Prothrombin complex concentrate (Beriplex® P/N) for emergency anticoagulation reversal: a prospective multinational clinical trial

Summary.  Background:  Prothrombin complex concentrate (PCC) can substantially shorten the time needed to reverse antivitamin K oral anticoagulant therapy (OAT). Objectives.  To determine the effectiveness and safety of emergency OAT reversal by a balanced pasteurized nanofiltered PCC (Beriplex^® P/N) containing coagulation factors II, VII, IX, and X, and anticoagulant proteins C and S. Patients and methods:  Patients receiving OAT were eligible for this prospective multinational study if their International Normalized Ratio (INR) exceeded 2 and they required either an emergency surgical or urgent invasive diagnostic intervention or INR normalization due to acute bleeding. Stratified 25, 35, or 50 IU kg⁻¹ PCC doses were infused based on initial INR. Study endpoints included INR normalization (≤1.3) by 30 min after PCC infusion and hemostatic efficacy. Results:  Forty-three patients, 26 requiring interventional procedures and 17 experiencing acute bleeding, received PCC infusions at a median rate of 7.5 mL min⁻¹ (188 IU min⁻¹). At 30 min thereafter, INR declined to ≤1.3 in 93% of patients. At all postinfusion time points through 48 h, median INR remained between 1.2 and 1.3. Clinical hemostatic efficacy was classified as very good or satisfactory in 42 patients (98%). Prompt and sustained increases in circulating coagulation factors and anticoagulant proteins were observed. One fatal suspected pulmonary embolism in a patient with metastatic cancer was judged to be possibly PCC-related. Conclusions:  PCC treatment serves as an effective rapid hemorrhage control resource in the emergency anticoagulant reversal setting. More widespread availability of PCC is warranted to ensure its benefits in appropriate patients.     

Urgent reversal of warfarin with prothrombin complex concentrate

BACKGROUND: When life-threatening bleeding occurs in patients on warfarin, timely reversal becomes imperative. In the USA, warfarin effect is commonly reversed with fresh frozen plasma (FFP). The use of FFP is complicated by delays in correction, volume overload and often, inadequate correction. OBJECTIVE: Evaluate the feasibility and efficacy of a protocol for rapid administration of prothrombin complex concentrate (PCC) in the setting of the urgent need for reversal of warfarin. METHODS/PATIENTS: We instituted a policy for rapid delivery and administration of PCC. Appropriate patients received 25-50 U kg(-1) of PCC. The prothrombin time (PT)/International Normalized Ratios (INR) was recorded before and immediately after dosing, and 24 h postdosing. Patients requiring surgical interventions were cleared for the operating room (OR) immediately. Fifty-eight patients were treated, with a median age of 75.5 years (range 26-92). RESULTS: The median INR on presentation was 3.8 (1.4-52.8). Immediately following PCC administration the median INR was 1.3 (0.9-5.7), only two patients with INRs exceeding 2.0. The benefit was maintained at 24 h with a median INR of 1.5 (1.1-3.4). Four patients experienced thrombotic events during their hospitalization, (two deep vein thrombosis, two non-q-wave myocardial infarction) although none was attributed to PPC therapy. CONCLUSIONS: PCC administration is an effective treatment modality for the correction of warfarin anticoagulation in the urgent setting. Advantages over FFP include more timely correction, absence of volume overload and potentially more complete correction. Broader use of PCC in this setting appears to be appropriate.     

Recombinant human factor VIIa and a factor VIIa-analogue reduces heparin and low molecular weight heparin (LMWH)-induced bleeding in rats

