Dabigatran Concentrations Research Articles

Protein S contributes to the paradoxical increase in thrombin generation by low-dose dabigatran in the presence of thrombomodulin.

Low dose of dabigatran paradoxically increased thrombin generation through inhibition of protein C activation. Protein S is a co-factor in the activation of protein C. However, the role of protein S in the enhancement of thrombin generation has not been addressed. Firstly, we measured thrombin generation by calibrated automated thrombinography (CAT) and prothrombin fragments 1+2 (F1+2) assays. Secondly, we assessed activated protein C (APC) formation in normal or protein S-deficient plasma spiking with dabigatran. Then, protein C activation was measured. Finally, heavy chain of factor Va (FVa) and its degradation products were detected by western blot. CAT assay showed that 70-141 ng/ml dabigatran paradoxically increased thrombin generation in normal plasma. However, higher concentrations of dabigatran (283 ng/ml) suppressed the level of ETP. F1+2 assay showed the similar results. In protein S-deficient or protein C-deficient plasma, the paradoxical increase in thrombin generation was absent. Level of generated APC was to a similar extent inhibited by dabigatran in normal and protein S-deficient plasma. Low-dose dabigatran inhibited the protein S-dependent inactivation of factor Va. Protein S participated in the paradoxical enhancement of thrombin generation in normal plasma spiking with low concentrations of dabigatran. Increased thrombin generation at low dabigatran can be explained by reduced thrombin-thrombomodulin mediated APC formation and subsequent reduced FVa inactivation that is protein S-dependent.

Pharmacokinetics and bioequivalence of the generic and original dabigatran etexilate after a single dose in healthy volunteers

Aim. To study the comparative pharmacokinetics and confirmation of bioequivalence of the generic (T) and original (R) dabigatran etexilate in healthy volunteers after a single oral dose under fasted conditions.Material and methods. To confirm bioequivalence, an open-label, randomized, replication, crossover, four-step study was conducted to compare the pharmacokinetics and bioequivalence of generic and original dabigatran with a single oral dose 150 mg dabigatran etexilate under fasted conditions in adult healthy male and female volunteers. Sixty-eight subjects participated in the study. During the study, blood plasma samples were taken from volunteers, in which the concentration of total and free dabigatran was determined. Based on the data obtained, pharmacokinetic and statistical analysis was carried out and 90% confidence intervals were calculated for the ratio of mean pharmacokinetic parameters (Сmax, Tmax, AUC0-t, AUC0-∞, AUCt-∞, T1/2, AUCt-∞/AUC0-∞) for total and free dabigatran.Results. The established 90% confidence intervals for the ratio of AUC0-t, AUC0-∞ and Cmax values for total dabigatran were 82,56-96,36% (mean ratio, 89,19%), 82,39-95,90% (mean ratio, 88,89%) and 85,98-99,17% (mean ratio, 92,34%), respectively. The established 90% confidence intervals for the ratio of AUC0-t, AUC0-∞ and Сmax values for free dabigatran were 83,37-98,29% (mean ratio, 90,53%), 82,98-97,33% (mean ratio, 89,87%) and 85,04-99,28% (mean ratio, 91,88%), respectively. For the estimated pharmacokinetic parameters of dabigatran etexilate, 90% confidence intervals ranged from 80-125% for AUC0-t, AUC0-∞ and Cmax. Additional safety analysis was carried out. Generic and original dabigatran were well tolerated by the volunteers. There were no significant differences in vital signs, paraclinical characteristics throughout the study compared with the initial data, as well as significant differences between the drugs in all studied parameters of adverse events.Conclusion. The study showed that generic and original dabigatran are bio­equivalent. In addition, the data obtained indicate that the agents have similar safety profiles.

Dabigatran accumulation in acute kidney injury: is more better than less to prevent bleeding? A case report

Dabigatran is an oral anticoagulant that is mainly renally excreted. Despite its efficacy in preventing thromboembolic events, concerns arise regarding bleeding complications in patients with acute kidney injury. Idarucizumab is its specific antidote and reverses quickly and effectively dabigatran anticoagulation effects in situations of severe bleeding or pending surgical procedures, but its benefit beyond these two indications remains uncertain. We present a case of a woman with atrial fibrillation anticoagulated by dabigatran and admitted with Streptococcus agalactiae meningitis, acute kidney injury and dabigatran accumulation. Idarucizumab was not administered initially as she did not meet its current strict indications. However, subsequently, significant bleeding necessitated its use. A rebound increase in dabigatran concentration was associated with an intracranial hemorrhage, but the combination of additional doses of idarucizumab with hemodialysis lowered the dabigatran concentration and prevented significant rebound increases. Further investigation into the optimal management of dabigatran accumulation and acute kidney injury-associated bleeding is needed to enhance patient outcomes and safety. Early initiation of hemodialysis together with idarucizumab administration may be crucial in preventing life-threatening bleeding events in these patients.

