Dose requirements for idarucizumab reversal of dabigatran in a lethal porcine trauma model with continuous bleeding

The Use of Large Animal Models in Trauma and Bleeding Studies

BACKGROUND

 Major trauma often results in significant bleeding and coagulopathy, posing a substantial clinical burden. To understand the underlying pathophysiology and to refine clinical strategies to overcome coagulopathy, preclinical large animal models are often used. This review scrutinizes the clinical relevance of large animal models in hemostasis research, emphasizing challenges in translating findings into clinical therapies.

METHODS

 We conducted a thorough search of PubMed and EMBASE databases from January 1, 2010, to December 31, 2022. We used specific keywords and inclusion/exclusion criteria centered on large animal models.

RESULTS

 Our review analyzed 84 pertinent articles, including four animal species: pigs, sheep, dogs, and nonhuman primates (NHPs). Eighty-five percent of the studies predominantly utilized porcine models. Meanwhile, sheep and dogs were less represented, making up only 2.5% of the total studies. Models with NHP were 10%. The most frequently used trauma models involved a combination of liver injury and femur fractures (eight studies), arterial hemorrhage (seven studies), and a combination of hemodilution and liver injury (seven studies). A wide array of coagulation parameters were employed to assess the efficacy of interventions in hemostasis and bleeding control.

CONCLUSIONS

 Recognizing the diverse strengths and weaknesses of large animal models is critical for trauma and hemorrhage research. Each model is unique and should be chosen based on how well it aligns with the specific scientific objectives of the study. By strategically considering each model's advantages and limitations, we can enhance our understanding of trauma and hemorrhage pathophysiology and further advance the development of effective treatments.

Elevated anti-human factor Xa activity in rabbit and rodent plasma: Implications for preclinical assessment of human factor X in animal models of hemostasis

A wide variety of animal models on thrombosis and hemostasis are used in thrombosis and hemostasis research for the preclinical assessment of hemostatic agents. While the vertebrate coagulome is highly conserved, human and animal plasmas differ considerably when evaluated in coagulation assays such as prothrombin time (PT), activated partial thromboplastin time (APTT), and calibrated automated thrombography (CAT). Here, we have aimed to provide a reference framework for the evaluation of coagulation assays and inhibition of activated human FXa (hFXa) in various animal plasmas. To do so, a side-by-side evaluation of the extrinsic and intrinsic pathway of coagulation was performed by means of PT, APTT, and CAT measurements on (diluted) pooled plasmas from goats, pigs, rabbits, rats, mice, and humans. Plasma anti-FXa activity was assessed by determining the rate of recombinant hFXa inhibition through chromogenic activity analyses and immunoblotting. In general, rabbit, rat, and mouse plasmas exhibited robust clotting upon stimulation of both the extrinsic and intrinsic pathway, produced more thrombin during CAT upon plasma dilution, and displayed relatively high hFXa inhibitory activities. By comparison, goat, porcine, and human plasma displayed a similar profile in PT and APTT assays, produced less thrombin during CAT upon plasma dilution, and displayed comparable hFXa inhibitory activities. In conclusion, the observed differences in clotting parameters and anti-hFXa activity point to a higher anticoagulant threshold in plasma from rabbits, rats, and particularly in mice relative to human, goat, and porcine plasma. Finally, rat plasma was found to be more relevant to the preclinical assessment of human FX(a) in comparison to murine plasma.

Evaluation of combined idarucizumab and prothrombin complex concentrate treatment for bleeding related to dabigatran in a lethal porcine model of double trauma

BACKGROUND

Idarucizumab (IDA) is approved for emergency reversal of dabigatran; prothrombin complex concentrates (PCCs) are recommended in the absence of specific antidote. The combined effects of IDA and PCC in trauma-related bleeding are unknown. The efficacy and safety of combined IDA + PCC were assessed in a lethal porcine model of double trauma under dabigatran anticoagulation.

