Efecto de las diferentes drogas anticoagulantes sobre el ensayo de fibrinógeno derivado del tiempo de protrombina / Effect of different anticoagulant drugs on the prothrombin time-derived fibrinogen assay

Resumen El objetivo de este trabajo fue comparar los niveles de fibrinógeno (FBG) obtenidos por el método de Clauss con los obtenidos por el método de fibrinógeno derivado del tiempo de protrombina (FBG PT-d), con dos tromboplastinas, en pacientes anticoagulados con distintas drogas. Se estudiaron pacientes anticoagulados consecutivos: 105 con antagonistas de la vitamina K (AVK), 55 con heparina no fraccionada (HNF), 58 con heparina de bajo peso molecular (HBPM), 60 con rivaroxabán, 45 con apixabán, 60 con dabigatrán y 100 controles normales (CN). El FBG se determinó por el método de Clauss y FBG PT-d utilizando tromboplastina de cerebro de conejo o recombinante humana; los niveles de heparina, rivaroxabán y apixabán por método cromogénico anti Xa; el dabigatrán con el ensayo de tiempo de trombina diluido. Existió un sesgo positivo (p<0,001) al comparar el FBG PT-d vs. FBG por Clauss: CN: 13,7%, AVK: 31,8%, rivaroxabán: 34,8% y apixabán: 20,0% cuando se utilizó tromboplastina de conejo. En el caso de las muestras que contenían HBPM se observó este desvío con ambas tromboplastinas. El sesgo porcentual en presencia de dabigatrán y heparina no fraccionada no fue estadísticamente distinto del obtenido en el grupo control. El ensayo de FBG PT-d no debe utilizarse en pacientes anticoagulados con rivaroxabán, apixabán, HBPM o AVK, ya que sobreestima los niveles de FBG. El porcentaje de sesgo depende del tipo de tromboplastina utilizado y fue mayor con la de cerebro de conejo en el sistema de detección utilizado.

Abstract The aim of this study was to compare fibrinogen (FBG) results obtained by Clauss method (FBG-C) and by the prothrombin time-derived fibrinogen assay (FBG PT-d) with two thromboplastins in patients under anticoagulation. Consecutive anticoagulated patients were studied: 105 vitamin-K antagonist (VKA), 55 unfractioned heparin, 58 LMWH, 60 rivaroxaban, 45 apixaban and 60 dabigatran, and 100 healthy controls (NC). FBG-C was performed by Clauss and FIB PT-d with rabbit brain and human recombinant thromboplastins, respectively. Heparins, rivaroxaban and apixaban levels were measured by antiXa; dabigatran by thrombin diluted assay. A positive bias of FBG PT-d vs. FBG-C with both thromboplastins were seen in NC (13.7 and 19.0 % for HS and RP, respectively), but bias with HS in rivaroxaban, apixaban and VKA patients were significantly higher compared to NC: 34.8%, 20.0 % and 31.8 %, respectively. LMWH presented higher BIAS compared to NC with both thromboplastins. Samples with unfraction heparin and dabigatran presented similar bias to NC. FBG PT-d should not be used in patients under anticoagulant treatment because of an important overestimation of FBG could be obtained in these patients. The percentage of bias depends on the type of thromboplastin used; it was higher with rabbit brain thromboplastin in the detection system used.

