensity of anticoagulation of all direct oral anticoagulants (DOACs). This study aimed to compare the performance of an optimized liquid-stable dRVVT-based DOAC assay (DRVV-DOAC) on clinical samples before and after mixing these with normal pooled plasma (NPP). MethodsForty-one apixaban, 25 dabigatran, 56 rivaroxaban and 49 vitamin K antagonists (VKAs) plasma samples were included for retrospective analysis. Plasma DOAC concentrations were determined by liquid chromatography coupled with tandem mass-spectrometry. INR was determined for all VKA samples. DRVV-DOAC was performed with an original ready-to-use reagent (Haematex Research™) where plasma samples were tested neat and in a 1:1 mix with NPP. ResultsPlasma concentrations ranged from 1 to 406ng/ml for apixaban, 0 to 386ng/ml for dabigatran and 0 to 719ng/ml for rivaroxaban. INR ranged from 2.2 to 6.1. DRVV-DOAC correlated well with plasma concentrations (r2=0.70, 0.94, 0.63 (non-mixed procedure) and 0.77, 0.97, 0.86 (mixed procedure) for apixaban, dabigatran and rivaroxaban, respectively). DRVV-DOAC measurements in the normal range ruled out dabigatran and rivaroxaban concentrations above 30 and 50ng/ml, but performance was lower for apixaban. DRVV-DOAC was sensitive to VKA samples but poorly reflected INR values. When VKA samples were mixed with NPP, DRVV-DOAC measurements decreased to values close to baseline clotting time. ConclusionsDRVV-DOAC is a quick method which showed increased sensitivity compared with other phospholipid-rich dRVVT reagents already investigated. Mixing samples with NPP improved the specificity but reduced sensitivity, especially for apixaban.

Dabigatran reduces thrombin-induced platelet aggregation and activation in a dose-dependent manner.

Dabigatran is an oral anticoagulant and a reversible inhibitor of thrombin. Further, dabigatran might affect platelet function through a direct effect on platelet thrombin receptors. The aim was to investigate the effect of dabigatran on platelet activation and platelet aggregation. Healthy donor blood was incubated with dabigatran 0, 50, 500ng/mL, corresponding to the therapeutic range of dabigatran peak plasma concentrations, and 10,000ng/mL comprising a supra-therapeutic dabigatran plasma level. Platelet aggregation was tested with 96-well aggregometry. Flow cytometry was used to test platelet activation and platelet thrombin receptor expression (SPAN-12 and WEDE-15 expression). Agonists were thrombin, thrombin receptor-activating peptide, protease-activated receptor-4 agonist, collagen, collagen-related peptide, arachidonic acid, and adenosine diphosphate. All concentrations of dabigatran fully inhibited platelet aggregation for thrombin up to 2IU/mL, while dabigatran did not affect platelet aggregation by other agonists. Platelet activation (percentage of platelets positive for activated GPIIb/IIIa, CD63, P-selectin) was reduced after thrombin stimulation in samples with dabigatran levels ≥500ng/mL. After stimulation with thrombin, the percentage of activated GPIIb/IIIa-positive platelets was 99.8 ± 0.2% without dabigatran, 14.7 ± 4.7% with 500ng/mL dabigatran, and 4.2 ± 0.2% with 10,000ng/mL dabigatran, both p < 0.001 when compared to samples without dabigatran. Also, the receptor expression of GPIIb/IIIa, CD63, andP-selectin were reduced after dabigatran treatment. The expression of thrombin receptors was reduced at dabigatran on ≥ 500ng/mL. In conclusion, dabigatran exclusively inhibits thrombin-induced platelet activation and aggregation with a dose-dependent response. Platelet stimulation with other agonists was not affected by dabigatran.

Whole blood coagulation assays ROTEM and T-TAS to monitor dabigatran treatment

BackgroundA rapid and reliable assessment of the dabigatran effect is desirable in dabigatran treated patients with uncontrolled bleeding or before acute surgery. ObjectiveTo evaluate how the viscoelastic point-of-care test Rotational thromboelastometry (ROTEM) and Total Thrombus-formation system (T-TAS), which studies thrombus formation under flowing conditions, correlate with dabigatran concentrations in patients with atrial fibrillation (AF). MethodROTEM using the reagents In-tem, Ex-tem, Fib-tem or low tissue factor concentration (TF), and T-TAS with the AR-chip (shear rate 600s−1, representing flow in large arteries) were investigated in whole blood samples. Plasma concentrations were determined by mass spectrometry (LC-MS/MS) at trough and post-dose in 30 patients on dabigatran 150mg BID. ResultsMedian plasma dabigatran concentrations at trough were 86ng/mL (29–150) and post-dose (2.8h after ingestion) 175ng/mL (67–490). The ROTEM clotting time (CT) correlated strongly with dabigatran concentrations when activated with the reagents Ex-tem (r=0.92, p<0.01) and Fib-tem (r=0.93, p<0.01), while with In-tem and low TF the correlation was weaker (r=0.72 and r=0.36, p<0.01). There were significant but weaker correlations also between dabigatran concentrations and T-TAS variables (r-values 0.39–0.41, p<0.01), aPTT (r=0.70, p<0.01) and PT-INR (r=0.43, p<0.01) respectively. ConclusionsROTEM Ex-tem and Fib-tem CT shows a strong correlation with dabigatran concentrations in real-life AF-patients, and results are obtained within minutes. This could make ROTEM useful in acute situations. T-TAS detect differences in hemostasis caused by dabigatran, but the relationships to plasma concentrations of dabigatran are weaker than for ROTEM CT with the settings used in this study.