STUDY DESIGN AND METHODS

Male pigs (n = 28) received oral dabigatran etexilate (30 mg/kg bid) for 3 days; a non-dabigatran control group (n = 7) received placebo. On Day 4, dabigatran-treated animals were randomized 1:1:1:1 to receive placebo + placebo (dabigatran-treated control), IDA + PCC (60 mg/kg + 50 IU/kg), PCC + IDA, or IDA + IDA. Trauma was induced at t = 0 (bilateral femur fractures and blunt liver injury) and t = 60 minutes (second blunt liver injury). Study treatment was administered 15 minutes after each trauma. Animals were monitored for 5 hours or until death.

RESULTS

Total blood loss in IDA + PCC, PCC + IDA, and IDA + IDA was 1673 ± 370, 1981 ± 361, and 1417 ± 135 mL, respectively, with 100% survival at 5 hours. Blood loss in dabigatran-treated controls was 4427 ± 162 mL with 100% mortality. With IDA + IDA, plasma coagulation parameters and thrombin generation were similar to non-dabigatran control group levels after the second dose and remained stable over time. In the IDA + PCC and PCC + IDA groups, thrombin generation and d-dimer levels after the second dose were higher than with IDA + IDA. No thromboembolic complications were found.

CONCLUSION

IDA and PCC are effective in treating trauma-related bleeding with dabigatran anticoagulation. IDA is preferable for emergency reversal of dabigatran, but PCC may be valuable when the anticoagulant is unknown.

Reversal of dabigatran by intraosseous or intravenous idarucizumab in a porcine polytrauma model

BACKGROUND

Idarucizumab is licensed to reverse dabigatran in life-threatening haemorrhage. Establishment of venous access can be challenging, and the intraosseous (IO) route is a potentially life-saving alternative. In this study, we compared the efficacy and safety of IO or intravenous (i.v.) idarucizumab for dabigatran reversal in a porcine polytrauma model.

METHODS

Male pigs (n=21) received oral dabigatran etexilate (30 mg kg^-1 bid) for 3 days. On the 4th day, animals received dabigatran infusion and were randomised 1:1:1 to receive IO saline (control), i.v. idarucizumab (60 mg kg^-1), or IO idarucizumab (60 mg kg^-1), or animals were included in a sham group (n=7). Study treatment was administered after polytrauma and the animals were monitored for 240 min, or until death. Coagulation status was monitored by thromboelastometry, thromboelastography, and thrombin measurements.

RESULTS

Total blood loss was lowest in sham animals [521 (52) ml, P<0.01 vs all other groups], and comparable in the two idarucizumab groups [IO: 1085 (102) ml vs i.v.: 1142 (125) ml], and highest in the control group [4065 (557) ml, P<0.001 vs all other groups]. Survival to 240 min was 100% in the sham group and both idarucizumab groups, and 14% in the control group. IO and i.v. idarucizumab promptly normalised global coagulation assays and thrombin generation. Thromboelastography showed a strong correlation between dabigatran concentrations and R-time (R²=0.90 and 0.89) in idarucizumab-treated animals.

CONCLUSIONS

Intravenous and intraosseous idarucizumab were comparable for reversing dabigatran in a porcine trauma model. Dabigatran reversal could be monitored using fully automated thromboelastography.

Direct oral anticoagulant reversal: how, when and issues faced

INTRODUCTION

The number of atrial fibrillation (AF) patients requiring thrombo-prophylaxis with oral anticoagulation is greatly increasing. The introduction of non-vitamin K oral anticoagulants (NOACs) in addition to standard therapy with dose-adjusted warfarin has increased the therapeutic options for AF patients. Despite a generally better safety profile of the NOACs, the risk of major bleedings still persists, and the management of serious bleeding is a clinical challenge. Areas covered: In the current review, risk of major bleeding in patients taking NOACs and general approaches to manage bleeding depending on severity, with a particular focus on specific reversal agents, are discussed. Expert commentary: Due to short half-life of NOACs compared to warfarin, discontinuation of drug, mechanical compression, and volume substitution are considered to be sufficient measures in most of bleeding cases. In case of life-threatening bleeding or urgent surgery, hemostasis can be achieved with non-specific reversal agents (prothrombin complex concentrates) in patients treated with factor Xa inhibitor until specific antidotes (andexanet α and ciraparantag) will receive approval. Thus far, idarucizumab has been the only reversal agent approved for dabigatran.