Effects of the Novel, Oral, Direct Factor Xa Inhibitor Rivaroxaban on Coagulation Assays

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3028-3028
Author(s):  
Meyer Michel Samama ◽  
Lena Le Flem ◽  
Celine Guinet ◽  
Elisabeth Perzborn ◽  
Jean-Luc Martinoli ◽  
...  
Keyword(s):  
Factor Xa ◽  
International Normalized Ratio ◽  
Peak Effect ◽  
Direct Factor ◽  
Clotting Time ◽  
Paradoxical Response ◽  
Low Concentrations ◽  
One Step ◽  
Standard Calibration

Abstract Rivaroxaban is an oral, direct Factor Xa (FXa) inhibitor that has been recommended for approval by the Committee for Medicinal Products for Human Use for the prevention of venous thromboembolism after elective hip and knee replacement, and is in advanced clinical development for the prevention and treatment of thromboembolic disorders. There is no need for routine laboratory monitoring with rivaroxaban. However, a hemostasis assay might be valuable to measure the pharmacodynamic (PD) effects of rivaroxaban in special situations. The aim of this study was to identify a widely available assay (clotting assay, or colorimetric or fluorometric assay) that could be used in clinical practice. Increasing concentrations of rivaroxaban were spiked into citrated pooled human platelet-poor plasma. The global clotting assays prothrombin time (PT), diluted PT (dPT), and activated partial thromboplastin time (aPTT) were compared, as well as the specific clotting assays HepTest® (heparin test), prothrombinase-induced clotting time (PiCT®), and diluted Russell’s viper venom time (dRVVT). In addition, the anti-FXa activity-based colorimetric assays STA Rotachrom® and Stachrom® and thrombin generation test (TGT) were measured. A concentration-dependent prolongation of PT, dPT, and aPTT was observed with rivaroxaban, although the results varied depending on the reagents used. When testing PT over time using frozen plasma spiked with defined concentrations of rivaroxaban, PT values did not change during storage. Using a standard calibration curve, the results of the PT test can be expressed in rivaroxaban (ng/mL) rather than as PT ratio or international normalized ratio (INR). A concentration-dependent prolongation of the clotting time was also observed with dPT, a test that may be clinically more significant than conventional PT because it is closer to in vivo conditions (i.e. it uses lower tissue factor concentrations). Conventional methods for the HepTest and two-step PiCT (incubation times of 120 seconds and 180 seconds, respectively) resulted in a paradoxical response, with low concentrations of rivaroxaban reducing clotting times. This paradoxical response was not observed with shorter incubation times (0 or 30 seconds for one-step PiCT and 30 seconds for HepTest), or when antithrombin-immunodepleted plasma was used. Rivaroxaban also increased the dRVVT concentration dependently. Rivaroxaban influenced the various parameters of the TGT concentration dependently; peak effect was the most informative parameter. Rivaroxaban concentration-dependently inhibited FXa activity in both the Rotachrom and Stachrom assays– the results were expressed as anti-FXa international unit/mL. PT assays, which are widely used, appear to be valuable assays for monitoring the PD effects of rivaroxaban. One-step PiCT and HepTest with shortened incubation times or anti-FXa assays could also be useful to monitor rivaroxaban, if standardized methods were used.

Assessment of laboratory assays to measure rivaroxaban – an oral, direct factor Xa inhibitor

2010 ◽  
Vol 103 (04) ◽  
pp. 815-825 ◽  
Author(s):  
Jean-Luc Martinoli ◽  
Léna LeFlem ◽  
Céline Guinet ◽  
Geneviève Plu-Bureau ◽  
François Depasse ◽  
...  
Keyword(s):  
Vitamin K Antagonists ◽  
Plasma Concentrations ◽  
Factor Xa ◽  
Specific Factor ◽  
Factor Xa Inhibitor ◽  
Direct Factor ◽  
Paradoxical Response ◽  
Pharmacodynamic Effects ◽  
Dependent Relationship ◽  
Low Concentrations