Summary.  Background:  Heparin and low molecular weight heparin (LMWH) are widely used for prevention and treatment of thromboemobolic events, but may occasionally cause uncontrollable bleeding. Heparin can readily be antagonized with protamine, but this is less effective against LMWH. Objectives:  To test the effects of rFVIIa or an analogue of rFVIIa, NN1731, on heparin- and LMWH-induced bleeding in rats. Methods:  Initially the doses of heparin and tinzaparin (a LMWH) were determined by dose-titration. Following pretreatment with heparin or tinzaparin in rats, tail-transection was performed, and the effect of rFVIIa and NN1731 on the bleeding was observed. Results:  rFVIIa (5, 10 and 20 mg kg⁻¹) reduced bleeding time and blood loss caused by heparin- and tinzaparin-induced bleeding, using doses of 200 IU kg⁻¹ ( n  = 8) and 500 IU kg⁻¹ ( n  = 9), respectively. Similarly, 10 mg kg⁻¹ NN1731 significantly reduced both heparin- and tinzaparin-induced bleeding to the normal level. Following severe anticoagulation with 1800 IU kg⁻¹ tinzaparin, 10 mg kg⁻¹ NN1731 reduced and normalized the bleeding, while the effect of 20 mg kg⁻¹ rFVIIa failed to reach statistical significance. These data are consistent with the hypothesis that rFVIIa/NN1731 are capable of generating sufficient thrombin locally on the surface of activated platelets to induce hemostasis in the presence of heparin/LMWH. Conclusions:  This study suggests that rFVIIa and NN1731 may have the potential to control bleedings caused by heparin or LMWH.     

Comparison of the capacities of two prothrombin complex concentrates to restore thrombin generation in plasma from orally anticoagulated patients: an in vitro study

Summary. Background: Human prothrombin complex concentrates (PCCs) are used for prevention and treatment of bleeding episodes in patients under warfarin therapy. PCCs contain human factor (F) II, FVII, FIX, FX, protein C and protein S. The concentrations of these coagulation factors contained in PCCs are variable and do not reflect entirely the capacity of these drugs to correct hemostasis. Furthermore, commercially available PCCs do not have exactly the same composition, though they are all labelled and prescribed in units per kg of FIX (10–40 IU of FIX/kg). As the final product generated by PCCs is thrombin, a thrombin generation (TG) test could theoretically be used for monitoring the hemostatic correction. Methods: TG was measured in platelet free plasma in the presence of tissue factor 5 pm and phospholipids 4 μm with a final concentration of PCC of 0–0.1–0.2–0.3–0.4–0.5–0.75–1 IU ml^?1. The activity of vitamin K‐dependent coagulation factors (i.e. FII, FVII, FIX, FX, protein C and protein S) were determined for each concentration of two different PCCs available on the French market. Results and Discussion: Our results showed that the addition of two different PCCs dose‐dependently increased the TG capacity in patients with INR of 2–2.5–3–4 and >7 (n = 15 subjects) that reached the normal values. We also found a significant correlation between endogenous thrombin potential (ETP) and INR (Pearson test, P < 0.0001). The two PCCs improved the TG parameters differently with increasing concentrations. The difference in the correction of TG capacity observed between the two drugs could be explained by a variable increase in FX, FVII and protein C with similar doses. These results strongly suggest that TG assay could be used for monitoring the clinical efficacy of PCC and for optimizing the therapeutic regimen towards a more individualized therapy involving the type of the bleeding complications, the level of inhibition of the coagulation system and the molecule content of the PCC.     

Suboptimal effect of a three-factor prothrombin complex concentrate (Profilnine-SD) in correcting supratherapeutic international normalized ratio due to warfarin overdose

BACKGROUND: Plasma transfusion is standard therapy for urgent warfarin reversal in the United States. "Four-factor" prothrombin complex concentrate (PCC), available in Europe, has advantages over plasma therapy for warfarin reversal; however, only "three-factor" PCCs (containing relatively low Factor [F]VII) are available in the United States.
STUDY DESIGN AND METHODS: The efficacy of a three-factor PCC for urgent warfarin reversal was evaluated in 40 patients presenting with supratherapeutic international normalized ratio (ST-INR > 5.0) with bleeding (n = 29) or at high risk for bleeding (n = 11). In 13 patients, pre- and posttherapy vitamin K-dependent factors were assayed. Historical controls (n = 42) treated with plasma alone were used for rate of ST-INR correction comparison.
RESULTS: Treatment with plasma alone (mean, 3.6 units) lowered the INR to less than 3.0 in 63 percent of historical controls. Low-dose (25 U/kg) and high-dose (50 U/kg) PCC alone lowered INR to less than 3.0 in 50 and 43 percent of patients, respectively. Additional transfusion of a small amount of plasma (mean, 2.1 units) increased the rate of achieving an INR of less than 3.0 to 89 and 88 percent for low- and high-dose PCC therapy, respectively. FII, F IX, and FX increments were similar for PCC-treated patients with or without supplemental plasma; FVII was significantly higher in the PCC plus plasma group compared to the PCC-only group (p = 0.001).
CONCLUSION: Three-factor PCC does not satisfactorily lower ST-INR due to low FVII content. Infusion of a small amount of plasma increases the likelihood of satisfactory INR lowering.     

