Pharmacokinetics of intramuscular tranexamic acid in bleeding trauma patients: a clinical trial

Tranexamic acid for trauma: optimal timing of administration based on the CRASH-2 and CRASH-3 trials

BACKGROUND

Tranexamic acid reduces bleeding deaths in trauma patients, but the treatment benefit depends on the time from injury. It is recommended that tranexamic acid be administered immediately and only within 3 h of injury; however, the optimal criteria have not been adequately studied.

METHODS

We applied machine learning-based causal forest models to investigate heterogeneity in the effects of tranexamic acid on 24-hour mortality rate conditional on covariates (for example age, sex, time from injury, systolic blood pressure, and Glasgow Coma Scale, GCS). We analysed data on 28 448 trauma patients in the CRASH-2 and CRASH-3 randomized trials. We used the policytree algorithm to determine the optimal criteria for tranexamic acid treatment.

RESULTS

The causal forest models showed heterogeneity in the effects of tranexamic acid on 24-hour mortality rate. The relative risk reduction was greatest in patients treated within 2 h of injury but thereafter decreased rapidly. The pattern was similar regardless of age or systolic blood pressure, although with decreasing GCS, the time to treatment effects were weaker, with benefits beyond 3 h. The largest absolute risk reductions were in patients with a low blood pressure and a low GCS when treated soon after injury. The optimal criterion was statistically determined as patients within 2 h of the injury or with GCS < 9.

CONCLUSIONS

Tranexamic acid administration was found to be beneficial when given within 2 h of injury. In patients with severe traumatic brain injury, the treatment benefits may persist beyond the 2-hour window.

Oral tranexamic acid for immediate use in major trauma: implications for mass casualty events

The early administration of tranexamic acid is recognised as significantly reducing mortality in traumatically injured patients with major haemorrhage, typically given via intravenous or intramuscular routes. In the context of mass casualty events, there may exist multiple traumatically injured casualties that would benefit from tranexamic acid, however, it's administration may be delayed through the need to establish intravenous access. Additionally, if the initial assessment of the traumatically injured casualty is undertaken by an individual who cannot administer intravenous or intramuscular medications, time to administration will be further delayed. This concepts paper seeks to discuss the potential for utilising oral tranexamic acid, in the context of mass casualty events, as an alternative administration route.

Cost of the Defence Medical Services Patient Group Directive for a 10-minute tranexamic acid (TXA) infusion in trauma: a bolus is safe and saves lives

Tranexamic acid (TXA) is a life-saving drug that reduces the risk of death from haemorrhage. Intervention is time critical with benefit decreasing with delayed administration. The current Joint Service Publication Patient Group Directive (PGD) for giving TXA during the tactical field care phase of the operational patient care pathway specifies it is given over 10 min via intravenous infusion based on TXA's Summary of Product Characteristics. This paper aims to explore the risks of administering TXA as a bolus rather than a 10-minute infusion. There is little evidence to support the risk of quoted adverse events from bolus administration of TXA, good-quality evidence for the mortality benefit of early administration and some evidence that bolus dosing is safe. The Defence Medical Service should consider a default PGD of rapid TXA administration to maximise mortality benefit.

Sex and gender reporting in UK emergency medicine trials from 2010 to 2023: a systematic review

BACKGROUND

Female participants are underrepresented in randomised control trials conducted in urgent care settings. Although sex and gender are frequently reported within demographic data, it is less common for primary outcomes to be disaggregated by sex or gender. The aim of this review is to report sex and gender of participants in the primary papers published on research listed on the National Institute of Health and Care Research (NIHR) Trauma and Emergency Care (TEC) portfolio and how these data are presented.

METHODS

This is a systematic review of the published outputs of interventional trials conducted in UK EDs. Interventional trials were eligible to be included in the review if they were registered on the NIHR TEC research portfolio from January 2010, if the primary paper was published before 31 December 2023 and if the research was delivered primarily in the ED. Trials were identified through the NIHR open data platform and the primary papers were identified through specific searches using MedLine, EMBASE and PubMed. The primary objective of the review is to quantify the proportion of sex-disaggregated or gender-disaggregated primary outcomes in clinical trials within UK emergency medicine.

