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Bourti Y, Fazavana J, Armand M, Saller F, Lasne D, Borgel D, Bianchini EP. Inactivated antithrombins as fondaparinux antidotes: a promising alternative to haemostatic agents as assessed in vitro in a thrombin-generation assay. Thromb Haemost 2016; 116:452-60. [PMID: 27412396 DOI: 10.1160/th15-12-0927] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 05/14/2016] [Indexed: 01/26/2023]
Abstract
In the absence of specific antidote to fondaparinux, two modified forms of antithrombin (AT), one recombinant inactive (ri-AT) and the other chemically inactivated (chi-AT), were designed to antagonise AT-mediated anticoagulants, e. g. heparins or fondaparinux. These inactive ATs were previously proven to effectively neutralise anticoagulant activity associated with heparin derivatives in vitro and in vivo, as assessed by direct measurement of anti-FXa activity. This study was undertaken to evaluate in vitro the effectivity of inactive ATs to reverse anticoagulation by heparin derivatives and to compare them with non-specific fondaparinux reversal agents, like recombinant-activated factor VII (rFVIIa) or activated prothrombin-complex concentrate (aPCC), in a thrombin-generation assay (TGA). Addition of fondaparinux (3 µg/ml) to normal plasma inhibited thrombin generation by prolonging lag time (LT) as much as 244 % and lowering endogenous thrombin potential (ETP) to 17 % of their control (normal plasma) values. Fondaparinux-anticoagulant activity was reversed by ri-AT and chi-AT, as reflected by the corrections of LT up to 117 % and 114 % of its control value, and ETP recovery to 78 % and 63 %, respectively. Unlike ri-AT that had no effect on thrombin generation in normal plasma, chi-AT retained anticoagulant activity that minimises its reversal capacity. However, both ATs were more effective than rFVIIa or aPCC at neutralising fondaparinux and, unlike non-specific antidotes, inactive ATs specifically reversed AT-mediated anticoagulant activities, as suggested by their absence of procoagulant activity in anticoagulant-free plasma.
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Affiliation(s)
| | | | | | | | | | | | - Elsa P Bianchini
- E. P. Bianchini, UMR-S1176, 80 rue du Général Leclerc, 94276 Le Kremlin-Bicêtre Cedex, France, Tel.: +33 1 49595646, Fax: +33 1 46719472, E-mail:
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Grounds RM, Seebach C, Knothe C, Paluszkiewicz P, Smith TS, Kasal E, Lecumberri R, Urbanec R, Haas T, Wujtewicz M, Rehorkova D, Pelichovska M, Lange M, Uranga M, Bosman R, Rommes JH, Koscielny J. Use of Recombinant Activated Factor VII (Novoseven) in Trauma and Surgery: Analysis of Outcomes Reported to an International Registry. J Intensive Care Med 2016; 21:27-39. [PMID: 16698742 DOI: 10.1177/0885066605285024] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The objective was to evaluate the efficacy and safety of recombinant activated factor VII in patients with massive bleeding. Forty-five patients with severe massive hemorrhage requiring= 14 transfusion units of packed red blood cells received recombinant activated factor VII. Postdrug blood loss and transfusion requirements were assessed, and mortality was compared with predicted outcomes. Blood loss was markedly reduced in 40 of 43 (93.0%) patients, and transfusion requirements decreased after recombinant activated factor VII administration. Mortality rate in trauma patients who had massive hemorrhage was significantly reduced compared with predictions using scoring systems. This may be associated with the use of recombinant activated factor VII. This study failed to demonstrate an improvement in surgical patients. The absence of concurrent controls prevents definitive conclusions regarding actual safety or efficacy of recombinant activated factor VII.
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Affiliation(s)
- R Michael Grounds
- Anaesthesia and Intensive Care Medicine, St George's Hospital, Tooting, London, UK.
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Hoffman M, Chang JY, Ezban M, Monroe DM. An activated factor VII variant with enhanced tissue factor-independent activity speeds wound healing in a mouse hemophilia B model. J Thromb Haemost 2016; 14:1249-54. [PMID: 26952654 DOI: 10.1111/jth.13311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 02/23/2016] [Indexed: 12/30/2022]
Abstract
UNLABELLED Essentials Disorders of hemostasis can lead to delayed and defective wound healing. In hemophilia B (HB) mice, 7 days of Factor (F)IX or VIIa are needed to normalize wound healing. One dose of a highly active FVIIa variant (DVQ) restored normal wound closure time in HB mice. Coagulation factors with enhanced activity may acquire biological effects not due to hemostasis. SUMMARY Introduction We have previously reported that hemophilia B (HB) mice have delayed healing of cutaneous wounds and alterations in wound histology. Administration of a single dose of either factor IX or recombinant activated FVII (rFVIIa) (NovoSeven) prior to wounding did not improve wound closure time or histology. The FVIIa analog DVQ (V158D, E296V and M298Q mutations) was designed to have higher tissue factor-independent activity than rVIIa. We hypothesized that a single dose of DVQ would be more effective in restoring wound healing in HB mice. Methods Cutaneous punch wounds were made on the backs of HB and wild-type mice, and the time to wound closure was monitored. HB mice were treated with a dose of rFVIIa (10 mg kg(-1) ) or DVQ (1 mg kg(-1) ) that corrected the tail bleeding time. Skin samples were taken at various time points after wounding, fixed, and stained, and the histology was examined. Results As previously reported, wound closure times in HB mice given one dose of rFVIIa were not improved over those in untreated HB mice. Surprisingly, healing times in HB mice treated with an equally hemostatic dose of DVQ were normalized to that in wild-type mice. However, DVQ did not correct all histologic abnormalities in HB mice. Conclusions As the doses of DVQ and rFVIIa were chosen to support comparable levels of hemostasis, our data suggest that the improved healing seen with DVQ is not solely attributable to its hemostatic activity. It is possible that the improved wound healing arises through the effect of DVQ on cell signaling mechanisms.
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Affiliation(s)
- M Hoffman
- Department of Pathology, Duke University and Durham Veterans Affairs Medical Centers, Durham, NC, USA
- Division of Hematology/Oncology, Department of Medicine, The University of North Carolina Medical Center, Chapel Hill, NC, USA
| | - J-Y Chang
- Division of Hematology/Oncology, Department of Medicine, The University of North Carolina Medical Center, Chapel Hill, NC, USA
| | - M Ezban
- Pharmacology, Novo Nordisk A/S, Måløv, Denmark
| | - D M Monroe
- Division of Hematology/Oncology, Department of Medicine, The University of North Carolina Medical Center, Chapel Hill, NC, USA
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Keshava S, Sundaram J, Rajulapati A, Pendurthi UR, Rao LVM. Pharmacological concentrations of recombinant factor VIIa restore hemostasis independent of tissue factor in antibody-induced hemophilia mice. J Thromb Haemost 2016; 14:546-50. [PMID: 26727350 PMCID: PMC4785069 DOI: 10.1111/jth.13244] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/10/2015] [Indexed: 11/28/2022]
Abstract
UNLABELLED ESSENTIALS: The role of tissue factor (TF) in recombinant factor VIIa (rFVIIa) therapy in hemophilia is unclear. An acquired mouse hemophilia model with very low or normal levels of human TF was used in the study. rFVIIa is equally effective in correcting the bleeding in mice expressing low or normal levels of TF. Pharmacological doses of rFVIIa restore hemostasis in hemophilia independent of TF. SUMMARY BACKGROUND Recombinant factor VIIa (rFVIIa) has been used widely for treating hemophilia patients with inhibitory autoantibodies against factor VIII or IX. Its mechanism of action is not entirely known. A majority of in vitro studies suggested that pharmacological concentrations of rFVIIa restore hemostasis in hemophilia in a phospholipid-dependent manner, independent of tissue factor (TF). However, a few studies suggested that a TF-dependent mechanism has a primary role in correction of bleeding by rFVIIa in hemophilia patients. Here, we investigated the potential contribution of TF in rFVIIa-induced hemostasis in hemophilia employing a model system of FVIII antibody-induced hemophilia in TF transgenic mice. METHODS Mice expressing low levels of human TF (LTF mice), mice expressing relatively high levels of human TF (HTF mice) and wild-type mice (WT mice) had neutralizing anti-FVIII antibodies administered in order to induce hemophilia in these mice. The mice were then treated with varying concentrations of rFVIIa. rFVIIa-induced hemostasis was evaluated with the saphenous vein bleeding model. RESULTS Administration of FVIII inhibitory antibodies induced the hemophilic bleeding phenotype in all three genotypes. rFVIIa administration rescued the bleeding phenotype in all three genotypes. No significant differences were observed in rFVIIa-induced correction of bleeding between LTF and HTF mice that had FVIII antibodies administered. CONCLUSIONS Our results provide strong evidence supporting the suggestion that the hemostatic effect of pharmacological doses of rFVIIa stems from a TF-independent mechanism.