Point-of-care testing for emergency assessment of coagulation in patients treated with direct oral anticoagulants

BackgroundPoint-of-care testing (POCT) of coagulation has been proven to be of great value in accelerating emergency treatment. Specific POCT for direct oral anticoagulants (DOAC) is not available, but the effects of DOAC on established POCT have been described. We aimed to determine the diagnostic accuracy of Hemochron® Signature coagulation POCT to qualitatively rule out relevant concentrations of apixaban, rivaroxaban, and dabigatran in real-life patients.MethodsWe enrolled 68 patients receiving apixaban, rivaroxaban, or dabigatran and obtained blood samples at six pre-specified time points. Coagulation testing was performed using prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), and activated clotting time (ACT+ and ACT-low range) POCT cards. For comparison, laboratory-based assays of diluted thrombin time (Hemoclot) and anti-Xa activity were conducted. DOAC concentrations were determined by liquid chromatography-tandem mass spectrometry.ResultsFour hundred and three samples were collected. POCT results of PT/INR and ACT+ correlated with both rivaroxaban and dabigatran concentrations. Insufficient correlation was found for apixaban. Rivaroxaban concentrations at <30 and <100 ng/mL were detected with >95% specificity at PT/INR POCT ≤1.0 and ≤1.1 and ACT+ POCT ≤120 and ≤130 s. Dabigatran concentrations at <30 and <50 ng/mL were detected with >95% specificity at PT/INR POCT ≤1.1 and ≤1.2 and ACT+ POCT ≤100 s.ConclusionsHemochron® Signature POCT can be a fast and reliable alternative for guiding emergency treatment during rivaroxaban and dabigatran therapy. It allows the rapid identification of a relevant fraction of patients that can be treated immediately without the need to await the results of much slower laboratory-based coagulation tests.Trial registrationUnique identifier, NCT02371070. Retrospectively registered on 18 February 2015.

Abstract 20: Specific Point-of-care Testing of Coagulation in Patients Treated with Non-vitamin K Antagonist Oral Anticoagulants Part I (SPOCT-NOAC I)

Introduction: Non-vitamin K antagonist oral anticoagulants (NOAC) are increasingly replacing vitamin K antagonists for prevention of thromboembolism in atrial fibrillation (AF). Despite treatment, stroke rate in NOAC-treated AF-patients remains 1-2% per year. Subsequently, stroke physicians face a growing number of NOAC-treated patients with acute stroke. Rapid assessment of coagulation in NOAC-treated patients is vital prior to thrombolysis or reversal therapy, but existing point-of-care testing (POCT) is suboptimal. For the first time we evaluate NOAC-specific POCT. Hypothesis: Ecarin clotting time (ECT)- and anti-Xa activity (ENOX)-POCT predict plasma concentrations of dabigatran and apixaban/edoxaban/rivaroxaban. Methods: 80 patients receiving first NOAC-dose and 80 already on NOAC-treatment are enrolled in the SPOCT-NOAC I trial (N=40 for each NOAC). Subjects receiving other anticoagulants are excluded. Six blood samples are collected from each patient: before drug intake, 30min, 1, 2, and 8h after intake, and before next dose. NOAC-concentrations are measured by mass spectrometry. Results: 240 blood samples of 40 dabigatran-treated patients were analyzed. Dabigatran-concentrations ranged from 0-274ng/mL. ECT-POCT ranged from 20-196s. Pearson’s correlation coefficient showed strong correlation between ECT-POCT and dabigatran-concentrations (r=0.87). Performance was improved through the use of citrated in place of non-citrated whole blood (r=0.93). Dabigatran-concentrations &gt;50ng/mL (threshold for thrombolysis according to expert recommendation) were detected by ECT-POCT &gt;50s with 98% sensitivity and 79% specificity. Baseline-samples not containing any dabigatran yielded normal ECT values. Conclusions: This is the first study evaluating NOAC-specific POCT. Final results in the dabigatran group of SPOCT-NOAC show excellent correlation between ECT-POCT and dabigatran plasma concentrations; performance of ECT-POCT is even increased through the use of citrated whole blood. Relevant dabigatran-concentrations are detected with excellent sensitivity and specificity. In addition to ECT-POCT, we will present data on ENOX-POCT from apixaban-, edoxaban- and rivaroxaban-treated patients.

Real life dabigatran and metabolite concentrations, focused on inter-patient variability and assay differences in patients with atrial fibrillation

Dabigatran is prescribed to increasing numbers of patients with atrial fibrillation (AF). Although routine monitoring is not considered to be useful, measuring drug concentrations can be clinically relevant in specific situations. The aim of this study was the comparison of different functional and non-functional assays for determination of dabigatran concentrations at different timepoints in a real-life patient population with AF. We focused on the differences between assays in identifying patients with low drug concentrations. Furthermore, we studied the effect of glucuronidation on the established concentration as determined with different assays. This study established dabigatran concentration ranges in 40 real-life AF patients by an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) reference method and compared these with results from coagulation assays (Hemoclot dTT, LD-dTT and ECA). Samples were taken just before and 2 and 4 h after taking the drug. A wide range of concentrations at different time points was found in this patient group. Coagulation assays correlate best with UPLC-MS/MS results that include the glucuronidated metabolites, showing that the pharmacologically active glucuronides are also measured in coagulation testing. The LD-dTT has the best agreement with UPLC-MS/MS and combines good sensitivity with high specificity. Several patients show consistently low or high drug concentrations, implying that drug exposure differs between patients. Based on the association of dabigatran concentrations with bleeding and thromboembolic risk, we believe that dabigatran monitoring could be beneficial for further optimizing anticoagulation therapy in AF.