SummaryAlthough there is no need for routine coagulation monitoring with rivaroxaban – an oral, direct factor Xa inhibitor – a haemostasis assay might be valuable to measure its pharmacodynamic effects. This study aimed to find assays, among those commercially available, to measure rivaroxaban pharmacodynamics. Several global conventional clotting tests, as well as clotting or chromogenic assays to measure anti-factor Xa activity, were studied. A thrombin generation test using calibrated automated thrombogram was also done. Tests were performed with the indirect factor Xa inhibitor fondaparinux for comparison. A concentration-dependent prolongation of prothrombin time (PT), dilute PT, and activated partial thromboplastin time was observed with rivaroxaban. The results varied depending on the reagents. This variability cannot be standardised with the international normalised ratio system commonly used for vitamin K antagonists. Using a standard calibration curve, PT test results can be expressed in plasma concentrations of rivaroxaban rather than PT seconds or ratio. Standard methods for HepTest and two-step prothrombinase-induced clotting time (PiCT) resulted in a paradoxical response, with low concentrations of rivaroxaban reducing clotting times. This was not observed with shorter incubation times, or when antithrombin-deficient (immunodepleted) plasma was used. The chromogenic tests found a dose-dependent relationship between anti-factor Xa activity and rivaroxaban concentration. Modified specific factor Xa chromogenic assays are being further investigated. One-step PiCT and HepTest with shortened incubation times, as well as the widely available PT assay (using a rivaroxaban calibrator) could be useful to monitor the pharmacodynamic effects of rivaroxaban accurately. Finally, all clotting and chromogenic assays showed a concentration-dependent effect induced by rivaroxaban.

Comparison of the Anticoagulant and Antithrombotic Effects of Synthetic Thrombin and Factor Xa Inhibitors

1990 ◽  
Vol 63 (02) ◽  
pp. 220-223 ◽  
Author(s):  
J Hauptmann ◽  
B Kaiser ◽  
G Nowak ◽  
J Stürzebecher ◽  
F Markwardt
Keyword(s):  
Factor Xa ◽  
Thrombin Inhibitors ◽  
Factor Xa Inhibitors ◽  
Venous Stasis ◽  
Clotting Time ◽  
Thrombosis Model ◽  
Activity Factor ◽  
Antithrombotic Effects

SummaryThe anticoagulant effect of selected synthetic inhibitors of thrombin and factor Xa was studied in vitro in commonly used clotting assays. The concentrations of the compounds doubling the clotting time in the various assays were mainly dependent on their thrombin inhibitory activity. Factor Xa inhibitors were somewhat more effective in prolonging the prothrombin time compared to the activated partial thromboplastin time, whereas the opposite was true of thrombin inhibitors.In vivo, in a venous stasis thrombosis model and a thromboplastin-induced microthrombosis model in rats the thrombin inhibitors were effective antithrombotically whereas factor Xa inhibitors of numerically similar IQ value for the respective enzyme were not effective at equimolar dosageThe results are discussed in the light of the different prelequisiles and conditions for inhibition of thrombin and factor Xa in the course of blood clotting.

scholarly journals Molecular Docking, Computational, and Antithrombotic Studies of Novel 1,3,4-Oxadiazole Derivatives

2018 ◽  
Vol 19 (11) ◽  
pp. 3606 ◽  
Author(s):  
Majda Batool ◽  
Affifa Tajammal ◽  
Firdous Farhat ◽  
Francis Verpoort ◽  
Zafar Khattak ◽  
...  
Keyword(s):  
Factor Xa ◽  
Clot Lysis ◽  
Clotting Time ◽  
Reference Drug ◽  
Docking Score ◽  
High Affinity ◽  
Oxadiazole Derivatives ◽  
Inhibitory Potential

A new series of 1,3,4-oxadiazoles derivatives was synthesized, characterized, and evaluated for their in vitro and in vivo anti-thrombotic activity. Compounds (3a–3i) exhibited significant clot lysis with respect to reference drug streptokinase (30,000 IU), and enhanced clotting time (CT) values (130–342 s) than heparin (110 s). High affinity towards 1NFY with greater docking score was observed for the compounds (3a, 3i, 3e, 3d, and 3h) than the control ligand RPR200095. In addition, impressive inhibitory potential against factor Xa (F-Xa) was observed with higher docking scores (5612–6270) with Atomic Contact Energy (ACE) values (−189.68 to −352.28 kcal/mol) than the control ligand RPR200095 (Docking score 5192; ACE −197.81 kcal/mol). In vitro, in vivo, and in silico results proposed that these newly synthesized compounds might be used as anticoagulant agents.

scholarly journals In vitro and in vivo studies of the novel antithrombotic agent BAY 59-7939-an oral, direct Factor Xa inhibitor