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Affiliation(s)
- S Keshava
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, USA
| | - J Sundaram
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, USA
| | - A Rajulapati
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, USA
| | - U R Pendurthi
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, USA
| | - L V M Rao
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, USA
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Abstract
Glanzmann's thrombasthenia (GT) and congenital factor VII deficiency (FVII CD) are rare autosomal recessive bleeding disorders: GT is the most frequent congenital platelet function disorder, and FVII CD is the most common factor-deficiency disease after haemophilia. The frequency of these disorders in the general population ranges from 1:500,000 to 1:2,000,000. Because GT and FVII CD are both rare, registries are the only approach possible to allow the collection and analysis of sufficient observational data. Recombinant activated factor VII (rFVIIa, eptacog alfa activated) is indicated for the treatment of acute bleeding episodes and for surgery coverage in patients with GT who are refractory to platelets and have antiplatelet or anti-human leukocyte antigen (HLA) antibodies, and for the prevention and treatment of bleeding in patients with FVII CD. This article summarises published data on the mechanism of action and use of rFVIIa in these disorders from two international, prospective, observational registries: the Glanzmann's Thrombasthenia Registry (GTR) for GT; and the Seven Treatment Evaluation Registry (STER) for FVII CD. Haemostatic effectiveness rates with rFVIIa were high across all patients with GT and those with FVII CD, and treatment with rFVIIa in the GTR and STER registries was well tolerated. The GTR and the STER are the largest collections of data in GT and FVII CD, respectively, and have expanded our knowledge of the management of these two rare bleeding disorders.
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New Insights Into the Treatment of Glanzmann Thrombasthenia. Transfus Med Rev 2016; 30:92-9. [PMID: 26968829 DOI: 10.1016/j.tmrv.2016.01.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 01/12/2016] [Accepted: 01/12/2016] [Indexed: 11/21/2022]
Abstract
Glanzmann thrombasthenia (GT) is a rare inherited autosomal recessive bleeding disorder of platelet function caused by a quantitative or qualitative defect of platelet membrane glycoprotein IIb/IIIa (integrin αIIbβ3), a fibrinogen receptor required for platelet aggregation. Bleeds in GT are variable and may be severe and unpredictable. Bleeding not responsive to local and adjunctive measures, as well as surgical procedures, is treated with platelets, recombinant activated factor VII (rFVIIa), or antifibrinolytics, alone or in combination. Although platelets are the standard treatment for GT, their use is associated with the risk of blood-borne infection transmission and may also cause the development of platelet antibodies (to human leukocyte antigens and/or αIIbβ3), potentially resulting in platelet refractoriness. Currently, where rFVIIa is approved for use in GT, this is mostly for patients with platelet antibodies and/or a history of platelet refractoriness. However, data from the prospective Glanzmann's Thrombasthenia Registry (829 bleeds and 206 procedures in 218 GT patients) show that rFVIIa was frequently used in nonsurgical and surgical bleeds, with high efficacy rates, irrespective of platelet antibodies/refractoriness status. The mechanisms underpinning rFVIIa effectiveness in GT have been studied. At therapeutic concentrations, rFVIIa binds to activated platelets and directly activates FX to FXa, resulting in a burst of thrombin generation. Thrombin converts fibrinogen to fibrin and also enhances GT platelet adhesion and aggregation mediated by the newly converted (polymeric) fibrin, leading to primary hemostasis at the wound site. In addition, thrombin improves the final clot structure and activates thrombin-activatable fibrinolysis inhibitor to decrease clot lysis.
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Petros S. [Therapy with blood products]. Med Klin Intensivmed Notfmed 2016; 111:241-9; quiz 250-1. [PMID: 26825633 DOI: 10.1007/s00063-015-0138-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 10/05/2015] [Accepted: 10/23/2015] [Indexed: 12/18/2022]
Abstract
Blood products are frequently used in intensive care medicine although there is little evidence of improvement in clinical outcome. The threshold for erythrocyte transfusion in non-bleeding critically ill patients is currently a hemoglobin level of 7.0 g/dl. The indications for platelet transfusion must be assessed after evaluation of the cause of thrombocytopenia, the clinical condition and the expected effect. The use of plasma should also be critically viewed, mainly due to hypervolemia. Prothrombin complex concentrates are better than plasma for warfarin reversal. There is good evidence for the use of albumin for massive paracentesis, in the treatment of hepatorenal syndrome type 1 and spontaneous bacterial peritonitis. Albumin infusion can have favorable effects in severe sepsis and septic shock. A restrictive strategy should be favored in the use of blood products and the decision should be based on a critical appraisal of the available evidence.
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Affiliation(s)
- S Petros
- Interdisziplinäre Internistische Intensivmedizin, Zentrum für Hämostaseologie, Universitätsklinikum Leipzig, Liebigstr. 20, 04103, Leipzig, Deutschland.
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Bhat V, von Drygalski A, Gale AJ, Griffin JH, Mosnier LO. Improved coagulation and haemostasis in haemophilia with inhibitors by combinations of superFactor Va and Factor VIIa. Thromb Haemost 2015; 115:551-61. [PMID: 26466980 DOI: 10.1160/th15-07-0525] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/23/2015] [Indexed: 01/14/2023]
Abstract
Bypassing inhibitors in haemophilia patients is limited to activated (a) Factor(F)VII products. We introduced "FVa activity augmentation" as another bypassing strategy and studied effects of an engineered FVa variant designated superFVa. Procoagulant and clot stabilising properties of superFVa and recombinant human (rh)FVIIa, either alone or in combination, were studied in thrombin generation and clot lysis assays in normal human plasma (NHP) with or without anti-FVIII inhibitors, in haemophilia plasma, and in FVIII-deficient mice or in wild-type mice with anti-FVIII inhibitors. SuperFVa was as effective as rhFVIIa to improve thrombin generation or clot lysis. Furthermore, procoagulant effects were significantly enhanced when these compounds were combined. RhFVIIa at 40 nM (a therapeutic concentration) improved thrombin generation mildly, but markedly improved thrombin generation when combined with a low concentration (e. g. 3 nM) of superFVa. In clot lysis studies, the concentration of rhFVIIa to normalise clot lysis times could be reduced by 100-fold (e. g. from 40 nM to 0.4 nM) when combined with a low concentration (0.37 nM) of superFVa. In haemostasis studies of FVIII-deficient mice, blood loss was dose-dependently reduced by either superFVa or rhFVIIa. SuperFVa (200 U/kg) corrected mean blood loss indistinguishably from rhFVIII. Blood loss correction by rhFVIIa was greatly improved when combined with superFVa. Similar blood loss correction results were observed for therapies in wild-type mice after infusion with anti-FVIII inhibitors. Thus, superFVa may be an effective procoagulant agent in the setting of haemophilia with inhibitors and it merits further evaluation for new bypassing strategies.