Dabigatran versus Warfarin for Acute Venous Thromboembolism in Elderly or Impaired Renal Function Patients: Pooled Analysis of RE-COVER and RE-COVER II.

Management of acute venous thromboembolism (VTE) with anticoagulants in elderly patients and those with chronic kidney disease poses special challenges. The RE-COVER and RE-COVER II trials showed that dabigatran 150 mg twice daily was as effective as warfarin over 6 months in preventing recurrent VTE, with a lower bleeding risk. We now assess the effects of old age and renal impairment (RI) on pooled trial outcomes in 5,107 patients: 4,504 aged <75 years and 603 aged ≥75 years. The primary efficacy outcome was symptomatic VTE/VTE-related death. Safety outcomes were centrally adjudicated major bleeding events (MBEs), MBEs or clinically relevant non-major bleeding events (MBEs/CRBEs) and any bleeds. Baseline renal function was categorized as normal, mild RI or moderate RI. A total of 3,698 had normal renal function and 1,100 and 237 had mild and moderate RI, respectively (23 patients with severe RI and 49 with missing creatinine clearance data were not included). For dabigatran, VTE/VTE-related death decreased from 3.1% (normal renal function) to 1.9% for mild RI and to 0.0% for moderate RI. For warfarin, the event rates were 2.6, 1.6 and 4.1%, respectively. Overall, major bleeding increased with increasing RI (p = 0.0037) and with age (p = 0.4350), with no apparent difference between the dabigatran and warfarin patients. Dabigatran shows better efficacy than warfarin in RI and in the elderly patients, probably because of an increase in the concentration of dabigatran. However, bleeding risk increases with both dabigatran and warfarin in the presence of RI.

In vitro and ex vivo Measurement of Prophylactic Dabigatran Concentrations with a New Ecarin-Based Thromboelastometry Test

Background: An increasing number of oral anticoagulants has been approved, including dabigatran etexilate (DE). DE is a direct thrombin inhibitor that requires no routine monitoring, but, if necessary (e.g. urgent surgery etc.), the diluted thrombin time measured with Hemoclot® has shown reliable results. So far, no point-of-care (PoC) assay is available to measure DE effects. The EcaTEM assay uses ecarin to initiate the coagulation cascade at the step of thrombin generation and measures the clotting time (CT) by thromboelastometry. Methods: This study investigated the correlation of the EcaTEM with standard laboratory assays in dabigatran-treated patients. Ten patients undergoing total hip or knee arthroplasty were included in the study. DE for thromboprophylaxis was started 4 h after surgery. Blood samples were taken before surgery as well as 2, 6 and 12 h after ingestion on the 3rd postoperative day. Dabigatran concentration (Hemoclot), activated partial thromboplastin time, thrombin time and CT EcaTEM were measured. Results: Only CT EcaTEM and Hemoclot showed a correlation > 0.75 for all measurements. Conclusion: CT EcaTEM appears a valid PoC method parameter to detect thrombin inhibition and thus the presence of dabigatran beside diluted thrombin time at different concentration levels. This may represent an opportunity to identify the presence of dabigatran, e.g., in emergency situations.

Microfluidic coagulation assay for monitoring anticoagulant therapy in acute stroke patients

Reliable detection of anticoagulation status in patients treated with non-vitamin K antagonist oral anticoagulants (NOACs) is challenging but of importance especially in the emergency setting. This study evaluated the potential of a whole-blood clotting time assay based on Surface Acoustic Waves (SAW-CT) in stroke-patients. The SAW-technology was used for quick and homogenous recalcification of whole blood inducing a surface-activated clotting reaction quantified and visualised by real-time fluorescence microscopy with automatic imaging processing. In 20 stroke or transient ischaemic attack (TIA)-patients taking NOACs kinetics of SAW-CT were assessed and correlated to other coagulation parameters (PT, aPTT) and NOAC-plasma concentration measured by tandem mass spectrometry (LC-MS/MS). In 225 emergency patients with suspicion of acute stroke or TIA, SAW-CT values were assessed. Mean (± SD) SAW-CT in non-anticoagulated stroke patients (n=180) was 124 s (± 21). In patients on dabigatran or rivaroxaban, SAW-CT values were significantly higher 2 and 8 hours (h) after intake rising up to 267 seconds (s) (dabigatran, 2 h after intake) and 250 s (rivaroxaban, 8 h after intake). In patients on apixaban, SAW-CT values were only moderately increased 2 h after intake (SAW-CT 153 s). In emergency patients, SAW-CT values were significantly higher in NOAC and vitamin K antagonist (VKA)-treated as compared to non-anticoagulated patients. In conclusion, the SAW-CT assay is capable to monitor anticoagulant level and effect in patients receiving dabigatran, rivaroxaban and the VKA phenprocoumon. It has a limited sensitivity for apixaban-detection. If specific SAW-CT results were used as cut-offs, SAW-CT yields high diagnostic accuracy to exclude relevant rivaroxaban and dabigatran concentrations in stroke-patients.