2005 ◽  
Vol 3 (3) ◽  
pp. 514-521 ◽  
Author(s):  
E. PERZBORN ◽  
J. STRASSBURGER ◽  
A. WILMEN ◽  
J. POHLMANN ◽  
S. ROEHRIG ◽  
...  
Keyword(s):  
Factor Xa ◽  
In Vivo Studies ◽  
Factor Xa Inhibitor ◽  
The Novel ◽  
Direct Factor ◽  
Antithrombotic Agent

scholarly journals Monitoring "mini-intensity" anticoagulation with warfarin: comparison of the prothrombin time using a sensitive thromboplastin with prothrombin fragment F1+2 levels

Blood ◽  
1992 ◽  
Vol 79 (8) ◽  
pp. 2034-2038 ◽  
Author(s):  
MM Millenson ◽  
KA Bauer ◽  
JP Kistler ◽  
S Barzegar ◽  
L Tulin ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Factor Xa ◽  
High Sensitivity ◽  
International Normalized Ratio ◽  
Target Range ◽  
Lower Sensitivity ◽  
Sensitivity Index ◽  
Plasma Samples ◽  
Prothrombin Activation

Treatment with warfarin using a target International Normalized Ratio (INR) range of 1.7 to 2.5 is efficacious for many clinical indications, but the minimal intensity of anticoagulation required for antithrombotic protection has yet to be determined. To evaluate whether patients could be reliably monitored with a less intense regimen, we anticoagulated patients with warfarin for several months using a target INR range of 1.3 to 1.6 as determined by prothrombin time (PT) using a sensitive thromboplastin (Dade IS, International Sensitivity Index [ISI] = 1.3). Plasma measurements of F1+2, a marker of factor Xa action on prothrombin in vivo, were also obtained to determine the suppressive effect of warfarin on hemostatic system activity. Overall, 20 of 21 patients with a history of cerebrovascular events (mean age, 61 years) could be reliably regulated with warfarin in the target INR range. F1+2 levels were significantly suppressed from baseline in all patients, with a mean reduction of 49% (range, 28% to 78%). We found a significant relationship between the extent of suppression of prothrombin activation levels and the baseline measurements. A mean reduction of 65% was observed for those patients with baseline F1+2 greater than or equal to 1.5 nmol/L, but only 38% for baseline F1+2 less than or equal to 0.5 nmol/L. Overall, 68% of plasma samples obtained during stable anticoagulation were within the target INR range. PTs were also determined on all plasma samples with two thromboplastins of lower sensitivity (C+, ISI = 2.09; and automated simplastin, ISI = 2.10). Only 47% and 35% of PT determinations, respectively, were within the target range with these reagents. We conclude that prothrombin activation can be significantly suppressed in vivo with use of warfarin in an INR range of 1.3 to 1.6. This level of anticoagulation can be reliably achieved by monitoring PTs with a thromboplastin of high sensitivity.

A Comparison of Anticoagulation Activity of a Potent Heparin Preparation in Different Test

1979 ◽  
Author(s):  
A.S. Bhargava ◽  
J. Heinick ◽  
Chr. Schöbel ◽  
P. Günzel
Keyword(s):  
Blood Clotting ◽  
Anticoagulant Activity ◽  
Factor Xa ◽  
Thrombin Time ◽  
Beagle Dogs ◽  
Clotting Time ◽  
Relative Potencies ◽  
Heparin Preparation

The anticoagulant effect of a new potent heparin preparation was compared with a commercially available heparin in vivo after intravenous application in beagle dogs. The anticoagulant activity was determined using thrombin time, activated partial thromboplastin time and whole blood clotting time after 5, 10 and 30 minutes of application. The relative potency of the new heparin preparation (Scherinq) was found to be 1.62 to 2.52 times higher than heparin used for comparison (150 USP units/mg, Dio-synth). The anticoagulant properties of both preparations were also studied in vitro using dog and human plasma. The relative potencies in vitro correlated well with those obtained in vivo. Further characterization with amidolytic method using chromogenic substrate for factor Xa and thrombin (S-2222 and S-2238 from KABI, Stockholm) showed that heparin (Schering) contains 243 to 378 USP units/raq depending upon the test systems used to assay the anticoagulation activity and in addition, proves the validity of the amidolytic method.

scholarly journals Monitoring "mini-intensity" anticoagulation with warfarin: comparison of the prothrombin time using a sensitive thromboplastin with prothrombin fragment F1+2 levels