RESULTS

The initial search revealed 169 registered research projects on the NIHR TEC portfolio during the study period, of which 24 met the inclusion criteria. Overall, 76 719 participants were included, of which 31 374 (40%) were female. Only one trial (CRYOSTAT-2) reported a sex-disaggregated analysis of the effect of the intervention on either primary or secondary outcomes, and no sex-based difference in treatment effect was detected.

CONCLUSIONS

Fewer females than males were included in TEC trials from 2010 to 2023. One trial reported the primary outcome stratified by sex. There is significant scope to increase the scientific value of TEC trials to females by funders.

Retrospective analysis of tranexamic acid administration in French war-wounded between October 2016 and September 2020

INTRODUCTION

Since 2013, the French Army Health Service, in agreement with international experts, has recommended the administration of 1 g of tranexamic acid (TXA) in trauma patients in haemorrhagic shock or at risk of bleeding within 3 hours of the trauma.

METHODS

The aim of this analysis was to describe the administration of TXA in French military personnel wounded during military operations in the Sahelo-Sahelian band between October 2016 and September 2020. Data were collected from forward health records and hospital data from the French hospital where the casualty was finally evacuated. Underuse of TXA was defined as the lack of administration in casualties who had received a blood transfusion with one or more of red blood cells, low-titre whole blood or French lyophilised plasma within the first 24 hours of injury and overuse as its administration in the non-transfused casualty.

RESULTS

Of the 76 patients included, 75 were men with an average age of 28 years. Five patients died during their management. 19 patients received TXA (25%) and 16 patients were transfused (21%). Underuse of TXA occurred in 3 of the 16 patients (18.8%) transfused. Overuse occurred in 6 of 60 (10%) non-transfused patients.

CONCLUSION

The analysis found an important underuse of TXA (almost 20%) and highlighted the need for optimising the prehospital clinical practice guidelines to aid prehospital medical practitioners more accurately in administering TXA to casualties that will require blood products.

Mussel-inspired oxidized sodium alginate/cellulose composite sponge with excellent shape recovery and antibacterial properties for the efficient control of non-compressible hemorrhage

Enhancing the hemostatic efficacy and minimizing blood loss in the body has consistently been a primary objective for researchers. This study improved the hemostatic efficacy and tissue adhesion strength of the hemostatic material by augmenting the aldehyde groups in the side chains of sodium alginate. Additionally, it immobilized the aldehyde-modified sodium alginate onto the surface of the hemostatic material through complexation with iron ions, thereby enhancing its antibacterial properties. The mechanical performance results demonstrated that the composite hemostatic sponge can rapidly absorb water, swell to counteract arterial blood pressure, and seal the bleeding wound. The results of tissue and blood cell adhesion and in vivo hemostasis showed that the composite hemostatic sponge can enhance the rate of blood clot formation and the adhesion strength of tissue, thereby reducing the hemostasis time and blood loss. The bacterial and cell growth results demonstrated that the composite hemostatic sponge displays excellent biocompatibility and antibacterial properties. Based on the excellent water absorption, swelling properties, and softness of cellulose sponge, the composite hemostatic sponge offered a significant advantage for achieving rapid hemostasis in penetrating wounds or deep wounds with substantial bleeding.

Population pharmacokinetic modelling and simulation of tranexamic acid in adult trauma patients

AIMS

The aim of this study is to describe the disposition of tranexamic acid (TXA) in adult trauma patients and derive a dosing regimen that optimizes exposure based on a predefined exposure target.

METHODS

We performed a population pharmacokinetic (popPK) analysis of participants enrolled in the Tranexamic Acid Mechanisms and Pharmacokinetics in Traumatic Injury (TAMPITI) trial (≥18 years with traumatic injury, given ≥1 blood product and/or requiring immediate transfer to the operating room) who were randomized to a single dose of either 2 or 4 g of TXA ≤2 h from time of injury. PopPK analysis was conducted using nonlinear mixed-effects modelling (NONMEM). Simulations were then performed using the final model to generate estimated plasma TXA concentrations in 1000 simulated participants. Dosing schemes were evaluated to determine maintenance of TXA plasma concentrations >10 mg/L for ≥8 h after administration of the initial dose.