Resumo O objetivo deste trabalho foi comparar os níveis de fibrinogênio (FBG) obtidos pelo método de Clauss com aqueles obtidos pelo método do fibrinogênio derivado do tempo de protrombina (FBG PT-d), com duas tromboplastinas, em pacientes anticoagulados com diferentes drogas. Pacientes anticoagulados consecutivos foram estudados: 105 com antagonista da vitamina K (AVK); 55 com heparina não fracionada (UFH); 58 com heparina de baixo peso molecular (HBPM), 60 com rivaroxabana, 45 com apixabana, 60 com dabigatrana e 100 controles normais (CN). FBG foi determinado pelo método de Clauss e FBG PT-d usando tromboplastina de cérebro de coelho ou tromboplastina humana recombinante; níveis de heparina, rivaroxabana e apixabana pelo método cromogênico anti-Xa; dabigatrana com ensaio de tempo de trombina diluída. Há um viés positivo (p<0,001) ao comparar o FBG PT-d vs FBG de Clauss: CN: 13,7%; AVK: 31,8%, rivaroxabana: 34,8% e apixabana 20,0% quando foi utilizada tromboplastina de coelho. No caso das amostras contendo HBPM, esse desvio foi observado com ambas as tromboplastinas. O viés percentual na presença de dabigatrana e heparina não fracionada não foi estatisticamente diferente daquela obtida no grupo controle. O ensaio de FBG PT-d não deve ser usado em pacientes anticoagulados com rivaroxabana, apixabana, LMWH ou VKA, pois superestima os níveis de FBG. A porcentagem de viés depende do tipo de tromboplastina utilizado e foi maior com a de cérebro de coelho, no sistema de detecção utilizado.

Andexanet Alfa or Prothrombin Complex Concentrate for Factor Xa Inhibitor Reversal in Acute Major Bleeding: A Systematic Review and Meta-Analysis.

OBJECTIVES: To combine evidence on andexanet alfa and prothrombin complex concentrates for factor Xa inhibitor-associated bleeding to guide clinicians on reversal strategies. DATA SOURCES: Embase, Pubmed, Web of Science, and the Cochrane Library. STUDY SELECTION: Observational studies and randomized clinical trials studying hemostatic effectiveness of andexanet alfa or prothrombin complex concentrate for acute reversal of factor Xa inhibitor-associated hemorrhage. DATA EXTRACTION: Two independent reviewers extracted the data from the studies. Visualization and comparison of hemostatic effectiveness using Sarode et al or International Society of Thrombosis and Hemostasis Scientific and Standardization Committee criteria at 12 and 24 hours, (venous) thrombotic event rates, and inhospital mortality were performed by constructing Forest plots. Exploratory analysis using a logistic mixed model analysis was performed to identify factors associated with effectiveness and venous thromboembolic event. DATA SYNTHESIS: A total of 21 studies were included (andexanet: 438 patients; prothrombin complex concentrate: 1,278 patients). The (weighted) mean effectiveness for andexanet alfa was 82% at 12 hours and 71% at 24 hours. The (weighted) mean effectiveness for prothrombin complex concentrate was 88% at 12 hours and 76% at 24 hours. The mean 30-day symptomatic venous thromboembolic event rates were 5.0% for andexanet alfa and 1.9% for prothrombin complex concentrate. The mean 30-day total thrombotic event rates for andexanet alfa and prothrombin complex concentrate were 10.7% and 3.1%, respectively. Mean inhospital mortality was 23.3% for andexanet versus 15.8% for prothrombin complex concentrate. Exploratory analysis controlling for potential confounders did not demonstrate significant differences between both reversal agents. CONCLUSIONS: Currently, available evidence does not unequivocally support the clinical effectiveness of andexanet alfa or prothrombin complex concentrate to reverse factor Xa inhibitor-associated acute major bleeding, nor does it permit conventional meta-analysis of potential superiority. Neither reversal agent was significantly associated with increased effectiveness or a higher rate of venous thromboembolic event. These results underscore the importance of randomized controlled trials comparing the two reversal agents and may provide guidance in designing institutional guidelines.

[Intravenous thrombolysis after reversion of acenocoumarol anticoagulation. Report of one case]. / Trombolisis endovenosa post reversión de acenocumarol con complejo de protrombina. Caso clínico.

We report an 89-year-old male under oral anticoagulant therapy with a therapeutic international normalized ratio, presenting at the emergency room with right side hemiparesis and aphasia. Neuroimaging was compatible with an acute middle cerebral artery ischemic stroke. Anticoagulation was reverted with the use of four factor prothrombin complex, followed by thrombolysis with alteplase, with a favorable evolution, returning to his basal functional status.