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Affiliation(s)
| | - Annette von Drygalski
- Annette von Drygalski, MD, Pharm D, The Scripps Research Institute, Department of Molecular and Experimental Medicine, MEM 180, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA, Tel.: +1 858 784 8220, Fax: +1 858 784 2243, E-mail:
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Lisman T, de Groot PG. The role of cell surfaces and cellular receptors in the mode of action of recombinant factor VIIa. Blood Rev 2015; 29:223-9. [DOI: 10.1016/j.blre.2014.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 12/08/2014] [Indexed: 11/27/2022]
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New oral anticoagulants - a practical guide. POLISH JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY 2015; 12:111-8. [PMID: 26336492 PMCID: PMC4550032 DOI: 10.5114/kitp.2015.52851] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 08/05/2014] [Accepted: 05/22/2015] [Indexed: 01/30/2023]
Abstract
Oral direct inhibitors of thrombin and activated factor Xa are approved as new anticoagulant drugs. In contrast to vitamin K antagonists (VKA) and heparins, the new agents have single targets in the coagulation cascade and more predictable pharmacokinetics, but they lack validated and available antidotes. Unlike VKA, they do not require routine monitoring of coagulation. However, the measurement of their pharmacologic effects might be of value in selected patients. They interfere with the routine coagulation tests, which should be interpreted with caution. Specific tests exist and can be used in case of emergencies. Adequate supportive care and temporary removal of all antithrombotic agents constitute the basis for management of serious bleeding complications. The administration of coagulation factors, such as fresh frozen plasma, prothrombin complex concentrates or recombinant activated FVII, can benefit in life-threatening bleeding or emergency surgery. Specific antidotes for non-vitamin K oral anticoagulants are in clinical development. This review aims at answering in a brief and simplified manner some clinical questions.
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Shibeko AM, Panteleev MA. Untangling the complexity of blood coagulation network: use of computational modelling in pharmacology and diagnostics. Brief Bioinform 2015; 17:429-39. [DOI: 10.1093/bib/bbv040] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Indexed: 01/22/2023] Open
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Spronk HMH, Braunschweig T, Rossaint R, Wüst DC, van Oerle R, Lauritzen B, Tolba R, Grottke O. Recombinant Factor VIIa Reduces Bleeding after Blunt Liver Injury in a Pig Model of Dilutional Coagulopathy under Severe Hypothermia. PLoS One 2015; 10:e0113979. [PMID: 26098426 PMCID: PMC4476676 DOI: 10.1371/journal.pone.0113979] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/31/2014] [Indexed: 11/29/2022] Open
Abstract
Background Recombinant factor VIIa (rFVIIa) is registered for use in haemophilia with inhibitors and other rare bleeding disorders, but has also been used in various other clinical conditions to terminate life-threatening bleeding. Underlying conditions (e.g. coagulopathy) and dosing may affect treatment efficacy. The objective of the present study was to evaluate the impact of increasing doses of rFVIIa on blood loss and coagulation assays in haemodiluted and hypothermic pigs undergoing blunt liver injury. Methods A grade III blunt liver injury was induced in 28 pigs after 70% haemodilution and cooling to 32.6–33.4°C. Ten minutes after trauma, animals randomly received placebo or 90, 180 or 360 μg/kg rFVIIa. Global coagulation parameters, thromboelastometry (TEM) and plasma thrombin generation (TG) were determined at different time points during the observation period of 120 minutes. Results Total blood loss was significantly lower following 90 μg/kg rFVIIa (1206 [1138–1470] mL) relative to placebo (2677 [2337–3068] mL; p<0.05), with no increased effect with higher dose levels of rFVIIa. Following trauma and haemodilution, coagulation was impaired relative to baseline in both TEM and TG analysis. At 60 and 120 minutes after trauma, TEM variables improved in the rFVIIa-treated animals compared with the placebo group. Similarly, rFVIIa improved coagulation kinetics in TG. As was observed with blood loss, no significant effect between different rFVIIa dose levels was found in TEM or TG. Macro- and microscopic post-mortem examination did not reveal any signs of thromboembolic events. Conclusion Early administration of 90 μg/kg rFVIIa reduced blood loss in pigs undergoing blunt liver injury even after severe haemodilution and hypothermia, with no further effect of higher dose levels. Coagulation assays showed impaired coagulation in coagulopathic animals, with a dose-independent improvement in animals treated with rFVIIa.
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Affiliation(s)
- Henri M. H. Spronk
- Laboratory for Clinical Thrombosis and Haemostasis, Department of Internal Medicine, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Till Braunschweig
- Department of Pathology, RWTH Aachen University Hospital, Aachen, Germany
| | - Rolf Rossaint
- Department of Anaesthesiology, RWTH Aachen University Hospital, Aachen, Germany
| | - Dirk C. Wüst
- Department of Anaesthesiology, RWTH Aachen University Hospital, Aachen, Germany
| | - Rene van Oerle
- Laboratory for Clinical Thrombosis and Haemostasis, Department of Internal Medicine, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | | | - Rene Tolba
- Institute for Laboratory Animal Science, RWTH Aachen University Hospital, Aachen, Germany
| | - Oliver Grottke
- Department of Anaesthesiology, RWTH Aachen University Hospital, Aachen, Germany
- * E-mail:
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64
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Neufeld EJ, Négrier C, Arkhammar P, el Fegoun SB, Simonsen MD, Rosholm A, Seremetis S. Safety update on the use of recombinant activated factor VII in approved indications. Blood Rev 2015; 29 Suppl 1:S34-41. [PMID: 26073367 DOI: 10.1016/s0268-960x(15)30006-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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65
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Enhanced Pharmacokinetics of Factor VIIa as a Monomeric Fc Fusion. Thromb Res 2015; 135:970-6. [DOI: 10.1016/j.thromres.2014.12.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 12/22/2014] [Accepted: 12/23/2014] [Indexed: 11/17/2022]
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66
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Anselmi A, Guinet P, Ruggieri VG, Aymami M, Lelong B, Granry S, Malledant Y, Le Tulzo Y, Gueret P, Verhoye JP, Flecher E. Safety of recombinant factor VIIa in patients under extracorporeal membrane oxygenation. Eur J Cardiothorac Surg 2015; 49:78-84. [DOI: 10.1093/ejcts/ezv140] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 02/19/2015] [Indexed: 12/12/2022] Open
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Structure-function relationships of factor Xa inhibitors: implications for the practicing clinician. J Thromb Thrombolysis 2014; 37:234-41. [PMID: 23996500 DOI: 10.1007/s11239-013-0991-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The recent development and approval of novel oral anticoagulants represents a significant success in the intelligent design of target-specific therapeutics. However, while these agents obviate many of the shortcomings of their predecessor (warfarin), they present novel challenges in pharmacologic management as well. Each was designed to have high oral bioavailability and high affinity for its target molecule, conveying significant anticoagulant effects. Yet, such unique drug-ligand binding, coupled with unfamiliar drug interactions and renal-based clearance, represent challenges to clinical management. The current review describes the development and pharmacokinetic properties of these agents, in the context of their clinical utility and pitfalls.
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68
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Li R, Panckeri KA, Fogarty PF, Diamond SL. Recombinant factor VIIa enhances platelet deposition from flowing haemophilic blood but requires the contact pathway to promote fibrin deposition. Haemophilia 2014; 21:266-274. [PMID: 25311576 DOI: 10.1111/hae.12558] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/15/2014] [Indexed: 01/17/2023]
Abstract
In prior microfluidic studies with haemophilic blood perfused over collagen, we found that a severe deficiency (<1% factor level) reduced platelet and fibrin deposition, while a moderate deficiency (1-5%) only reduced fibrin deposition. We investigated: (i) the differential effect of rFVIIa (0.04-20 nm) on platelet and fibrin deposition, and (ii) the contribution of the contact pathway to rFVIIa-induced haemophilic blood clotting. Haemophilic or healthy blood with low and high corn trypsin inhibitor (CTI, 4 or 40 μg mL(-1) ) was perfused over collagen at an initial venous wall shear rate of 100 s(-1) . At 100 s(-1) wall shear rate, where FXIIa leads to thrombin production without added tissue factor, FXI-deficient blood (3%) or severely FVIII-deficient blood (<1%) produced no fibrin at either CTI level. Whereas rFVIIa potently enhanced platelet deposition, fibrin generation was not rescued. Distinct from the high CTI condition, engagement of the contact pathway (low CTI) in moderately FVIII-deficient (3%) or moderately FIX-deficient blood (5%) resulted in enhanced platelet and fibrin deposition following 4 nm rFVIIa supplementation. In mildly FVIII-deficient blood (15%) at <24 h since haemostatic therapy, rFVIIa enhanced both platelet and fibrin generation in either CTI condition although fibrin was produced more quickly and abundantly in low CTI. For tissue factor-free conditions of severe haemophilic blood clotting, we conclude that rFVIIa reliably generates low levels of 'signaling' thrombin sufficient to enhance platelet deposition on collagen, but is insufficient to drive fibrin polymerization unless potentiated by the contact pathway.