Dabigatran pharmacokinetic-pharmacodynamic in sheep: Informing dose for anticoagulation during cardiopulmonary bypass.

The effect of the anticoagulant, dabigatran, and its antagonist, idarucizumab, on coagulation remains poorly quantified. There are few pharmacokinetic-pharmacodynamic data available to determine dabigatran dose in humans or animals undergoing cardiopulmonary bypass. Five sheep were given intravenous dabigatran 4mg/kg. Blood samples were collected for thromboelastometric reaction time (R-time) and drug assay at 5, 15, 30, 60, 120, 240, 480min, and 24h. Plasma dabigatran concentrations and R-times were analyzed using an integrated pharmacokinetic-pharmacodynamic model using non-linear mixed effects. The impact of idarucizumab 15mg/kg administered 120min after dabigatran 4mg/kg and its effect on R-time was observed. A 2-compartment model described dabigatran pharmacokinetics with a clearance (CL 0.0453L/min/70kg), intercompartment clearance (Q 0.268L/min/70kg), central volume of distribution (V1 2.94L/70kg), peripheral volume of distribution (V2 9.51L/70kg). The effect compartment model estimates for a sigmoid EMAX model using Reaction time had an effect site concentration (Ce50 64.2mg/L) eliciting half of the maximal effect (EMAX 180min). The plasma-effect compartment equilibration half time (T1/2keo) was 1.04min. Idarucizumab 15mg/kg reduced R-time by approximately 5min. Dabigatran reversibly binds to the active site on the thrombin molecule, preventing activation of coagulation factors. The pharmacologic target concentration strategy uses pharmacokinetic-pharmacodynamic information to inform dose. A loading dose of dabigatran 0.25mg/kg followed by a maintenance infusion of dabigatran 0.0175mg/kg/min for 30min and a subsequent infusion dabigatran 0.0075mg/kg/min achieves a steady state target concentration of 5mg/L in a sheep model.

DOAC plasma concentration upon hospital admission in a cohort of trauma patients. An observational real-life study.

Due to a better safety profile, direct oral anticoagulants (DOACs) are increasingly prescribed for prevention of thromboembolic events. However, little is known about DOAC plasma concentrations in trauma patients upon hospital admission. Thus, we investigated the frequency and extent of DOAC possible over- and underdosing in trauma patients upon hospital admission. In this single-center retrospective study, DOAC plasma concentrations of adult trauma patients were analyzed with specific calibrated anti-IIa (dabigatran) and anti-Xa (apixaban, edoxaban and rivaroxaban) tests within 4h after hospital admission. A total of 210 trauma patients, admitted between 2019 and 2022, were included in the analyses. Low DOAC levels < 30ng/mL were detected in 13.3% of the patients. In 7.1% of the patients, DOAC plasma levels ranged between 300-399ng/mL and further 7.1% exhibited plasma concentrations > 400ng/mL. The highest incidence of high to very high DOAC plasma concentration was observed for patients on rivaroxaban and dabigatran. A moderate correlation was observed between dabigatran plasma concentration and estimated glomerular filtration rate (rho = - 0.5338, p = 0.0003). For rivaroxaban no clear association between plasma concentration and liver or renal function could be detected. Patients on statins had significantly higher DOAC concentration in comparison with those not taking statins (153 (76-274) vs 108 (51-217) ng/mL, p = 0.046). The current study revealed that patients on dabigatran and rivaroxaban were prone to higher DOAC plasma levels upon hospital admission in comparison with apixaban and edoxaban. DOAC plasma level measurement in trauma patients might be warranted due to unpredictively low or high plasma concentrations. However, the clinical impact of altered plasma levels on both, bleeding and thromboembolic events, remains to be determined by future studies.