Blood ◽  
1992 ◽  
Vol 79 (8) ◽  
pp. 2034-2038 ◽  
Author(s):  
MM Millenson ◽  
KA Bauer ◽  
JP Kistler ◽  
S Barzegar ◽  
L Tulin ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Factor Xa ◽  
High Sensitivity ◽  
International Normalized Ratio ◽  
Target Range ◽  
Lower Sensitivity ◽  
Sensitivity Index ◽  
Plasma Samples ◽  
Prothrombin Activation

Abstract Treatment with warfarin using a target International Normalized Ratio (INR) range of 1.7 to 2.5 is efficacious for many clinical indications, but the minimal intensity of anticoagulation required for antithrombotic protection has yet to be determined. To evaluate whether patients could be reliably monitored with a less intense regimen, we anticoagulated patients with warfarin for several months using a target INR range of 1.3 to 1.6 as determined by prothrombin time (PT) using a sensitive thromboplastin (Dade IS, International Sensitivity Index [ISI] = 1.3). Plasma measurements of F1+2, a marker of factor Xa action on prothrombin in vivo, were also obtained to determine the suppressive effect of warfarin on hemostatic system activity. Overall, 20 of 21 patients with a history of cerebrovascular events (mean age, 61 years) could be reliably regulated with warfarin in the target INR range. F1+2 levels were significantly suppressed from baseline in all patients, with a mean reduction of 49% (range, 28% to 78%). We found a significant relationship between the extent of suppression of prothrombin activation levels and the baseline measurements. A mean reduction of 65% was observed for those patients with baseline F1+2 greater than or equal to 1.5 nmol/L, but only 38% for baseline F1+2 less than or equal to 0.5 nmol/L. Overall, 68% of plasma samples obtained during stable anticoagulation were within the target INR range. PTs were also determined on all plasma samples with two thromboplastins of lower sensitivity (C+, ISI = 2.09; and automated simplastin, ISI = 2.10). Only 47% and 35% of PT determinations, respectively, were within the target range with these reagents. We conclude that prothrombin activation can be significantly suppressed in vivo with use of warfarin in an INR range of 1.3 to 1.6. This level of anticoagulation can be reliably achieved by monitoring PTs with a thromboplastin of high sensitivity.

scholarly journals Effects of a Synthetic Factor Xa Inhibitor (JTV-803) on Various Laboratory Tests

2002 ◽  
Vol 8 (4) ◽  
pp. 325-336 ◽  
Author(s):  
Mahmut Tobu ◽  
Omer Iqbal ◽  
Debra A. Hoppensteadt ◽  
Christopher Shultz ◽  
Walter Jeske ◽  
...  
Keyword(s):  
Oral Anticoagulant ◽  
Laboratory Tests ◽  
Factor Xa ◽  
International Normalized Ratio ◽  
Factor Xa Inhibitors ◽  
Rabbit Brain ◽  
Factor Xa Inhibitor ◽  
Thrombin Time ◽  
Clotting Time ◽  
Direct Inhibitors

Synthetic direct inhibitors of factor Xa are capable of prolonging the global anticoagulant assay times in a concentration-dependent fashion. The relative degree of thrombin generation inhibition at an equivalent prolongation is not similar to the results observed with heparins and oral anticoagulant drugs. In addition, the direct factor Xa inhibitors prolong the Russell' viper venom test (RVVT) and Heptest clotting times. Ecarin clotting time (ECT) and thrombin time (TT) remain unaffected. The kinetics of factor Xa inhibition are markedly different than those observed with pentasac-charide and heparins. Therefore, the methods developed for heparins and pentasaccharides may not be applicable for the monitoring of factor Xa inhibitors. To test the feasibility of using the prothrombin time (PT), International Normalized Ratio (INR), activated partial thromboplastin time (aPTT), Heptest, thrombin time, RVVT, ECT, and a modified anti-Xa amidolytic assay, to monitor a synthetic factor Xa inhibitor, normal human pool plasma samples were spiked with a synthetic factor Xa inhibitor in the concentration range of 0 to 1 μg/mL and 0 to 25 μg/mL. Different laboratory tests were performed and INR and other ratios were calculated. The anticoagulant effects on whole blood were measured using the activated clotting time (ACT). Further studies on the effect of factor Xa inhibitor on platelet aggregation; factor II, VII, and X functional levels; and fibrinopeptide A (FPA) generation were carried out at equivalent INR levels in comparison to oral anticoagulant and antithrombin agents. FPA generation at equivalent anticoagulant level in comparison to heparin (twice the baseline) was also carried out. Factor Xa inhibitor produced a concentration-dependent prolongation of the ACT. ACT was doubled at a concentration of 4 to 5 μg/mL. There was a marked difference in the prolongation of the PT by a synthetic factor Xa inhibitor dependent on the ISI of the PT reagent used. When the results were calculated to determine INR, marked variations were noted between the recombinant thromboplastin and rabbit brain thromboplastin. The rabbit brain thromboplastin reagent gave markedly high INR values. Similar results were observed when different aPTT reagents were studied. In the anti-Xa assay, modification of the incubation time was employed to extend the proper sensitivity range. These studies warrant further investigation to understand the mechanism of action of factor Xa inhibitors.