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Affiliation(s)
- R Li
- Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA, USA
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Rao VK, Lobato RL, Bartlett B, Klanjac M, Mora-Mangano CT, David Soran P, Oakes DA, Hill CC, van der Starre PJ. Factor VIII Inhibitor Bypass Activity and Recombinant Activated Factor VII in Cardiac Surgery. J Cardiothorac Vasc Anesth 2014; 28:1221-6. [DOI: 10.1053/j.jvca.2014.04.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Indexed: 11/11/2022]
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In vitro evidence of a tissue factor-independent mode of action of recombinant factor VIIa in hemophilia. Blood 2014; 124:3172-4. [PMID: 25232061 DOI: 10.1182/blood-2014-05-576892] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Successful competition of activated factor VII (FVIIa) with zymogen factor VII (FVII) for tissue factor (TF) and loading of the platelet surface with FVIIa are plausible driving forces behind the pharmacological effect of recombinant FVIIa (rFVIIa) in hemophilia patients. Thrombin generation measurements in platelet-rich hemophilia A plasma revealed competition for TF, which potentially could reduce the effective (r)FVIIa:TF complex concentration and thereby attenuate factor Xa production. However, (auto)activation of FVII apparently counteracted the negative effect of zymogen binding; a small impact was observed at endogenous concentrations of FVII and FVIIa but was virtually absent at pharmacological amounts of rFVIIa. Moreover, corrections of the propagation phase in hemophilia A required rFVIIa concentrations above the range where a physiological level of FVII was capable to downregulate thrombin generation. These data strongly suggest that rFVIIa acts independently of TF in hemophilia therapy and that FVII displacement by rFVIIa is a negligible mechanistic component.
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71
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Shapiro AD, Hedner U. Advances in bypassing agent therapy for hemophilia patients with inhibitors to close care gaps and improve outcomes. Ther Adv Drug Saf 2014; 2:213-25. [PMID: 25083214 DOI: 10.1177/2042098611415566] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In the past, patients with hemophilia and inhibitors have had less-than-optimal treatment and have experienced more orthopedic complications than patients without inhibitors. Bypassing agents offer the potential to close treatment gaps between inhibitor and noninhibitor patients by helping the former better attain key treatment goals, including: facilitating early initiation of treatment and hemostatic control in hemarthroses; providing effective treatment in serious hemorrhagic episodes; and performance of major surgery. Effective treatment with a bypassing agent minimizes joint and/or muscle damage and potentially can serve as an effective prophylactic agent to minimize the number of hemarthroses experienced per year, thereby mitigating the development of arthropathy. The reported efficacy of the currently available bypassing agents ranges from approximately 50-80% (50-64% in controlled studies) for plasma-derived activated prothrombin complex concentrate (pd-aPCC) and 81-91% (in controlled studies) for recombinant activated factor VII (rFVIIa), including use in major orthopedic surgery. Both bypassing agents have undergone key improvements in their formulation and/or properties in recent years. The nanofiltered, vapor-heated formulation of pd-aPCC has diminished the risk of acquiring blood-borne viral infections and the room temperature stable formulation of rFVIIa allows more convenient storage, increased ease to dissolve and inject, and smaller volumes, thereby increasing overall ease of administration. Use of recommended dosing has been demonstrated to provide effective hemostasis with a minimal number of injections for both agents. In this paper, we review the individual characteristics of pd-aPCC and rFVIIa and discuss clinical data from studies conducted in inhibitor patients that demonstrate the potential benefits of these bypassing agents in this difficult-to-treat population, and underscore the potential opportunities to close the gap in care between inhibitor and noninhibitor hemophilic patients.
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Affiliation(s)
- Amy D Shapiro
- Indiana Hemophilia and Thrombosis Center, 8402 Harcourt Road, Suite 500, Indianapolis, IN 46260, USA
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72
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Breik O, Cheng A, Sambrook PJ, Goss AN. Protocol in managing oral surgical patients taking dabigatran. Aust Dent J 2014; 59:296-301; quiz 401. [DOI: 10.1111/adj.12199] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2013] [Indexed: 11/27/2022]
Affiliation(s)
- O Breik
- Oral and Maxillofacial Surgery Unit; Royal Adelaide Hospital; Adelaide South Australia
| | - A Cheng
- Oral and Maxillofacial Surgery Unit; Royal Adelaide Hospital; Adelaide South Australia
| | - PJ Sambrook
- Oral and Maxillofacial Surgery Unit; Royal Adelaide Hospital; Adelaide South Australia
| | - AN Goss
- The University of Adelaide and Emeritus Consultant; Oral and Maxillofacial Surgery Unit; Royal Adelaide Hospital; Adelaide South Australia
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Reversal of dabigatran-induced bleeding by coagulation factor concentrates in a rat-tail bleeding model and lack of effect on assays of coagulation. Anesthesiology 2014; 120:1429-40. [PMID: 24714118 DOI: 10.1097/aln.0000000000000255] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND Dabigatran is a potent oral anticoagulant. Like any anticoagulant, there is an increased risk of bleeding associated with its use, and reversal may be needed in cases of severe bleeding. METHODS In this study, six coagulation factor concentrates (CFCs) were tested for their ability to reduce bleeding induced by oral dabigatran etexilate (30 mg/kg) in a rat-tail bleeding model (n = 5 to 8 per group): three-factor (Profilnine [Grifols Biologicals Inc., Los Angeles, CA] and Bebulin [Baxter BioScience, Westlake Village, CA]) and four-factor prothrombin complex concentrates (Beriplex [CSL Behring, Marburg, Germany] and Octaplex [Octapharma AG, Lachen, Switzerland]), activated prothrombin complex concentrate (Factor Eight Inhibitor Bypassing Activity; Baxter AG, Vienna, Austria), and recombinant factor VIIa (NovoSeven; NovoNordisk, Bagsværd, Denmark). The effect of CFCs on prolongation of coagulation assays was measured. Thrombin generation after administration of each CFC was compared in vitro using human plasma (n = 5) spiked with dabigatran in concentrations corresponding to median peak (200 ng/ml) and supratherapeutic values (600 and 1,000 ng/ml). RESULTS Dabigatran resulted in an approximately three-fold increase in bleeding time, consistent with supratherapeutic dabigatran plasma levels. Beriplex (35 and 50 IU/kg), Octaplex (40 IU/kg), Profilnine (50 IU/kg), Bebulin (60 IU/kg), Factor Eight Inhibitor Bypassing Activity (100 U/kg), and NovoSeven (500 μg/kg) significantly decreased this prolonged bleeding time over 30 min (P < 0.001). The coagulation assays were prolonged three- to eight-fold over baseline (P = 0.01). None of the CFCs produced a consistent change in these assays that was predictive of reduced bleeding. Thrombin generation reversal was dependent on the concentration of dabigatran and each CFC; normalization occurred at the lower concentration of dabigatran with most CFCs, but not at higher concentrations. CONCLUSIONS In this animal model, bleeding induced by high doses of dabigatran can be reduced by CFCs. However, routine coagulation assays do not predict this effect.
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75
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The endothelial protein C receptor enhances hemostasis of FVIIa administration in hemophilic mice in vivo. Blood 2014; 124:1157-65. [PMID: 24957146 DOI: 10.1182/blood-2014-04-567297] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Recombinant activated human factor VII (rhFVIIa) is an established hemostatic agent in hemophilia, but its mechanism of action remains unclear. Although tissue factor (TF) is its natural receptor, rhFVIIa also interacts with the endothelial protein C receptor (EPCR) through its γ-carboxyglutamic acid (Gla) domain, with unknown hemostatic consequences in vivo. Here, we study whether EPCR facilitates rhFVIIa hemostasis in hemophilia using a mouse model system. Mouse activated FVII (mFVIIa) is functionally homologous to rhFVIIa, but binds poorly to mouse EPCR (mEPCR). We modified mFVIIa to gain mEPCR binding using 3 amino acid changes in its Gla domain (L4F/L8M/W9R). The resulting molecule mFVIIa-FMR specifically bound mEPCR in vitro and in vivo and was identical to mFVIIa with respect to TF affinity and procoagulant functions. In macrovascular injury models, hemophilic mice administered mFVIIa-FMR exhibited superior hemostatic activity compared with mFVIIa. This was abolished by blocking mEPCR and was absent in ex vivo whole blood coagulation assays, implicating a specific mFVIIa-FMR and endothelial mEPCR interaction. Because mFVIIa-FMR models the TF-dependent and EPCR binding properties of rhFVIIa, our data unmask a novel contribution of EPCR on the action of rhFVIIa administration in hemophilia, prompting the rational design of improved and safer rhFVIIa therapeutics.
