Intramuscular administration of tranexamic acid in a large swine model of hemorrhage with hyperfibrinolysis

BACKGROUND

Traumatic injury with subsequent hemorrhage is one of the leading causes of mortality among military personnel and civilians alike. Posttraumatic hemorrhage accounts for 40% to 50% of deaths in severe trauma patients occurring secondary to direct vessel injury or the development of trauma-induced coagulopathy (TIC). Hyperfibrinolysis plays a major role in TIC and its presence increases a patient's risk of mortality. Early therapeutic intervention with intravenous (IV) tranexamic acid (TXA) prevents development of hyperfibrinolysis and subsequent TIC leading to decreased mortality. However, obtaining IV access in an austere environment can be challenging. In this study, we evaluated the efficacy of intramuscular (IM) versus IV TXA at preventing hyperfibrinolysis in a hemorrhaged swine.

METHODS

Yorkshire cross swine were randomized on the day of study to receive IM or IV TXA or no treatment. Swine were sedated, intubated, and determined to be hemodynamically stable before experimentation. Controlled hemorrhaged was induced by the removal of 30% total blood volume. After hemorrhage, swine were treated with 1,000 mg of IM or IV TXA. Control animals received no treatment. Thirty minutes post-TXA treatment, fibrinolysis was induced with a 50-mg bolus of tissue plasminogen activator. Blood samples were collected to evaluate blood TXA concentrations, blood gases, blood chemistry, and fibrinolysis.

RESULTS

Blood TXA concentrations were significantly different between administration routes at the early time points but were equivalent by 20 minutes after injection, remaining consistently elevated for up to 3 hours postadministration. Induction of fibrinolysis resulted in 87.18 ± 4.63% lysis in control animals, compared with swine treated with IM TXA, 1.96 ± 2.66% and 1.5 ± 0.42% lysis in the IV TXA group.

CONCLUSION

In the large swine model of hemorrhage with hyperfibrinolysis, IM TXA is bioequivalent and equally efficacious in preventing hyperfibrinolysis as IV TXA administration.

Synergism of red blood cells and tranexamic acid in the inhibition of fibrinolysis

BACKGROUND

Postpartum hemorrhage (PPH) is the leading cause of maternal death worldwide. The World Maternal Antifibrinolytic trial showed that antifibrinolytic tranexamic acid (TXA) reduces PPH deaths. Maternal anemia increases the risk of PPH. The World Maternal Antifibrinolytic-2 trial is now assessing whether TXA can prevent PPH in women with anemia. Low red blood cell (RBC) counts promote fibrinolysis by altering fibrin structure and plasminogen activation.

OBJECTIVES

We explored interactions between RBCs and TXA in inhibiting fibrinolysis.

METHODS

We used global fibrinolytic assays (ball sedimentation and viscoelasticity) to monitor the lysis of fibrin containing plasminogen and tissue-type plasminogen activator. We applied a fluorogenic kinetic assay to measure plasmin generation in fibrin clots and scanning electron microscopy to study fibrin structure.

RESULTS

According to parallel-line bioassay analysis of the fibrin lysis-time data, the antifibrinolytic potency of 4-128 μM TXA was increased in the presence of 10% to 40% (v/v) RBCs. Global fibrinolysis assays showed that the joint effect of RBCs and TXA was about 15% larger than the sum of their individual effects in the inhibition of fibrinolysis. In plasminogen activation, TXA added the same increment of inhibition to the effect of RBCs at any cell count in the fibrin clot. Regarding fibrin structure, TXA thickened fibrin fibers, which impaired plasminogen activation, whereas RBCs promoted fine fibers that were more resistant to plasmin.

CONCLUSIONS

The antifibrinolytic potency of TXA is enhanced in fibrin formed in the presence of RBCs through inhibition of plasminogen activation and fibrin lysis, which correlates with modifications of fibrin structures.

Tranexamic Acid Attenuates the Progression of Posttraumatic Osteoarthritis in Mice

BACKGROUND

Posttraumatic osteoarthritis (OA) is a common disorder associated with a high socioeconomic burden, particularly in young, physically active, and working patients. Tranexamic acid (TXA) is commonly used in orthopaedic trauma surgery as an antifibrinolytic agent to control excessive bleeding. Previous studies have reported that TXA modulates inflammation and bone cell function, both of which are dysregulated during posttraumatic OA disease progression.

PURPOSE

To evaluate the therapeutic effects of systemic and topical TXA treatment on the progression of posttraumatic OA in the knee of mice.

STUDY DESIGN

Controlled laboratory study.

METHODS

OA was induced via anterior cruciate ligament (ACL) transection on the right knee of female mice. Mice were treated with TXA or vehicle intraperitoneally daily or intra-articularly weekly for 4 weeks, starting on the day of surgery. Articular cartilage degeneration, synovitis, bone erosion, and osteophyte formation were scored histologically. Micro-computed tomography evaluation was conducted to measure the subchondral bone microstructure and osteophyte volume. Cartilage thickness and bone remodeling were assessed histomorphometrically.

RESULTS

Both systemic and topical TXA treatment significantly reduced cartilage degeneration, synovitis, and bone erosion scores and increased the ratio of hyaline to calcified cartilage thickness in posttraumatic OA. Systemic TXA reversed ACL transection-induced subchondral bone loss and osteophyte formation, whereas topical treatment had no effect. Systemic TXA decreased the number and surface area of osteoclasts, whereas those of osteoblasts were not affected. No effect of topical TXA on osteoblast or osteoclast parameters was observed.

CONCLUSION

Both systemic and topical TXA exerted protective effects on the progression of posttraumatic OA. Drug repurposing of TXA may, therefore, be useful for the prevention or treatment of posttraumatic OA, particularly after ACL surgery.

CLINICAL RELEVANCE

TXA might be beneficial in patients with posttraumatic OA of the knee.

Hemostatic Tranexamic Acid-Induced Fast Gelation and Mechanical Reinforcement of Polydimethylacrylamide/Carboxymethyl Chitosan Hydrogel for Hemostasis and Wound Healing

The combinational properties with excellent mechanical properties, adhesive performance, hemostatic ability, antibacterial action, and wound healing efficacy are highly desirable for injectable hydrogels' practical applications in hemorrhage control and wound closure, but designing one single hydrogel system integrating with such properties is still difficult. Herein, a simplified yet straightforward strategy is proposed to prepare an injectable and robust poly(N,N-dimethylacrylamide) (PDMAA)/carboxymethyl chitosan (CMCS) hydrogel induced by tranexamic acid (TXA). TXA not only promotes the rapid generation of free radicals but also introduces multiple hydrogen bonds into the hydrogel network. Moreover, as a common clinical hemostatic drug, TXA itself has excellent hemostatic effects. In addition, CMCS imparts sterilization and hemostasis effects to the hydrogel, thereby promoting wound healing. Besides, the amino and carboxyl groups on TXA molecules and the hydroxyl, amino, and carboxyl groups on CMCS molecules can form multiple hydrogen bonds with wet biological tissues, leading to good wet tissue adhesion of the hydrogel. As a result, the hydrogel with excellent mechanical properties (up to 1.83 MPa at 90% compression strain), adhesion performance (up to 18.7 kPa adhesion strength to porcine skin tissue), biocompatibility, hemostatic ability, antibacterial activity, and wound healing properties can be fabricated within several minutes. These combinational advantages enable the hydrogel to efficiently stop hemorrhage (blood loss amount: 110 mg; hemostasis time: 25 s) and promote the wound healing process (wound closure rate at 2 weeks: 83%), which can be verified using rat models of liver bleeding and infected full thickness skin defect. Overall, this facile strategy to design a hydrogel incorporating such unique advantages will greatly advance the hydrogel's clinical application in rapid hemostasis and wound healing.

Concentration-effect relationship for tranexamic acid inhibition of tissue plasminogen activator-induced fibrinolysis in vitro using the viscoelastic ClotPro® TPA-test

BACKGROUND

Tranexamic acid is an antifibrinolytic drug that is commonly administered for obstetric haemorrhage. Conventional viscoelastic tests are not sensitive to tranexamic acid, but the novel ClotPro® TPA-test can measure tranexamic acid-induced inhibition of fibrinolysis. We aimed to evaluate the TPA-test in pregnant and non-pregnant women.

METHODS

We performed an in vitro study of whole blood samples spiked with tranexamic acid from pregnant women in the first, second, and third trimester (n=20 per group) and from non-pregnant women (n=20). We performed ClotPro TPA-tests of whole blood sample and ClotPro EX-tests, FIB-tests, and TPA-tests.

RESULTS

Clot lysis was inhibited in a concentration-dependent manner up to a tranexamic acid concentration of 6.25 mg L-1. At tranexamic acid concentrations of 12.5 mg L-1 and above, clot lysis was completely inhibited. The concentration-effect relationship of tranexamic acid did not differ in a clinically important manner in blood from pregnant women across all three trimesters or from non-pregnant controls. A median maximum lysis cut-off value of at9 least 16% (25-75th percentiles 15-18), a median clot lysis time of 3600 s (25-75th percentiles 3600-3600), or both was associated with a tranexamic acid concentration of least 12.5 mg L-1.

CONCLUSIONS

The ClotPro® TPA-test is sensitive in detecting inhibition of fibrinolysis by tranexamic acid in whole blood samples of pregnant and non-pregnant women. The concentration-effect relationship of tranexamic acid to inhibit fibrinolysis in whole blood did not differ for women in the first, second, and third trimester or for non-pregnant women.

Tranexamic acid administered intraarticularly to the knee is safer for the articular cartilage and anterior cruciate ligament compared to intravenous administration: Histological analysis of an experimental rat model

In this study, the effects of tranexamic acid (TXA) on the knee's articular cartilage, anterior cruciate ligament (ACL), and joint capsule were assessed histologically. There were 15 rats in each of the 3 groups, totaling 45 rats. Intraarticular (IA) saline injections were applied for the first group, IA TXA injections for the second group, and intravenous (IV) TXA injections for the third group. Using samples taken from the knee joint 3 weeks later, the medial/lateral femoral condyle and medial/lateral tibial plateau articular cartilages were evaluated with Osteoarthritis Research Society International (OARSI) scoring, while ACL diameter and joint capsule thickness were analyzed histologically. In comparisons of OARSI scores for the medial/lateral femoral condyle and medial/lateral tibial plateau cartilage regions, the scores obtained for the IV TXA group were significantly higher than those of the IA saline group (P < 0.001, P = 0.001, P = 0.003, P = 0.011). In comparisons of medial/lateral femoral condyle and medial/lateral tibial plateau OARSI scores, the scores obtained for the IV TXA group were again significantly higher than those of the IA TXA group (P < 0.001, P < 0.001, P < 0.001, P = 0.002). When ACL diameters were compared, a significant decrease was observed in the ACL diameters of the IV TXA group compared to the IA saline and IA TXA groups (P < 0.001, P = 0.039). Histologically, IV TXA damages the articular cartilage and ACL more than IA TXA. IA administration of TXA is more protective when the articular cartilage and ACL are preserved.