Trombolisis endovenosa post reversión de acenocumarol con complejo de protrombina: caso clínico / Intravenous thrombolysis after reversion of acenocoumarol anticoagulation: report of one case

We report an 89-year-old male under oral anticoagulant therapy with a therapeutic international normalized ratio, presenting at the emergency room with right side hemiparesis and aphasia. Neuroimaging was compatible with an acute middle cerebral artery ischemic stroke. Anticoagulation was reverted with the use of four factor prothrombin complex, followed by thrombolysis with alteplase, with a favorable evolution, returning to his basal functional status.

Fixed-Dose Four-Factor Prothrombin Complex Concentrate for Vitamin K Antagonist Reversal: Does One Dose Fit All?

Four-factor prothrombin complex concentrate (4F-PCC) has emerged as the preferred option for emergent reversal of vitamin K antagonists (VKAs); however, the optimal dosing strategy is unknown. Although several studies have attempted to determine the optimal dose of 4F-PCC using a variety of dosing regimens, no dosing strategy has been found to be superior. Many of these studies have evaluated a low, fixed dose of 4F-PCC rather than individualized dosing as recommended in product labeling. The purpose of this review was to evaluate the efficacy and safety of various fixed-dose strategies of 4F-PCC for emergent VKA reversal and to assess limitations of the existing literature. A search of the PubMed database was performed from the earliest available date through 2018 for relevant articles describing fixed-dose 4F-PCC for VKA reversal. Reference lists of relevant articles were also manually reviewed. Most currently available studies are primarily observational and heterogeneous in design. A very low fixed dose of 500 IU is likely inadequate for successful VKA reversal, but increased fixed doses of 1000-1500 IU have found some degree of success and may be considered for VKA reversal. However, many of these studies consistently identified a trend toward international normalized ratio (INR) reversal failure in patients presenting with high baseline INR values or intracranial hemorrhage, suggesting that higher 4F-PCC doses are needed in these patients. Available studies are underpowered to determine whether a dose-dependent association with thrombotic risk exists. Additional large, randomized studies are needed to determine the optimal dosing strategy and ascertain the role for fixed-dose 4F-PCC.

Effects of modification of trauma bleeding management: A before and after study.

OBJECTIVE: We hypothesised that the association of tranexamic acid (TXA) administration and thromboelastometry-guided haemostatic therapy (TGHT) with implementation of Damage Control Resuscitation (DCR) reduced blood products (BP) use and massive transfusion (MT). METHODS: Retrospective comparison of 2 cohorts of trauma patients admitted in a university hospital, before (Period 1) and after implementation of DCR, TXA (first 3-hours) and TGHT (Period 2). Patients were included if they received at least 1 BP (RBC, FFP or platelet) or coagulation factor concentrates (fibrinogen or prothrombin complex) during the first 24-hours following the admission. RESULTS: 380 patients were included. Patients in Period 2 (n = 182) received less frequently a MT (8% vs. 33%, P < 0.01), significantly less BP (RBC: 2 units [1-5] vs. 6 [3-11]; FFP: 0 units [0-2] vs. 4 [2-8]) but more fibrinogen concentrates (3.0 g [1.5-4.5] vs. 0.0 g [0.0-3.0], P < 0.01). Multivariate logistic regression analysis identified Period 1 as being associated with an increased risk of receiving MT (OR: 26.1, 95% CI: 9.7-70.2) and decreased survival at 28 days (OR: 2.0, 95% CI: 1.0-3.9). After propensity matching, the same results were observed but there was no difference for survival and a significant decrease for the cost of BP (2370 ± 2126 vs. 3284 ± 3812 €, P: 0.036). CONCLUSION: Following the implementation of a bundle of care including DCR, TGHT and administration of TXA, we observed a decrease to the use of blood products, need for MT and an improvement of survival.

The impact of microbubble-enhanced therapeutic ultrasound combined with prothrombin on microwave ablation in the rabbit liver.