Assessment of the potential of the MET inhibitor tepotinib to affect the pharmacokinetics of CYP3A4 and P-gp substrates

SummaryTepotinib is a highly selective, potent, mesenchymal-epithelial transition factor (MET) inhibitor, approved for the treatment of non-small cell lung cancer harboring MET exon 14 skipping alterations. The aims of this work were to investigate the potential for drug-drug interactions via cytochrome P450 (CYP) 3A4/5 or P-glycoprotein (P-gp) inhibition. In vitro studies were conducted in human liver microsomes, human hepatocyte cultures and Caco-2 cell monolayers to investigate whether tepotinib or its major metabolite (MSC2571109A) inhibited or induced CYP3A4/5 or inhibited P-gp. Two clinical studies were conducted to investigate the effect of multiple dose tepotinib (500 mg once daily orally) on the single dose pharmacokinetics of a sensitive CYP3A4 substrate (midazolam 7.5 mg orally) and a P-gp substrate (dabigatran etexilate 75 mg orally) in healthy participants. Tepotinib and MSC2571109A showed little evidence of direct or time-dependent CYP3A4/5 inhibition (IC50 > 15 μM) in vitro, although MSC2571109A did show mechanism-based CYP3A4/5 inhibition. Tepotinib did not induce CYP3A4/5 activity in vitro, although both tepotinib and MSC2571109A increased CYP3A4 mRNA. In clinical studies, tepotinib had no effect on the pharmacokinetics of midazolam or its metabolite 1’-hydroxymidazolam. Tepotinib increased dabigatran maximum concentration and area under the curve extrapolated to infinity by 38% and 51%, respectively. These changes were not considered to be clinically relevant. Tepotinib was considered safe and well tolerated in both studies. The potential of tepotinib to cause clinically relevant DDI with CYP3A4- or P-gp-dependent drugs at the clinical dose is considered low. Study 1 (midazolam): NCT03628339 (registered 14 August 2018). Study 2 (dabigatran): NCT03492437 (registered 10 April 2018).

The Distribution of the Genotypes of ABCB1 and CES1 Polymorphisms in Kazakhstani Patients with Atrial Fibrillation Treated with DOAC.

Nowadays, direct oral anticoagulants (DOACs) are the first-line anticoagulant strategy in patients with non-valvular atrial fibrillation (NVAF). We aimed to identify the influence of polymorphisms of the genes encoding P-glycoprotein (ABCB1) and carboxylesterase 1 (CES1) on the variability of plasma concentrations of DOACs in Kazakhstani patients with NVAF. We analyzed polymorphisms rs4148738, rs1045642, rs2032582 and rs1128503 in ABCB1 and rs8192935, rs2244613 and rs71647871 CES1 genes and measured the plasma concentrations of dabigatran/apixaban and biochemical parameters in 150 Kazakhstani NVAF patients. Polymorphism rs8192935 in the CES1 gene (p = 0.04), BMI (p = 0.01) and APTT level (p = 0.01) were statistically significant independent factors of trough plasma concentration of dabigatran. In contrast, polymorphisms rs4148738, rs1045642, rs2032582 and rs1128503 in ABCB1 and rs8192935, rs2244613 and rs71647871 CES1 genes did not show significant influence on plasma concentrations of dabigatran/apixaban drugs (p > 0.05). Patients with GG genotype (138.8 ± 100.1 ng/mL) had higher peak plasma concentration of dabigatran than with AA genotype (100.9 ± 59.6 ng/mL) and AG genotype (98.7 ± 72.3 ng/mL) (Kruskal-Wallis test, p = 0.25). Thus, CES1 rs8192935 is significantly associated with plasma concentrations of dabigatran in Kazakhstani NVAF patients (p < 0.05). The level of the plasma concentration shows that biotransformation of the dabigatran processed faster in individual carriers of GG genotype rs8192935 in the CES1 gene than with AA genotype.

Dabigatran Dosing Proposal for Adults With Atrial Fibrillation: Stress-Testing Renal Function Range in Real World Patients.

Dabigatran is the first of four direct-acting oral anticoagulants approved to prevent stroke in adult patients with atrial fibrillation using a fixed two-dose scheme compared with warfarin dosing adjusted to a prothrombin time range associated with optimal risk reduction in stroke and serious bleeding. The pivotal phase III trial found dabigatran, depending on dose, is superior to warfarin in stroke reduction and similar in bleeding risk while also showing dabigatran efficacy and safety correlate with steady-state plasma concentrations. Because the relationship between dabigatran dose and plasma concentration is highly variable, a previously developed population pharmacokinetic model of over 9,000 clinical trial patients was used as a basis for simulations comparing the performance of dosing via the drug label to other proposed doses and regimens. Assessment of dosing regimen performance was based on simulations of trough plasma levels within the therapeutic concentration range of 75-150 ng/mL over a renal function range of 15-250 mL/min creatinine clearance, representing extremes for real-world patients. An improved regimen that best achieves this therapeutic range was identified, requiring five different dosing schedules, corresponding to specified renal function ranges, compared with the two approved in the label. The discussion focuses on how this information could better inform patient outcomes and future dabigatran development.