Delayed tranexamic acid after traumatic brain injury impedes learning and memory: Early tranexamic acid is favorable but not in sham animals

BACKGROUND

Early but not late tranexamic acid (TXA) after TBI preserves blood-brain-barrier integrity, but it is unclear if and how dose timing affects cognitive recovery beyond hours postinjury. We hypothesized that early (1 hour post-TBI) but not late (24 hours post-TBI) TXA administration improves cognitive recovery for 14 days.

METHODS

CD1 male mice (n = 25) were randomized to severe TBI (injury [I], by controlled cortical impact) or sham craniotomy (S) followed by intravenous saline at 1 hour (placebo [P1]) or 30 mg/kg TXA at 1 hour (TXA1) or 24 hours (TXA24). Daily body weights, Garcia Neurological Test scores, brain/lung water content, and Morris water maze exercises quantifying swimming traffic in the platform quadrant (zone [Z] 1) and platform area (Z5) were recorded for up to 14 days.

RESULTS

Among injured groups, I-TXA1 demonstrated fastest weight gain for 14 days and only I-TXA1 showed rapid (day 1) normalization of Garcia Neurological Test ( p = 0.01 vs. I-P1, I-TXA24). In cumulative spatial trials, compared with I-TXA1, I-TXA24 hindered learning (distance to Z5 and % time in Z1, p < 0.05). Compared with I-TXA1, I-TXA24 showed poorer memory with less Z5 time (0.51 vs. 0.16 seconds, p < 0.01) and Z5 crossing frequency. Unexpectedly, TXA in uninjured animals (S-TXA1) displayed faster weight gain but inferior learning and memory.

CONCLUSION

Early TXA appears beneficial for cognitive and behavioral outcomes following TBI, although administration 24 hours postinjury consistently impairs cognitive recovery. Tranexamic acid in sham animals may lead to adverse effects on cognition.

Role of interleukin-6 and endothelin-1 receptors in enhanced melanocyte dendricity of facial spots and suppression of their ligands by niacinamide and tranexamic acid

BACKGROUND

Hyperpigmented spots are common issues in all ethnicities with a hallmark characteristic of increased melanocyte dendricity.

OBJECTIVES

To determine (1) potential receptors and/or cytokines that are involved in increased melanocyte dendricity in multiple facial spot types; (2) treatment effects of skin-lightening compounds on identified cytokine release from keratinocytes and on dendricity in melanocytes.

METHODS

Facial spots (melasma, solar lentigo, acne-induced post-inflammatory hyperpigmentation) and adjacent non-spot skin biopsies were collected from Chinese women (age 20-70). The epidermal supra and basal layers were laser dissected to enrich keratinocyte or melanocyte biology respectively for transcriptome analysis. Melanocyte dendricity was assessed histologically by immunofluorescent staining. Effect of interleukin-6 (IL-6) and endothelin-1 (ET-1) on melanocyte dendricity and melanosome transfer were assessed in human melanocytes or melanocyte-keratinocyte co-culture models. Treatment effects of skin-lightening compounds (niacinamide, tranexamic acid [TxA], sucrose laurate/dilaurate mixture [SDL]) were assessed on IL-6 or ET-1 release from keratinocytes and on dendricity in melanocytes.

RESULTS

Transcriptome analysis revealed IL-6 receptor and ET-1 receptor were significantly upregulated compared to the adjacent normal skin, visually confirmed at the protein level through immunostaining. Melanocytes in spot areas are more dendritic than melanocytes in adjacent non-spot skin. The addition of IL-6 and ET-1 to cell culture models increased melanocyte dendricity and melanosome transfer. IL-6 release was significantly suppressed by niacinamide and its combination, while ET-1 release was significantly reduced by both niacinamide and TxA. In contrast, SDL acted directly upon melanocytes to reduce dendricity.

CONCLUSION

Interleukin-6 and ET-1 receptors are significantly upregulated in multiple facial spot types. The in vitro testing demonstrated their respective ligands increased melanocyte dendricity. Tested skin-lightening compounds showed reduction in release of IL-6/ET-1 from epidermal keratinocytes and/or inhibition of melanocyte dendricity. This work sheds light on pathophysiological mechanism of facial spots and potential new mechanisms of these skin-lightening compounds which warrant further human clinical validation.

Topical or intravenous administration of tranexamic acid accelerates wound healing

OBJECTIVES

In this study, we aimed to investigate the morphological and histological effects of tranexamic acid (TA) on wound healing in a rat wound model.

MATERIALS AND METHODS

A total of 24 adult male Wistar Albino rats were used in this study. All rats were simple randomly divided into three groups including eight rats in each group. A full-thickness skin defect was created on the back of the rats in all groups. Serum physiological (2 mL) was instilled saline drops after wound formation (control group). Wound was created and topical TA (0.12 to 0.15 mL [30 mg/kg]) was applied (local group). Intravenous TA (0.12 to 0.15 mL [30 mg/kg]) was applied intravenously before the wound was created (intravenous group). The wound diameters of the groups were photographed and measured on Days 0, 3, 7, 10, 14 and, at the end of Day 14, the rats were sacrificed and their histopathological results and wound diameters were compared.

RESULTS

Fibroblast count values of the control group were found to be significantly lower than the local group (p=0.002), and no significant difference was observed between the local and intravenous groups (p>0.05). The collagen density (%) values of the control group were found to be significantly higher than the local and intravenous groups (p=0.016 and p=0.044). Wound diameter values of the control group on Day 10 day were found to be significantly higher than the local and intravenous groups (p=0.001). In addition, the wound diameter values of the control group on Day 14 were found to be significantly higher than the local and intravenous groups (p=0.001 and p=0.0001). The wound diameter changes of the control group on Days 0-10 were found to be significantly lower than the local and intravenous groups (p=0.001). In addition, the wound diameter changes of the control group on Days 0-14 were found to be lower than those of the local and intravenous groups (p=0.001 and p=0.0001).

CONCLUSION

The use of local or intravenous TA may have positive effects on the fibroblast count and wound contraction in a rat wound model.

Tranexamic acid (class I drug) reduced and capped gold nanoparticles as a potential hemostatic agent with enhanced performance

External hemostatic agents play a crucial role in stabilizing an impaired process during pathological conditions. The idea is to stabilize thein vivosystem as soon as possible. This study uses a class I hemostatic drug tranexamic acid as a reducing and capping agent for synthesizing the gold nanoparticles (Tr-AuNPs). Being the synthetic analogue of lysine and a biologically inspired alkylamine molecule, the chemistry can be fine-tuned for stable material that can simultaneously target the intrinsic and extrinsic hemostatic pathway, making it promising for hemostatic applications. The Tr-AuNPs of hydrodynamic diameter ∼46 nm were synthesized and evaluated physio-chemically using various analytical techniques wherein they showed hemocompatibility and increased thrombus weight compared to the native drug. The decrease in prothrombin time (PT) and international normalized ratio supported by the dynamic thromboelastography (TEG) study indicates the prepared nano-conjugate's potential in reducing time for attaining hemostasis as compared to the native tranexamic acid drug. At a 9μg ml-1concentration, Tr-AuNPs had a procoagulant effect, shown by decreased reaction time (R) and coagulation time (K) with improvedαangle and MA. There was a significant increase in the rate of coagulationin vivoby Tr-AuNPs, i.e. (52 s) compared to the native tranexamic acid (360 s). Radiolabelling studies ascertained thein vivobiocompatibility (non-invasive distribution, residence, clearance, and stability) of the Tr-AuNPs. The short-term toxicity studies were conducted to establish a proof of concept for the biomedical application of the material. The results highlighted the use of biologically alkyl amine molecules as capping and reducing agents for the synthesis of nanoparticles, which have shown a synergistic effect on the coagulation cascade while holding the potential for also acting as potential theranostic agents.

The effect of tranexamic acid on synovium of patients undergoing arthroplasty and anterior cruciate ligament reconstruction surgery

Preoperative hemorrhage can be reduced using anti-fibrinolytic medicine tranexamic acid (TXA). During surgical procedures, local administration is being used more and more frequently, either as an intra-articular infusion or as a perioperative rinse. Serious harm to adult soft tissues can be detrimental to the individual since they possess a weak ability for regeneration. Synovial tissues and primary fibroblast-like synoviocytes (FLS) isolated from patients were examined using TXA treatment in this investigation. FLS is obtained from rheumatoid arthritis (RA), osteoarthritis (OA), and anterior cruciate ligament (ACL)-ruptured patients. The in vitro effect of TXA on primary FLS was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assays for cell death, annexin V/propidium iodide (PI) staining for apoptotic rate, real-time PCR for p65 and MMP-3 expression, and enzyme-linked immunosorbent assay (ELISA) for IL-6 measurement. MTT assays revealed a significant decrease in cell viability in FLS of all groups of patients following treatment with 0.8-60 mg/ml of TXA within 24 h. There was a significant increase in cell apoptosis after 24 h of exposure to TXA (15 mg/ml) in all groups, especially in RA-FLS. TXA increases the expression of MMP-3 and p65 expression. There was no significant change in IL-6 production after TXA treatment. An increase in receptor activator of nuclear factor kappa-Β ligand (RANK-L) production was seen only in RA-FLS. This study demonstrates that TXA caused significant synovial tissue toxicity via the increase in cell death and elevation of inflammatory and invasive gene expression in FLS cells.

Tranexamic Acid Causes Chondral Injury Through Chondrocytes Apoptosis Induced by Activating Endoplasmic Reticulum Stress

PURPOSE

To investigate whether tranexamic acid (TXA) is cytotoxic in chondrocyte and cartilage tissues, as well as explore the mechanisms behind the possible toxicity in detail.

METHODS

We detected the cell viability of chondrocytes in vitro and the change of morphology and specific in vivo contents of cartilage after TXA treatment. Furthermore, we detected apoptosis in cartilage. We used apoptosis-specific staining, reactive oxygen species detection, mitochondrial membrane potential detection, flow cytometry, and western blot for apoptosis detection. Finally, we detected the activation of endoplasmic reticulum stress (ERS) in TXA-treated chondrocytes to clarify the mechanism behind chondrocyte apoptosis.