Biochemical comparison of seven commercially available prothrombin complex concentrates

Aims: A number of prothrombin complex concentrates (PCCs) are commercially available but they differ in terms of composition. We performed a series of studies to compare the biochemical properties of seven PCCs. Methods: The following products were investigated: Beriplex P/N, Octaplex, S‐TIM 4, PPSB Solvent Detergent, Uman Complex DI, Kaskadil and Cofact. Assays were performed to investigate levels of coagulation factors and their inhibitors, activated coagulation factors and heparin. The thrombin inhibitory capacity of each PCC was determined. Protein content was assessed using the Lowry method and sodium dodecyl sulphate–polyacrylamide gel electrophoresis. Results: The data indicated little difference between most of the products in their levels of factors II, VII, IX and X, with the exception of Uman Complex which had no detectable factor VII. In all cases, the measured levels of coagulation factors were broadly similar to those labelled. Beriplex P/N showed the greatest capacity for thrombin inhibition, a reflection of the observed high levels of the coagulation inhibitors protein C, protein S, protein Z, and small amounts of antithrombin III and heparin in this product. All of the PCCs tested were negative for activated coagulation factors. Purity (i.e. therapeutic protein as a percentage of total protein) was highest in Beriplex P/N, and the second purest product was Uman Complex. Conclusion: This in vitro study showed considerable differences between PCCs in terms of coagulation inhibitory capacity and purity.     

Prothrombin complex concentrates reduce blood loss in murine coagulopathy induced by warfarin,but not in that induced by dabigatran etexilate

Summary. Background: Both established oral anticoagulants such as warfarin and newer agents such as dabigatran etexilate (DE) effectively prevent thromboembolic disease, but may provoke bleeding. Limited clinical data exist linking oral anticoagulant reversal and bleeding tendency, as opposed to surrogate laboratory markers. Objective: To quantify bleeding in warfarin‐anticoagulated and DE‐anticoagulated mice by tail transection with or without pretreatment with potential reversal agents: prothrombin complex concentrate (PCC); activated PCC (APCC); recombinant factor VIIa (rFVIIa); or murine fresh‐frozen plasma (FFP). Methods: CD1 mice were given warfarin or DE by gavage, and the effects on in vitro coagulation assays, volume of blood loss and the bleeding time following tail transection injury were evaluated with different reversal agents. Results: PCC (14.3 IU kg^?1), but not rFVIIa (3 mg kg^?1) or FFP (12 mL kg^?1), normalized blood loss and bleeding time in mice with warfarin‐induced elevations of mean prothrombin time at two intensities (prothrombin time ratios of either 4.3 or 24). Neither separate nor combined PCC and/or rFVIIa treatment nor APCC (100 U kg^?1) treatment significantly reduced blood loss in mice anticoagulated with 60 mg kg^?1 DE 75 min prior to tail transection. Both combined PCC plus rFVIIa treatment and APCC treatment significantly reduced bleeding time in the DE‐treated mice. Conclusions: Our data suggest that PCC treatment prevents excess bleeding much more effectively in warfarin‐induced coagulopathy than in DE‐induced coagulopathy.     

Using prothrombin complex concentrates to rapidly reverse oral anticoagulant effects

Warfarin is a commonly prescribed anticoagulant that may, in selected situations, require rapid reversal of its effects. Several approaches to achieve reversal have been explored, including the administration of prothrombin complex concentrates (PCCs), Many factors can influence determination of an appropriate PCC dose and the resulting effects. Considerations on the use of PCC products to expedite the reversal of warfarin are described.     

