Correlation of coagulation markers and 4F-PCC-mediated reversal of rivaroxaban in a rabbit model of acute bleeding.

INTRODUCTION: Rivaroxaban is an oral, selective direct factor Xa inhibitor approved for several indications in patients at risk of thrombotic events. One limitation of its clinical use is the lack of data pertaining to its reversal in situations where urgent response is critical (e.g. acute bleeding events or emergency surgery). MATERIALS AND METHODS: This study assessed the effectiveness of a four-factor prothrombin complex concentrate (4F-PCC; Beriplex(®)/Kcentra(®)) for the reversal of rivaroxaban-associated bleeding in an in vivo rabbit model, and evaluated the correlations between in vitro coagulation parameters and haemostasis in vivo. RESULTS: Administration of single intravenous doses of rivaroxaban (150-450 µg/kg) resulted in increased and prolonged bleeding following standardised kidney incision. Pre-incision treatment with 4F-PCC (25-100 IU/kg) resulted in a dose-dependent reversal of rivaroxaban (150 and 300 µg/kg)-associated increases in time to haemostasis and blood loss; no reversal was seen at the highest rivaroxaban dose (450 µg/kg). Of the in vitro biomarkers tested, thrombin generation and whole-blood clotting time correlated well with in vivo measures of 4F-PCC-mediated effects. Thrombin generation was highly reagent-dependent, with the assay initiated using the phospholipid-only reagent being the most predictive of effective haemostasis in vivo. CONCLUSIONS: In summary, in a rabbit model of acute bleeding, treatment with 4F-PCC reduced bleeding to control levels following rivaroxaban 150 µg/kg and 300 µg/kg administration.

Effective reversal of edoxaban-associated bleeding with four-factor prothrombin complex concentrate in a rabbit model of acute hemorrhage.

BACKGROUND: Edoxaban is an oral, selective direct factor Xa inhibitor approved in Japan for venous thromboembolism prevention after orthopedic surgery. Data are lacking regarding reversal strategies for edoxaban; this study assessed whether four-factor prothrombin complex concentrate (Beriplex/Kcentra; CSL Behring GmbH, Marburg, Germany) can effectively reverse its effects on hemostasis using a previously described rabbit model. METHODS: The study comprised assessments of thrombin generation in vitro, pharmacokinetic parameters, and edoxaban reversal in vivo. In a blinded in vivo stage, a standardized kidney incision was performed in animals (n = 11 per group) randomized to receive vehicle + saline, edoxaban (1,200 µg/kg) + saline, or edoxaban (1,200 µg/kg) + four-factor prothrombin complex concentrate (50 IU/kg). Animals were monitored for treatment impact on hemostasis and coagulation parameters. Data are median (range). Statistical tests were adjusted for multiple testing. RESULTS: Edoxaban administration increased blood loss (30 [2 to 44] ml) and time to hemostasis (23 [8.5 to 30.0] min) compared with the control group (3 [1 to 8] ml and 3 [2.0 to 5.0] min, respectively). Biomarkers of coagulation (prothrombin time, activated partial thromboplastin time, whole blood clotting time) and thrombin generation parameters (e.g., peak thrombin, endogenous thrombin potential, lag time) were also affected by edoxaban. Administration of four-factor prothrombin complex concentrate significantly reduced time to hemostasis (to 8 [6.5 to 14.0] min, observed P < 0.0001) and total blood loss (to 9 [4 to 22] ml, observed P = 0.0050) compared with the edoxaban + saline group. Of the biomarkers tested, prothrombin time, whole blood clotting time, and endogenous thrombin potential correlated best with clinical parameters. CONCLUSION: In a rabbit model of hemostasis, four-factor prothrombin complex concentrate administration significantly decreased edoxaban-associated hemorrhage.

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 concentrate versus recombinant factor VIIa for reversal of hemodilutional coagulopathy in a porcine trauma model.

BACKGROUND: Fluid resuscitation after traumatic injury may necessitate coagulation factor replacement to prevent bleeding complications of dilutional coagulopathy. Recombinant activated factor VII (rFVIIa) is being widely investigated as a hemostatic agent in trauma. Multicomponent therapy with prothrombin complex concentrate (PCC) containing coagulation factors II, VII, IX, and X might offer potential advantages. METHODS: Anesthetized mildly hypothermic normotensive pigs were hemodiluted by substituting 65% to 70% of total blood volume in phases with hydroxyethyl starch and red cells. Thereafter, animals received 12.5 mL . kg isotonic saline placebo, 35 IU . kg PCC, or 180 microg x kg rFVIIa. Immediately afterward, a standardized spleen injury was inflicted, and prothrombin time (PT) and hemostasis were assessed. Thrombin generation was also determined. RESULTS: Hemodilution depleted levels of factors II, VII, IX, and X markedly, prolonged PT and decreased thrombin formation. PCC and rFVIIa both fully normalized the hemodilution-induced lengthening of PT. In PCC recipients, peak thrombin generation was greater by a median of 60.7 nM (confidence interval 56.4-64.9 nM) compared with the rFVIIa group (p = 0.008). After spleen trauma, time to hemostasis was shortened to a median of 35 minutes in animals treated with PCC versus 94 minutes with rFVIIa (p = 0.016). CONCLUSIONS: In a pilot study involving an in vivo large-animal model of spleen trauma, PCC accelerated hemostasis and augmented thrombin generation compared with rFVIIa. Further investigations are warranted on PCC as a hemostatic agent in trauma.