AIM: This study aimed to investigate the effect of microbubble-enhanced ultrasound (MEUS) combined with prothrombin on regional hepatic circulation and microwave ablation (MWA) in rabbit livers. MATERIALS AND METHODS: High-pressureamplitude therapeutic ultrasound (TUS) was used to treat 52 surgically exposed livers of healthy New Zealand rabbits: 13 livers were treated with MEUS alone, 13 with MEUS and prothrombin (PMEUS), 13 with ultrasound plus normal saline and 13 with ultrasound plus prothrombin as controls. Contrast-enhanced ultrasound (CEUS) imaging was performed on the exposed livers before and after treatment, and acoustic quantification was done to assess liver perfusion. Then, the liver was divided into two parts, one was used for pathologic examination and the other was ablated with microwave (MWA) and then processedfor pathologic examination. RESULTS: The CEUS images and Peak value after treatment in the PMEUS group were significantly reduced as compared to the remaining 3 groups (p<0.05). Occasional piecemeal hemorrhage was evidenced in the pathological examination in the MEUS group. Obvious cellular degeneration and necrosis with thrombosis were observed in the PMEUS group. Electron microscopy showed endothelial damage in both the MEUS group and PMEUS group. After MWA, coagulated volumes (V) in the PMEUS group were larger than in the remaining 3 groups (p<0.05). The cell ultrastructure disorder wasmore severe in the PMEUS group than in remaining 3 groups. CONCLUSION: PMEUS promotes endothelial injury and produces more obvious thrombotic occlusion, improving the therapeutic effect of MWA on the rabbit liver.

Disruption of Prostate Microvasculature by Combining Microbubble-Enhanced Ultrasound and Prothrombin.

Previous studies have shown a unique method to disrupt tumor vasculature using pulsed, high-pressure amplitude therapeutic ultrasound combined with microbubbles. In this study, we attempted to destroy the prostate vasculature of canine prostates using microbubble-enhanced ultrasound (MEUS) and prothrombin. The prostates of 43 male mongrel canines were surgically exposed. Twenty-two prostates were treated using MEUS (n = 11) or MEUS and prothrombin (PMEUS, n = 11). The other 21 prostates, which were treated using microbubbles (n = 7), ultrasound (n = 7) or prothrombin (n = 7) only, served as the controls. Prothrombin was intravenously infused at 20 IU/kg. MEUS was induced using a therapeutic ultrasound device at a peak negative pressure of 4.47 MPa and a microbubble injection. Contrast-enhanced ultrasound was performed to assess the blood perfusion of the prostates. Then, the prostate tissue was harvested immediately after treatment and at 48 hours later for pathological examination. The contrast-enhanced ultrasound peak value of the prostate decreased significantly from 36.2 ± 5.6 to 27.1 ± 6.3 after treatment in the PMEUS group, but it remained unchanged in the other groups. Histological examination found severe microvascular rupture, hemorrhage and thrombosis in both MEUS- and PMEUS-treated prostates immediately after treatment, while disruption in the PMEUS group was more severe than in the MEUS group. Forty-eight hours after treatment, massive necrosis and infiltration of white blood cells occurred in the PMEUS group. This study demonstrated that PMEUS disrupted the normal microvasculature of canine prostates and induced massive necrosis. PMEUS could potentially become a new noninvasive method used for the treatment of benign prostatic hyperplasia.

[Direct oral anticoagulant associated bleeding]. / Hémorragie survenant chez un patient traité par un anticoagulant oral direct.

Direct oral anticoagulants (DOAC) are recommended for stroke prevention in atrial fibrillation and for the treatment of venous thromboembolism. However, they are associated with hemorrhagic complications. Management of DOAC-induced bleeding remains challenging. Activated or non-activated prothrombin concentrates are proposed, although their efficacy to reverse DOAC is uncertain. Therapeutic options also include antidotes: idarucizumab, antidote for dabigatran, has been approved for use whereas andexanet alpha, antidote for anti-Xa agents, and aripazine, antidote for all DOAC, are under development. Other options include hemodialysis for the treatment of dabigatran-associated bleeding and administration of oral charcoal if recent DOAC ingestion. DOAC plasma concentration measurement is necessary to guide DOAC reversal. We propose an update on DOAC-associated bleeding, integrating the availability of dabigatran antidote and the critical place of DOAC concentration measurements.