PHARMACOGENETIC ASPECTS OF NEW ORAL ANTICOAGULANTS APPLICATION

The aim of this review is to assess the effect of genetic factors on the pharmacokinetic parameters of new oral anticoagulants. The review presents data from studies investigating the effect of gene polymorphisms that encode biotransformation enzymes and transporter proteins of new oral anticoagulants on the pharmacokinetics of these drugs. RE-LY study showed a 15% decrease in trough dabigatran concentration and 27% lower risk of bleeding in carriers of CES1 gene rs2244613 polymorphism, there was also a tendency to reduce the risk of major bleeding. Further study of CES1 gene rs8192935 polymorphism showed a 3% decrease in trough dabigatran concentration in heterozygotes and 11% in homozygotes. There was found a 2% and 3% decrease in trough concentrations in hetero- and homozygotes for the minor allele of CES1 gene rs2244613 polymorphism, respectively. There was no significant effect of ABCB1 gene rs2032582 and rs1045642 polymorphisms on dabigatran pharmacokinetics. It is known the case of gastrointestinal bleeding in the carrier of allelic variants of ABCB1 gene rs2032582 and rs1045642 polymorphisms. However, there was no significant effect of genotype on rivaroxaban pharmacokinetics in the study involving the carriers of ABCB1 gene rs2032582 and rs1045642 polymorphisms. ABCB1 gene rs4148738 polymorphism was associated with higher apixaban peak concentration. But groups of patients with acute cardioembolic stroke showed no statistically significant difference of apixaban peak concentration depending on ABCB1 gene rs1045642 polymorphism genotype. ABCB1 gene rs1045642 and SLCO1B1 gene rs4149056 polymorphisms have no effect on edoxaban pharmacokinetics. Elevation of edoxaban metabolite concentration in carriers of SLCO1B1 gene allelic variants was not clinically significant because the proportion of metabolite is about 10% of the concentration of the main substance. It is necessary to provide large population studies with control of treatment efficacy and safety to prove clinical significance of genotyping for new oral anticoagulants use.

Pharmacokinetics, Pharmacodynamics, Safety and Tolerability of a Single-Dose Oral Solution of Dabigatran Given after Standard Anticoagulant Therapy in Children (Two Age Groups: 1-

Background:The incidence of venous thromboembolism (VTE) in children is increasing. The current standard of care is unfractionated heparin (UFH), low-molecular-weight heparin (LMWH) and Vitamin K antagonists (VKAs), all of which have limitations. Dabigatran, which is orally administered as the prodrug, dabigatran etexilate (DE), is effective for the treatment of VTE in adults and may overcome some of the limitations associated with standard care.Objective:The objectives of this phase IIa study were to obtain pharmacokinetic (PK) and pharmacodynamic (PD) data and to evaluate the tolerability and safety of an oral liquid formulation (OLF) of DE in patients aged 1 to < 12 years.Methods:The open-label, multinational, multicenter, non-randomized, single-arm study was conducted in patients aged 1 to < 2 years and 2 to < 12 years with a diagnosis of VTE, who had completed planned treatment with LMWH or oral anticoagulants (VKAs) for VTE.DE was administered as an OLF at a weight and age-adjusted dose (calculated using a nomogram) equivalent to 150 mg twice daily (bid) in adults. Originally, all patients were to receive multiple dosing (bid for 3 days). However, this was replaced with single dosing (SD) in the course of the study. A 30-day follow-up was included. Here we report data from SD patients only.The primary PK endpoints were plasma concentration of total dabigatran, free dabigatran, unchanged DE and intermediate metabolites. To compare the exposure to DE in pediatrics with that in adults with VTE, gMean concentrations at 10 hours after SD of DE were extrapolated to steady-state trough concentration. An accumulation ratio was calculated based on the terminal half-life (t1/2) and the dosing interval (for a bid dosing regimen) to project the steady-state dabigatran plasma concentration. Primary PD endpoints were activated partial thromboplastin time (aPTT), ecarin clotting time (ECT), and diluted thrombin time (dTT). Primary safety endpoints were incidence of all bleeding events and incidence of all adverse events (AEs).Results:Six patients aged 1 to < 2 years and 9 patients aged 2 to < 12 years received SD DE; 3 patients aged 2 to < 12 received multiple doses (bid for 3 days).In the SD groups, plasma concentration of total dabigatran increased at 2 hours (peak) after dosing then decreased until 10 hours after dosing. The projected steady-state dabigatran trough concentrations of both age groups of children studied were largely comparable to those observed in adults with VTE, i.e. the projected results for children fell between the first and the third quartile of adult trough concentrations (Table).Data from the SD groups indicated that there was a linear PK/PD relationship for ECT and dTT (see Figure) and a non-linear PK/PD relationship for aPTT. The PK/PD relationships were similar to those seen in adults (for all coagulation parameters analyzed) and adolescents (dTT and ECT) with VTE.During the on-treatment period there were no study drug related AEs; one patient had AEs (leukopenia and dizziness), which were mild in intensity and unrelated to the study drug. No AEs were reported during the post-treatment or post-study periods. No bleeding events were reported.Conclusion:The OLF of DE was well tolerated in pediatrics, with no drug-related AEs or bleeding events. Projected steady-state dabigatran trough concentrations were largely comparable to those seen in adults with VTE. The observed PK/PD relationship was similar to that seen in adults and adolescents with VTE. [Display omitted] [Display omitted] DisclosuresHalton:Boehringer Ingelheim: Other: Pediatric Expert Working Group for Boehringer Ingelheim. Albisetti:Boehringer Ingelheim: Other: Pediatric Expert Working Group. Luciani:Boehringer Ingelheim: Other: Member of Pediatric Expert Working Group for Boehringer Ingelheim. Huang:Boehringer Ingelheim: Employment. Biss:Boehringer Ingelheim: Employment. Brueckmann:Boehringer Ingelheim: Employment. Gropper:Boehringer Ingelheim: Employment. Maas:Boehringer Ingelheim: Employment. Tartakovsky:Boehringer Ingelheim: Employment. Mitchell:Boehringer Ingelheim: Consultancy; Pfizer: Consultancy; Bristol Myers Squibb: Consultancy.

