Effect of recombinant factor VIIa on melagatran-induced inhibition of thrombin generation and platelet activation in healthy volunteers

2004 ◽  
Vol 91 (06) ◽  
pp. 1090-1096 ◽  
Author(s):  
Marcel Levi ◽  
Troy Sarich ◽  
Stig Boström ◽  
Ulf Eriksson ◽  
Maria Eriksson-Lepkowska ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Thrombin Generation ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Venous Blood ◽  
Active Form ◽  
Coagulation Cascade ◽  
Thrombin Inhibitor ◽  
Shed Blood ◽  
Inhibition Of Thrombin

SummaryThe objectives were to investigate whether activation of the extrinsic coagulation cascade by recombinant factor VIIa (rFVIIa) reverses the inhibition of thrombin generation and platelet activation by melagatran, the active form of the oral direct thrombin inhibitor ximelagatran. In a single-blind, randomized, parallel-group study, volunteers (20 per group) received a 5-hour intravenous (iv) infusion to achieve steadystate melagatran plasma concentrations of approximately 0.5 µmol/L, with a single iv bolus of rFVIIa (90 µg/kg) or placebo at 60 minutes. Prothrombin fragment 1+2, thrombin-antithrombin complex, fibrinopeptide A, β-thromboglobulin, and thrombin-activatable fibrinolysis inhibitor were quantified for venous and shed blood. Activated partial thromboplastin time (APTT), prothrombin time (PT), endogenous thrombin potential, thrombus precursor protein (TpP), and plasmin-α2-antiplasmin complex concentrations were determined in venous blood. Shed blood volume was measured. Melagatran reduced markers of thrombin generation and platelet activation in shed blood and prolonged APTT. rFVIIa increased FVIIa activity, PT, and TpP in venous blood. All other parameters were unaffected. In conclusion, rFVIIa did not reverse the anticoagulant effects of high constant concentrations of melagatran. However, the potential value of higher, continuous or repeated doses of rFVIIa or its use with lower melagatran concentrations has not been excluded.

Inhibition of Thrombin Generation by the Oral Direct Thrombin Inhibitor Ximelagatran in Shed Blood from Healthy Male Subjects

2002 ◽  
Vol 87 (02) ◽  
pp. 300-305 ◽  
Author(s):  
Ulf Eriksson ◽  
Christer Mattsson ◽  
Michael Wolzt ◽  
Lars Frison ◽  
Gunnar Fager ◽  
...  
Keyword(s):  
Thrombin Generation ◽  
Active Form ◽  
Direct Thrombin Inhibitor ◽  
Thrombin Inhibitor ◽  
Healthy Male ◽  
Oral Direct Thrombin Inhibitor ◽  
Shed Blood ◽  
Dose Levels ◽  
Male Subjects ◽  
Control Water

SummaryXimelagatran, an oral direct thrombin inhibitor, whose active form is melagatran, was studied using a model of thrombin generation in humans. Healthy male volunteers (18 per group) received ximelagatran (60 mg p.o.), dalteparin (120 IU/kg s.c.) or a control (water p.o.). Shed blood, collected after incision of the forearm with standardised bleeding time devices at pre-dose, and at 2, 4 and 10 h post-dosing, was analysed for markers of thrombin generation. Statistically significant reductions (p < 0.05) in levels of prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin complex (TAT) in shed blood were detected at 2 and 4 h post-dosing in both the ximelagatran and dalteparin groups. Shed blood F1+2 and TAT levels had returned to pre-dose levels at 10 h post-dosing. Using a shed blood model, we demonstrate that the reversible thrombin inhibitor melagatran and, therefore, oral administration of ximelagatran, inhibits thrombin generation in humans after acute activation of coagulation.

Monitoring low dose recombinant factor VIIa therapy in patients with severe factor XI deficiency undergoing surgery

2011 ◽  
Vol 106 (09) ◽  
pp. 521-527 ◽  
Author(s):  
Anne Riddell ◽  
Rezan Abdul-Kadir ◽  
Debra Pollard ◽  
Edward Tuddenham ◽  
Keith Gomez
Keyword(s):  
Thrombin Generation ◽  
Low Dose ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Venous Blood ◽  
Optimal Dose ◽  
Factor Xi ◽  
Factor Xi Deficiency