RESULTS

TXA presented an increasing toxic effect with increasing concentrations, especially in the 100 mg/mL group. In addition, we found that 50 mg/mL and 100 mg/mL TXA significantly increased apoptosis in cartilage and subchondral bone. TXA could induce chondrocyte apoptosis in cell and protein levels with reactive oxygen species generation and mitochondrial membrane depolarization. An apoptosis inhibitor could inhibit the induced apoptosis. Next, TXA induced calcium overload in chondrocytes and increased ERS-specific protein expression, whereas ERS inhibitor blocked ERS activation and further inhibited chondrocyte apoptosis.

CONCLUSIONS

We concluded that TXA had a toxic effect on chondrocytes by inducing apoptosis through ERS activation, especially in 50 mg/mL and 100 mg/mL groups. We recommend TXA concentrations of less than 50 mg/mL in joint surgeries.

CLINICAL RELEVANCE

It is still unclear whether TXA has a toxic effect on cartilage when topically used in joint surgeries. The concentration also varies. This study provides additional evidence that TXA at high concentrations will cause cartilage damage, which will help to provide a new understanding of the clinical administration of TXA.

The effect of tranexamic acid on perioperative blood loss in transurethral resection of the prostate: A double-blind, randomized controlled trial

BACKGROUND

Bleeding and bleeding-related complications remain common after bipolar transurethral resection of the prostate (TURP) for benign prostatic hyperplasia. This may possibly lead to prolonged postoperative irrigation, catheterization, and hospital stay. The objective of this trial was to evaluate the effect of high-dose tranexamic acid (TXA) on perioperative blood loss in patients treated with bipolar TURP for prostate sizes between 30 and 80 g.

METHODS

We conducted a single-center, prospective, double-blind, randomized controlled trial. Eighty patients were screened for inclusion between March 2020 and January 2023. After exclusion, 65 patients were randomized in two comparable groups. The TXA group (31 patients) received a TXA intravenous loading dose of 10 mg/kg over 30 min before induction, followed by a maintenance dose of 5 mg/kg/h over 12 h. The placebo group (34 patients) received an equal dose of saline infusion. We measured age, weight, preoperative prostate size, anticoagulant use, 5-alpha reductase inhibitor use, preoperative urinary tract infection, American Society of Anesthesiologists score, difference in pre- and 24 h postoperative hemoglobin and hematocrit levels, operative time, resected adenoma weight, duration of postoperative irrigation, total amount of postoperative irrigation fluid, indwelling catheter time, duration of hospital stay, blood transfusion rate, and 4-week complication rate.

RESULTS

Baseline characteristics in both groups were comparable. Postoperative hemoglobin decrease in TXA versus placebo group was 1 versus 1.6 mg/dL, respectively (p = 0.04). In addition, the amount of postoperative irrigation fluid (10.7 vs. 18.5 L), irrigation time (24.3 vs. 37.9 h), catheterization time (40.8 vs. 53.7 h), and hospital stay (46.9 vs. 59.2 h) were statistically significant in favor of TXA use. No blood transfusions were carried out. Four-week complication rate was comparable between the two groups.

CONCLUSIONS

Perioperative high-dose TXA seems beneficial in reducing hemoglobin loss, postoperative irrigation, catheterization time, and hospital stay in bipolar TURP for prostate sizes between 30 and 80 g, without increased risk of TXA-related thromboembolic events.

Topical Fibrin Sealant (Tisseel@) Does Not Provide a Synergic Blood-Conservation Effect with Tranexamic Acid in Total Knee Arthroplasty-A Prospective Randomized Controlled Trial

Background and Objectives: The efficacy of tranexamic acid (TXA) in reducing perioperative blood loss during total knee arthroplasty (TKA) is well established. However, the potential synergistic blood-conservation effect of topical fibrin sealant (Tisseel@) remains unclear. This study aims to assess the effectiveness of the combination of Tisseel and TXA during TKA. Materials and Methods: A single-blinded, prospective, randomized controlled trial was conducted with 100 patients (100 knees) undergoing primary TKA. Participants were randomly assigned to either the TXA group (n = 50), receiving intravenous (IV) TXA, or the Tisseel@ + TXA group (n = 50), receiving intra-articular Tisseel@ combined with IV TXA. The primary outcomes included blood transfusion rate, decrease in Hb level, calculated blood loss, and estimated total postoperative blood loss. Secondary outcomes involved assessing clinical differences between the groups. Results: The transfusion rate was zero in both groups. The average estimated blood loss in the Tisseel@ + TXA group was 0.463 ± 0.2422 L, which was similar to that of the TXA group at 0.455 ± 0.2522 L. The total calculated blood loss in the Tisseel@ + TXA group was 0.259 ± 0.1 L, compared with the TXA group's 0.268 ± 0.108 L. The mean hemoglobin reduction in the first 24 h postoperatively was 1.57 ± 0.83 g/dL for the Tisseel@ + TXA group and 1.46 ± 0.82 g/dL for the TXA-only group. The reduction in blood loss in the topical Tisseel@ + TXA group was not significantly different from that achieved in the TXA-only group. The clinical results of TKA up to the 6-week follow-up were comparable between the groups. Conclusions: The combination of the topical fibrin sealant Tisseel@ and perioperative IV TXA administration, following the described protocol, demonstrated no significant synergistic blood-conservation effect in patients undergoing TKR.

Rapid disappearance of acute subdural hematoma due to abrogated hyper-fibrinolytic activity by tranexamic acid: Case report

RATIONALE

Acute subdural hematoma (ASDH) occurs after tearing of bridging veins within the dura resulting in the accumulation of blood between the arachnoid and dura layers within 72 hours after traumatic head injury. Also, antigen fibrin D-dimer (DD) is the principal enzymatic degradation product of cross-linked fibrin by plasmin. We observed that early tranexamic acid (TXA) treatment resolved hyper-fibrinolysis and rapid disappearance ASDH.

PATIENTS CONCERNS

A 48-year-old female presented with unconsciousness for 2 hours after head trauma. Her Glasgow Coma Scale score was >8 points.

DIAGNOSIS

Computed tomography scan established ASDH with midline shift and brainstem compression and surgery was scheduled. Also, laboratory results indicated high DD spike of 34,820 μg/L and a reduction in plasma fibrinogen 1 hour after the injury.

INTERVENTION

She was treated with intravenous TXA immediately after admission.

OUTCOMES

Her DD spike decreased remarkably in 48 hours with associated rapid disappearance of ASDH thereby averting surgical intervention. She recovered fully with no long-term complications.

LESSONS

Historically, hyper-fibrinolysis is associated with poor outcome in head trauma. However, early initiation of TXA which is noninvasive treatment modality for ASDH could avert surgery and reduce cost, anesthesia, and other complications associated with surgery.

Ruggedized Self-Propelling Hemostatic Gauze Delivers Low Dose of Thrombin and Systemic Tranexamic Acid and Achieves High Survival in Swine With Junctional Hemorrhage

INTRODUCTION

Hemorrhage is responsible for 91% of preventable prehospital deaths in combat. Bleeding from anatomic junctions such as the groin, neck, and axillae make up 19% of these deaths, and reports estimate that effective control of junctional hemorrhage could have prevented 5% of fatalities in Afghanistan. Hemostatic dressings are effective but are time-consuming to apply and are limited when proper packing and manual pressure are not feasible, such as during care under fire. CounterFlow-Gauze is a hemostatic dressing that is effective without compression and delivers thrombin and tranexamic acid into wounds. Here, an advanced prototype of CounterFlow-Gauze, containing a range of low thrombin doses, was tested in a lethal swine model of junctional hemorrhage. Outcomes were compared with those of Combat Gauze, the current dressing recommended by Tactical Combat Casualty Care.

MATERIALS AND METHODS

CounterFlow-Gauze containing thrombin doses of 0, 20, 200, and 500 IU was prepared. Swine received femoral arteriotomies, and CounterFlow-Gauze was packed into wounds without additional manual compression. In a separate study using a similar model of junctional hemorrhage without additional compression, CounterFlow-Gauze containing 500 IU thrombin was tested and compared with Combat Gauze. In both studies, the primary outcomes were survival to 3 h and volume of blood loss.

RESULTS

CounterFlow-Gauze with 200 and 500 IU had the highest 3-h survival, achieving 70 and 75% survival, respectively. CounterFlow-Gauze resulted in mean peak plasma tranexamic acid concentrations of 9.6 ± 1.0 µg/mL (mean ± SEM) within 3 h. In a separate study with smaller injury, CounterFlow-Gauze with 500 IU achieved 100% survival to 3 h compared with 92% in Combat Gauze animals.

CONCLUSIONS

An advanced preclinical prototype of CounterFlow-Gauze formulated with a minimized thrombin dose is highly effective at managing junctional hemorrhage without compression. These results demonstrate that CounterFlow-Gauze could be developed into a feasible alternative to Combat Gauze for hemorrhage control on the battlefield.

Bacteriosynthetic Degradable Tranexamic Acid-Functionalized Short Fibers for Inhibiting Invisible Hemorrhage

Current research on hemostatic materials have focused on the inhibition of visible hemorrhage, however, invisible hemorrhage is the unavoidable internal bleeding that occurs after trauma or surgery, leading directly to a dramatic drop in hemoglobin and then to anemia and even death. In this study, bacterial nanocellulose (BNC) was synthesized and oxidized from the primary alcohols to carboxyl groups, and then grafted with tranexamic acid through amide bonds to construct degradable nanoscale short fibers (OBNC-TXA), which rapidly activated the coagulation response. The hemostatic material is made up of nanoscale short fibers that can be constructed into different forms such as emulsions, gels, powders, and sponges to meet different clinical applications. In the hemostatic experiments in vitro, the composites had significantly superior pro-coagulant properties due to the rapid aggregation of blood cells. In the coagulation experiments with rat tail amputation and liver trauma hemorrhage models, the group treated with OBNC-TXA1 sponge showed low hemorrhage and inhibited invisible hemorrhage in rectus abdominis muscle defect hemorrhage models, with a rapid recovery of hemoglobin values from 128±5.5 to 165±2.6 g L-1 within 4 days. In conclusion, the degradable short fibers constructed from bacterial nano-cellulose achieved inhibition of invisible hemorrhage in vivo.