Modified version of the American College of Cardiology's recommendation for low-dose prothrombin complex concentrate is effective for warfarin reversal

BackgroundDosing of four factor prothrombin complex concentrate (4PCC) for warfarin reversal remains controversial. Recently, the American College of Cardiology (ACC) recommended a low-dose PCC regimen as an option for warfarin reversal in acute major bleeding. We performed a retrospective study evaluating if a modified version of the ACC guideline recommendations was effective for warfarin reversal in acute major bleeds when compared to traditional variable dosing.MethodsThis was a retrospective cohort study of patients who received 4PCC for warfarin reversal in a 12 month period. We included patients that were ≥18 years of age, received 4PCC for warfarin reversal, and had an initial International Normalized Ratio (INR) of >2. Our primary outcome was the number of patients who had a post-4PCC infusion INR of <1.6.ResultsA total of 60 patients were included in the final analysis with 30 patients stratified to the traditional dosing and low-dose groups, respectively. Patient demographics were similar between both groups. We found no difference in the number of patients who had a post-4PCC infusion INR <1.6 between the traditional dosing and low dosing group (90.0% vs. 86.7%; p = 0.68). Additionally, we found no difference between post-infusion median INRs in each group (1.35 vs. 1.30; p = 0.16). Approximately 1000 units per patient were spared when utilizing the low-dose regimen.ConclusionA modified version of the ACC's low-dose 4PCC option for warfarin reversal achieves similar outcomes for lowering INR values compared to traditional variable dosing regimens.     

Retrospective evaluation of a method to predict fresh-frozen plasma dosage in anticoagulated patients

In the United States, fresh-frozen plasma (FFP) is commonly used for urgent reversal of warfarin; however, dosage recommendations are difficult to find. If validated, a proposed method that uses a nonlinear relationship between international normalized ratio (INR) and clotting factor activity (CFa) would be useful. This study retrospectively evaluated a proposed equation with adult medical inpatients who received FFP for warfarin reversal. For each patient the equation was used to predict the dose of FFP required to achieve the observed change in INR, which was then compared to the actual dose. The equation was considered successful if the predicted dose was within +/-20% of the actual dose. Subgroup analyses included subjects who received concomitant vitamin K; subjects with supratherapeutic INRs (>3); and subjects with significantly elevated INRs (>5). Of the 209 patients screened, 91 met criteria for inclusion in the study. Use of the equation to calculate the predicted dose of FFP was successful in 11 patients (12.1%) with use of actual body weight for prediction and in 23 patients (25.3%) with use of ideal body weight (P = 0.02). The equation performed similarly in all subgroups analyzed. The mean predicted FFP dose was significantly greater than the actual dose in all patients when actual body weight was used (925.2 mL vs. 620.6 mL; P < 0.001). Least-squares regression modeling of repeat INR (converted to CFa) produced a model that accounted for 57% of the variance in repeat INR. The value predicted from the model was closer to the actual CFa than was the value predicted from the published equation in every comparison, but it was statistically different only when actual body weight was used. This study revealed that a published equation for calculation of FFP dose to reverse oral anticoagulation resulted in doses that were significantly higher than the actual dose. Use of ideal body weight improved accuracy but was still not successful for the majority of patients. Until trials are able to prospectively demonstrate the accuracy of a dose-prediction model for FFP, dosing will remain largely empiric.     