scholarly journals Factor XI contributes to thrombin generation in the absence of factor XII

Blood ◽  
2009 ◽  
Vol 114 (2) ◽  
pp. 452-458 ◽  
Author(s):  
Dmitri V. Kravtsov ◽  
Anton Matafonov ◽  
Erik I. Tucker ◽  
Mao-fu Sun ◽  
Peter N. Walsh ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Factor Xa ◽  
Factor Ix ◽  
Factor Xii ◽  
Factor Xi ◽  
Factor Xii Deficiency ◽  
Low Concentrations

Abstract During surface-initiated blood coagulation in vitro, activated factor XII (fXIIa) converts factor XI (fXI) to fXIa. Whereas fXI deficiency is associated with a hemorrhagic disorder, factor XII deficiency is not, suggesting that fXI can be activated by other mechanisms in vivo. Thrombin activates fXI, and several studies suggest that fXI promotes coagulation independent of fXII. However, a recent study failed to find evidence for fXII-independent activation of fXI in plasma. Using plasma in which fXII is either inhibited or absent, we show that fXI contributes to plasma thrombin generation when coagulation is initiated with low concentrations of tissue factor, factor Xa, or α-thrombin. The results could not be accounted for by fXIa contamination of the plasma systems. Replacing fXI with recombinant fXI that activates factor IX poorly, or fXI that is activated poorly by thrombin, reduced thrombin generation. An antibody that blocks fXIa activation of factor IX reduced thrombin generation; however, an antibody that specifically interferes with fXI activation by fXIIa did not. The results support a model in which fXI is activated by thrombin or another protease generated early in coagulation, with the resulting fXIa contributing to sustained thrombin generation through activation of factor IX.

scholarly journals Slightly elevated international normalized ratio predicts bleeding episodes in patients treated with direct oral anticoagulants

2020 ◽  
Vol 48 (6) ◽  
pp. 030006051989443
Author(s):  
Priya Bhardwaj ◽  
Louise Breum Petersen ◽  
Tomas Sorm Binko ◽  
Jan Roland Petersen ◽  
Gitte Gleerup Fornitz
Keyword(s):  
Oral Anticoagulants ◽  
Direct Oral Anticoagulants ◽  
Factor Xa ◽  
Bleeding Risk ◽  
International Normalized Ratio ◽  
Direct Factor ◽  
Risk Of Bleeding ◽  
Increased Risk ◽  
Direct Factor Xa Inhibitors ◽  
Bleeding Episodes

Introduction Patients treated with direct oral anticoagulants (DOACs) are at increased bleeding risk. It is therefore of increasing interest to identify predictors of bleeding episodes to increase safety during treatment with DOACs. Methods This retrospective cohort study systematically reviewed medical records of 235 patients treated with either apixaban, rivaroxaban or dabigatran for non-valvular atrial fibrillation or venous thromboembolism and collected data on the international normalized ratio (INR) and all bleeding episodes. Results INR ≥ 1.5 was significantly associated with increased risk of minor and major bleeding events in patients treated with direct factor Xa inhibitors. This association was not present in patients treated with dabigatran. However, a high negative predictive value was identified for INR < 1.5 for all drugs. The relative risks of bleeding episodes in patients with INR ≥ 1.5 and INR < 1.5 were 5.1 and 0.20, respectively. Conclusions Our results demonstrate a strong correlation between INR and risk of bleeding episodes during DOAC treatment. INR < 1.5 was a strong negative predictor for low bleeding risk independent of indication or choice of drug, and INR ≥ 1.5 was associated with increased risk of bleeding episodes in patients treated with direct factor Xa-inhibitors.

Sign in / Sign up

Export Citation Format

Share Document