Tranexamic acid improves psoriasis-like skin inflammation: Evidence from in vivo and in vitro studies

The chronic disease psoriasis is associated with severe inflammation and abnormal keratinocyte propagation in the skin. Tranexamic acid (TXA), a plasmin inhibitor, is used to cure serious bleeding. We investigated whether TXA ointment mitigated Imiquimod (IMQ)-induced psoriasis-like inflammation. Furthermore, this study investigated the effect of noncytotoxic concentrations of TXA on IL-17-induced human keratinocyte (HaCaT) cells to determine the status of proliferative psoriatic keratinocytes. We found that TXA reduced IMQ-induced psoriasis-like erythema, thickness, scaling, and cumulative scores (erythema plus thickness plus scaling) on the back skin of BALB/c mice. Additionally, TXA decreased ear thickness and suppressed hyperkeratosis, hyperplasia, and inflammation of the ear epidermis in IMQ-induced BALB/c mice. Furthermore, TXA inhibited IMQ-induced splenomegaly in BALB/c mouse models. In IL-17-induced HaCaT cells, TXA inhibited ROS production and IL-8 secretion. Interestingly, TXA suppressed the IL-17-induced NFκB signaling pathway via IKK-mediated IκB degradation. TXA inhibited IL-17-induced activation of the NLRP3 inflammasome through caspase-1 and IL1β expression. TXA inhibited IL-17-induced NLRP3 inflammasome activation by enhancing autophagy, as indicated by LC3-II accumulation, p62/SQSTM1 expression, ATG4B inhibition, and Beclin-1/Bcl-2 dysregulation. Notably, TXA suppressed IL-17-induced Nrf2-mediated keratin 17 expression. N-acetylcysteine pretreatment reversed the effects of TXA on NFκB, NLRP3 inflammasomes, and the Nrf2-mediated keratin 17 pathway in IL-17-induced HaCaT cells. Results further confirmed that in the ear skin of IMQ-induced mice, psoriasis biomarkers such as NLRP3, IL1β, Nrf2, and keratin 17 expression were downregulated by TXA treatment. TXA improves IMQ-induced psoriasis-like inflammation in vivo and psoriatic keratinocytes in vitro. Tranexamic acid is a promising future treatment for psoriasis.

Chondrotoxic effects of tranexamic acid and povidone-iodine on the articular cartilage of rabbits

PURPOSE

To evaluate the chondrotoxic effects of intra-articular use of TXA 20 mg/kg and/or 0.35% PVPI on knee joint cartilage in an experimental model of rabbits.

METHODS

Forty-four male New Zealand adult rabbits were randomly assigned to four groups (control, tranexamic acid (TXA), povidone-iodine (PVPI), and PVPI + TXA). The knee joint cartilage was accessed through an arthrotomy and exposed to physiological saline SF 0.9% (control group), TXA, PVPI, and PVPI followed by TXA. Sixty days after surgical procedure, the animals were sacrificed and osteochondral specimens of the distal femur were obtained. Histological sections of cartilage from this area were stained with hematoxylin/eosin and toluidine blue. The following cartilage parameters were evaluated by the Mankin histological/histochemical grading system: structure, cellularity, glycosaminoglycan content in the extracellular matrix, and integrity of the tidemark.

RESULTS

The isolated use of PVPI causes statistically significant changes in cartilage cellularity (p-value = 0.005) and decrease glycosaminoglycan content (p = 0.001), whereas the isolated use of TXA decreased significantly the glycosaminoglycan content (p = 0.031). The sequential use of PVPI + TXA causes more pronounced alterations in the structure (p = 0.039) and cellularity (p = 0.002) and decreased content of glycosaminoglycans (p < 0.001) all with statistical significance.

CONCLUSION

Data suggest that intra-articular use of tranexamic acid 20 mg/kg and intraoperative lavage with 0.35% povidone-iodine solution for three min are toxic to the articular cartilage of the knee in an experimental in vivo study in rabbits.

Evaluating the hemostatic effects of tranexamic acid in women with pre-eclampsia

OBJECTIVE

To evaluate the hemostatic effects of tranexamic acid (TXA) ex vivo in women with pre-eclampsia.

METHODS

This was an ex vivo study involving 45 normal pregnant women and 45 women with pre-eclampsia (nine with mild and 36 with severe features) matched for age, gestational age, and body mass index. Blood samples were collected and divided into two parts. The first served as the pre-TXA sample, while the second was spiked with TXA and served as the post-TXA sample. Plasma levels of D-dimer and plasmin-antiplasmin complex (PAP) were determined using enzyme-linked immunosorbent assay.

RESULTS

The mean D-dimer and PAP values in the pre-TXA samples differed significantly between groups. Following spiking with TXA, the mean D-dimer and PAP levels did not differ significantly in the pre-TXA and post-TXA samples (P = 0.560 and P = 0.500, respectively) in the pre-eclampsia cohort. In normal pregnancy, the mean D-dimer and PAP levels in the post-TXA samples did not differ significantly (P = 0.070 and P = 0.050, respectively) from the pre-TXA samples following TXA spiking.

CONCLUSION

TXA did not significantly affect D-dimer and PAP levels in pre-eclampsia, suggesting that TXA may not increase the thrombotic risks in patients with pre-eclampsia.

Effects of repeated intravenous doses of tranexamic acid on closed tibial fracture healing: Experimental study based on the rat model

OBJECTIVE

The aim of this study was to assess the effects of tranexamic acid on fracture healing in the rat tibia closed fracture model.

METHODS

Sixty-four male Sprague-Dawley rats were included in this study, where closed fracture and intramedullary nailing were performed on their right tibial diaphyses. They were divided into 2 main groups, the experimental group, which was given weekly tranexamic acid injections, and the control group, which received no additional treatment. Eight rats from each group were sacrificed and evaluated for fracture healing at the first experimental group and control group, second experimental group and control group, third experimental group and control group, and fourth experimental group and control group weeks. Fracture healing was radiologically assessed according to the "Spencer Index" and "Lane and Sandhu Scoring System," and histologically evaluated according to the scoring system devised by Huo et al. Results: According to the Spencer Index, the mean union score was statistically significantly higher in the E3 group than in the third con- trol group (P = .014). Furthermore, the mean union score was statistically significantly higher in the fourth experimental group compared to the fourth control group (P=.047). According to the Lane and Sandhu Scoring System, only the mean union scores of the E3-4 groups were statistically significantly higher than the mean union scores of the C3-4 groups (P=.048). There was no histological difference between groups in terms of union, according to the criteria defined by Huo et al (P > .05).

CONCLUSION

This study showed us that repeated intravenous administrations of tranexamic acid had no negative effect on fracture heal- ing in the rat tibia fracture model. Although tranexamic acid demonstrated better radiological healing in the late period, it had no effect on histological union.

Effects of Tranexamic Acid in Patients with Subarachnoid Hemorrhage in Brazil: A Prospective Observational Study with Propensity Score Analysis

BACKGROUND

Rebleeding from a ruptured aneurysm increases the risk of unfavorable outcomes after subarachnoid hemorrhage (SAH) and is prevented by early aneurysm occlusion. The role of antifibrinolytics before aneurysm obliteration remains controversial. We investigated the effects of tranexamic acid on long-term functional outcomes of patients with aneurysmal SAH (aSAH).

METHODS

This was a single-center, prospective, observational study conducted in a high-volume tertiary hospital in a middle-income country from December 2016 to February 2020. We included all consecutive patients with aSAH who either received or did not receive tranexamic acid (TXA) treatment. Multivariate logistic regression analysis using propensity score was used to evaluate the association of TXA use with long-term functional outcomes, measured by the modified Rankin Scale (mRS) at 6 months.

RESULTS

A total of 230 patients with aSAH were analyzed. The median (interquartile range) age was 55 (46-63) years, 72% were women, 75% presented with good clinical grade (World Federation of Neurological Surgeons grade 1-3), and 83% had a Fisher scale of 3 or 4. Around 80% of patients were admitted up to 72 h from ictus. The aneurysm occlusion method was surgical clipping in 80% of the patients. A total of 129 patients (56%) received TXA. In multivariable logistic regression using inverse probability treatment weighting, the long-term rate of unfavorable outcomes (modified Rankin scale 4-6) was the same in the TXA and non-TXA groups (61 [48%] in TXA group vs. 33 [33%] in non-TXA group; odds ratio [OR] 1.39, 95% confidence interval [CI] 0.67-2.92; p = 0.377). The TXA group had higher in-hospital mortality (33 vs. 11% in non-TXA group; OR 4.13, 95% CI 1.55-12.53, p = 0.007). There were no differences between the groups concerning intensive care unit length of stay (16 ± 11.22 days in TXA group vs. 14 ± 9.24 days in non-TXA group; p = 0.2) or hospital (23 ± 13.35 days in TXA group vs. 22 ± 13.36 days in non-TXA group; p = 0.9). There was no difference in the rates of rebleeding (7.8% in TXA group vs. 8.9% in non-TXA group; p = 0.31) or delayed cerebral ischemia (27% in TXA group vs. 19% in non-TXA group; p = 0.14). For the propensity-matched analysis, 128 individuals were selected (64 in TXA group and 64 in non-TXA group), and the rates of unfavorable outcomes at 6 months were also similar between groups (45% in TXA group and 36% in non-TXA group; OR 1.22, 95% CI 0.51-2.89; p = 0.655).

CONCLUSIONS

Our findings in a cohort with delayed aneurysm treatment reinforce previous data that TXA use before aneurysm occlusion does not improve functional outcomes in aSAH.

Early posttraumatic brain injury tranexamic acid prevents blood-brain barrier hyperpermeability and improves surrogates of neuroclinical recovery

BACKGROUND

Tranexamic acid (TXA) given early, but not late, after traumatic brain injury (TBI) appears to improve survival. This may be partly related to TXA-driven profibrinolysis and increased leukocyte (LEU)-mediated inflammation when administered late post-injury. We hypothesized that early TXA (1 hour post-TBI), blunts penumbral, blood-brain barrier (BBB) leukocyte-endothelial cell (LEU-EC) interactions and microvascular permeability, in vivo when compared with late administration (24 hours post-TBI).

METHODS

CD1 male mice (n = 35) were randomized to severe TBI (injury by controlled cortical impact; injury: velocity, 6 m/s; depth, 1 mm; diameter, 3 mm) or sham craniotomy followed by intravenous saline (placebo) at 1 hour, or TXA (30 mg/kg) at 1 hour or 24 hours. At 48 hours, in vivo pial intravital microscopy visualized live penumbral LEU-EC interactions and BBB microvascular fluorescent albumin leakage. Neuroclinical recovery was assessed by the Garcia Neurological Test (motor, sensory, reflex, and balance assessments) and body weight loss recovery at 1 and 2 days after injury. Analysis of variance with Bonferroni correction assessed intergroup differences ( p < 0.05).

RESULTS

One-hour, but not 24-hour, TXA improved Garcia Neurological Test performance on day 1 post-TBI compared with placebo. Both 1 hour and 24 hours TXA similarly improved day 1 weight loss recovery, but only 1 hour TXA significantly improved weight loss recovery on day 2 compared with placebo ( p = 0.04). No intergroup differences were found in LEU rolling or adhesion between injured animal groups. Compared with untreated injured animals, only TXA at 1 hour reduced BBB permeability.