Enhanced thrombin generation in patients with cirrhosis‐induced coagulopathy

Summary. Background: Prothrombin time (PT) and the international normalized ratio (INR) are still routinely measured in patients with liver cirrhosis to ‘assess’ their bleeding risk despite the lack of correlation with the two. Thrombin generation (TG) assays are global assays of coagulation that are showing promise in assessing bleeding and thrombosis risks. Aim: To study the relationship between the INR and TG profiles in cirrhosis‐induced coagulopathy. Methods: Seventy‐three patients with cirrhosis were studied. All TG parameters were compared with those from a normal control group. Contact activation was prevented using corn trypsin inhibitor. TG was also assayed in the presence of Protac^®. The endogenous thrombin potential (ETP) ratio was derived by dividing the ETP with Protac® by the ETP without Protac®. Results: The INR (mean 1.7) did not correlate with the ETP and the velocity of TG (P > 0.05). There was no difference between the lag time and ETP of the two groups (P > 0.05). The velocity of TG was increased in cirrhosis (67.95 ± 34.8 vs. 45.05 ± 25.9 nM min^?1; P = 0.016) especially in patients with INRs between 1.21 and 2.0. Both the ETP with Protac^® and the ETP ratio were increased in cirrhosis (mean 1074 ± 461.4 vs. 818 ± 357.9 nM min, P = 0.004 and 0.80 ± 0.21 vs. 0.44 ± 0.15, P ≤ 0.0001, respectively). Conclusion: Despite a raised INR, TG parameters are consistent with a hypercoagulable profile in cirrhosis‐related coagulopathy. This confirms that the PT or INR should not be used to assess bleeding risk in these patients, and other parameters, such as TG, need to be explored as clinical markers of coagulopathy.     

rFVIIa and a new enhanced rFVIIa-analogue, NN1731, reduce bleeding in clopidogrel-treated and in thrombocytopenic rats

Summary.  Background: The pharmacological effect of rFVIIa occurs at the surface of activated platelets by enhancing thrombin generation at the site of vascular damage. It is therefore important to study the effects of rFVIIa in platelet-related bleeding situations. We examined the effect of rFVIIa and an rFVIIa-analogue, NN1731, on clopidogrel-induced and thrombocytopenic bleeding in rats. Methods and results: Clopidogrel [10 mg kg⁻¹; per oral (p.o.)] severely inhibited platelet aggregation and increased blood loss after tail-transection four hours after administration. Treatment with rFVIIa (5, 10, 20 mg kg⁻¹) or NN1731 (1, 5, 10 mg  kg⁻¹), administered five minutes after induction of bleeding, reduced blood loss significantly and dose-dependently. NN1731 had an increased hemostatic potential compared with rFVIIa, reducing blood loss to the control level, whereas this was not even achieved with the highest dose of rFVIIa. Antibody-induced thrombocytopenia reduced platelet numbers by more than 90% and increased the blood loss after tail-transection. Treatment with 10 and 20 mg kg⁻¹ rFVIIa significantly reduced blood loss, whereas 10 mg kg⁻¹ NN1731 reduced the bleeding to control levels. Conclusions: The hemostatic effect of rFVIIa and NN1731 was demonstrated in thrombocytopenic and clopidogrel-treated rats, showing efficacy in situations with decreased platelet number or functionality. Our findings are consistent with the hypothesis that rFVIIa/NN1731 contribute to hemostasis by thrombin generation even in situations with platelet disorders. Furthermore, NN1731 demonstrated a higher hemostatic potential than rFVIIa.     

Activated prothrombin complex concentrate factor VIII inhibitor bypassing activity (FEIBA) for the reversal of warfarin-induced coagulopathy

Aims

The purpose of this study was to evaluate the effectiveness of a new, fixed, yet individualized dosing regimen of activated prothrombin complex concentrate factor VIII inhibitor bypassing activity (FEIBA) for warfarin reversal in the setting of a life-threatening bleeding in a secondary care center.

Methods

In this report we present a retrospective chart review of 72 patients who received FEIBA and 69 patients who received fresh-frozen plasma (FFP) to reverse the effects of warfarin in a setting of a life-threatening bleeding. In the FEIBA cohort, patients received 500 units of FEIBA when the initial INR was <5 or 1,000 units of FEIBA when initial INR was ≥5.

Results

FEIBA administration resulted in lower subsequent INR when compared with FFP and shorter time elapsed from drug administration to an INR ≤1.4 when compared with FFP. No significant differences in survival or in the length of hospital stay were observed. A higher FEIBA dose induced a bigger decrease in INR than the lower dose. We observed five adverse events (7%) that could potentially be related to FEIBA administration.