RESULTS

TXA PK was best described by a two-compartment model with proportional residual error and allometric scaling on all parameters. Platelet count, skeletal muscle oxygen saturation measured by near-infrared spectroscopy and interleukin-8 concentration were significant covariates on TXA clearance. Based on simulations, a 2 g IV bolus dose, repeated 3 h later, best achieved the target exposure.

CONCLUSIONS

According to simulations from a popPK model of TXA, a 2 g IV bolus with a repeated dose 3 h later would be most likely to maintain concentrations >10 mg/L for 8 h in >95% of adult trauma patients and should be considered for patients with ongoing haemorrhage.

Prehospital Trauma Care

Prehospital trauma evaluation begins with the primary assessment of airway, breathing, circulation, disability, and exposure. This is closely followed by vital signs and a secondary assessment. Key prehospital interventions include management and resuscitation according to the aforementioned principles with a focus on major hemorrhage control, airway compromise, and invasive management of tension pneumothorax. Determining the appropriate time and method for transportation (eg, ground ambulance, helicopter, police, private vehicle) to the hospital or when to terminate resuscitation are also important decisions to be made by emergency medical services clinicians.

Dosing of tranexamic acid in trauma

PURPOSE OF REVIEW

Tranexamic acid is routinely used as part of the management of traumatic bleeding. The dose recommendation in trauma was extrapolated from other clinical settings and the results of pragmatic randomized trials rather than pharmaco-kinetic and -dynamic evaluations. The review addresses current evidence on dosing of tranexamic acid in traumatized patients with a focus on efficacy, safety and risk-benefit profile.

RECENT FINDINGS

A majority, but not all, of existing randomized clinical trials reports a reduction in mortality and/or blood loss with tranexamic acid administration. Increasing dose above the general recommendation (1 g bolus + 1 g infusion/8 h intravenously) has not been shown to further increase efficacy and could potentially increase side effects.

SUMMARY

The benefit of tranexamic acid as adjuvant therapy in the management of bleeding trauma patients on mortality and transfusion requirements is clear and well documented, being most effective if given early and to patients with clinical signs of hemorrhagic shock. Recent reports suggest that in some patients presenting with a shutdown of their fibrinolytic pathway the administration of tranexamic acid could be associated with an increased risk of thromboembolic events and poor outcomes. A more personalized approach based on bedside assessment of fibrinolytic activation and pharmacokinetic-based dose regimen should be developed moving forward.

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.

When to use tranexamic acid for the treatment of major bleeding?

Tranexamic acid (TXA) is an antifibrinolytic agent originally developed for the management of bleeding in the setting of postpartum hemorrhage (PPH). Over the last 15 years, there has been accumulating evidence on the use of TXA for the treatment of active bleeding in a variety of clinical contexts. Clinical trials have shown that the efficacy and safety of TXA for the treatment of bleeding differ according to the clinical context in which it is being administered, timing of administration, and dose. Early administration is important for efficacy, particularly in trauma and PPH. Further studies are needed to understand the mechanisms by which TXA provides benefit, optimal modes of administration and dosing, and its effect in some clinical settings, such as spontaneous intracerebral hemorrhage. There is no evidence that TXA increases the risk of thrombotic events in patients with major bleeding overall. However, there is evidence of increased risk of venous thrombosis in patients with gastrointestinal bleeding. There is also evidence of increased risk of seizures with the use of higher doses. This review summarizes the current evidence for the use of TXA for patients with active bleeding and highlights the importance of generating evidence of efficacy and safety of hemostatic interventions specific to the bleeding contexts-as findings from 1 clinical setting may not be generalizable to other contexts-and that of individual patient assessment for bleeding, thrombotic, and other risks, as well as important logistical and other practical considerations, to optimize care and outcomes in these settings.