Markers of Thromboembolic Risk Were Insignificantly Affected By Either Intraosseous or Intravenous Idarucizumab in a Dabigatran-Anticoagulated Porcine Polytrauma Model

Introduction: Idarucizumab is a monoclonal humanized antibody fragment (Fab), designed to reverse dabigatran anticoagulation. It is approved for urgent reversal of dabigatran anticoagulant effects in massive bleeding or prior to urgent interventions. It is administered intravenously (i.v.), either as a bolus or a short infusion (2x2.5 g). In hemorrhagic shock gaining i.v. might be challenging, and alternative methods such as intraosseous (i.o.) administration are an alternative life-saving procedure. Due to the molecular size of idarucizumab (50 kDa), the efficacy and safety, including the passage from the i.o. compartment to circulation, are unknown. In this study we investigated the efficacy and the prothrombotic risk of idarucizumab, given i.v. and i.o. in a large animal polytrauma model.Methods: After ethical approval, 21 male pigs were administered oral dabigatran etexilate for 3 days (30 mg/kg twice daily). Following anesthesia, to achieve constant plasma levels, further dabigatran was infused on day 4 (0.77 mg/kg/h for 30 min plus 0.2 mg/kg/h for 60 min). Animals were randomized 1:1:1 to receive 1) i.o. placebo (control group), 2) i.o. idarucizumab (60 mg/kg), or 3) i.v. idarucizumab (60 mg/kg). The standardized polytrauma consisted of a blunt liver injury and a femur fracture. After trauma and hemorrhagic shock, animals were resuscitated with Ringer’s solution. Idarucizumab (i.o. or i.v.) or placebo (i.o.) were administered 15 min after trauma, either via an i.o. access (left tibial plateau, EZ-IO¨), or an i.v. access. Animals were observed up to 240 min after trauma, and total blood loss was assessed after the observation period or animal’s death. Coagulation variables included dabigatran plasma concentration, global coagulation assays (PT, aPTT) and thromboelastometry. For a differentiated risk assessment, thrombin generation and thrombin-antithrombin (TAT) levels, indicating the extent of coagulation activation, and D-Dimers, as markers of thromboembolic risk, were obtained. Hemodynamic monitoring comprised cardiac output, mean arterial and mean pulmonary arterial pressure. For statistical analysis, ANOVA (mean ± SD) and the log-rank test for survival were used.Results: Prior to trauma, all animals showed comparable plasma concentration of dabigatran (583 ± 139 ng/mL). Following idarucizumab administration, dabigatran plasma concentration was not detectable in both groups. Binding of dabigatran was associated with a normalization of whole blood and plasma coagulation variables. Total blood loss post-injury was comparable between both idarucizumab groups (i.o.: 1085 ± 102 mL, i.v.: 1142 ± 125 mL; P>0.05) with 100% survival. In contrast, control animals (no anticoagulation and no idarucizumab) exhibited the highest total blood loss, which was significantly higher than in idarucizumab treated pigs (4065 ± 557 mL, P<0.001). 6 out of 7 control animals died within the observation period (mean survival: 117 min; P<0.00001). Dabigatran concentration remained elevated throughout the observation period (last sampling point; mean: 302 ng/mL; range: 176-468 ng/mL). Thrombin generation after dabigatran infusion and trauma was not measurable. After idarucizumab, thrombin generation was restored close to baseline levels (Peak height: 128 ± 39 nM, ETP: 360 ± 106 nM*min) (both i.o. and i.v., P<0.05 vs. control). Likewise, only in idarucizumab groups TAT levels indicated re-appearance of activation of coagulation, as compared to the control group. However, there was no significant difference in D-dimers 60 min after trauma between all groups (i.o.: 1164 ± 553 ng/mL; i.v.: 1216 ± 520 ng/mL; control: 747 ± 572 ng/mL; P>0.05). Clinically no signs of thromboembolic adverse were observed.Conclusion: The route of application (i.o. or i.v.) of idarucizumab has no impact on the efficacy of the reversal of dabigatran. Despite the size of idarucizumab, therapy can be safely applied via an i.o. access. In patients with severe bleeding and hemorrhagic shock under dabigatran application, i.o. administration of idarucizumab is a safe alternative. [Display omitted] DisclosuresHonickel:Böhringer Ingelheim Pharma GmbH & Co KG: Other: travel support. ten Cate:Böhringer Ingelheim: Consultancy, Honoraria, Research Funding; CSL Behring: Research Funding; Stago: Consultancy; Bayer: Consultancy, Honoraria, Research Funding; Philips: Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Leo Pharma: Consultancy, Honoraria. Rossaint:CSL Behring: Consultancy, Honoraria; Böhringer Ingelheim: Consultancy, Honoraria; Novo Nordisk: Consultancy, Honoraria. Grottke:Böringer Ingelheim: Consultancy, Honoraria, Research Funding; Novo Nordisk: Research Funding; Biotest: Research Funding; CSL Behring: Consultancy, Honoraria, Research Funding; Nycomed: Research Funding; Bayer: Consultancy, Honoraria; Octapharma: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Portola: Consultancy, Honoraria.