CONCLUSION

Only early post-TBI TXA consistently improves murine neurological recovery. Tranexamic acid preserves BBB integrity but only when administered early. This effect appears independent of LEU-EC interactions and demonstrates a time-sensitive effect that supports only early TXA administration.

Absence of hyperfibrinolysis may explain lack of efficacy of tranexamic acid in hypoproliferative thrombocytopenia

The American Trial Using Tranexamic Acid (TXA) in Thrombocytopenia (A-TREAT, NCT02578901) demonstrated no superiority of TXA over placebo in preventing World Health Organization (WHO) grade 2 or higher bleeding in patients with severe thrombocytopenia requiring supportive platelet transfusion following myeloablative therapy for hematologic disorders. In this ancillary study, we sought to determine whether this clinical outcome could be explained on the basis of correlative assays of fibrinolysis. Plasma was collected from A-TREAT participants (n = 115) before the initiation of study drug (baseline) and when TXA was at steady-state trough concentration (follow-up). Global fibrinolysis was measured by 3 assays: euglobulin clot lysis time (ECLT), plasmin generation (PG), and tissue-type plasminogen activator (tPA)-challenged clot lysis time (tPA-CLT). TXA was quantified in follow-up samples by tandem mass spectrometry. Baseline samples did not demonstrate fibrinolytic activation by ECLT or tPA-CLT. Furthermore, neither ECLT nor levels of plasminogen activator inhibitor-1, tPA, plasminogen, alpha2-antiplasmin, or plasmin-antiplasmin complexes were associated with a greater risk of WHO grade 2+ bleeding. TXA trough concentrations were highly variable (range, 0.7-10 μg/mL) and did not correlate with bleeding severity, despite the fact that plasma TXA levels correlated strongly with pharmacodynamic assessments by PG (Spearman r, -0.78) and tPA-CLT (r, 0.74). We conclude that (1) no evidence of fibrinolytic activation was observed in these patients with thrombocytopenia, (2) trough TXA concentrations varied significantly between patients receiving the same dosing schedule, and (3) tPA-CLT and PG correlated well with TXA drug levels.

Effects of tranexamic acid on coagulofibrinolytic markers during the early stage of severe trauma: A propensity score-matched analysis

Tranexamic acid (TXA) reduces the risk of bleeding trauma death without altering the need for blood transfusion. We examined the effects of TXA on coagulation and fibrinolysis dynamics and the volume of transfusion during the early stage of trauma. This subanalysis of a prospective multicenter study of severe trauma included 276 patients divided into propensity score-matched groups with and without TXA administration. The effects of TXA on coagulation and fibrinolysis markers immediately at (time point 0) and 3 hours after (time point 3) arrival at the emergency department were investigated. The transfusion volume was determined at 24 hours after admission. TXA was administered to the patients within 3 hours (median, 64 minutes) after injury. Significant reductions in fibrin/fibrinogen degradation products and D-dimer levels from time points 0 to 3 in the TXA group compared with the non-TXA group were confirmed, with no marked differences noted in the 24-hour transfusion volumes between the 2 groups. Continuously increased levels of soluble fibrin, a marker of thrombin generation, from time points 0 to 3 and high levels of plasminogen activator inhibitor-1, a marker of inhibition of fibrinolysis, at time point 3 were observed in both groups. TXA inhibited fibrin(ogen)olysis during the early stage of severe trauma, although this was not associated with a reduction in the transfusion volume. Other confounders affecting the dynamics of fibrinolysis and transfusion requirement need to be clarified.

Effects of antifibrinolytics on systemic and cerebral inflammation after traumatic brain injury

BACKGROUND

Administration of antifibrinolytic medications, including tranexamic acid (TXA), may reduce head injury-related mortality. The effect of these medications on post-traumatic brain injury (TBI) inflammatory response is unknown. The goal of this study was to investigate the role of available antifibrinolytic medications on both systemic and cerebral inflammation after TBI.

METHODS

An established murine weight drop model was used to induce a moderate TBI. Mice were administered 1, 10, or 100 mg/kg of TXA, 400 mg/kg of aminocaproic acid (Amicar, Hospira, Lake Forest, IL), 100 kIU/kg of aprotonin, or equivalent volume of normal saline (NS) 10 minutes after recovery. Mice were euthanized at 1, 6, or 24 hours. Serum and cerebral tissue were analyzed for neuron-specific enolase and inflammatory cytokines. Hippocampal histology was evaluated at 30 days for phosphorylated tau accumulation.

RESULTS

One hour after TBI, mice given TXA displayed decreased cerebral cytokine concentrations of tumor necrosis factor α (TNF-α) and, by 24 hours, displayed decreased concentrations of cerebral TNF-α, interleukin (IL)-6, and monocyte chemoattractant protein 1 compared with TBI-NS. However, serum concentrations of TNF-α and macrophage inflammatory protein 1α (MIP-1α) were significantly elevated from 1 to 24 hours in TBI-TXA groups compared with TBI-NS. The concentration of phosphorylated tau was significantly decreased in a dose-dependent manner in TBI-TXA groups compared with TBI-NS. By contrast, Amicar administration increased cerebral cytokine levels of IL-6 1 hour after TBI, with serum elevations noted in TNF-α, MIP-1α, and monocyte chemoattractant protein 1 at 24 hours compared with TBI-NS. Aprotonin administration increased serum TNF-α, IL-6, and MIP-1α from 1 to 24 hours without differences in cerebral cytokines compared with TBI-NS.

CONCLUSION

Tranexamic acid administration may provide acute neuroinflammatory protection in a dose-dependent manner. Amicar administration may be detrimental after TBI with increased cerebral and systemic inflammatory effects. Aprotonin administration may increase systemic inflammation without significant contributions to neuroinflammation. While no antifibrinolytic medication improved systemic inflammation, these data suggest that TXA may provide the most beneficial inflammatory modulation after TBI.

Iota-carrageenan/xyloglucan/serine powders loaded with tranexamic acid for simultaneously hemostatic, antibacterial, and antioxidant performance

This study sought to prepare powder hemostats based on iota-carrageenan (ιC), xyloglucan (XYL), l-serine (SER), and tranexamic acid (TA). The powder form was chosen because it enables the hemostat to be used in wounds of any shape and depth. The powder hemostats showed irregular shapes and specific surface areas ranging from 34 to 46 m²/g. Increasing TA amount decreases the specific surface area, bulk density, water and blood absorption, and the antibacterial activities of the powder hemostats, but not the water retention ability. Conversely, in vitro biodegradation was positively impacted by increasing the TA content in the powder hemostats. In both the in vitro and in vivo tests, powder hemostats showed reduced bleeding time, significant adhesion of red blood cells, great hemocompatibility, moderate antioxidant activity, and high biocompatibility. These findings shed new light on designing powder hemostats with intrinsic antibacterial and antioxidant activity and excellent hemostatic performance.

The effect of tranexamic acid dosing regimen on trauma/hemorrhagic shock-related glycocalyx degradation and endothelial barrier permeability: An in vitro model

BACKGROUND

Improved outcomes with early tranexamic acid (TXA) following trauma hemorrhagic shock (T/HS) may be related to its antifibrinolytic, as well as anti-inflammatory properties. Previous in vitro studies have shown that early TXA administration protects against T/HS endothelial barrier dysfunction and associated glycocalyx degradation. An intact endothelial glycocalyx may protect against subsequent neutrophil mediated tissue injury. We postulated that early TXA administration would mitigate against glycocalyx damage and resultant neutrophil adherence and transmigration through the endothelial barrier. This was studied in vitro using a microfluidic flow platform.

METHODS

Human umbilical vein endothelial cell monolayers were subjected to control or shock conditions (hypoxia + epinephrine) followed by administration of TXA 90 minutes or 180 minutes later.

RESULTS

"Early" TXA administration protected against glycocalyx degradation, biomarkers of increased permeability and the development of a fibrinolytic phenotype. This was associated with decreased neutrophil endothelial adherence and transmigration. There were no differences in low versus high TXA concentrations. The protective effects were only significant with "early" TXA administration.

CONCLUSION

There was a concentration and temporal effect of TXA administration on endothelial glycocalyx degradation. This was associated with "vascular leakiness" as indexed by the relative ratio of Ang-2/1 and polymorphonuclear neutrophil transmigration. Tranexamic acid if administered in patients with T/HS should be administered "early"; this includes in the prehospital setting.

Evaluation of Novel Tranexamic Acid/Montmorillonite Intercalation Composite, as a New Type of Hemostatic Material

Radiation enteritis-clinically manifested as diarrhea, intestinal bleeding, and so on-is frequently caused when the body is exposed to radiation or radiotherapy because the intestine is radiation-sensitive as an abdominal organ. Therefore, strategies to modulate intestinal hemostasis had inspired an important research trend in the process of preventing and treating radiation enteritis. Based on the structural characteristics of montmorillonite (MMT) and the hemostatic drug tranexamic acid (TXA) which was used clinically to treat enteritis, the tranexamic acid-montmorillonite composite material (TXA-MMT) was prepared through intercalation composite technology. According to the analysis of FTIR, XRD, TG-DTG, SEM, and XRF, the prepared TXA-MMT was verified that tranexamic acid could intercalate into layers of montmorillonite. To evaluate the biocompatibility, two experiments were conducted by in vitro hemolysis and in vitro cytotoxicity experiments and results showed that TXA-MMT exhibited good visible biocompatibility. Activated partial thromboplastin time, prothrombin time, and in vitro clotting time were adopted to determine the hemostatic effect of TXA-MMT. Compared with other groups, TXA-MMT revealed a significant decrease in clotting time variations, APTT, and PT. In addition, to investigate the preventive effect of TXA-MMT by the intervention of radiation enteritis mice, inflammatory factors IL-1β, IL-6, and TNF-α and the content of endotoxin in the serum of mice were detected. It demonstrated that TXA-MMT reduced the levels of these factors. Besides, the expression and the pathological changes of the small intestine tissue of mice were relieved. Our findings suggests that TXA-MMT as a promising intercalation composite has a great potential for application in the field of intestinal hemostasis.

Tranexamic acid-loaded hemostatic nanoclay microsphere frameworks

Fast acting topical hemostatic agents play a key role in hemorrhage control. Retarding fibrinolysis is also critical in improving coagulation, thereby expanding chances of survival. The purpose of the present work was to investigate the physical properties, loading capacity and hemostatic efficacy of newly developed nanoclay microsphere frameworks (NMFs) loaded with tranexamic acid (TA), as antifibrinolytic agent. Nanoclay compositions were prepared with increasing levels of TA. Results showed that TA was successfully incorporated into the nanoclay structure and released when solvated with ethanol. Both doped and undoped NMFs significantly decreased activated partial thromboplastin time and increased clot stiffness, which was attributed to significantly thinner fibrin fibers and a denser clot structure.