Intravenous tranexamic acid for intracerebral meningioma resections: A randomized, parallel-group, non-inferiority trial

STUDY OBJECTIVES

Tranexamic acid (TXA) is an antifibrinolytic that is widely used to reduce surgical bleeding. However, TXA occasionally causes seizures and the risk might be especially great after neurosurgery. We therefore tested the hypothesis that TXA does not meaningfully increase the risk of postoperative seizures within 7 days after intracranial tumor resections.

DESIGN

Randomized, double-blind, placebo-controlled, non-inferiority trial.

SETTING

Beijing Tiantan Hospital, Capital Medical University.

PATIENTS

600 patients undergoing supratentorial meningioma resection were included from October 2020 to August 2022.

INTERVENTIONS

Patients were randomly assigned to a single dose of 20 mg/kg of TXA after induction (n = 300) or to the same volume of normal saline (n = 300).

MEASUREMENT

The primary outcome was postoperative seizures occurring within 7 days after surgery, analyzed in both the intention-to-treat and per-protocol populations. Non-inferiority was defined by an upper limit of the 95% confidence interval for the absolute difference being <5.5%. Secondary outcomes included incidence of non-epileptic complication within 7 days, changes in hemoglobin concentration, estimated intraoperative blood loss. Post hoc analyses included the types and timing of seizures, oozing assessment, and a sensitivity analysis for the primary outcome in patients with pathologic diagnosis of meningioma.

MAIN RESULTS

All 600 enrolled patients adhered to the protocol and completed the follow-up for the primary outcome. Postoperative seizures occurred in 11 of 300 (3.7%) of patients randomized to normal saline and 13 of 300 (4.3%) patients assigned to tranexamic acid (mean risk difference, 0.7%; 1-sided 97.5% CI, -∞ to 4.3%; P = 0.001 for noninferiority). No significant differences were observed in any secondary outcome. Post hoc analysis indicated similar amounts of oozing, calculated blood loss, recurrent seizures, and timing of seizures.

CONCLUSION

Among patients having supratentorial meningioma resection, a single intraoperative dose of TXA did not significantly reduce bleeding and was non-inferior with respect to postoperative seizures after surgery.

REGISTRY INFORMATION

This trial was registered at clinicaltrials.gov (NCT04595786) on October 22, 2020, by Dr.Yuming Peng.

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.

The Role of Tranexamic Acid in Sleeve Gastrectomy: A Systematic Review and Meta-Analysis

Tranexamic acid (TXA) is an essential procoagulant drug used in various intra- and postoperative situations. Its efficacy and safety profile in obese cases undergoing laparoscopic sleeve gastrectomy (LSG) is still unresolved. Therefore, this meta-analysis evaluated and investigated the current intra- and postoperative effects and hazards of TXA on patients undergoing LSG. As for methodology, Web of Science, Cochrane Library, Scopus, and PubMed were thoroughly searched for relevant studies. Retrieved results were prepared for screening through Endnote, helping to identify eligible studies. Relevant patient characteristics and outcomes were extracted. The methodological quality of the relevant studies was appraised using the respected appraisal tool. Six studies of different designs were enrolled, comprising 753 cases that underwent LSG and administered TXA. Their mean BMI and age went from 37.3 to 56.25 kg/m2 and 33.5 to 43.25 years, respectively. Tranexamic acid significantly linked to reduction in intraoperative bleeding instances, operative blood loss, and operative duration, compared to placebo ((RR = 0.66, 95% CI [0.44, 0.98], P=0.04, I2 = 81%); (MD = -39.64, 95%CI [-75.49, -3.78], P=0.03, I2=94%); (MD=-5.84, 95%CI [-9.62, -2.05], P=0.003, I2=73%)). Tranexamic acid also significantly showed superiority regarding postoperative bleeding events and duration of hospitalization compared to the control group ((RR= 0.45, 95%CI [0.29, 0.69], P=0.0002, I2 =0%); (MD=-0.24, 95%CI [-0.32, -0.17], P< 0.0000, I2 =0%)). Moreover, follow-up of the enrolled patients for a minimum of three to six months resulted in no reported thromboembolic instances, suggesting a negligible risk for thromboembolism among patients undergoing LSG and receiving TXA. In conclusion, tranexamic acid demonstrates a robust safety and efficacy profile for its use in patients undergoing LSG, with no reported instances of thromboembolism. Variations in TXA administration regimens, bleeding definitions, procedural techniques, and potential confounding medications could not be accounted for, necessitating additional large-scale RCTs to address and bridge knowledge gaps.