Pharmacokinetics (PK) and Pharmacodynamics (PD), Safety and Tolerability of a Single-Dose Oral Solution of Dabigatran Etexilate Given after Standard Anticoagulant Therapy in Children from Birth to Less Than One Year Old, with Venous Thromboembolism

Background: Venous thromboembolism (VTE) events are more frequent in neonates than in children of other age groups. The standard of care for pediatric anticoagulation includes unfractionated or low-molecular-weight heparin, or vitamin K antagonists. However, these treatments have limitations in terms of practicality of use in infants, such as parenteral administration, frequent monitoring and drug interactions. Alternative oral agents that address these shortcomings may improve compliance, efficacy and safety. The safety and efficacy of dabigatran etexilate (DE), a direct thrombin inhibitor, are established in adults; pharmacokinetic/pharmacodynamic (PK/PD) studies indicate linear PK. There is a relationship between dabigatran plasma concentration (PK) and its PD effects, resulting in reproducible dose-dependent prolongation in clotting times with rapid onset and offset of effect, which is consistent across populations. Although phase IIa studies suggest a similar PK/PD relationship of dabigatran in children and adults, the hemostatic system in infants differs from older children and adults, which may lead to a different PK/PD effect.Objective: To demonstrate comparable PK/PD relationship of DE oral liquid formulation (OLF) between infants and older children and adults, and to assess safety and tolerability.Methods: Open-label, multicenter, single-dose, single-arm, phase IIa pediatric study. Infants aged < 1 year diagnosed with VTE who completed standard anticoagulant treatment for VTE were enrolled. Exclusion criteria included < 37 weeks gestational age at birth, weight < 3 kg, major bleed with standard anticoagulant and swallowing abnormalities. Patients received DE OLF (based on age- and weight-adjusted nomogram) and were followed up for 30 (+7) days. The primary endpoints were PK/PD related, measured at 2 hrs and 12 (±2) hrs after DE administration. The PK endpoint was plasma concentration of total dabigatran, and PD endpoints were activated partial thromboplastin time (aPTT), ecarin clotting time (ECT) and diluted thrombin time (dTT). Secondary endpoints included incidence of all bleeding events and adverse events (AEs), acceptability and tolerability. Descriptive statistics were applied to the endpoints. PK/PD relationship was analyzed using a simple linear regression model and nonlinear Emax model to confirm whether models used in previous studies were consistent with the pediatric data of this study.Results: Ten patients were screened and 8 entered the study (mean age [SD]: 89 [52] days; range: 41-169 days). Patients received a single dose of DE OLF. The geometric mean (gMean) total dabigatran plasma concentrations 2 hrs post dose (around peak concentrations) was 120 ng/mL with geometric coefficient of variation (gCV) of 62.1%, which indicated moderate variability. The gMean at 12 hrs post dosing was 60.4 ng/mL (gCV 30%), which indicated low variability. The projected steady-state dabigatran trough concentrations were largely comparable to those observed in adults with VTE (Table).A linear PK/PD relationship was observed for ECT (ECT ratio) and dTT (dTT ratio) (Figure). The relationship between total dabigatran concentration and aPTT (aPTT ratio) was nonlinear. The observed PK/PD relationships were similar to those in adult and adolescent patients with VTE, except for patients aged < 2 months, in whom a slight upward shift of aPTT of 10-20% (average) and ECT by 10-15% was observed relative to adults. There were no AEs, deaths or treatment discontinuations during the treatment period. None of the treated patients had any bleeding events or thromboembolic events during the study. One patient had a serious AE (aortic stenosis) during the post-treatment period, which was not considered treatment related by the investigator. There were no clinically relevant or unexpected laboratory findings. The majority of patients were assessed with good tolerability (six patients, 75%), and one patient each (12.5%) was evaluated with satisfactory or bad tolerability.Conclusion:In this small population of infants (aged < 1 year), DE OLF was well tolerated without any treatment-related AEs, thromboembolic or bleeding events. The observed PK/PD relationships were consistent with the established profile in adult and adolescent patients with VTE. [Display omitted] [Display omitted] DisclosuresHalton:Boehringer Ingelheim: Other: Pediatric Expert Working Group for Boehringer Ingelheim. Picard:Boehringer Ingelheim: Employment. Harper:Boehringer Ingelheim: Employment. Huang:Boehringer Ingelheim: Employment. Brueckmann:Boehringer Ingelheim: Employment. Gropper:Boehringer Ingelheim: Employment. Maas:Boehringer Ingelheim: Employment. Tartakovsky:Boehringer Ingelheim: Employment. Nurmeev:Boehringer Ingelheim: Other: Investigator fees. Mitchell:Boehringer Ingelheim: Consultancy; Pfizer: Consultancy; Bristol Myers Squibb: Consultancy. Albisetti:Boehringer Ingelheim: Other: Pediatric Expert Working Group.