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Reversal of New, Factor-specific Oral Anticoagulants by rFVIIa, Prothrombin Complex Concentrate and Activated Prothrombin Complex Concentrate: A Review of Animal and Human Studies. Thromb Res 2014; 133:705-13. [DOI: 10.1016/j.thromres.2014.01.031] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Revised: 01/23/2014] [Accepted: 01/26/2014] [Indexed: 01/13/2023]
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Abstract
In this issue of Blood, Feng et al shed incisive light on how recombinant activated factor VII (rFVIIa) corrects the bleeding defect in hemophilia.1
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Platelets do not express the oxidized or reduced forms of tissue factor. Biochim Biophys Acta Gen Subj 2013; 1840:1188-93. [PMID: 24361609 DOI: 10.1016/j.bbagen.2013.11.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/11/2013] [Accepted: 11/25/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND Expression of tissue factor (TF) antigen and activity in platelets is controversial and dependent upon the laboratory and reagents used. Two forms of TF were described: an oxidized functional form and a reduced nonfunctional form that is converted to the active form through the formation of an allosteric disulfide. This study tests the hypothesis that the discrepancies regarding platelet TF expression are due to differential expression of the two forms. METHODS Specific reagents that recognize both oxidized and reduced TF were used in flow cytometry of unactivated and activated platelets and western blotting of whole platelet lysates. TF-dependent activity measurements were used to confirm the results. RESULTS Western blotting analyses of placental TF demonstrated that, in contrast to anti-TF#5, which is directed against the oxidized form of TF, a sheep anti-human TF polyclonal antibody recognizes both the reduced and oxidized forms. Flow cytometric analyses demonstrated that the sheep antibody did not react with the surface of unactivated platelets or platelets activated with thrombin receptor agonist peptide, PAR-1. This observation was confirmed using biotinylated active site-blocked factor (F)VIIa: no binding was observed. Likewise, neither form of TF was detected by western blotting of whole platelet lysates with sheep anti-hTF. Consistent with these observations, no FXa or FIXa generation by FVIIa was detected at the surface of these platelets. Similarly, no TF-related activity was observed in whole blood using thromboelastography. CONCLUSION AND SIGNIFICANCE Platelets from healthy donors do not express either oxidized (functional) or reduced (nonfunctional) forms of TF.
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Onasoga-Jarvis AA, Leiderman K, Fogelson AL, Wang M, Manco-Johnson MJ, Di Paola JA, Neeves KB. The effect of factor VIII deficiencies and replacement and bypass therapies on thrombus formation under venous flow conditions in microfluidic and computational models. PLoS One 2013; 8:e78732. [PMID: 24236042 PMCID: PMC3827262 DOI: 10.1371/journal.pone.0078732] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 09/14/2013] [Indexed: 12/02/2022] Open
Abstract
Clinical evidence suggests that individuals with factor VIII (FVIII) deficiency (hemophilia A) are protected against venous thrombosis, but treatment with recombinant proteins can increase their risk for thrombosis. In this study we examined the dynamics of thrombus formation in individuals with hemophilia A and their response to replacement and bypass therapies under venous flow conditions. Fibrin and platelet accumulation were measured in microfluidic flow assays on a TF-rich surface at a shear rate of 100 s−1. Thrombin generation was calculated with a computational spatial-temporal model of thrombus formation. Mild FVIII deficiencies (5–30% normal levels) could support fibrin fiber formation, while severe (<1%) and moderate (1–5%) deficiencies could not. Based on these experimental observations, computational calculations estimate an average thrombin concentration of ∼10 nM is necessary to support fibrin formation under flow. There was no difference in fibrin formation between severe and moderate deficiencies, but platelet aggregate size was significantly larger for moderate deficiencies. Computational calculations estimate that the local thrombin concentration in moderate deficiencies is high enough to induce platelet activation (>1 nM), but too low to support fibrin formation (<10 nM). In the absence of platelets, fibrin formation was not supported even at normal FVIII levels, suggesting platelet adhesion is necessary for fibrin formation. Individuals treated by replacement therapy, recombinant FVIII, showed normalized fibrin formation. Individuals treated with bypass therapy, recombinant FVIIa, had a reduced lag time in fibrin formation, as well as elevated fibrin accumulation compared to healthy controls. Treatment of rFVIIa, but not rFVIII, resulted in significant changes in fibrin dynamics that could lead to a prothrombotic state.
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Affiliation(s)
- Abimbola A. Onasoga-Jarvis
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, United States of America
| | - Karin Leiderman
- Applied Math Unit, School of Natural Sciences, University of California Merced, Merced, California, United States of America
| | - Aaron L. Fogelson
- Department of Mathematics and Department of Bioengineering, University of Utah, Salt Lake City, Utah, United States of America
| | - Michael Wang
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Marilyn J. Manco-Johnson
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Jorge A. Di Paola
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Keith B. Neeves
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, United States of America
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
- * E-mail:
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Almomen A, Aleem A, Alshaik M, Hasanato R. Intrapulmonary rFVIIa for life threatening pulmonary hemorrhage in a case of relapsing acute lymphoblastic leukemia and platelet refractoriness. Platelets 2013; 25:452-4. [PMID: 24102447 DOI: 10.3109/09537104.2013.835797] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Platelet refractoriness may lead to life-threatening gastro-intestinal, intracranial or pulmonary hemorrhage that is difficult to control despite massive platelet and red cell transfusion, antifibrinolytic agents, high dose corticosteroids, immunoglobulin and intravenous (I.V.) recombinant activated factor VII (rFVIIa). In cases with pulmonary hemorrhage, intrapulmonary administration of rFVIIa may be more effective in non-responsive cases. We report a 51-year-old man with relapsing acute lymphoblastic leukemia (ALL) and platelet refractoriness, who suffered a life-threatening pulmonary hemorrhage that was refractory to massive platelet transfusion, tranexamic acid, high dose corticosteroids, immunoglobulin and intravenous rFVIIa, but responded immediately to a single intrapulmonary dose of rFVIIa that was inhaled with a jet nebulizer assistance through the endotracheal tube.
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Affiliation(s)
- Abdulkareem Almomen
- Center of Excellence in Thrombosis and Hemostasis, College of Medicine and King Khalid University Hospital, King Saud University , Riyadh , Saudi Arabia
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Abstract
Currently, recombinant activated factor VII (rFVIIa) (NovoSeven) is indicated for the treatment of spontaneous and surgical bleeding in congenital haemophilia A and B patients with inhibitors to factors VIII (FVIII) and IX (FIX) >5 Bethesda units (BU) worldwide, and in patients with acquired haemophilia, congenital FVII deficiency and Glanzmann's thrombasthenia in Europe. Until April 2003, almost three-quarters of a milion doses of rFVIIa have been administered proving its efficacy and excellent safety record. According to results from initial clinical trials and a large number of case reports, the rFVIIa may be effective not only in treating haemophilia patients but also in treatment of bleeding in patients on oral anticoagulation or heparin, patients with liver diseases, von Willebrand disease (vWD), thrombocytopenia, various platelet defects, congenital or acquired deficiency of FVII, and in subjects without any pre-existing coagulopathy with diffuse life-threatening bleeding triggered by surgery or trauma. This review will briefly summarize rFVIIa mode of action in haemostasis, the current clinical experience with rFVIIa and focus on the alternative use of rFVIIa in patients at the high risk of bleeding in both spontaneous cases and clinical trials reports.