Evaluation of the prothrombotic potential of four-factor prothrombin complex concentrate (4F-PCC) in animal models

OBJECTIVES

Acquired coagulopathy may be associated with bleeding risk. Approaches to restore haemostasis include administration of coagulation factor concentrates, but there are concerns regarding potential prothrombotic risk. The present study assessed the prothrombotic potential of four-factor prothrombin complex concentrate (4F-PCC) versus activated PCC (aPCC) and recombinant factor VIIa (rFVIIa), using three preclinical animal models.

METHODS

The first model was a modified Wessler model of venous stasis-induced thrombosis in rabbit, focusing on dilutional coagulopathy; the second model employed the same system but focused on direct oral anticoagulant reversal (i.e. edoxaban). The third model assessed the prothrombotic impact of 4F-PCC, aPCC and rFVIIa in a rat model of ferric chloride-induced arterial thrombosis.

RESULTS

In the first model, thrombi were observed at aPCC doses ≥10 IU/kg (therapeutic dose 100 IU/kg) and rFVIIa doses ≥50 μg/kg (therapeutic dose 90 μg/kg), but not 4F-PCC 50 IU/kg (therapeutic dose 50 IU/kg). The impact of 4F-PCC (up to 300 IU/kg) on thrombus formation was evident from 10 minutes post-administration, but not at 24 hours post-administration; this did not change with addition of tranexamic acid and/or fibrinogen concentrate. 4F-PCC-induced thrombus formation was lower after haemodilution versus non-haemodilution. In the second model, no prothrombotic effect was confirmed at 4F-PCC 50 IU/kg. The third model showed lower incidence of thrombus formation for 4F-PCC 50 IU/kg versus aPCC (50 U/kg) and rFVIIa (90 μg/kg).

CONCLUSIONS

These results suggest that 4F-PCC has a low thrombotic potential versus aPCC or rFVIIa, supporting the clinical use of 4F-PCC for the treatment of coagulopathy-mediated bleeding.

Tranexamic Acid Promotes Murine Bone Marrow-Derived Osteoblast Proliferation and Inhibits Osteoclast Formation In Vitro

Despite modern surgical trauma care, bleeding contributes to one-third of trauma-related death. A significant improvement was obtained through the introduction of tranexamic acid (TXA), which today is widely used in emergency and elective orthopedic surgery to control bleeding. However, concerns remain regarding potential adverse effects on bone turnover and regeneration. Therefore, we employed standardized cell culture systems including primary osteoblasts, osteoclasts, and macrophages to evaluate potential effects of TXA on murine bone cells. While osteoblasts derived from calvarial digestion were not affected, TXA increased cell proliferation and matrix mineralization in bone marrow-derived osteoblasts. Short-term TXA treatment (6 h) failed to alter the expression of osteoblast markers; however, long-term TXA stimulation (10 days) was associated with the increased expression of genes involved in osteoblast differentiation and extracellular matrix synthesis. Similarly, whereas short-term TXA treatment did not affect gene expression in terminally differentiated osteoclasts, long-term TXA stimulation resulted in the potent inhibition of osteoclastogenesis. Finally, in bone marrow-derived macrophages activated with LPS, simultaneous TXA treatment led to a reduced expression of inflammatory cytokines and chemokines. Collectively, our study demonstrates a differential action of TXA on bone cells including osteoanabolic, anti-resorptive, and anti-inflammatory effects in vitro which suggests novel treatment applications.

Application of a plasmin generation assay to define pharmacodynamic effects of tranexamic acid in women undergoing cesarean delivery

Essentials Tranexamic acid (TXA) is an antifibrinolytic drug used to reduce bleeding. Assaying plasmin generation (PG) in plasma detects clinically relevant TXA levels in vitro and ex vivo. 3.1-16.2 µg/mL TXA half-maximally inhibits PG in plasma from women undergoing cesarean delivery. PG velocity shows the strongest dose-relationship at low TXA concentrations (≤10 µg/mL). ABSTRACT: Background Tranexamic acid (TXA) is used to reduce bleeding. TXA inhibits plasmin(ogen) binding to fibrin and reduces fibrinolysis. TXA antifibrinolytic activity is typically measured by clot lysis assays; however, effects on plasmin generation (PG) are unclear due to a lack of tools to measure PG in plasma. Aims Develop an assay to measure PG kinetics in human plasma. Determine effects of TXA on PG and compare with fibrinolysis measured by rotational thromboelastometry (ROTEM). Methods We characterized effects of plasminogen, tissue plasminogen activator, fibrinogen, and α2 -antiplasmin on PG in vitro. We also studied effects of TXA on PG in plasma from 30 pregnant women administered intravenous TXA (5, 10, or 15 mg/kg) during cesarean delivery. PG was measured by calibrated fluorescence. PG parameters were compared with TXA measured by mass spectrometry and ROTEM of whole blood. Results The PG assay is specific for plasmin and sensitive to tissue plasminogen activator, fibrin(ogen), and α2 -antiplasmin. Addition of TXA to plasma in vitro dose dependently prolonged the clot lysis time and delayed and reduced PG. For all doses of TXA administered intravenously, the PG assay detected delayed time-to-peak (≤3 hours) and reduced the velocity, peak, and endogenous plasmin potential (≤24 hours) in plasma samples obtained after infusion. The PG time-to-peak, velocity, and peak correlated significantly with TXA concentration and showed less variability than the ROTEM lysis index at 30 minutes or maximum lysis. Conclusions The PG assay detects pharmacologically relevant concentrations of TXA administered in vitro and in vivo, and demonstrates TXA-mediated inhibition of PG in women undergoing cesarean delivery.

The effects of intravenous and local tranexamic acid on bone healing: An experimental study in the rat tibia fracture model

BACKGROUND

Tranexamic acid (TXA) is an antifibrinolytic agent. It has long been used to reduce the need for perioperative blood loss in various surgeries. Few studies have investigated the effects of local and intravenous administration of TXA on fracture healing. Thus, we aimed to evaluate if TXA influences hematoma volume and fracture healing in the rat tibia fracture model.

MATERIALS AND METHODS

A tibia fracture with intramedullary Kirschner wire fixation was created in all animals. Rats were randomly divided into three groups as local TXA, intravenous TXA, and control. A dose of 50 mg/kg local and intravenous TXA was administered to the study groups. Hematoma volume was measured on the first and third days of the study. The animals were sacrificed on the 14th and 21st days for radiological and histopathological examinations.

RESULTS

There was no significant difference between the groups in terms of hematoma volume measured on Day 1 and the mean decrease of hematoma volume from Day 1 to Day 3 (p = 0.158 and p = 0.239, respectively). The total radiological scores of Day 14 and Day 21 were similar in all groups (p > 0.05 for all). There was also no significant difference between the histological staging of the fracture repair on Day 14 and Day 21 for all groups (p > 0.05 for all).

CONCLUSION

Our findings suggest that TXA's local and intravenous application makes no significant difference in fracture healing.

Sex-dependent effects of tranexamic acid on blood-brain barrier permeability and the immune response following traumatic brain injury in mice

BACKGROUND

Tranexamic acid (TXA) is an anti-fibrinolytic agent used to reduce bleeding in various conditions including traumatic brain injury (TBI). As the fibrinolytic system also influences the central nervous system and the immune response, TXA may also modulate these parameters following TBI.

OBJECTIVES

To determine the effect of TXA on blood-brain barrier (BBB) integrity and changes in immune and motor function in male and female mice subjected to TBI.

METHODS

Wild-type and plasminogen deficient (plg-/-) mice were subjected to TBI then administered either TXA/vehicle. The degree of BBB breakdown, intracerebral hemorrhage (ICH), motor dysfunction, and changes in inflammatory subsets in blood and brain were determined.

RESULTS AND CONCLUSIONS

Tranexamic acid significantly reduced BBB breakdown, and increased blood neutrophils in male mice 3 hours post-TBI. In contrast, TXA treatment of female mice increased BBB permeability and ICH but had no effect on blood neutrophils at the same time-point. TXA improved motor function in male mice but still increased BBB breakdown in female mice 24 hours post-TBI. Brain urokinase-type plasminogen activator (u-PA) antigen and activity levels were significantly higher in injured females compared to males. Because TXA can promote a pro-fibrinolytic effect via u-PA, these sex differences may be related to brain u-PA levels. TXA also increased monocyte subsets and dendritic cells in the injured brain of wild-type male mice 1 week post-TBI. Plg-/- mice of both sexes had reduced BBB damage and were protected from TBI irrespective of treatment indicating that TXA modulation of the BBB is plasmin-dependent. In conclusion, TXA is protective post-TBI but only in male mice.

Hemostatic agents for prehospital hemorrhage control: a narrative review

Hemorrhage is the leading cause of preventable death in combat trauma and the secondary cause of death in civilian trauma. A significant number of deaths due to hemorrhage occur before and in the first hour after hospital arrival. A literature search was performed through PubMed, Scopus, and Institute of Scientific Information databases for English language articles using terms relating to hemostatic agents, prehospital, battlefield or combat dressings, and prehospital hemostatic resuscitation, followed by cross-reference searching. Abstracts were screened to determine relevance and whether appropriate further review of the original articles was warranted. Based on these findings, this paper provides a review of a variety of hemostatic agents ranging from clinically approved products for human use to newly developed concepts with great potential for use in prehospital settings. These hemostatic agents can be administered either systemically or locally to stop bleeding through different mechanisms of action. Comparisons of current hemostatic products and further directions for prehospital hemorrhage control are also discussed.

Efficacy and safety of tranexamic acid for reducing blood loss in elderly patients with intertrochanteric fracture treated with intramedullary fixation surgery: A meta-analysis of randomized controlled trials

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of tranexamic acid (TXA) in elderly patients with intertrochanteric fracture undergoing intramedullary fixation surgery.

METHODS

We searched MEDLINE, the Cochrane Library and EMBASE for published randomized clinical trials relevant to use of TXA in elderly patients with intertrochanteric fracture treated with intramedullary fixation surgery. Meta-analysis was performed according to the guidelines of the Cochrane Reviewer's Hand book.