Conclusions

The presented dosing regimen results in safe reversal of warfarin-induced coagulopathy, which appears to be faster and more profound than following FFP. Moreover, the use of activated PCC (FEIBA) does not appear to carry an increased risk of thrombotic events when compared to the rate reported for several non-activated PCC preparations.     

Fixed-dose prothrombin complex concentrate for emergent warfarin reversal among patients with intracranial hemorrhage

IntroductionFour-factor prothrombin complex concentrate (4PCC) is the preferred reversal agent for warfarin reversal, although the ideal dose is unknown. Fixed-dose 4PCC offers simplified dosing compared to standard-dosing algorithms with potentially lower risks of thromboembolic complications given lower doses are typically utilized.MethodsRetrospective, observational, multicentered, pre- post- study of patients who received 4PCC for warfarin reversal among four hospitals within the same regional health system. Standard-dose patients received variable doses ranging from 25 to 50 units/kg based on total body weight and initial INR and fixed-dose patients received 2000 units. The primary outcome was achievement of a target INR ≤ 1.4 on the first post-4PCC INR result.ResultsAfter exclusions, 48 and 42 patients were analyzed in the standard-dose and fixed-dose groups, respectively. There was no difference in the ability to achieve a target INR of ≤1.4 (82.6% vs 81.5%, p = 0.14). Both groups received the same median dose of 2000 units, although fixed-dose patients actually received a higher weight-based dose than standard-dose patients (27 units/kg vs 24.5 units/kg).ConclusionA fixed-dose 4PCC regimen of 2000 units among patients with ICH was as effective as standard-dose 4PCC for INR reversal among patients with ICH. However, fixed-doses of 2000 units at times exceeded standard 4PCC doses which may be contradictory to the goals of fixed-dose 4PCC for warfarin reversal.     

Use and effectiveness of prothrombin complex concentrates vs fresh frozen plasma in gastrointestinal hemorrhage due to warfarin usage in the ED

Objectives

High International Normalized Ratio (INR) level resulting from warfarin use increases the risk of gastrointestinal hemorrhages. We aimed to compare the efficacy of prothrombin complex concentrates (PCC) and fresh frozen plasma (FFP) at lowering the INR level, decreasing active hemorrhages visible by endoscopy, and shortening the length of stay at the emergency department (ED).

Method

This study is a prospective cohort study of consecutive patents with gastrointestinal hemorrhages that received either PCC or FFP. With strict exclusion criteria, only patients over 18 years of age with a high INR level (> 2.1) due to warfarin usage were included.

Results

A total of 40 patients (18 female) were included in the study, 20 each in the PCC and FFP groups. For the PCC group, the mean INR levels at the second and sixth hours were lower than those for the FFP group (second hour INR: 1.53 vs 4.50, P < .01, sixth hour INR: 1.52 vs 2.41, P < .01). Seven patients experienced active bleeding (Forrest 1) in the FFP group, whereas no patient experienced active bleeding in the PCC group based on the Forrest classification (35% vs 0%, P < .01), and only 3 patients in the FFP group underwent invasive/surgical treatment (15% vs 0%, P < .01). The ED length of stay was lower for the PCC group (1.62 days vs 3.46 days, P < .01).

Conclusion

For patients experiencing a gastrointestinal hemorrhage, INR levels were reversed more quickly, there was less active bleeding on endoscopy, and the ED length of stay was lower in the PCC group than in the FFP group.     

Prothrombin complex concentrate (Beriplex P/N) in severe bleeding: experience in a large tertiary hospital

Introduction

Major blood loss can often be life-threatening and is most commonly encountered in the settings of surgery and trauma. Patients receiving anticoagulant therapy are also at increased risk of bleeding. We investigated the use of a prothrombin complex concentrate (PCC; Beriplex P/N, CSL Behring, Marburg, Germany) to treat severe bleeding in a variety of settings: cardiac surgery, warfarin therapy and other surgery.

Methods

Thirty consecutive patients who had received PCC were identified from blood transfusion records. For cardiac surgery and warfarin reversal, PCC was administered in accordance with hospital protocols. PCC was administered to cardiac and other surgical patients responding poorly to recognized blood products, whereas it was administered first-line to patients with life-threatening bleeds and requiring warfarin reversal, in accordance with British Committee for Standards in Haematology guidelines. We conducted a retrospective analysis of patient records in order to ascertain PCC dose, use of other blood products and response to PCC (clotting screen results before and after PCC administration, haemostasis achievement, and survival).