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Affiliation(s)
- Peter Kubisz
- Department of Hematology and Blood Transfusion, Jessenius Medical School of Comenius University, Martin, Slovakia.
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83
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Chaudhary P, Wakim J, Khadim H, Karumbaiah KK, Gajra A. Acquired factor X deficiency in systemic amyloidosis: management of two cases. Haemophilia 2013; 19:e375-6. [DOI: 10.1111/hae.12232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2013] [Indexed: 11/29/2022]
Affiliation(s)
- P. Chaudhary
- Department of Internal Medicine; SUNY Upstate Medical University; Syracuse NY USA
| | - J. Wakim
- Department of Internal Medicine; SUNY Upstate Medical University; Syracuse NY USA
| | - H. Khadim
- Department of Internal Medicine; SUNY Upstate Medical University; Syracuse NY USA
| | - K. K. Karumbaiah
- Department of Internal Medicine; SUNY Upstate Medical University; Syracuse NY USA
| | - A. Gajra
- Department of Internal Medicine; SUNY Upstate Medical University; Syracuse NY USA
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84
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Abstract
Platelets contribute to hemostasis by forming the platelet plug and then contributing to coagulation by providing a catalytic surface where thrombin generation occurs efficiently. This catalytic activity, known as the platelet procoagulant response, is being recognized as a nuanced response. This review examines platelets’ response to strong stimuli, which results in the formation of a platelet subpopulation (superactivated platelets) with several unique properties, including enhanced procoagulant activity. These platelets contribute uniquely to thrombus architecture and seem to have thrombus regulatory activity. Superactivated platelets’ role in diseases of thrombosis and hemostasis, as either potentiating or mitigating factors, is not currently known, but may be an important pharmacological target.
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Affiliation(s)
- Marshall Mazepa
- From the Department of Pathology, University of North Carolina Hospitals, Chapel Hill, NC (M.M.); Department of Pathology, Duke University, Lab Service Durham Veterans Affairs Medical Center, Durham, NC (M.H.); and Division of Hematology/Oncology, School of Medicine, University of North Carolina at Chapel Hill, NC (D.M.)
| | - Maureane Hoffman
- From the Department of Pathology, University of North Carolina Hospitals, Chapel Hill, NC (M.M.); Department of Pathology, Duke University, Lab Service Durham Veterans Affairs Medical Center, Durham, NC (M.H.); and Division of Hematology/Oncology, School of Medicine, University of North Carolina at Chapel Hill, NC (D.M.)
| | - Dougald Monroe
- From the Department of Pathology, University of North Carolina Hospitals, Chapel Hill, NC (M.M.); Department of Pathology, Duke University, Lab Service Durham Veterans Affairs Medical Center, Durham, NC (M.H.); and Division of Hematology/Oncology, School of Medicine, University of North Carolina at Chapel Hill, NC (D.M.)
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Pham HP, Hsu SX, Parker-Jones S, Samstein B, Diuguid D, Schwartz J. Recombinant activated factor VII in patients with acute liver failure with UNOS Status 1A: a single tertiary academic centre experience. Vox Sang 2013; 106:75-82. [PMID: 23815226 DOI: 10.1111/vox.12067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 06/03/2013] [Accepted: 06/05/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND OBJECTIVES Recombinant activated factor VII (rFVIIa) is often used in off-label indications, including many situations in which the patients are at risk of thrombosis. In this study, we retrospectively reviewed the use of rFVIIa in patients with acute liver failure - UNOS Status 1A (ALF-1A) to determine its efficacy and safety profile. MATERIALS AND METHODS Using the transplantation records, all adult patients with ALF-1A were identified from 6/2001 to 3/2009. From patients' medical charts, rFVIIa dose, blood component usage, short-term outcomes [length of intensive care unit (ICU) and hospital stay, ability to undergo orthotopic liver transplant (OLT) and in-hospital survival rate] and adverse events were examined. RESULTS Forty-two patients with ALF-1A were identified. Fifteen patients received rFVIIa with doses ranging between 24·4 μg/kg and 126·8 μg/kg. Three patients received two doses of rFVIIa. The age, baseline activated partial thromboplastin time (aPTT) and platelet (PLT) count were not statistically different between the group receiving rFVIIa versus the group that did not. However, the prothrombin time (PT) was significantly higher in the rFVIIa group. Although the rFVIIa group stayed in the ICU longer and required significant more blood products during admission, there was no statistical difference between the two groups in terms of length of hospital stay, ability to undergo OLT and survival rate. There was no increase in complications, including thrombosis, after receiving rFVIIa. CONCLUSION Recombinant activated factor VII (rFVIIa) appears to be safe in patients with ALF-1A, but to elucidate its full role, a randomized controlled trial would be ideal.
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Affiliation(s)
- H P Pham
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York-Presbyterian Hospital, New York, NY, USA
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86
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Shirahata A, Fukutake K, Takamatsu J, Shima M, Hanabusa H, Mugishima H, Amano K, Takedani H, Tamashima S, Matsushita T, Tawa A, Tanaka I, Higasa S, Kosaka Y, Fujii T, Sakai M, Migita M, Kawakami K, Ohashi Y, Saito H. A Phase II clinical trial of a mixture of plasma-derived factor VIIa and factor X (MC710) in haemophilia patients with inhibitors: haemostatic efficacy, safety and pharmacokinetics/pharmacodynamics. Haemophilia 2013; 19:853-60. [DOI: 10.1111/hae.12205] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2013] [Indexed: 11/29/2022]
Affiliation(s)
- A. Shirahata
- Kitakyushu Yahata Higashi Hospital; Kitakyushu Fukuoka
| | - K. Fukutake
- Department of Laboratory Medicine; Tokyo Medical University; Tokyo
| | - J. Takamatsu
- Japanese Red Cross Aichi Blood Center; Seto Aichi
| | - M. Shima
- Department of Paediatrics; Nara Medical University; Kashihara Nara
| | - H. Hanabusa
- Department of Haematology; Ogikubo Hospital; Tokyo
| | - H. Mugishima
- Department of Paediatrics; Nihon University Itabashi Hospital; Tokyo
| | - K. Amano
- Department of Laboratory Medicine; Tokyo Medical University; Tokyo
| | - H. Takedani
- Department of Joint Surgery; Research Hospital of the Institute of Medical Science; The University of Tokyo; Tokyo
| | - S. Tamashima
- Department of Haematology and Oncology; Seirei Hamamatsu General Hospital; Hamamatsu Shizuoka
| | - T. Matsushita
- Department of Transfusion Medicine; Nagoya University Hospital; Nagoya
| | - A. Tawa
- Department of Paediatrics; National Hospital Organization Osaka National Hospital; Osaka
| | - I. Tanaka
- Department of Paediatrics; Nara Medical University; Kashihara Nara
| | - S. Higasa
- Division of Haematology; Department of Internal Medicine; Hyogo College of Medicine; Nishinomiya Hyogo
| | - Y. Kosaka
- Department of Haematology and Oncology; Kobe Children's Hospital; Kobe
| | - T. Fujii
- Division of the Blood Transfusion; Hiroshima University Hospital; Hiroshima
| | - M. Sakai
- Department of Paediatrics; University of Occupational and Environmental Health; Kitakyushu Fukuoka
| | - M. Migita
- Department of Paediatrics; Kumamoto Red Cross Hospital; Kumamoto
| | - K. Kawakami
- Department of Paediatrics; Kagoshima City Hospital; Kagoshima
| | - Y. Ohashi
- Department of Biostatistics; School of Public Health; The University of Tokyo; Tokyo
| | - H. Saito
- National Hospital Organization Nagoya Medical Center; Nagoya Japan
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Tanaka KA, Kor DJ. Emerging haemostatic agents and patient blood management. Best Pract Res Clin Anaesthesiol 2013; 27:141-60. [DOI: 10.1016/j.bpa.2013.02.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 02/20/2013] [Indexed: 12/20/2022]
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Abstract
Significant advancements in nonsurgical and surgical approaches to control bleeding in severely injured patients have also improved the treatment of critical trauma-related coagulopathy. Nonsurgical procedures such as angiographic embolization are progressively considered to terminate arterial bleeding from pelvic fractures. The disturbance of coagulation may aggravate bleeding and hamper surgical procedures. The administration of coagulation factors and factor concentrates may be useful for correcting systemic coagulopathy and reducing the need for fresh frozen plasma, platelet, and red blood cell transfusions, which are associated with various adverse outcomes. In this review, nonsurgical management of critical trauma bleeding is discussed.