SummaryAlthough factor XI (FXI) concentrate is an effective replacement therapy in severe FXI deficiency without inhibitors, some patients are unwilling to receive it because it is plasma-derived. We report on the use and monitoring of low dose, recombinant factor VIIa (rFVIIa, NovoSeven®), to cover surgery (caesarean section, cholecystectomy and abdominoplasty) in four female patients (FXI:C 2–4 IU/dl, aged 32–51 years) who wished to avoid exposure to plasma. None of our patients had inhibitors to FXI. Our aim was to find the optimal dose of rFVIIa by in vitro spiking of patient samples and to correlate this with the response to rFVIIa in vivo. Prior to surgery, venous blood was collected into sodium citrate with corn trypsin inhibitor and spiked with 0.25–1.0 μg/ml rFVIIa in vitro, equivalent to a 15–70 μg/kg dose of rFVIIa in vivo. Analysis using thromboelastometry and thrombin generation assays, triggered with tissue factor, showed that the thrombin generation assay was insufficiently sensitive to the haemostatic defect in these patients. A concentration of 0.5 μg/ml was as effective as 1.0 μg/ml FVIIa in normalising thromboelastometry in vitro in all four patients. Therefore, patients received 15–30 μg/kg rFVIIa at 2–4 hourly intervals with tranexamic acid 1g every six hours. Post treatment samples were taken at 10–240 minutes and showed initial normalisation of thromboelastometry with gradual return to baseline after 2–4 hours. In conclusion, low-dose rFVIIa therapy was successfully used in four patients with severe FXI deficiency undergoing surgery to prevent bleeding and can be monitored using thromboelastometry.

Inhibition of Thrombin Generation in Plasma by Inhibitors of Factor Xa

1997 ◽  
Vol 78 (04) ◽  
pp. 1215-1220 ◽  
Author(s):  
D Prasa ◽  
L Svendsen ◽  
J Stürzebecher
Keyword(s):  
Thrombin Generation ◽  
Factor Xa ◽  
Thrombin Inhibitors ◽  
Thrombin Inhibitor ◽  
Thrombin Generation Assay ◽  
Ic50 Values ◽  
Fxa Inhibitor ◽  
20 Nm ◽  
Tick Anticoagulant Peptide ◽  
Inhibition Of Thrombin

SummaryA series of inhibitors of factor Xa (FXa) were investigated using the thrombin generation assay to evaluate the potency and specificity needed to efficiently block thrombin generation in activated human plasma. By inhibiting FXa the generation of thrombin in plasma is delayed and decreased. Inhibitor concentrations which cause 50 percent inhibition of thrombin generation (IC50) correlate in principle with the Ki values for inhibition of free FXa. Recombinant tick anticoagulant peptide (r-TAP) is able to inhibit thrombin generation with considerably low IC50 values of 49 nM and 37 nM for extrinsic and intrinsic activation, respectively. However, the potent synthetic, low molecular weight inhibitors of FXa (Ki values of about 20 nM) are less effective in inhibiting the generation of thrombin with IC50 values at micromolar concentrations.The overall effect of inhibitors of FXa in the thrombin generation assay was compared to that of thrombin inhibitors. On the basis of similar Ki values for the inhibition of the respective enzyme, synthetic FXa inhibitors are less effective than thrombin inhibitors. In contrast, the highly potent FXa inhibitor r-TAP causes a stronger reduction of the thrombin activity in plasma than the most potent thrombin inhibitor hirudin.

scholarly journals Management of the Bleeding Patient Receiving New Oral Anticoagulants: A Role for Prothrombin Complex Concentrates

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Lisa M. Baumann Kreuziger ◽  
Joseph C. Keenan ◽  
Colleen T. Morton ◽  
David J. Dries
Keyword(s):  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Oral Anticoagulants ◽  
New Oral Anticoagulants ◽  
Coagulation Cascade ◽  
Clotting Factors ◽  
Prothrombin Complex Concentrates ◽  
Clotting System ◽  
Clinical Trial Evidence