Study of Modifications Induced by Continued Direct Oral Anticoagulant Therapy during Atrial Fibrillation Ablation Procedures on Standard Hemostasis Parameters

Unfractionated heparin (UFH) is used as an anticoagulant during the atrial fibrillation (AF) ablation procedure to prevent the occurrence of thromboembolic events. Guidelines recommend an activated clotting time (ACT) greater than 300 s (s) based on studies of patients treated with vitamin K antagonist (VKA) for their AF. However, direct oral anticoagulants (DOACs) have supplanted VKAs in AF and are now used as first-line therapy. It is recommended not to interrupt them during the procedure, which could interfere with the ACT measures. To assess the real-life relationship between ACT, DOAC concentrations, and UFH anti-Xa activity in patients treated by uninterrupted DOAC therapy. We conducted a single-center retrospective study. We analyzed consecutive patients with AF who underwent catheter ablation under DOAC therapy. In total, 40 patients were included, including 15 (37.5%), 20 (50.0%), and 5 (12.5%) on rivaroxaban, apixaban, and dabigatran, respectively. Baseline ACT was significantly lower in the apixaban group. ACT was linearly correlated with the residual concentration of apixaban and dabigatran but not with rivaroxaban. After UFH injection, ACT was linearly correlated with the anti-Xa activity, regardless of DOAC. Patients in the apixaban group received a higher total dose of UFH during the procedure to achieve a target ACT > 300 s, which resulted in significantly higher anti-Xa activity during the procedure. Our results raise the question of optimal management of intra-procedural heparin therapy and highlight the limitations of the ACT test, particularly in patients on apixaban.

Intravenous Dabigatran Provides Adequate Anticoagulation for Cardiopulmonary Bypass Using a Rabbit Model.

Heparin anticoagulation has been used successfully for cardiopulmonary bypass (CPB). However, an alternative anticoagulant approach is desirable due to the cases of heparin-induced thrombocytopenia. Dabigatran provides anticoagulation for an in vitro model of simulated CPB. The current analysis tests the hypothesis that dabigatran provides sufficient anticoagulation for CPB in intact rabbits. Nonlinear mixed effects models were used to estimate dabigatran parameters for a two-compartment pharmacokinetic model in 10 New Zealand White rabbits. A dabigatran infusion designed to maintain a plasma concentration of 90 µg/ml was run throughout CPB based on the pharmacokinetics. Animals were subjected to sternotomy and anticoagulated with IV dabigatran (six animals) or heparin (four animals). Rabbits were cannulated centrally using the right atrium and ascending aorta and CPB was maintained for 120 min. Measurement of activated clotting time, thromboelastometric reaction time, and blood gases were performed during CPB. Then, the animals were euthanized, and the brain and one kidney were removed for histology. Sections of the arterial filters were inspected using electron microscopy. The observed dabigatran concentrations during CPB were greater than the target concentration, ranging from 137 ± 40 μg/ml at 5 min of CPB to 428 ± 150 μg/ml at 60 min, and 295 ± 35 μg/ml at 120 min. All rabbits completed 2 h of CPB without visible thrombosis. In the two groups, reaction time values were elevated, reaching 10,262 ± 4,198 s (dabigatran group) and 354 ± 141 s (heparin group) at 120 min of CPB. Brains and kidneys showed no evidence of thrombosis or ultrastructural damage. Sections of the arterial line filter showed minimal or no fibrin. There was no significant difference in outcomes between dabigatran- and heparin-treated animals. In this first-use, proof-of-concept study, the authors have shown that dabigatran provides acceptable anticoagulation similar to heparin to prevent thrombosis using a rabbit CPB model.