Prothrombin complex concentrate (Beriplex P/N) for control of bleeding after kidney trauma in a rabbit dilutional coagulopathy model.

INTRODUCTION: Fluid resuscitation after trauma often results in dilutional coagulopathy that may hinder control of bleeding and, once initial hemostasis has been secured, heighten risk of perioperative bleeding when further surgery is required. Since multiple coagulation factor deficiencies typically accompany fluid resuscitation, prothrombin complex concentrate (PCC) containing factors II, VII, IX and X may potentially offer greater hemostatic efficacy than coagulation factor monotherapy. MATERIALS AND METHODS: Anesthetized normothermic rabbits were hemodiluted 50-60% by phased blood withdrawal and infusion of hydroxyethyl starch and erythrocytes. The animals were randomly assigned to receive saline placebo, 25 IU x kg(-1) PCC (Beriplex P/N) or 180 microg x kg(-1) activated recombinant factor VII (rFVIIa; NovoSeven). Immediately thereafter, bleeding was precipitated by a standardized kidney incision. RESULTS: PCC accelerated hemostasis compared both with saline and rFVIIa (p=0.002 for both comparisons). The median times to hemostasis in the PCC, saline and rFVIIa groups were 12, 19 and 28 min, respectively. PCC reduced blood loss by a median of 43 mL with a 95% confidence interval (CI) of 8.0-67.5 mL vs. saline and 82 mL (CI, 35.0-110.0 mL) vs. rFVIIa. PCC augmented peak thrombin generation by a median of 104.1 nM (CI, 78.3-142.3 nM) compared with saline and 105.8 nM (CI, 70.7-139.5 nM ) relative to rFVIIa. At the respective 180 microg x kg(-1) and 25 IU x kg(-1) doses tested, rFVIIa displayed thrombogenicity in the Wessler stasis model, while PCC did not. CONCLUSIONS: In an animal model of dilutional coagulopathy and kidney trauma, PCC accelerated hemostasis and diminished blood loss compared with rFVIIa monotherapy.

Characterization of the coagulation deficit in porcine dilutional coagulopathy and substitution with a prothrombin complex concentrate.

BACKGROUND: In this study, we used a porcine model to investigate whether impaired coagulation and severe arterial or venous bleeding could be normalized by substitution with a prothrombin complex concentrate (PCC), Beriplex P/N, containing coagulation factors II, VII, IX, and X. METHODS: Dilutional coagulopathy was induced in anesthetized pigs by fractionated blood withdrawal (approximately 65% of total volume), followed by erythrocyte retransfusion and volume substitution with a total of 1000 mL of hydroxyethyl starch (Infukoll 6%). Animals were randomized to no treatment, treatment with placebo, or treatment with 35 U/kg PCC. Arterial (spleen incision) or venous (bone injury) bleeding was inflicted. Thromboelastometry, hematology, and coagulation tests were performed at baseline, after dilution, and after study treatments had been administered and injury inflicted. The primary end-point was postinjury time to hemostasis. RESULTS: Hemodilution resulted in a decrease in coagulation factor concentrations to approximately 35% and prolonged prothrombin time. Platelet numbers decreased from approximately 400,000 to approximately 100,000/microL, and aggregation and adhesion were impaired. PCC effectively substituted the deficient prothrombin factors (II, VII, IX, and X) and normalized the prolonged prothrombin time. After spleen injury, PCC significantly reduced time to hemostasis versus dilutional control (median, 35 vs 82.5 min; P < 0.0001), and produced a nonsignificant trend towards reduction in blood loss (mean, 275 vs 589 mL). PCC also significantly reduced time to hemostasis (median, 27 vs 97 min; P < 0.0011) and blood loss (mean, 71 vs 589 mL; P < 0.0017) after bone injury. CONCLUSIONS: Dilutional coagulopathy produced a generalized decrease in coagulation factors and impaired platelet function. Substitution with PCC effectively normalized coagulation and significantly improved hemostasis after venous and arterial bleeding.

The effect of fibrinogen concentrate administration on coagulation abnormalities in a rat sepsis model.

Disseminated intravascular coagulation is a disorder that affects the function of the clotting system and is frequently associated with sepsis or septic shock. One of its leading symptoms is the decrease in circulating fibrinogen. We investigated the effect of fibrinogen concentrate (Haemocomplettan P) on fibrinogen plasma levels, coagulation parameters and mortality in a rat model of sepsis-induced disseminated intravascular coagulation. The disseminated intravascular coagulation was characterized by elevated thrombin-antithrombin complex and a sharp drop in circulating fibrinogen. Coagulation abnormalities were evaluated by thrombelastography. Plasma fibrinogen levels decreased from 2.06 +/- 0.2 to 0.16 +/- 0.1 g/l following administration of bacterial lipopolysaccharide. Thrombelastographic measurements revealed a concurrent decrease in maximum amplitude and an increase in reaction time. Treatment with fibrinogen concentrate (Haemocomplettan P, 25-200 mg/kg body weight intravenously) resulted in a statistically significant dose-dependent increase in fibrinogen plasma levels and amelioration of the measured coagulation abnormalities. Fibrinogen plasma concentrations were restored to normal levels when 200 mg/kg body weight fibrinogen concentrate was administered. A significant decrease in sepsis-induced mortality was observed in animals treated with Haemocomplettan P.