Idarucizumab, a Specific Reversal Agent for Dabigatran: Immediate, Complete and Sustained Reversal of Dabigatran-Induced Anticoagulation in Japanese Healthy Male Volunteers

Background: Specific reversal agents for oral anticoagulants may be necessary to manage life-threatening bleeding or prior to emergency surgical procedures. While many reversal agents are in development, idarucizumab is approved and now available commercially in many countries. Idarucizumab is a humanized antibody fragment that specifically binds to dabigatran with high affinity and has shown immediate, complete and sustained reversal of dabigatran-induced anticoagulation in healthy male Caucasian volunteers. The present study investigated the safety, tolerability and pharmacokinetics of idarucizumab (part 1) and explored the effective dose of idarucizumab to reverse the dabigatran-induced anticoagulant effect (part 2) in healthy male Japanese volunteers.Methods: This was a two-part, phase I, randomized, placebo-controlled, double-blind, single-center, rising dose study. In part 1, subjects (n = 32) were randomized to receive either placebo (n = 2/dose group) or single intravenous doses of idarucizumab, 1, 2, or 4 g as a 5-minute infusion or 8 g as a 1-hour infusion (n = 6/group). In part 2, subjects (n = 48) were treated orally for 3 days with dabigatran etexilate (DE, 220 mg bid). On day 4, subjects received a final DE dose, followed a 3-day wash out period. Subjects were again treated orally for 3 days with DE, 220 mg bid. On Day 11, subjects received a final DE dose followed 2 hours later by placebo (n = 3/group) or idarucizumab (1, 2, 4, or 5 g [2.5 g followed by 2.5 g given 15 minutes apart]) as a 5-minute intravenous infusion, n = 9/group). The number of subjects with adverse events (AEs), emergence of anti-idarucizumab antibodies (ADAs), pharmacokinetics and the impact of idarucizumab on coagulation parameters were assessed (diluted thrombin time, ecarin clotting time, activated partial thromboplastin time, and thrombin time). In addition, potential procoagulant effects were monitored as D-dimer and prothrombin fragment F1.2.Results: Idarucizumab attained a maximum concentration in plasma around the end of each infusion followed by a biphasic decline in plasma concentrations with a rapid initial phase and a longer terminal phase.. Dabigatran treatment prolonged the clotting times of all coagulation parameters. Idarucizumab infusion resulted in immediate and complete reversal of dabigatran-induced anticoagulation, reducing coagulation parameters below the upper limit of normal. The duration was dose-dependent; at 4 and 5 g of idarucizumab, complete reversal was sustained up to 72 hours, at lower doses ≤ 2 g a partial return of the anticoagulation activity of dabigatran was observed 1-2 hours after idarucizumab administration. Concentration of unbound dabigatran decreased to below the limit of quantification immediately after administration of a single dose of idarucizumab. Idarucizumab was safe and well tolerated, and no AEs were reported. There was no elevation of either D-dimer or F1.2 levels post idarucizumab as compared to levels prior to infusion in any of the dose groups. Treatment-emergent ADAs occurred in 6 of 60 patients receiving idarucizumab.Conclusion: Idarucizumab infusion achieved immediate, complete and sustained reversal of dabigatran-associated anticoagulation in healthy male Japanese volunteers. Idarucizumab was safe and well tolerated with no procoagulant effects. Disclosuresvan Ryn:Boehringer Ingelheim: Employment. Yasaka:Sanofi: Research Funding; Nippon Boehringer Ingelheim: Other: received lecture fees (over 1 million Yen); Bristol-Myers Squibb: Other: received lecture fees (over 1 million Yen); Bayer Yakuhin: Other: received lecture fees (over 1 million Yen); Daiichi-Sankyo: Other: received lecture fees (over 1 million Yen). Harada:Boehringer Ingelheim: Employment. Taniguchi:Boehringer Ingelheim: Employment. Imazu:Boehringer Ingelheim: Employment. Norris:Boehringer Ingelheim: Employment. Gansser:Boehringer Ingelheim: Employment. Stangier:Boehringer Ingelheim: Employment.

Dosage Adjustment of Dabigatran Etexilate Based on Creatinine Clearance in Patients With Cardioembolic Stroke or Atrial Fibrillation.

A recommendation for dosage adjustment of dabigatran etexilate, a prodrug of dabigatran, seems to be desirable based on creatinine clearance to avoid bleeding and stroke. Outpatients and inpatients having a history of cardioembolic stroke or atrial fibrillation were included. After taking dabigatran etexilate orally (75-150 mg twice daily) for at least 1 week, plasma trough concentration (Ctrough, ng/mL) of dabigatran and creatinine clearance (CLcr, mL/min) of patients according to Cockcroft and Gault equation were determined. Among the 38 patients studied, Ctrough of dabigatran and CLcr were scattered in a range from 31.4 to 329.5 ng/mL and 15.4-133.4 mL/min, respectively. Temporal CLtotal (Temp-CLtotal) of dabigatran, estimated by dividing the daily absorbed amount of dabigatran etexilate with Ctrough of dabigatran, was linearly correlated with CLcr of patients (P = 0.0018). Based on the findings, the daily dose of dabigatran etexilate that provides Ctrough of dabigatran at approximately 70 ng/mL was estimated. A linear relationship was found between Temp-CLtotal of dabigatran and CLcr of patients. Depending on CLxr of patients, we recommend 4 different dosages of dabigatran etexilate to obtain Ctrough of dabigatran at approximately 70 ng/mL.