ダビガトラン過量服薬に対するイダルシズマブの静脈内投与：血漿中ダビガトラン濃度と血液凝固能の関連性(Intravenous idarucizumab for dabigatran overdose: association between plasma dabigatran concentration and coagulation profile)

要旨ダビガトランは直接トロンビンを阻害することで抗凝固作用を示す経口抗凝固薬であり，近年処方機会が急増している。過量内服症例における，血漿中ダビガトラン濃度および血液凝固能の推移に関するデータは不足している。腎機能障害のない，非弁膜症性心房細動をもつ71歳邦人女性が近医より処方されていたダビガトランを合計7,480mg自殺目的に過量内服し，当院に搬送された。過量内服4時間後の血漿中ダビガトラン濃度は4,217ng/mL（治療域濃度100～400ng/mL）であり，APTTは160.3秒，PT–INRは9.46であった。イダルシズマブ5g経静脈投与後，血漿中ダビガトラン濃度は経時的に低下し，それに伴いAPTTとPT–INRも正常化した。血漿中ダビガトラン濃度とAPTT（R2=0.9898），およびPT–INR（R2=0.9998）との間には強固な関連性が認められた。本症例は第9病日に後遺症なく独歩退院した。治療域の40倍の血漿中濃度を示すダビガトラン大量内服症例において，イダルシズマブは血漿中ダビガトラン濃度を安全に，かつ効果的に低下させた。また，血液凝固能は，血漿中ダビガトラン濃度を強固に反映した。本症例により，一般的な血液凝固能検査を用いることで，ダビガトランの血中薬物動態を推定できる可能性が示された。

Coagulation assays and direct oral anticoagulant levels among patients having an elective surgery or procedure

BackgroundThe Perioperative Anticoagulation Use for Surgery Evaluation study prospectively evaluated a prespecified periprocedural interruption strategy of direct oral anticoagulants (DOACs) among patients with atrial fibrillation. Coagulation testing is widely available and frequently requested prior to invasive procedures. Coagulation assays display poor sensitivity to clinically relevant DOAC concentrations. ObjectivesDetermine the utility of routinely available coagulation testing at predicting a DOAC concentration of <30 ng/ml among patients in the preprocedural setting. MethodsWe calculated the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive and negative likelihood ratio (LR+ and LR−) of a normal coagulation assay result for identifying patients with a preprocedural DOAC level < 30 ng/ml. ResultsWe identified weak or very weak correlations between coagulation assay results and DOAC levels in the preprocedural setting, except for a moderate correlation between the thrombin time (TT) and dabigatran concentrations (ρ = 0.68; p < .001). The prothrombin time (PT) and activated partial thromboplastin time (APTT) demonstrated modest sensitivity (78.9% to 88.2%) and PPVs (76.4% to 93.1%) but poor specificity (13.2% to 53.3%) and NPVs (16.3% to 30.2%) across all three DOACs. A normal TT was associated with 100% specificity and PPV values for a dabigatran level < 30 ng/ml. A normal APTT among patients on dabigatran was associated with an LR+ of 1.671 (95% confidence interval [CI] 1.297, 2.154) and an LR− of 0.395 (95% CI 0.207, 0.751) for levels <30 ng/ml. ConclusionsThe PT and APTT perform poorly at safely identifying patients with negligible DOAC levels in the preprocedural setting.

Evaluation of Coaguchek®Pro II coagulation testing device performance to assess direct oral anticoagulant action. The DOAC-CHECK study

Direct oral anticoagulants (DOAC) measurement is recommended in specific conditions. A point-of-care testing should be used in emergency to qualitatively rule out relevant DOAC concentrations. The DOAC-CHECK Study aims to evaluate whether the use of CoaguChek® Pro II (Roche Diagnostics International Ltd, Rotkreuz, Switzerland) coagulation testing device can provide reliable information in patients treated with DOAC. The study was carried out in two FCSA (Italian Federation of Thrombosis Centers) centers. We choose 3 different concentration thresholds for our analysis (30, 50 and 100 ng/mL) and by ROC curves the ideal cut-off point was selected to be the one that yielded a sensitivity of at least 95% associated with the highest possible specificity. 512 patients were enrolled. For Edoxaban and Rivaroxaban, both CoaguChek® Pro II prothrombin time (PT) and activated partial thromboplastin time (aPTT) tests showed a sensitivity &gt;95% corresponding to satisfying specificity values; negative predictive values resulted in the range 90-100%. At variance, CoaguChek® Pro II PT and aPTT tests did not seem to be useful for identifying Apixaban and Dabigatran concentrations higher than the pre-defined thresholds. Our results suggest that CoaguChek® Pro II coagulation testing device can be used to qualitatively identify relevant concentrations of Edoxaban or Rivaroxaban, but not of Apixaban or Dabigatran.