RESULTS

Five trials assessing 540 patients were included for meta-analysis. The pooled results showed that the mean total blood loss in TXA group was significant lower than that in the control group (mean difference - 172.83, 95% CI -241.43 to -104.23; p<0.00001, fixed-effect model). The intra- and postoperative transfusion rate for the TXA group was 34.4% (91/264) and for the control group was 49.27% (136/276), and the relative risk was 0.71 (95% CI 0.52 to 0.97; p<0.03, random-effect model) with substantial heterogeneity (I2=63%, p=0.03). The overall incidence of thrombotic events was 6.43% (17/264) in the intravenous TXA group, 7.63% (21/275) in the control group, with no significant difference (relative risk 0.84, 95% CI 0.46 to 1.54; p=0.57, fixed-effect model).

CONCLUSION

The present evidence shows that TXA can significantly reduce total and hidden blood loss, transfusion rate, and do not increase the risk of thrombotic events in elderly patients with intertrochanteric fracture undergoing intramedullary fixation surgery. However, the impact of TXA on thrombotic events needs to be researched in more high-quality, large-sample randomized clinical trials.

LEVEL OF EVIDENCE

Level I Therapeutic Study.

Tranexamic acid modulates the cellular immune profile after traumatic brain injury in mice without hyperfibrinolysis

BACKGROUND

Traumatic brain injury (TBI) is known to promote immunosuppression, making patients more susceptible to infection, yet potentially exerting protective effects by inhibiting central nervous system (CNS) reactivity. Plasmin, the effector protease of the fibrinolytic system, is now recognized for its involvement in modulating immune function.

OBJECTIVE

To evaluate the effects of plasmin and tranexamic acid (TXA) on the immune response in wild-type and plasminogen-deficient (plg-/- ) mice subjected to TBI.

METHODS

Leukocyte subsets in lymph nodes and the brain in mice post TBI were evaluated by flow cytometry and in blood with a hemocytometer. Immune responsiveness to CNS antigens was determined by Enzyme-linked Immunosorbent Spot (ELISpot) assay.  Fibrinolysis was determined by thromboelastography and measuring D-dimer and plasmin-antiplasmin complex levels.

RESULTS

Plg-/-  mice, but not plg+/+  mice displayed increases in both the number and activation of various antigen-presenting cells and T cells in the cLN 1 week post TBI. Wild-type mice treated with TXA also displayed increased cellularity of the cLN 1 week post TBI together with increases in innate and adaptive immune cells. These changes occurred despite the absence of systemic hyperfibrinolysis or coagulopathy in this model of TBI. Importantly, neither plg deficiency nor TXA treatment enhanced the autoreactivity within the CNS.

CONCLUSION

In the absence of systemic hyperfibrinolysis, plasmin deficiency or blockade with TXA increases migration and proliferation of conventional dendritic cells (cDCs) and various antigen-presenting cells and T cells in the draining cervical lymph node (cLN) post TBI. Tranexamic acid might also be clinically beneficial in modulating the inflammatory and immune response after TBI, but without promoting CNS autoreactivity.

Tranexamic acid reduces heme cytotoxicity via the TLR4/TNF axis and ameliorates functional recovery after spinal cord injury

BACKGROUND

Spinal cord injury (SCI) is a catastrophic trauma accompanied by intralesional bleeding and neuroinflammation. Recently, there is increasing interest in tranexamic acid (TXA), an anti-fibrinolytic drug, which can reduce the bleeding volume after physical trauma. However, the efficacy of TXA on the pathology of SCI remains unknown.

METHODS

After producing a contusion SCI at the thoracic level of mice, TXA was intraperitoneally administered and the bleeding volume in the lesion area was quantified. Tissue damage was evaluated by immunohistochemical and gene expression analyses. Since heme is one of the degraded products of red blood cells (RBCs) and damage-associated molecular pattern molecules (DAMPs), we examined the influence of heme on the pathology of SCI. Functional recovery was assessed using the open field motor score, a foot print analysis, a grid walk test, and a novel kinematic analysis system. Statistical analyses were performed using Wilcoxon's rank-sum test, Dunnett's test, and an ANOVA with the Tukey-Kramer post-hoc test.

RESULTS

After SCI, the intralesional bleeding volume was correlated with the heme content and the demyelinated area at the lesion site, which were significantly reduced by the administration of TXA. In the injured spinal cord, toll-like receptor 4 (TLR4), which is a DAMP receptor, was predominantly expressed in microglial cells. Heme stimulation increased TLR4 and tumor necrosis factor (TNF) expression levels in primary microglial cells in a dose-dependent manner. Similarly to the in vitro experiments, the injection of non-lysed RBCs had little pathological influence on the spinal cord, whereas the injection of lysed RBCs or heme solution significantly upregulated the TLR4 and TNF expression in microglial cells. In TXA-treated SCI mice, the decreased expressions of TLR4 and TNF were observed at the lesion sites, accompanied by a significant reduction in the number of apoptotic cells and better functional recovery in comparison to saline-treated control mice.

CONCLUSION

The administration of TXA ameliorated the intralesional cytotoxicity both by reducing the intralesional bleeding volume and preventing heme induction of the TLR4/TNF axis in the SCI lesion. Our findings suggest that TXA treatment may be a therapeutic option for acute-phase SCI.

Clinical trial on the effect of tranexamic acid on bleeding and fibrinolysis in primary hip and knee replacement

BACKGROUND

Tourniquet-induced ischaemia could increase fibrinolysis and enhance tranexamic acid (TXA) efficacy in total knee arthroplasty (TKA) compared to total hip arthroplasty (THA). The aims of this study are to compare the effect of TXA on bleeding and fibrinolysis in both types of surgery, and to record thromboembolic complications.

METHODS

A prospective double-blind study was conducted on patients scheduled for TKA or THA who received TXA (2 bolus of 10mg/kg) or placebo. Bleeding and fibrinolysis were evaluated. Doppler-ultrasound and computed tomography were performed in order to assess any thromboembolic complications.

RESULTS

A total of 44 patients were included (11 THA and 11 TKA treated with TXA; 11 THA and 11 TKA as controls). Blood losses were significantly lower in the TXA group (mean 921mL vs 1,383mL in THA and 969mL vs 1,223mL in TKA), and no transfusions were needed with TXA, whereas 5 blood units were transfused in controls. TXA was equally effecting in reducing bleeding in both surgeries (33% in THA and 21% in TKA). The significant mean increase in D-dimers from baseline to 6 hours after surgery (1,004 ug/L to 10,284 ug/L in THA and 571 ug/L to 6,480 ug/L in TKA) was attenuated by TXA (1,077 ug/L to 2,590 ug/L in THA and 655 ug/L to 2,535 ug/L in TKA). There were no differences in thromboembolic episodes.

CONCLUSIONS

Prophylactic use of tranexamic acid is equally effective in reducing bleeding in TKA and THA. Both surgeries have a similar effect on fibrinolysis.

Short exposure to tranexamic acid does not affect, in vitro, the viability of human chondrocytes

BACKGROUND

Only few studies have investigated the effect of topical application of tranexamic acid (TXA) on "minimally" invasive joint surgical procedures in which articular cartilage is preserved; for this reason, actually many surgeons avoid the use of topical TXA even if the disadvantage related to a blood loss can occur. The aim of this study was to evaluate the cytotoxicity, on human chondrocytes, of TXA at different concentrations and times of exposure and the mechanisms of cell death.

METHODS

Experiments were carried out on isolated human chondrocytes harvested from eight patients who underwent total knee replacement. Cell viability was determined using XTT assay and was assessed at 0, 24 and 48 h intervals after a 10-min-long treatment, followed by thorough washes, or at 24 and 48 h of treatment at TXA concentrations of 20, 50, 70 and 100 mg/ml. Cell cycle alterations and occurrence of cell death for apoptosis or necrosis were assessed by cytofluorimetry. Data were analyzed using Proc Mixed Procedure; LSMEANS was used to compare multiple group means with Tukey's honestly significant difference test.

RESULTS

A significant correlation between the controlled for factors (type of treatment, time and concentration) was found in the performed experiment. No significant effect on cell viability was observed when the TXA exposure was limited to 10 min, while for increased exposure, 24 and 48 h, a remarkable reduction was found; cell death occurred by apoptosis and was already appreciable after 24 h, reaching a statistical significance after the 48-h-long treatment.

CONCLUSION

A prolonged exposure to TXA may cause cartilage damage, thus its topical application can be expanded also to clinical scenarios that include retention of native cartilage chondrocytes, only if it is limited to few minutes and used at concentrations of 70 mg/ml or less.

Pharmacokinetics of tranexamic acid in healthy dogs and assessment of its antifibrinolytic properties in canine blood

OBJECTIVE To assess pharmacokinetics of tranexamic acid (TXA) in dogs and assess antifibrinolytic properties of TXA in canine blood by use of a thromboelastography-based in vitro model of hyperfibrinolysis. ANIMALS 6 healthy adult dogs. PROCEDURES Dogs received each of 4 TXA treatments (10 mg/kg, IV; 20 mg/kg, IV; approx 15 mg/kg, PO; and approx 20 mg/kg, PO) in a randomized crossover-design study. Blood samples were collected at baseline (time 0; immediately prior to drug administration) and predetermined time points afterward for pharmacokinetic analysis and pharmacodynamic (thromboelastography) analysis by use of an in vitro hyperfibrinolysis model. RESULTS Maximum amplitude (MA [representing maximum clot strength]) significantly increased from baseline at all time points for all treatments. The MA was lower at 360 minutes for the 10-mg/kg IV treatment than for other treatments. Percentage of clot lysis 30 minutes after MA was detected was significantly decreased from baseline at all time points for all treatments; at 360 minutes, this value was higher for the 10-mg/kg IV treatment than for other treatments and higher for the 20-mg/kg IV treatment than for the 20-mg/kg PO treatment. Maximum plasma TXA concentrations were dose dependent. At 20 mg/kg, IV, plasma TXA concentrations briefly exceeded concentrations suggested for complete inhibition of fibrinolysis. Oral drug administration resulted in a later peak antifibrinolytic effect than did IV administration. CONCLUSIONS AND CLINICAL RELEVANCE Administration of TXA improved clot strength and decreased fibrinolysis in blood samples from healthy dogs in an in vitro hyperfibrinolysis model. Further research is needed to determine clinical effects of TXA in dogs with hyperfibrinolysis.