Results

Six patients (20%) were excluded because of inadequate documentation (n = 5) or acquired haemophilia (n = 1). Therefore, 24 patients were included in the analysis: coronary artery bypass graft (n = 5), mitral/aortic valve replacement (n = 2), other surgery (n = 9) and warfarin reversal (n = 8). Most patients (83.3%) received no more than 1500 IU of Beriplex P/N 500. Considerable reduction in administration of other blood products was seen during the 24 hours after PCC administration. Partial or complete haemostasis was achieved in 14 out of 18 cases (77.8%). In total, 12 out of 24 patients (50%) died during the study; two-thirds of the deaths were considered unrelated to bleeding. No thrombotic complications or adverse drug reactions were observed.

Conclusion

This study emphasizes the value of PCC in reversing the effects of oral anticoagulant therapy in bleeding patients. It also demonstrates the potential value of PCC in controlling bleeding in patients undergoing cardiac and other surgical procedures. The use of PCC in bleeding patients without hereditary or anticoagulation-related coagulopathy is novel, and further investigation is warranted. In the future, it may be possible to use PCC as a substitute for fresh frozen plasma in this setting; adequate documentation is crucial for all blood products.     

Reversal of dabigatran anticoagulation by prothrombin complex concentrate (Beriplex P/N) in a rabbit model

Summary. Background: One limitation of the direct thrombin inhibitor dabigatran is the lack of specific antidotes that allow acute bleeding events to be managed or urgent interventional procedures performed. Prothrombin complex concentrates (PCCs) have served as a standard treatment for the reversal of coumarin anticoagulation. Objectives: This study was designed to determine in an animal model whether a PCC (Beriplex P/N) can effectively reverse the effects of dabigatran. An additional objective was to evaluate markers of dabigatran‐associated bleeding diathesis. Methods: Anesthetized rabbits were treated with 0.4 mg kg^?1 dabigatran followed by PCC doses of 20, 35 or 50 IU kg^?1 or placebo. After a standardized kidney incision, volume of blood loss and time to hemostasis were determined. Results: From an initial mean of 29 mL, blood loss progressively declined by 5.44 mL with a 95% confidence interval (CI) of 2.21–8.67 mL per 10 IU kg^?1 increment in PCC dose (P = 0.002). At a PCC dose of 50 IU kg^?1 blood loss was fully normalized. Increasing PCC doses shortened the median time to hemostasis from 20.0 to 5.7 min (P < 0.001). The rate of hemostasis was nearly trebled with each 10 IU kg^?1 increment in PCC dose (rate ratio, 2.89; CI, 1.64–5.09). Conclusions: In this animal study, PCC showed potential as an agent for reversing the effects of dabigatran. Further investigation is warranted.     

Prothrombin complex concentrates and a specific antidote to dabigatran are effective ex-vivo in reversing the effects of dabigatran in an anticoagulation/liver trauma experimental model

Introduction

New oral anticoagulants are effective alternatives to warfarin. However, no specific reversal agents are available for life-threatening bleeding or emergency surgery. Using a porcine model of trauma, this study assessed the ability of prothrombin complex concentrate (PCC), activated PCC (aPCC), recombinant FVIIa (rFVIIa) and a specific antidote to dabigatran (aDabi-Fab) to reverse the anticoagulant effects of dabigatran.

Methods

Dabigatran etexilate (DE) was given orally for 3 days (30 mg/kg bid) and intravenously on day 4 to achieve consistent, supratherapeutic concentrations of dabigatran. Blood samples were collected at baseline, after oral DE, after intravenous dabigatran, and 60 minutes post-injury. PCC (30 and 60 U/kg), aPCC (30 and 60 U/kg), rFVIIa (90 and 180 μg/kg) and antidote (60 and 120 mg/kg) were added to blood samples ex-vivo. Coagulation was assessed by thromboelastometry, global coagulation assays and diluted thrombin time.