The impact of ABCB1 and CES1 polymorphisms on the safety of dabigatran in patients with non-valvular atrial fibrillation

BackgroundThis study aimed to analyze associations between genetic variants and plasma concentrations along with clinical outcomes in dabigatran in patients with non-valvular atrial fibrillation (NVAF).MethodsWe conducted a prospective study and enrolled NVAF patients treated with dabigatran in the real world. A total of 86 patients treated with 110 mg DE twice daily were recruited for this study. Blood samples were obtained from each patient and used for genotyping and determination of plasma dabigatran concentration. All bleeding and thromboembolic complications were recorded during the 1.5 years of follow-up.ResultsEighty-three patients provided samples at the trough plasma level of dabigatran, and 58 patients provided samples at the peak plasma level of dabigatran. There was a significant association between the CES1 SNP rs8192935 and trough plasma concentrations of dabigatran (P = 0.013). Our results showed that the CES1 SNP rs8192935 significantly influenced dabigatran trough concentrations in the Chinese population, and carriers of the G allele had increased trough plasma concentrations of dabigatran compared to noncarriers. The ABCB1 SNP c.2482-2236G > A (rs4148738) was associated with major bleeding events in the addictive model (P = 0.046, OR = 3.29) and dominant model (P = 0.040, OR = 8.17). Additionally, the ABCB1 SNP c.3435 C > T (rs1045642) was associated with the incidence of major bleeding events in the addictive model (P = 0.043, OR = 3.34) and dominant model (P = 0.046, OR = 7.77). However, no significant associations were found between all the SNPs and the incidence of minor bleeding events.ConclusionOur results indicated that the CES1 polymorphism rs8192935 was associated with trough plasma concentrations of dabigatran. Carriers of the G allele had increased trough plasma concentrations of dabigatran compared to noncarriers. The ABCB1 polymorphisms rs4148738 and rs1045642 were associated with an increased risk for major bleeding events for the first time in a Chinese population.

Thrombolysis after dabigatran reversal: A nation-wide Italian multicentre study, systematic review and meta-analysis.

Recent anticoagulant intake represents a contraindication for thrombolysis in acute ischemic stroke. Idarucizumab reverses the anticoagulant effect of dabigatran, potentially allowing for thrombolysis. This nation-wide observational cohort study, systematic review, and meta-analysis evaluated the efficacy and safety of thrombolysis preceded by dabigatran-reversal in people with acute ischemic stroke. We recruited people undergoing thrombolysis following dabigatran-reversal at 17 stroke centers in Italy (reversal-group), people on dabigatran treated with thrombolysis without reversal (no-reversal group), and age, sex, hypertension, stroke severity, and reperfusion treatment-matched controls in 1:7 ratio (control-group). We compared groups for symptomatic intracranial hemorrhage (sICH, main outcome), any brain hemorrhage, good functional outcome (mRS 0-2 at 3 months), and death. The systematic review followed a predefined protocol (CRD42017060274), and odds ratio (OR) meta-analysis was implemented to compare groups. Thirty-nine patients in dabigatran-reversal group and 300 matched controls were included. Reversal was associated with a non-significant increase in sICH (10.3% vs 6%, aOR = 1.32, 95% CI = 0.39-4.52), death (17.9% vs 10%, aOR = 0.77, 95% CI = 0.12-4.93) and good functional outcome (64.1% vs 52.8%, aOR = 1.41, 95% CI = 0.63-3.19). No hemorrhagic events or deaths were registered in no-reversal group (n = 12). Pooling data from 3 studies after systematic review (n = 1879), reversal carried a non-significant trend for sICH (OR = 1.53, 95% CI = 0.67-3.50), death (OR = 1.53, 95% CI = 0.73-3.24) and good functional outcome (OR = 2.46, 95% CI = 0.85-7.16). People treated with reperfusion strategies after dabigatran reversal with idarucizumab seem to have a marginal increase in the risk of sICH but comparable functional recovery to matched patients with stroke. Further studies are needed to define treatment cost-effectiveness and potential thresholds in plasma dabigatran concentration for reversal.

Population pharmacokinetic analysis for dabigatran etexilate in Chinese patients with non-valvular atrial fibrillation.