Periprocedural management of patients receiving a vitamin K antagonist or a direct oral anticoagulant requiring an elective procedure or surgery.

The periprocedural management of patients receiving chronic therapy with oral anticoagulants (OACs), including vitamin K antagonists (VKAs) such as warfarin and direct OACs (DOACs), is a common clinical problem. The optimal perioperative management of patients receiving chronic OAC therapy is anchored on four key principles: (i) risk stratification of patient-related and procedure-related risks of thrombosis and bleeding; (ii) the clinical consequences of a thrombotic or bleeding event; (iii) discontinuation and reinitiation of OAC therapy on the basis of the pharmacokinetic properties of each agent; and (iv) whether aggressive management such as the use of periprocedural heparin bridging has advantages for the prevention of postoperative thromboembolism at the cost of a possible increase in bleeding risk. Recent data from randomized trials in patients receiving VKAs undergoing pacemaker/defibrillator implantation or using heparin bridging therapy for elective procedures or surgeries can now inform best practice. There are also emerging data on periprocedural outcomes in the DOAC trials for patients with non-valvular atrial fibrillation. This review summarizes the evidence for the periprocedural management of patients receiving chronic OAC therapy, focusing on recent randomized trials and large outcome studies, to address three key clinical scenarios: (i) can OAC therapy be safely continued for minor procedures or surgeries; (ii) if therapy with VKAs (especially warfarin) needs to be temporarily interrupted for an elective procedure/surgery, is heparin bridging necessary; and (iii) what is the optimal periprocedural management of the DOACs? In answering these questions, we aim to provide updated clinical guidance for the periprocedural management of patients receiving VKA or DOAC therapy, including the use of heparin bridging.

Efficacy and safety of bovine activated factors IIa/VIIa/IXa/Xa in patients with active gastrointestinal bleeding: a proof of concept study.

BACKGROUND AND STUDY AIMS: Endoscopic treatment of active gastrointestinal bleeding often remains difficult, and considerable technical expertise is required. Our aim was to assess the efficacy and safety of endoscopic hemostasis with a liquid combination of bovine activated factors IIa/VIIa/IXa/Xa (SeraSeal). METHODS: Patients with active gastrointestinal bleeding were prospectively included. In group A, 5 mL of bovine activated factors IIa/VIIa/IXa/Xa was topically applied via catheters to the bleeding site as initial hemostasis; group B received a similar application but as rescue therapy after failure of conventional endoscopic hemostasis. RESULTS: In group A, bleeding was stopped by the agent in 15 /22 patients (68 %) and by conventional endoscopic hemostasis in 5 of the other 7, with coiling and surgery required for definitive hemostasis in 2. In group B, the addition of the agent definitively stopped bleeding in 13 /15 patients (87 %), with hemostasis in the remaining 2 achieved with fibrin glue. Rebleeding was observed in 1 patient. CONCLUSIONS: Our proof of concept study suggests that the use of bovine activated factors IIa/VIIa/IXa/Xa might be a safe and effective addition to current endoscopic hemostatic strategies, but further studies are necessary.ClinicalTrials.gov identifier: NCT02349490.

[Direct oral anticoagulation and gastrointestinal bleeding: Interventional therapy management]. / Direkt wirkende orale Antikoagulanzien bei gastrointestinaler Blutung : Interventionelles Therapiemanagement.