Increased urokinase and consumption of α2 -antiplasmin as an explanation for the loss of benefit of tranexamic acid after treatment delay

Essentials Delayed treatment with tranexamic acid results in loss of efficacy and poor outcomes. Increasing urokinase activity may account for adverse effects of late tranexamic acid treatment. Urokinase + tranexamic acid produces plasmin in plasma or blood and disrupts clotting. α2 -Antiplasmin consumption with ongoing fibrinolysis increases plasmin-induced coagulopathy. SUMMARY: Background Tranexamic acid (TXA) is an effective antifibrinolytic agent with a proven safety record. However, large clinical trials show TXA becomes ineffective or harmful if treatment is delayed beyond 3 h. The mechanism is unknown but urokinase plasminogen activator (uPA) has been implicated. Methods Inhibitory mechanisms of TXA were explored in a variety of clot lysis systems using plasma and whole blood. Lysis by tissue plasminogen activator (tPA), uPA and plasmin were investigated. Coagulopathy was investigated using ROTEM and activated partial thromboplastin time (APTT). Results IC50 values for antifibrinolytic activity of TXA varied from < 10 to > 1000 μmol L-1 depending on the system, but good fibrin protection was observed in the presence of tPA, uPA and plasmin. However, in plasma or blood, active plasmin was generated by TXA + uPA (but not tPA) and coagulopathy developed leading to no or poor clot formation. The extent of coagulopathy was sensitive to available α2 -antiplasmin. No clot formed with plasma containing 40% normal α2 -antiplasmin after short incubation with TXA + uPA. Adding purified α2 -antiplasmin progressively restored clotting. Plasmin could be inhibited by aprotinin, IC50 = 530 nmol L-1 , in plasma. Conclusions Tranexamic acid protects fibrin but stimulates uPA activity and slows inhibition of plasmin by α2 -antiplasmin. Plasmin proteolytic activity digests fibrinogen and disrupts coagulation, exacerbated when α2 -antiplasmin is consumed by ongoing fibrinolysis. Additional direct inhibition of plasmin by aprotinin may prevent development of coagulopathy and extend the useful time window of TXA treatment.

Abrogating fibrinolysis does not improve bleeding or rFVIIa/rFVIII treatment in a non-mucosal venous injury model in haemophilic rodents

Essentials The efficacy of systemic antifibrinolytics for hemophilic non-mucosal bleeding is undetermined. The effect of systemically inhibiting fibrinolysis in hemophilic mice and rats was explored. Neither bleeding nor the response to factor treatment was improved after inhibiting fibrinolysis. The non-mucosal bleeding phenotype in hemophilia A appears largely unaffected by fibrinolysis.

SUMMARY

Background Fibrinolysis may exacerbate bleeding in patients with hemophilia A (HA). Accordingly, antifibrinolytics have been used to help maintain hemostatic control. Although antifibrinolytic drugs have been proven to be effective in the treatment of mucosal bleeds in the oral cavity, their efficacy in non-mucosal tissues remain an open question of significant clinical interest. Objective To determine whether inhibiting fibrinolysis improves the outcome in non-mucosal hemophilic tail vein transection (TVT) bleeding models, and to determine whether a standard ex vivo clotting/fibrinolysis assay can be used as a predictive surrogate for in vivo efficacy. Methods A highly sensitive TVT model was employed in hemophilic rodents with a suppressed fibrinolytic system to examine the effect of inhibiting fibrinolysis on bleeding in non-mucosal tissue. In mice, induced and congenital hemophilia models were combined with fibrinolytic attenuation achieved either genetically or pharmacologically (tranexamic acid [TXA]). In hemophilic rats, tail bleeding was followed by whole blood rotational thromboelastometry evaluation of the same animals to gauge the predictive value of such assays. Results The beneficial effect of systemic TXA therapy observed ex vivo could not be confirmed in vivo in hemophilic rats. Furthermore, neither intravenously administered TXA nor congenital knockout of the fibrinolytic genes encoding plasminogen or tissue-type plasminogen activator markedly improved the TVT bleeding phenotype or response to factor therapy in hemophilic mice. Conclusions The findings here suggest that inhibition of fibrinolysis is not effective in limiting the TVT bleeding phenotype of HA rodents in non-mucosal tissues.

Plasma coadministration improves resuscitation with tranexamic acid or prothrombin complex in a porcine hemorrhagic shock model

BACKGROUND

Traumatic coagulopathy has now been well characterized and carries high rates of mortality owing to bleeding. A 'factor-based' resuscitation strategy using procoagulant drugs and factor concentrates in lieu of plasma is being used by some, but with little evidentiary support. We sought to evaluate and compare resuscitation strategies using combinations of tranexamic acid (TXA), prothrombin complex concentrate (PCC), and fresh frozen plasma (FFP).

METHODS

Sixty adult swine underwent 35% blood volume hemorrhage combined with a truncal ischemia-reperfusion injury to produce uniform shock and coagulopathy. Animals were randomized to control (n = 12), a single-agent group (TXA, n = 10; PCC, n = 8; or FFP, n = 6) or combination groups (TXA-FFP, n = 10; PCC-FFP, n = 8; TXA-PCC, n = 6). Resuscitation was continued to 6 hours. Key outcomes included hemodynamics, laboratory values, and rotational thromboelastometry. Results were compared between all groups, with additional comparisons between FFP and non-FFP groups.

RESULTS

All 60 animals survived to 6 hours. Shock was seen in all animals, with hypotension (mean arterial pressure, 44 mm Hg), tachycardia (heart rate, 145), acidosis (pH 7.18; lactate, 11), anemia (hematocrit, 17), and coagulopathy (fibrinogen, 107). There were clear differences between groups for mean pH (p = 0.02), international normalized ratio (p < 0.01), clotting time (CT; p < 0.01), lactate (p = 0.01), creatinine (p < 0.01), and fibrinogen (p = 0.02). Fresh frozen plasma groups had significantly improved resuscitation and clotting parameters (Figures), with lower lactate at 6.5 versus 8.4 (p = 0.04), and increased fibrinogen at 126 versus 95 (p < 0.01). Rotational thromboelastometry also demonstrated shortened CT at 60 seconds in the FFP group vs 65 seconds in the non-FFP group (p = 0.04).

CONCLUSION

When used to correct traumatic coagulopathy, combinations of FFP with TXA or PCC were superior in improving acidosis, coagulopathy, and CT than when these agents are given alone or in combination without plasma. Further validation of pure factor-based strategies is needed.

Prevention of haematoma progression by tranexamic acid in intracerebral haemorrhage patients with and without spot sign on admission scan: a statistical analysis plan of a pre-specified sub-study of the TICH-2 trial

OBJECTIVE

We present the statistical analysis plan of a prespecified Tranexamic Acid for Hyperacute Primary Intracerebral Haemorrhage (TICH)-2 sub-study aiming to investigate, if tranexamic acid has a different effect in intracerebral haemorrhage patients with the spot sign on admission compared to spot sign negative patients. The TICH-2 trial recruited above 2000 participants with intracerebral haemorrhage arriving in hospital within 8 h after symptom onset. They were included irrespective of radiological signs of on-going haematoma expansion. Participants were randomised to tranexamic acid versus matching placebo. In this subgroup analysis, we will include all participants in TICH-2 with a computed tomography angiography on admission allowing adjudication of the participants' spot sign status.

RESULTS

Primary outcome will be the ability of tranexamic acid to limit absolute haematoma volume on computed tomography at 24 h (± 12 h) after randomisation among spot sign positive and spot sign negative participants, respectively. Within all outcome measures, the effect of tranexamic acid in spot sign positive/negative participants will be compared using tests of interaction. This sub-study will investigate the important clinical hypothesis that spot sign positive patients might benefit more from administration of tranexamic acid compared to spot sign negative patients. Trial registration ISRCTN93732214 ( http://www.isrctn.com ).

The effect of oral versus intravenous tranexamic acid in reducing blood loss after primary total hip arthroplasty: A randomized clinical trial

BACKGROUND

The purpose of this study was to determine whether the administration of multiple boluses of oral and intravenous tranexamic acid (TXA) postoperatively was equivalent in reducing blood loss in primary THA.

METHODS

A total of 108 patients were randomized into two groups: oral TXA group (54 patients receiving 1 dose of 20 mg/kg intravenous TXA 5-10 min before skin incision and 3 doses of 2 g oral TXA 4 h, 10 h and 16 h postoperatively) and intravenous TXA group (54 patients receiving 1 dose of 20 mg/kg intravenous TXA 5-10 min before skin incision and 3 doses of 1 g intravenous TXA 6 h, 12 h and 18 h postoperatively). The primary outcomes were total blood loss, hidden blood loss, length of hospital stay, hemoglobin (Hb) and hematocrit (Hct) drop. The secondary outcomes were the level of inflammation markers and complications.

RESULTS

There was no difference in the mean total blood loss or hidden blood loss [728.4 (645.8-806.9) mL vs 703.6 (576.9-832.8) mL, p = 0.745; 634.6 (552.0-715.7) mL vs 606.4 (480.1-734.5) mL, p = 0.710] and length of hospital stay was similar between the two groups. No patients received allogenic blood transfusion. The Hb and Hct drop on the first and second postoperative days were similar (p > 0.05). The level of inflammation markers did not reach statistical significance. The incidence of complications did not differ significantly between the two groups.

CONCLUSIONS

Multiple boluses of oral TXA and intravenous TXA postoperatively are equivalent in reducing blood loss, Hb and Hct drop in primary THA without increasing the risk of thromboembolic diseases and wound complications.

Tranexamic Acid Use in Prehospital Uncontrolled Hemorrhage

The use of tranexamic acid (TXA) in the treatment of trauma patients was relatively unexplored until the landmark Clinical Randomisation of an Antifibrinolytic in Significant Haemorrhage-2 (CRASH-2) trial in 2010 demonstrated a reduction in mortality with the use of TXA. Although this trial was a randomized, double-blinded, placebo-controlled study incorporating >20,000 patients, numerous limitations and weaknesses have been described. As a result, additional studies have followed, delineating the potential risks and benefits of TXA administration. A systematic review of the literature to date reveals a mortality benefit of early (ideally <1 hour and no later than 3 hours after injury) TXA administration in the treatment of severely injured trauma patients (systolic blood pressure <90 mm Hg, heart rate >110). Combined with abundant literature showing a reduction in bleeding in elective surgery, the most significant benefit may be administration of TXA before the patient goes into shock. Those trials that failed to show a mortality benefit of TXA in the treatment of hemorrhagic shock acknowledged that most patients received blood products before TXA administration, thus confounding the results. Although the use of prehospital TXA in the severely injured trauma patient will become more clear with the trauma studies currently underway, the current literature supports the use of prehospital TXA in this high-risk population. We recommend considering a 1 g TXA bolus en route to definitive care in high-risk patients and withholding subsequent doses until hyperfibrinolysis is confirmed by thromboelastography.

Tranexamic Acid in Total Hip Arthoplasty: Management of Complications and Use

Use of tranexamic acid for management of blood loss in total hip arthroplasty is growing. It is important for healthcare providers to be aware of the pharmacology, efficacy, management, complica- tions, and side effects of this medication.