We aimed to develop a pharmacokinetic (PK) and pharmacodynamic (PD) model from healthy Chinese subjects and real-world non-valvular atrial fibrillation (NVAF) patients. We also investigated meaningful intrinsic and extrinsic factors and related biomarkers for bleeding events. We characterized the integrated PK/PD models based on rich PK/PD data [dabigatran concentration, activated partial thromboplastin time (APTT), prothrombin time (PT), and anti-factor IIa (anti-FIIa) activity] from 118 healthy volunteers and sparse PD data [APTT, PT, and anti-FIIa] from 167 patients with NVAF after verifying the model extrapolation performance. We also documented the correlations between PD biomarkers and clinically relevant bleeding events over one year. Next, we used the final integrated PK/PD model (a two-compartment, linear model with first-order absorption) to evaluate the influence of dosage and individual covariates on PD parameters. The age, high-density liptein cholesterol (HDL-C), and creatinine clearance (CrCL) improved the PK model fit. The linear direct-effects PD model described the correlation between APTT, PT, and anti-FIIa and plasma concentration. CrCL improved the PD model fit. Anti-FIIa was more sensitive to the increase in dabigatran exposure than APTT and PT in the PD model. Therefore, fixed dabigatran doses could be prescribed for patients with NVAF without adjusting for age and HDL-C. We observed an elevated bleeding tendency with higher peak and trough values of APTT, PT, and anti-FIIa. Randomized studies should be performed to evaluate the efficacy and safety of low-dose dabigatran in Chinese patients with NVAF.

Application of Activators Ecarin and Factor Xa in Thrombelastography for Measurement of Anticoagulant Effect of Direct Oral Anticoagulants Using TEG 5000.

There are situations where monitoring direct oral anticoagulants (DOACs) would be useful, including bleedings and trauma. The thromboelastographic technique has proven useful in bleeding situations in trauma and heart surgery. The aim of this study was to examine the effect of DOACs on all currently commercially available conventional TEG®5000 assays as well as novel modified assay using Ecarin and human factor Xa (HFXa). Healthy male volunteers were given single dose of oral dabigatran 150 mg, rivaroxaban 20 mg, or apixaban 5 mg. Kaolin, RapidTEG, functional fibrinogen, PlateletMapping assay, and novel modified assays using Ecarin and HFXa were prepared. All TEG parameters were recorded. DOAC concentrations were correlated to the parameters with highest response to the DOAC effect. Sensitivity and negative predictive value of the parameter with highest response to DOAC concentration of 50 ng/mL was calculated. None of the conventional TEG assays demonstrated significant response to the effect on apixaban. Using Ecarin, reaction time R was strongly correlated with dabigatran concentrations. Using HFXa assay, R was strongly correlated with rivaroxaban and apixaban concentrations: r = 0.96, 0.84, and 0.86, respectively; p < 0.0001 for all. The R times obtained with the modified assays demonstrated strong sensitivity and negative predictive values for DOAC levels of ≥50 ng/mL. We have demonstrated that TEG®5000 can monitor the DOAC effect on hemostasis when the appropriate activator is used with significant correlation with DOAC concentrations. Larger clinical studies are warranted for correlation of TEG profile and clinical outcomes.

Anticoagulant Effects of Dabigatran on Coagulation Laboratory Parameters in Pediatric Patients: Combined Data from Five Pediatric Clinical Trials.

Background Dabigatran etexilate, a direct oral thrombin inhibitor, is approved to treat venous thromboembolism (VTE) in both adults and children. Objectives This population analysis characterized relationships between dabigatran total plasma concentrations and coagulation laboratory parameters (activated partial thromboplastin time [aPTT]; diluted thrombin time [dTT]; ecarin clotting time [ECT]). Methods Data from three phase 2a and one single-arm and one randomized, comparative phase 2b/3 pediatric studies (measurements: aPTT 2,925 [ N = 358]; dTT 2,348 [ N = 324]; ECT 2,929 [ N = 357]) were compared with adult data (5,740 aPTT, 3,472 dTT, 3,817 ECT measurements; N = 1,978). Population models were fitted using nonlinear mixed-effects modeling. Covariates (e.g., sex, age) were assessed on baseline and drug-effect parameters, using a stepwise covariate model-building procedure. Results Overall, relationships between dabigatran, aPTT, dTT, and ECT were similar in children and adults. For children aged <6 months, a higher proportion of baseline samples were outside or close to the upper aPTT and ECT adult ranges. No age-related differences were detected for dTT. With increasing dabigatran concentration, aPTT rose nonlinearly (half the maximum effect at 368 ng/mL dabigatran) while dTT and ECT increased linearly (0.37 and 0.73% change per ng/mL dabigatran, respectively). Mean baseline aPTT (45 vs. 36 seconds) and ECT (40 vs. 36 seconds) were slightly increased for those aged <6 months versus older children. Conclusion The similar relationships of laboratory parameters observed across pediatric age groups suggests that developmental changes in the hemostatic system may have little effect on response to dabigatran.