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Affiliation(s)
- Christian Zentai
- Department of Anesthesiology, RWTH Aachen University Hospital, Aachen, Germany.
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89
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Breik O, Tadros R, Devitt P. Thrombin inhibitors: surgical considerations and pharmacology. ANZ J Surg 2013; 83:215-21. [PMID: 23384088 DOI: 10.1111/ans.12078] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2012] [Indexed: 11/28/2022]
Abstract
The new thrombin inhibitors have provided an exciting opportunity for effective thromboprophylaxis without some of the disadvantages of the current anticoagulants. These drugs are orally administered, have predictable pharmacokinetics and dose-response, do not require monitoring and have an acceptable safety profile when used appropriately. However, inappropriate prescribing of these drugs may lead to catastrophic consequences. Clinicians need to be aware of some of the drawbacks associated with the use of dabigatran and, in particular, its reduced clearance in the setting of renal failure and the lack of an effective reversing agent when bleeding does occur. In this review, the evidence for efficacy and safety of dabigatran is discussed. We also aim to provide practical clinical advice on the pre- and post-operative management of the elective and emergency surgical patient on dabigatran and provide guidelines for the management of acute haemorrhage in the context of dabigatran therapy.
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Affiliation(s)
- Omar Breik
- Department of Surgery, Royal Adelaide Hospital, Adelaide, South Australia, Australia
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90
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Factor VIIa. Platelets 2013. [DOI: 10.1016/b978-0-12-387837-3.00061-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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91
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Winch PD, Naguib AN, Bradshaw JR, Galantowicz M, Tobias JD. Decreasing the need for transfusion: infant cardiac surgery using hemodilution and recombinant factor VIIa. Pediatr Cardiol 2013; 34:119-24. [PMID: 22760694 DOI: 10.1007/s00246-012-0398-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 05/17/2012] [Indexed: 11/28/2022]
Abstract
Many strategies, including intraoperative acute normovolemic hemodilution (ANH) and pharmacologic agents, exist to minimize the use of allogeneic blood products in pediatric congenital heart surgery. Recombinant activated factor VIIa (rFVIIa) is a hemostatic agent approved for the treatment of bleeding episodes and prevention of bleeding in surgical interventions in patients with hemophilia A or B with inhibitors, acquired hemophilia, or congenital factor VII deficiency. Off-label use in nonhemophilic patients for uncontrolled hemorrhage is increasing although still under investigation. We present our experience with ANH and rFVIIa in nine patients. All were <16 months of age and underwent complex cardiac surgery with the end point of achieving hemostasis while decreasing or eliminating the need for allogeneic blood products. Clinically, we have observed rapid hemostasis in patients who underwent ANH and then had autologous blood reinfused after cardiopulmonary bypass, along with rFVIIa, without any time delay. The patients required no allogeneic blood products and therefore results suggested the potential utility of this practice. The study group consisted of nine patients <16 months of age who received rFVIIa in the operating room after open-heart surgery. Amount of autologous blood removed preoperatively, blood product use, time from protamine to rFVIIa administration, platelet count, INR, and fibrinogen level were retrospectively obtained. Of the nine patients, the three who underwent the most aggressive hemodilution received rFVIIa most rapidly and required no allogeneic blood products to achieve hemostasis although they had an average lower fibrinogen level on admission to the cardiothoracic intensive care unit. These preliminary data suggest that hemodilution before surgical stimulation and the rapid administration of rFVIIa, along with the reintroduction of autologous blood, may decrease or potentially eliminate the need for allogeneic blood products. Prospective trials are warranted to further explore this technique.
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Affiliation(s)
- Peter D Winch
- Department of Anesthesiology and Pain Medicine and The Heart Center, Nationwide Children's Hospital, Columbus, OH, USA.
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Gurion R, Siu A, Weiss AR, Masterson M. Use of Recombinant Factor VIIa in a Pediatric Patient With Initial Presentation of Refractory Acute Immune Thrombocytopenic Purpura and Severe Bleeding. J Pediatr Pharmacol Ther 2012; 17:274-80. [PMID: 23258971 DOI: 10.5863/1551-6776-17.3.274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Severe bleeding in acute immune thrombocytopenic purpura (ITP) is rare but can cause significant complications to the patient. Here we report the case of a pediatric patient with acute ITP and hematuria refractory to anti-D immune globulin, high dose intravenous immunoglobulin G, and high dose steroids. Her hematuria was successfully treated with recombinant factor VIIa (rFVIIa). While further investigation on the use of rFVIIa in ITP is warranted, this case report contributes to the pediatric literature for its use during the course of an initial presentation of ITP with hemorrhagic complications.
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Affiliation(s)
- Reut Gurion
- Division of Pediatric Rheumatology, University Hospitals Case Medical Center, Rainbow Babies & Children's Hospital, Cleveland, Ohio
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Motwani P, Howard L, Ali SS. Successful management of a possible antibiotic-related acquired factor V inhibitor: a case report and review of the literature. Acta Haematol 2012; 129:182-4. [PMID: 23257771 DOI: 10.1159/000345244] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 10/03/2012] [Indexed: 12/26/2022]
Abstract
Acquired factor inhibitors are rare. We report a case of an elderly male who presented with a bleeding diathesis associated with an elevated prothrombin time and an activated partial thromboplastin time. Work-up revealed undetectable factor V activity and a factor V inhibitor level of >50 Bethesda units. The inhibitor may have been triggered by antibiotics. With a multimodality approach using steroids, platelet transfusions, intravenous immunoglobulin, factor VIII inhibitor bypass activity agent and cyclophosphamide, we successfully eliminated the inhibitor and controlled the bleeding.
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Affiliation(s)
- Pooja Motwani
- Baystate Medical Center, Western Campus of Tuft’s University, School of Medicine, Springfield, MA 01107, USA.
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Larsen OH, Stentoft J, Radia D, Ingerslev J, Sørensen B. Combination of recombinant factor VIIa and fibrinogen corrects clot formation in primary immune thrombocytopenia at very low platelet counts. Br J Haematol 2012; 160:228-36. [DOI: 10.1111/bjh.12118] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 09/12/2012] [Indexed: 11/26/2022]
Affiliation(s)
| | - Jesper Stentoft
- Department of Haematology; Aarhus University Hospital; Aarhus; Denmark
| | - Deepti Radia
- Department of Haematology; Guy's and St Thomas' NHS Foundation Trust; London; UK
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Abstract
Inherited diseases of the megakaryocyte lineage give rise to bleeding when platelets fail to fulfill their hemostatic function upon vessel injury. Platelet defects extend from the absence or malfunctioning of adhesion (GPIb-IX-V, Bernard-Soulier syndrome) or aggregation receptors (integrin αIIbβ3, Glanzmann thrombasthenia) to defects of primary receptors for soluble agonists, secretion from storage organelles, activation pathways and the generation of procoagulant activity. In disorders such as the Chediak-Higashi, Hermansky-Pudlak, Wiskott-Aldrich and Scott syndromes the molecular lesion extends to other cells. In familial thrombocytopenia (FT), platelets are produced in insufficient numbers to assure hemostasis. Some FT affect platelet morphology and give rise to the 'giant platelet' syndromes (e.g. MYH9-related diseases) with changes in megakaryocyte maturation within the bone marrow and premature release of platelets. Diseases of platelet production may also affect other cells and in some cases interfere with development and/or functioning of major organs. Diagnosis of platelet disorders requires platelet function testing, studies often aided by the quantitative analysis of receptors by flow cytometry and fluorescence and electron microscopy. New generation DNA-based procedures including whole exome sequencing offer an exciting new perspective. Transfusion of platelets remains the most common treatment of severe bleeding, management with desmopressin is often used for mild disorders. Substitute therapies are available including rFVIIa and the potential use of thrombopoietin analogues for FT. Stem cell or bone marrow transplantation has been successful for several diseases while gene therapy shows promise in the Wiskott-Aldrich syndrome.