Ease of dosing and simplicity of monitoring make new oral anticoagulants an attractive therapy in a growing range of clinical conditions. However, newer oral anticoagulants interact with the coagulation cascade in different ways than traditional warfarin therapy. Replacement of clotting factors will not reverse the effects of dabigatran, rivaroxaban, or apixaban. Currently, antidotes for these drugs are not widely available. Fortunately, withholding the anticoagulant and dialysis are freqnently effective treatments, particularly with rivaroxaban and dabigatran. Emergent bleeding, however, requires utilization of Prothrombin Complex Concentrates (PCCs). PCCs, in addition to recombinant factor VIIa, are used to activate the clotting system to reverse the effects of the new oral anticoagulants. In cases of refractory or emergent bleeding, the recommended factor concentrate in our protocols differs between the new oral anticoagulants. In patients taking dabigatran, we administer an activated PCC (aPCC) [FELBA] due to reported benefit in human in vitro studies. Based on human clinical trial evidence, the 4-factor PCC (Kcentra) is suggested for patients with refractory rivaroxaban- or apixaban-associated hemorrhage. If bleeding continues, recombinant factor VIIa may be employed. With all of these new procoagulant agents, the risk of thrombosis associated with administration of factor concentrates must be weighed against the relative risk of hemorrhage.

The glycoprotein Ib-IX-V complex contributes to tissue factor–independent thrombin generation by recombinant factor VIIa on the activated platelet surface

Blood ◽  
2008 ◽  
Vol 112 (8) ◽  
pp. 3227-3233 ◽  
Author(s):  
Cees Weeterings ◽  
Philip G. de Groot ◽  
Jelle Adelmeijer ◽  
Ton Lisman
Keyword(s):  
Tissue Factor ◽  
Cho Cells ◽  
Thrombin Generation ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Affinity Constant ◽  
Activate Factor ◽  
Platelet Surface ◽  
Static Conditions ◽  
Lines Of Evidence

Abstract Several lines of evidence suggest that recombinant factor VIIa (rFVIIa) is able to activate factor X on an activated platelet, in a tissue factor-independent manner. We hypothesized that, besides the anionic surface, a receptor on the activated platelet surface is involved in this process. Here, we showed that, in an ELISA setup, a purified extracellular fragment of GPIbα bound to immobilized rFVIIa. Surface plasmon resonance established a affinity constant (Kd) of approximately 20 nM for this interaction. In addition, CHO cells transfected with the GPIb-IX-V complex could adhere to immobilized rFVIIa, whereas wild-type CHO cells could not. Furthermore, platelets sti-mulated with a combination of collagen and thrombin adhered to immobilized rFVIIa under static conditions. Platelet adhesion was inhibited by treatment with O-sialoglycoprotein endopeptidase, which specifically cleaves GPIbα from the platelet surface. In addition, rFVIIa-mediated thrombin generation on the activated platelet surface was inhibited by cleaving GPIbα from its surface. In summary, 3 lines of evidence showed that rFVIIa interacts with the GPIb-IX-V complex, and this interaction enhanced tissue factor-independent thrombin generation mediated by rFVIIa on the activated platelet surface. The rFVIIa-GPIbα interaction could contribute to cessation of bleeding after administration of rFVIIa to patients with bleeding disorders.

Dual Inhibition of Blood Coagulation Factors Xa and Iia Synergize To Reduce Thrombus Weight and Thrombin Generation in a Rabbit Arteriovenous Shunt Model of Thrombosis.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1866-1866
Author(s):  
Thomas B. McClanahan ◽  
Sangita M. Baxi ◽  
Liguo Chi ◽  
Tawny Dahring ◽  
Weston R. Gould ◽  
...  
Keyword(s):  
Blood Coagulation ◽  
Single Molecule ◽  
Thrombin Generation ◽  
Ex Vivo ◽  
Factor Xa ◽  
Coagulation Cascade ◽  
Vehicle Group ◽  
Thrombin Inhibitor ◽  
Antithrombotic Effect ◽  
Dual Inhibitor