A comparative analysis of tranexamic acid dosing strategies in traumatic major hemorrhage

INTRODUCTION

Tranexamic acid (TXA) is a life-saving treatment for traumatic hemorrhage, but the optimal dosing regimen remains unknown. Different doses and treatment strategies have been proposed, including single bolus, repeated bolus, or bolus plus infusion. The aim of this study was to determine the effect of different TXA dosing strategies on clinical outcomes in bleeding trauma patients.

METHODS

Secondary analysis of a perpetual cohort study from a UK Level I trauma center. Adult patients who activated the local major hemorrhage protocol and received TXA were included. The primary outcome was 28-day mortality. Secondary outcomes were 24-hour mortality, multiple organ dysfunction syndrome, venous thromboembolism, and rotational thromboelastometry fibrinolysis.

RESULTS

Over an 11-year period, 525 patients were included. Three dosing groups were identified: 1 g bolus only (n = 317), 1 g bolus +1 g infusion over 8 hours (n = 80), and 2 g bolus (n = 128). Demographics and admission physiology were similar, but there were differences in injury severity (median Injury Severity Score, 25, 29, and 25); and admission systolic blood pressure (median Systolic Blood Pressure, 99, 108, 99 mm Hg) across the 1-g, 1 g + 1 g, and 2-g groups. 28-day mortality was 21% in each treatment group. The incidence of multiple organ dysfunction syndrome was significantly higher in the bolus plus infusion group (84%) vs. 1 g bolus (64%) and 2 g bolus (62%) group, p = 0.002, but on multivariable analysis was nonsignificant. Venous thromboembolism rates were similar in the 1-g bolus (4%), 2 g bolus (8%) and bolus plus infusion groups (7%). There was no difference in rotational thromboelastometry maximum lysis at 24 hours: 5% in both the 1-g and 2-g bolus groups vs. 4% in bolus plus infusion group.

CONCLUSION

Clinical outcomes and 24-hour fibrinolysis state were equivalent across three different dosing strategies of TXA. Single bolus administration is likely preferable to a bolus plus infusion regimen.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level III.

Tranexamic acid by the intramuscular or intravenous route for the prevention of postpartum haemorrhage in women at increased risk: a randomised placebo-controlled trial (I'M WOMAN)

BACKGROUND

Postpartum haemorrhage (PPH) causes about 70,000 maternal deaths every year. Tranexamic acid (TXA) is a life-saving treatment for women with PPH. Intravenous (IV) TXA reduces deaths due to PPH by one-third when given within 3 h of childbirth. Because TXA is more effective when given early and PPH usually occurs soon after childbirth, giving TXA just before childbirth might prevent PPH. Although several randomised trials have examined TXA for PPH prevention, the results are inconclusive. Because PPH only affects a small proportion of births, we need good evidence on the balance of benefits and harms before using TXA to prevent PPH. TXA is usually given by slow IV injection. However, recent research shows that TXA is well tolerated and rapidly absorbed after intramuscular (IM) injection, achieving therapeutic blood levels within minutes of injection.

METHODS

The I'M WOMAN trial is an international, multicentre, three-arm, randomised, double-blind, placebo-controlled trial to assess the effects of IM and IV TXA for the prevention of PPH in women with one or more risk factors for PPH giving birth vaginally or by caesarean section.

DISCUSSION

The trial will provide evidence of the benefits and harms of TXA for PPH prevention and the effects of the IM and IV routes of administration. The IM route should be as effective as the IV route for preventing bleeding. There may be fewer side effects with IM TXA because peak blood concentrations are lower than with the IV route. IM TXA also has practical advantages as it is quicker and simpler to administer. By avoiding the need for IV line insertion and a slow IV injection, IM administration would free up overstretched midwives and doctors to focus on looking after the mother and baby and expand access to timely TXA treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05562609. Registered on 3 October 2022. ISRCTN Registry ISRCTN12590098. Registered on 20 January 2023. Pan African Clinical Trial Registry PACTR202305473136570. Registered on 18 May 2023.