BACKGROUND: More and more patients are being treated with direct oral anticoagulants (DOAC). Under treatment with DOACs gastrointestinal bleeding appears to occur more frequently, particularly in the lower gastrointestinal tract, compared to treatment with vitamin K antagonists (e.g. warfarin). OBJECTIVE: A possible approach should now be elaborated in a joint effort by gastroenterologists and cardiologists. MATERIAL AND METHODS: A selective literatue search was carried out and own experiences were also included. RESULTS: The decision to perform procoagulant therapy by slowly injecting 30-50 IU prothrombin complex concentrate (PPSB) per kg body weight intravenously depends on various factors and should be assessed critically. Specific antidotes are awaiting approval. After a bleeding episode potentially controllable and reversible triggers must be excluded (e.g. drug interactions and renal impairment). The risk of recurrent bleeding and the risk of thromboembolic events have to be weighed against each other before deciding to readminister an anticoagulant and its form. Dose reduction and changing to apixaban (in reduced dosage) are options for risk reduction and vitamin K antagonists can also be considered. DISCUSSION: It is still unclear what role specific antidotes will play.

The effect of recombinant and plasma-derived prothrombin on prothrombin time in human plasma.

INTRODUCTION: When investigating coagulation assays to measure the effect of infused prothrombin (FII) in in vivo coagulopathy models, we found that addition of FII, plasma-derived human FII (pd-hFII) or recombinant human FII (r-hFII), to normal plasma resulted in a concentration-dependent increase in prothrombin time (PT) initiated with Innovin(®) . METHODS: The effect on PT by addition to plasma of either pd-hFII or r-hFII, using different commercial PT reagents, was studied both by turbidimetry and viscometry. RESULT: Addition of FII to plasma resulted in increased PT when initiated with Innovin(®) : PT increased with 20% by doubling the concentration. The prolongation of PT became more pronounced with 2-6000 times diluted Innovin(®) . However, by adjustment of the final free Ca(2+) concentration in the assay with diluted Innovin(®) from 8.3 to 1.3 mmol/L, no FII-dependent increase in PT was found. In contrast, no prolongation of PT was found with other commercial PT reagents. A KM = 3 nmol/L was obtained with pd-hFII, respectively, r-hFII with FII-depleted plasma using Thromborel(®) to initiate PT. CONCLUSION: At normal plasma concentration of FII, addition of FII should not have an effect on PT. The prolonged PT with Innovin(®) , but not with other PT reagents, at supranormal FII concentration is an artefact.

WEDGE: an anticoagulant thrombin mutant produced by autoactivation.

BACKGROUND: The production of therapeutically relevant proteases typically involves activation of a zymogen precursor by external enzymes, which may raise regulatory issues about availability and purity. Recent studies of thrombin precursors have shown how to engineer constructs that spontaneously convert to the mature protease by autoactivation, without the need for external enzymes. OBJECTIVES: Autoactivation is an innovative strategy that promises to simplify the production of proteases of therapeutic relevance, but has not been tested in practical applications. The aim of this study was to provide a direct test of this strategy. METHODS: An autoactivating version of the thrombin mutant W215A/E217A (WE), which is currently in preclinical development as an anticoagulant, was engineered. RESULTS AND CONCLUSIONS: The autoactivating version of WE can be produced in large quantities, like WE made in BHK cells or Escherichia coli, and retains all significant functional properties in vitro and in vivo. The results serve as proof of principle that autoactivation is an innovative and effective strategy for the production of trypsin-like proteases of therapeutic relevance.

[CORRECTION OF HEMOSTASIS WITH BLOOD PRODUCTS IN THE SURGICAL TREATMENT OF CONGENITAL HEART DISEASE IN INFANTS AND YOUNG CHILDREN].

The article deals with the safety and efficiency of recombinant activated factor VII (Coagil VII, Russia) and prothrombin complex concentrate (protromplex-600, Baxter Austria) in the neonatal and pediatric cardiac surgery. The study included 56 children aged from 7 days to 5.5 years underwent surgery with cardiopulmonary bypass for congenital heart defects repair. Clinical and laboratory evidences suggest that Coagil VII and protromplex-600 effective for bleeding stop. The drugs have no negative impact on hemodynamics. We did not identify allergic reactions and thrombosis associated with the introduction of drugs in the pen operative period.