Abstract Several compounds currently in development for the treatment of thrombotic disorders demonstrate high levels of specificity for single targets of the blood coagulation cascade such as factor Xa and thrombin. However, development of a single molecule dual inhibitor against factor Xa and thrombin may expand the efficacy to safety ratio of treatment options for arterial and venous thrombosis. The objective of this study was to determine if simultaneous administration of PD 0313052, a selective Xa inhibitor and argatroban, a direct thrombin inhibitor, would lead to a synergistic antithrombotic effect in a rabbit AV shunt model of thrombosis. Intravenous administration of PD 0313052 alone at doses of 0.1, 0.3, and 1.0 mg/kg/min resulted in thrombus weight (TW) reductions of 11±3, 25±10 and 67±7 % compared to the vehicle group. Argatroban at 1, 3 and 10 mg/kg/min reduced TW 16±13, 47±10 and 75±6 %. When PD 0313052 was administered at 0.1 mg/kg/min in combination with argatroban at 1, 3 or 10 mg/kg/min TW was reduced 50±7, 60±7 and 82±9 %. Likewise, argatroban at 1 mg/kg/min combined with 0.1, 0.3 or 1mg/kg/min of PD 0313052 resulted in TW reductions of 56±9, 60±9 and 84±5 %, respectively. At the lowest combined doses of PD 0313052 and argatroban there was no change in bleeding time relative to the additive fold-increases from each drug alone. The EC50 of intravenously administered PD 0313052 and argatroban was 67±23 and 178±58 ng/ml, respectively. When the drugs were combined the EC50 was reduced to 12±6 ng/ml with the PD 0313052/argatroban combination and to 83±29 ng/ml with the argatroban/PD 0313052 combination. A synergistic effect was also observed in an ex vivo assay of thrombin generation (TG). Predicted additive inhibition of TG based on the individual effects of each compound was −9±7, 9±2 and 29±7 % compared to 10±5, 32±5 and 55±3 % with the 313052/argatroban combination. The predicted effects of the argatroban/PD 0313052 combination was −9±7, 1±7 and 16±9 % compared to the actual inhibition of 5±3, 14±5 and 31±7 %. These results demonstrate a significant synergistic antithrombotic effect by combining low doses of a factor Xa and a thrombin inhibitor and support the hypothesis that development of a single molecule inhibitor against different hemostatic targets may offer greater efficacy in the prevention and treatment of venous and arterial thrombosis.

Platelet-dependent thrombin generation assay for monitoring the efficacy of recombinant Factor VIIa

Platelets ◽  
2005 ◽  
Vol 16 (1) ◽  
pp. 45-50 ◽  
Author(s):  
W. Wegert ◽  
S. Harder ◽  
S. Bassus ◽  
C. M. Kirchmaier
Keyword(s):  
Thrombin Generation ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Thrombin Generation Assay

Recombinant factor VIIa enhances deposition of platelets with congenital or acquired αIIbβ3 deficiency to endothelial cell matrix and collagen under conditions of flow via tissue factor–independent thrombin generation

Blood ◽  
2003 ◽  
Vol 101 (5) ◽  
pp. 1864-1870 ◽  
Author(s):  
Ton Lisman ◽  
Sultana Moschatsis ◽  
Jelle Adelmeijer ◽  
H. Karel Nieuwenhuis ◽  
Philip G. De Groot
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Umbilical Vein ◽  
Novel Approach ◽  
Platelet Deposition ◽  
Platelet Aggregate ◽  
Umbilical Vein Endothelial Cells ◽  
Thrombin Formation

A novel approach to treat bleeding episodes in patients with Glanzmann thrombasthenia (GT) and perhaps also in patients receiving αIIbβ3 inhibitors is the administration of recombinant factor VIIa (rFVIIa). The mechanism of action of rFVIIa in these patients is, however, still unclear. We studied the effect of rFVIIa-mediated thrombin formation on adhesion of αIIbβ3-deficient platelets under flow conditions. Adhesion of αIIbβ3-deficient platelets to the extracellular matrix (ECM) of stimulated human umbilical vein endothelial cells or to collagen type III was studied using a model system with washed platelets and red cells. When αIIbβ3-deficient platelets were perfused over the surface at arterial shear rate for 5 minutes, a low surface coverage was observed (GT platelets, mean ± SEM, 37.5% ± 5.0%; normal platelets preincubated with an RGD-containing peptide, 7.4% ± 2.1%). When rFVIIa, together with factors X and II, was added to the perfusate, platelet deposition significantly increased (GT platelets, mean ± SEM, 67.0% ± 4.3%; normal platelets preincubated with an RGD-containing peptide, 48.2% ± 2.9%). The same effect was observed when normal platelets were pretreated with the commercially available anti-αIIbβ3 drugs abciximab, eptifibatide, or tirofiban. It was shown that tissue factor–independent thrombin generation (presumably induced by binding of rFVIIa to adhered platelets) was responsible for the increase in platelet deposition. In conclusion, defective adhesion of αIIbβ3-deficient platelets to ECM can be restored by tissue factor–independent rFVIIa-mediated thrombin formation. The enhanced generation of platelet procoagulant surface facilitates fibrin formation, so that lack of platelet aggregate formation might be compensated for.

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