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Affiliation(s)
- A T Nurden
- Centre de Référence des Pathologies Plaquettaires, Plateforme Technologique et d'Innovation Biomédicale, Hôpital Xavier Arnozan, Pessac, France.
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Abstract
For patients affected by severe inherited platelet dysfunctions, e.g. Glanzmann thrombasthenia (GT) or Bernard-Soulier syndrome (BSS), platelet transfusion is frequently needed for controlling spontaneous bleeding, and is always needed when trauma occurs or surgery is performed. For the mild-to-moderate bleeding entities, e.g. storage pool disease, thrombaxane A2 receptor defect, platelet transfusion is usually unnecessary. Transfusion of platelets should be used selectively and sparingly because of the substantial risk of alloimmunization against HLA antigens and/or platelet glycoproteins (GP) αIIb, β(3), or αIIbβ(3) in GT, and GPI-IX-V in BSS, which may lead to refractoriness to therapy. To reduce the risk, HLA-matched single donors of platelets should be used. If such donors are unavailable, leucocyte-depleted blood components should be used. Therapy other than platelet transfusion includes: (i) Prevention (vaccination against hepatitis B, avoidance of non-steroidal anti-inflammatory drugs, preservation of dental hygiene, correction of iron deficiency and prenatal diagnosis). (ii) Topical measures (compression with gauze soaked with tranexamic acid, fibrin sealants, splints for dental extractions and packing for nose bleeds). (iii) Antifibrinolytic agents that are useful for minor surgery and as adjuncts for other treatment modalities. (iv) Desmopressin that increases plasma levels of von Willebrand factor and factor VIII giving rise to increased platelet adhesiveness and aggregation associated with shortened bleeding time. (v) Recombinant factor VIIa (rFVIIa). GT patients have been treated for bleeding episodes by rFVIIa with partial success. The mechanism by which rFVIIa arrests bleeding is probably related to increased thrombin generation by a tissue factor-independent process, enhanced platelet adhesion and restoration of platelet aggregation. (vi) Female hormones. Excessive bleeding during menarche in patients with GT or BSS can be controlled by high doses of oestrogen followed by high doses of oral oestrogen-progestin. Menorrhagia later in life can be managed by continuous oral contraceptives. Depo-medroxyprogesterone acetate administered every 3 months is an alternative when combined oral contraceptives are contraindicated.
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Affiliation(s)
- U Seligsohn
- Amalia Biron Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel Hashomer and Sackler Faculity of Medicine, Tel Aviv University, Israel.
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Mandal SK, Sagar G, Sahoo M, Jasuja S. Recombinant activated factor VII for diffuse alveolar hemorrhage in microscopic polyangiitis. Indian J Nephrol 2012; 22:130-2. [PMID: 22787316 PMCID: PMC3391811 DOI: 10.4103/0971-4065.97134] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Diffuse alveolar hemorrhage is a serious complication of the small vessel vasculitis syndromes and carries a high mortality. Recombinant activated factor VII (rFVIIa) is a powerful hemostatic agent developed for treatment of bleeding in patients with hemophilia and antibodies to factors VIII or IX. It has been used increasingly in life-threatening hemorrhage in a variety of other settings in which conventional medical or surgical therapy is unsuccessful. We report the successful use of rFVIIa for massive pulmonary hemorrhage in a patient of microscopic polyangiitis, which was later complicated by thrombotic microangiopathy and posterior reversible encephalopathy syndrome.
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Affiliation(s)
- S K Mandal
- Department of Nephrology, Indraprastha Apollo Hospital, New Delhi, India
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Shirahata A, Fukutake K, Mimaya J, Takamatsu J, Shima M, Hanabusa H, Takedani H, Takashima Y, Matsushita T, Tawa A, Higasa S, Takata N, Sakai M, Kawakami K, Ohashi Y, Saito H. Results of clot waveform analysis and thrombin generation test for a plasma-derived factor VIIa and X mixture (MC710) in haemophilia patients with inhibitors-phase I trial: 2nd report. Haemophilia 2012; 19:330-7. [DOI: 10.1111/hae.12024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2012] [Indexed: 11/27/2022]
Affiliation(s)
- A. Shirahata
- Department of Paediatrics; University of Occupational and Environmental Health; Kitakyushu; Fukuoka; Japan
| | - K. Fukutake
- Department of Laboratory Medicine; Tokyo Medical University; Tokyo; Japan
| | - J. Mimaya
- Division of Haematology and Oncology; Shizuoka Children's Hospital; Shizuoka; Japan
| | - J. Takamatsu
- Department of Transfusion Medicine; Nagoya University Hospital; Nagoya; Japan
| | - M. Shima
- Department of Paediatrics; Nara Medical University; Kashihara; Nara; Japan
| | - H. Hanabusa
- Department of Haematology; Ogikubo Hospital; Tokyo; Japan
| | - H. Takedani
- Department of Joint Surgery, Research Hospital of the Institute of Medical Science; the University of Tokyo; Tokyo; Japan
| | - Y. Takashima
- Division of Haematology and Oncology; Shizuoka Children's Hospital; Shizuoka; Japan
| | - T. Matsushita
- Department of Haematology and Oncology; Nagoya University Graduate School of Medicine; Nagoya; Japan
| | - A. Tawa
- Department of Paediatrics; National Hospital Organization Osaka National Hospital; Osaka; Japan
| | - S. Higasa
- Division of Haematology, Department of Internal Medicine; Hyogo College of Medicine; Nishinomiya; Hyogo; Japan
| | - N. Takata
- Division of the Blood Transfusion Services; Hiroshima University Hospital; Hiroshima; Japan
| | - M. Sakai
- Department of Paediatrics; University of Occupational and Environmental Health; Kitakyushu; Fukuoka; Japan
| | - K. Kawakami
- Department of Paediatrics; Kagoshima City Hospital; Kagoshima; Japan
| | - Y. Ohashi
- Department of Biostatistics, School of Public Health; the University of Tokyo; Tokyo; Japan
| | - H. Saito
- Nagoya Central Hospital; Nagoya; Japan
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Agarwal MB, Verma S, Mahapatra M, Tripathi AK, Bhave A, Deshpande A, Vora A, Dalal JJ, Shah AB, Bichu S. Balancing efficacy and bleeding risk in the prevention of stroke due to atrial fibrillation with newer oral anticoagulants. Indian J Hematol Blood Transfus 2012; 28:129-43. [PMID: 23997448 PMCID: PMC3422392 DOI: 10.1007/s12288-012-0167-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 05/21/2012] [Indexed: 12/15/2022] Open
Abstract
With the evaluation and approval of newer oral anticoagulants such as the factor IIa inhibitor, dabigatran etexilate and the factor Xa inhibitors, rivaroxaban and apixaban, strategies for stroke prevention in atrial fibrillation need a thorough re-evaluation of current options. Clinicians are naturally excited about the imminent introduction of these newer drugs that do not need international normalized ratio (INR) monitoring, besides having no drug-food and minimal drug-drug interactions. However, as with all new drugs, it is always prudent to use these judiciously so that they stay in our therapeutic armamentarium for a long time. More than 56 years after the introduction of warfarin we now have three drugs, viz., dabigatran 150 mg bid, rivaroxaban 20 mg od, and apixaban 5 mg bid which were effective in comparison with warfarin in reducing the risk of stroke and bleeding in the landmark trials, RE-LY, ROCKET-AF, and ARISTOTLE respectively. There is a thin dividing line between physiological hemostasis and pathological thrombosis. Routine INR monitoring may not be required but in special situations, such as prior to major surgery, overdose, non-compliance or stroke while on the anticoagulant, one may wish to know whether there are any laboratory measures of efficacy or means of reversal of over anticoagulation. Similar questions may be raised about other situations such as renal dysfunction, cardioversion, ablation procedures, post-stenting, or switch to and from warfarin, heparin or LMWH? This document is an attempt to address these concerns based on available evidence and give physicians a perspective and practice guidelines on how best to use these agents, both old and new, for optimal patient outcomes, maximizing efficacy and minimizing risk.
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