Hemoclot Thrombin Inhibitor Assay and Expected Peak-Trough Levels of Dabigatran: A Multicenter Study.

PurposeDabigatran concentrations monitoring are gaining importance of special situations, but limited data are available for the expected peak and trough levels. The hemoclot thrombin inhibitor (HTI) is dabigatran-calibrated quantitative determination of dabigatran concentration. This study aims to validate HTI assay as the quantification choice of dabigatran, and providing the expected peak and trough levels.Materials and MethodsThis is a multi-center methodology validate study, including seven hospitals from Beijing, Shanghai, Henan, Hunan, Chongqing, and Fujian. We retrospectively analyzed plasma samples taken from 118 healthy subjects and 183 patients receiving dabigatran. Dabigatran concentrations were measured with HTI assay and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Linear regression, Spearman correlation and Bland-Altman analysis were used in this study.ResultsThe mean concentration ratio of HPLC-MS/MS and HTI assays was 1.03 and 0.98 at 2 and 12 h, and the acceptance ranges for both the ratio limit as well as the limit of agreement were met, suggesting good agreement between the HTI-derived plasma concentrations and HPLC-MS/MS. The reference detection range of single dose dabigatran 150 mg in healthy subjects was 33–159 ng/ml. About 500 blood samples were taken from 183 patients suggested that the expected peak and trough levels range of dabigatran 110 mg was about 95–196 and 36–92 ng/ml.ConclusionHemoclot thrombin inhibitor assay can be a good quantitative detection method of dabigatran. Expected peak and trough levels provide a basis for the rational use of dabigatran, and provide important Asian population data for the update of the international clinical guidelines for hematological testing.Clinical Trial Registration[https://clinicaltrials.gov], identifier [NCT03161496].

Delayed concentration effect models for dabigatran anticoagulation.

IntroductionDabigatran is an anticoagulant with potential use during cardiopulmonary bypass in children and adults. The pharmacokinetic–pharmacodynamic relationship for dabigatran anticoagulation effect was investigated in an intact animal model using rabbits.MethodsTen male New Zealand white rabbits were given a novel preparation of intravenous dabigatran 15 mg.kg−1. Blood samples were collected for activated clotting time, thromboelastometric reaction time, and drug assay at 5, 15, 30, 60, 120, 180, 300, and 420 min. Plasma dabigatran concentrations and coagulation measures were analyzed using an integrated pharmacokinetic–pharmacodynamic model using nonlinear mixed effects. Effects (activated clotting and thromboelastometric reaction times) were described using a sigmoidal EMAX model. Pharmacokinetic parameters were scaled using allometry and standardized to a 70 kg size standard. Pharmacodynamics were investigated using both an effect compartment model and an indirect response (turnover) model.ResultsA two‐compartment model described dabigatran pharmacokinetics with a clearance (CL 0.135 L.min−1.70 kg−1), intercompartment clearance (Q 0.33 L.min−1.70 kg−1), central volume of distribution (V1 12.3 L.70 kg−1), and peripheral volume of distribution (V2 30.1 L.70 kg−1). The effect compartment model estimates for a sigmoid EMAX model with activated clotting time had an effect site concentration (Ce50 20.1 mg.L−1) eliciting half of the maximal effect (EMAX 899 s) and a Hill coefficient (N 0.66). The equilibration half time (T1/2keo) was 1.4 min. Results for the reaction time were plasma concentration (Cp50 65.3 mg.L−1), EMAX 34 min, N 0.80 with a baseline thromboelastometric reaction time of 0.4 min. The equilibration half time (T1/2keo) was 2.04 min.ConclusionsDabigatran reversibly binds to the active site on the thrombin molecule, preventing thrombin‐mediated activation of coagulation factors. The effect compartment model performed slightly better than the turnover model and was able to adequately capture pharmacodynamics for both activated clotting and thromboelastometric reaction times. The equilibration half time was short (<2 min). These data can be used to inform future animal preclinical studies for those undergoing cardiopulmonary bypass. These preclinical data also demonstrate the magnitude of parameter values for a delayed effect compartment model that are applicable to humans.