A systematic review of prothrombin complex concentrate dosing strategies to reverse vitamin K antagonist therapy.

Management of patients with a major bleed while on vitamin K antagonist (VKA) is a common clinical challenge. Prothrombin Complex Concentrates (PCC) provide a rapid reversal of VKA induced coagulopathy. However, a well-defined PCC dosing strategy, especially in emergency setting, is still lacking. We performed a systematic review to describe the currently used PCC dosing strategies and to present their efficacy in terms of target INR achievement and clinical outcome. We used outcome definitions as used in the individual studies. MEDLINE and EMBASE databases were searched for studies reporting the use of PCC for emergency VKA reversal. Twenty-eight studies, including 4 randomized trials, were found. In these, fifteen different PCC dosing protocols were identified in which the PCC dose ranged from 8 to 50IU factor IX/kg. These strategies were based on: bodyweight; bodyweight and initial INR; bodyweight and initial INR and target INR; individual doctors decision; or a fixed dose. Study quality was moderate with large variation in outcome definitions. Relatively good clinical and INR outcomes were reported with the use of any treatment protocol while less good results were reported for INR outcome when a predefined protocol was missing (doctor strategy). Lowest PCC dosages were infused in the fixed dose strategy. In emergency VKA reversal, a predefined PCC dosing protocol seems essential. We found no evidence that one dosing strategy is superior. Future studies should be designed to investigate if body weight and INR are relevant for PCC dosing. In these, we need uniform outcome definitions.

Thrombotic safety of prothrombin complex concentrate (Beriplex P/N) for dabigatran reversal in a rabbit model.

INTRODUCTION: In vivo animal data have shown prothrombin complex concentrate (PCC) to be effective in preventing bleeding induced by excessive plasma levels of the direct thrombin inhibitor dabigatran. This animal model study was designed to determine the risk of thrombosis associated with administration of a PCC (Beriplex P/N) to reverse dabigatran-induced bleeding. MATERIALS AND METHODS: Anesthetized rabbits were treated with initial 0, 75, 200 or 450 µg kg(-1) dabigatran boluses followed by continuous infusions to maintain elevated plasma dabigatran levels. At 15 min after the start of dabigatran administration, PCC doses of 0, 50 or 300 IU kg(-1) were administered. Thereafter, coagulation in an arteriovenous (AV) shunt was evaluated and histopathologic examination for thrombotic changes performed. Venous thrombosis was also assessed in a modified Wessler model. RESULTS: At the suprapharmacologic dose of 300 IU kg(-1), PCC increased thrombus weight during AV shunting, but this effect could be prevented by dabigatran at all tested doses. AV shunt occlusion after PCC administration was delayed by 75 µg kg(-1) dabigatran and abolished by progressively higher dabigatran doses. High-dose treatment with 300 IU kg(-1) PCC resulted in histologically evident low-grade pulmonary thrombi; however, that effect could be blocked by dabigatran in a dose-dependent manner (p=0.034). In rabbits treated with high-dose PCC, dabigatran inhibited thrombus formation during venous stasis. PCC effectively reversed dabigatran-induced bleeding. CONCLUSIONS: In this animal study, thrombosis after PCC administration could be prevented in the presence of dabigatran. PCC reversed dabigatran-induced excessive bleeding while retaining protective anticoagulatory activity of dabigatran.

Prothrombin complex concentrates as reversal agents for new oral anticoagulants: lessons from preclinical studies with Beriplex.

Although new oral anticoagulants (NOACs) represent an advance in anticoagulant therapy over vitamin K antagonists (VKAs), they nevertheless have a low, but significant risk for bleeding complications. Reversal agents for VKAs, such as prothrombin complex concentrates (PCCs), are currently being evaluated in preclinical studies for NOAC reversal. This article reviews the preclinical data for the most extensively studied PCC for NOAC reversal, Beriplex, a 4-factor PCC. The results from the Beriplex studies are also compared with those obtained with other reversal agents, including different nonactivated PCCs, activated PCCs, and recombinant activated factor VII.