Results

Plasma concentrations of dabigatran were 380 ± 106 ng/ml and 1423 ± 432 ng/ml after oral and intravenous administration, respectively, and all coagulation parameters were affected by dabigatran. Both PCCs and aDabi-Fab, but not rFVIIa, reversed the effects of dabigatran on thromboelastometry parameters and prothrombin time. In contrast, aPTT was only normalised by aDabi-Fab. Plasma concentration (activity) of dabigatran remained elevated after PCC and rFVIIa therapy, but was not measureable after aDabi-Fab.

Conclusion

In conclusion, PCC and aPCC were effective in reducing the anticoagulant effects of dabigatran under different conditions, while aDabi-Fab fully corrected all coagulation measures and decreased the plasma concentration of dabigatran below the limit of detection. No significant effects were observed with rFVIIa.     

Multi-centered evaluation of a novel fixed-dose four-factor prothrombin complex concentrate protocol for warfarin reversal

IntroductionPrevious studies have shown fixed-dose 4PCC to be as effective as standard-dose 4PCC for warfarin reversal. However, certain patient populations such as those with high total body weight (TBW) or elevated baseline INR may be at increased risk for treatment failure. The purpose of this study was to validate the efficacy of a novel fixed-dose 4PCC protocol for warfarin reversal.MethodsThis was a multi-centered observational comparison of patients who received 4PCC for warfarin reversal. Fixed-dose patients received 1500 units of 4PCC with the dose increased to 2000 units in patients with a baseline INR ≥ 7.5, a TBW ≥ 100 kg, or for intracranial hemorrhage (ICH). Standard-dosing followed manufacturer recommendations. The primary outcome was achievement of a post-4PCC INR of ≤1.4. Secondary outcomes included target INR achievement among patients with a baseline INR ≥ 7.5, a TBW ≥ 100 kg, or neurologic bleeding indications; hospital length of stay; cost of therapy; and thromboembolic complications.ResultsA total of 116 patients were included in the standard-dose group and 75 in the fixed-dose group. There was no difference in the primary outcome (65% vs 57%, p = 0.32). There was no difference in secondary outcomes aside from cost of therapy in which fixed-dose 4PCC was less expensive than standard-dose 4PCC.ConclusionA fixed-dose 4PCC regimen for warfarin reversal of 1500 units, with an increased dose of 2000 units for select patients, is as effective as standard-dose 4PCC for INR reversal.     

Fresh Frozen Plasma Dosing for Warfarin Reversal: A Practical Formula

ObjectiveTo provide a practical formula for fresh frozen plasma (FFP) dosing for warfarin reversal.Patients and MethodsWe reviewed data on all adult patients who received a total of 7778 units of FFP for warfarin reversal at Sentara Norfolk General Hospital (Norfolk, VA) between April 1, 2009, and March 31, 2010. Patients with advanced liver disease, consumptive or dilutional coagulopathy, and administration of activated factor VII or prothrombin complex concentrate were excluded. First, we used regression analysis on the FFP1 subset (patients whose international normalized ratio [INR] was checked before and after 1 FFP administration) and derived a simple formula: DeltaINR (PreINR – PostINR) after 1 FFP = a × PreINR + b, where PreINR and PostINR are the INR values before and after FFP administration, respectively, and a and b are constants. In the validation step, the formula obtained for the FFP1 subset was repeatedly applied to the FFP2 (patients who received 2 units of FFP back-to-back without an intervening INR check), FFP3, and FFP4 subsets.ResultsA total of 956 patients were included. The formula DeltaINR after 1 FFP = 0.57 × PreINR – 0.72 explained 82.6% of the total variance in INR change in the FFP1 subset (n=308; P<.01). Including age, sex, weight, FFP-to-PostINR interval, or administration of vitamin K marginally improved the model. Repeated application of the FFP1 formula to the FFP2 to 4 subsets combined confirmed the accuracy of the FFP1 formula across the entire data set (n=643; R²=95% between predicted and actual DeltaINR; P<.01).ConclusionThis formula provides a practical and accurate method for FFP dosing for warfarin reversal.