An in-vitro evaluation of direct thrombin inhibitor and factor Xa inhibitor on tissue factor-induced thrombin generation and platelet aggregation: a comparison of dabigatran and rivaroxaban.

Dabigatran and rivaroxaban may simultaneously inhibit coagulation and platelet activation. This study aimed to reveal the in-vitro effects of dabigatran and rivaroxaban on thrombin generation and platelet aggregation (PAg) derived via tissue factor (TF) pathway. Citrated blood was obtained from six healthy adults (26-60 years old) and pretreated with increasing concentrations of dabigatran or rivaroxaban. Plasmatic endogenous thrombin potential (ETP) was measured by the calibrated automated thrombogram method. The whole blood PAg was evaluated via a kinetic counting method. TF produced an ETP of 1904.69 ± 121.42 nmol min and a PAg of 78 ± 5%. Dabigatran and rivaroxaban concentration-dependently reduced ETP with half-maximal inhibitory concentrations of 460.1 ± 1.4 and 678.1 ± 1.4 nmol/l, and inhibited PAg with half-maximal inhibitory concentrations of 119.5 ± 1.5 and 77.5 ± 1.6 nmol, respectively. Dabigatran and rivaroxaban significantly inhibit TF-induced hypercoagulation and platelet activation in vitro in a concentration-dependent manner. Rivaroxaban displays stronger inhibition on thrombin generation and PAg than dabigatran.

Glomerular filtration rate assessed by using creatinine and cystatin in patients treated with dabigatran

Dabigatran (DAB) is 80 % renally excreted. Glomerular filtration rate (GFR) estimation is recommended to evaluate the kidney function for DAB dosage adjusting. In this paper we report same results about evaluation of creatinine (CRE) GFR and cystatin-C (CYS) GFR in comparison with drug concentration in a group of patients treated with DAB. We considered 77 patients in which an evaluation of kidney function using CRE and CYS based GFR was performed. After GFR-CRE and GFR-CYS calculation these patients were classified as recommended by KDIGO guidelines. Moreover we evaluated the relationship between trough DAB concentration and GFR-CRE or GFR-CYS. We observed a satisfactory correlation between GFR-CRE and GFR-CYS ( $R=0.85$ ). Following KDIGO criteria, patients’ classification performed by using GFR-CRE or GFR-CYS was concordant in 52 (68 %) subjects and discordant in 25 (32 %). We observed an inverse relationship between trough DAB concentration versus GFR-CRE ( $R=-0.71$ ) and GFR-CYS ( $R=-0.79$ ). Results obtained in this study, although preliminary, suggested that, in this particular subset of patients, the determination of GFR-CYS can be a better renal function indicator than GFR-CRE. Moreover, we observed that GFR evaluation alone is not able to explain in a satisfactory manner, individual responses to dabigatran etexilate evaluated as a trough DAB concentration.

Idarucizumab for dabigatran overdose in a child

Idarucizumab for dabigatran overdose in a child

Laboratory Assessment of the Anticoagulant Activity of Direct Oral Anticoagulants: A Systematic Review

Direct oral anticoagulants (DOACs) are the treatment of choice for most patients with atrial fibrillation and/or noncancer-associated venous thromboembolic disease. Although routine monitoring of these agents is not required, assessment of anticoagulant effect may be desirable in special situations. The objective of this review was to summarize systematically evidence regarding laboratory assessment of the anticoagulant effects of dabigatran, rivaroxaban, apixaban, and edoxaban. PubMed, Embase, and Web of Science were searched for studies reporting relationships between drug levels and coagulation assay results. We identified 109 eligible studies: 35 for dabigatran, 50 for rivaroxaban, 11 for apixaban, and 13 for edoxaban. The performance of standard anticoagulation tests varied across DOACs and reagents; most assays, showed insufficient correlation to provide a reliable assessment of DOAC effects. Dilute thrombin time (TT) assays demonstrated linear correlation (r2= 0.67-0.99) across a range of expected concentrations of dabigatran, as did ecarin-based assays. Calibrated anti-Xa assays demonstrated linear correlation (r2= 0.78-1.00) across a wide range of concentrations for rivaroxaban, apixaban, and edoxaban. An ideal test, offering both accuracy and precision for measurement of any DOAC is not widely available. We recommend a dilute TT or ecarin-based assay for assessment of the anticoagulant effect of dabigatran and anti-Xa assays with drug-specific calibrators for direct Xa inhibitors. In the absence of these tests, TT orAPTT is recommended over PT/INR for assessment of dabigatran, and PT/INR is recommended over APTT for detection of factor Xa inhibitors. Time since last dose, the presence or absence of druginteractions, and renal and hepatic function should impact clinical estimates of anticoagulant effectin a patient for whom laboratory test results are not available.

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

BackgroundIn 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. MethodsSingle-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). ResultsOf 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%. ConclusionsThese 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.