HOW SHOULD TRANEXAMIC ACID BE ADMINISTERED IN HEMORRHAGIC SHOCK? CONTINUOUS SERUM CONCENTRATION MEASUREMENTS IN A SWINE MODEL

ABSTRACT

Background : Tranexamic acid (TXA) reduces mortality in trauma patients. Intramuscular (IM) administration could be advantageous in low-resource and military settings. Achieving the same serum concentration as intravenous (IV) administration is important to achieve equal mortality reduction. Therefore, we aimed to investigate whether dividing an IM dose of TXA between two injection sites and whether an increase in dose would lead to serum concentrations comparable to those achieved by IV administration. Methods : Norwegian landrace pigs (n = 29) from a course in hemostatic emergency surgery were given TXA 1 h after start of surgery. Blood samples were drawn at 0, 5, 10, 15, 20, 25, 35, 45, 60, and 85 min. The samples were centrifuged and serum TXA concentrations quantified with liquid chromatography-tandem mass spectrometry. The use of two injection sites was compared with distributing the dose on one injection site, and a dose of 15 mg/kg was compared with a dose of 30 mg/kg. All IM groups were compared with IV administration. Results : The groups were in a similar degree of shock. Increasing the IM dose from the standard of 15 mg/kg to 30 mg/kg resulted in significantly higher serum concentrations of TXA, comparable to those achieved by IV administration. Distributing the IM dose on two injection sites did not affect drug uptake, as shown by equal serum concentrations. Conclusions : For IM administration of TXA, 30 mg/kg should be the standard dose. With a short delay, IM administration will provide equal serum concentrations as IV administration, above what is considered necessary to inhibit fibrinolysis.

Alternative routes for tranexamic acid treatment in obstetric bleeding (WOMAN-PharmacoTXA trial): a randomised trial and pharmacological study in caesarean section births

OBJECTIVE

To examine the safety, efficacy and pharmacology of intravenous (IV), intramuscular (IM) and oral tranexamic acid (TXA) use in pregnant women.

DESIGN

Randomised, open-label trial.

SETTING

Hospitals in Pakistan and Zambia.

POPULATION

Women giving birth by caesarean section.

METHODS

Women were randomised to receive 1 g IV, 1 g IM, 4 g oral TXA or no TXA. Adverse events in women and neonates were recorded. TXA concentration in whole blood was measured and the concentrations over time were examined with population pharmacokinetics. The relationship between drug exposure and D-dimer was explored. The trial registration is NCT04274335.

MAIN OUTCOME MEASURES

Concentration of TXA in maternal blood.

RESULTS

Of the 120 women included in the randomised safety study, there were no serious maternal or neonatal adverse events. TXA concentrations in 755 maternal blood and 87 cord blood samples were described by a two-compartment model with one effect compartment linked by rate transfer constants. Maximum maternal concentrations were 46.9, 21.6 and 18.1 mg/L for IV, IM and oral administration, respectively, and 9.5, 7.9 and 9.1 mg/L in the neonates. The TXA response was modelled as an inhibitory effect on the D-dimer production rate. The half-maximal inhibitory concentration (IC50 ) was 7.5 mg/L and was achieved after 2.6, 6.4 and 47 minutes with IV, IM and oral administration of TXA, respectively.

CONCLUSIONS

Both IM and oral TXA are well tolerated. Oral TXA took about 1 hour to reach minimum therapeutic concentrations and would not be suitable for emergency treatment. Intramuscular TXA inhibits fibrinolysis within 10 minutes and may be a suitable alternative to IV.

Prehospital tranexamic acid for trauma victims

The public enquiry into the mass casualty incident at the Manchester Arena in the UK in which 23 people died and over 1000 were injured, identified the need for timely intramuscular administration of tranexamic acid to trauma patients. Since then, a number of studies and trials have been carried out and UK paramedics are now authorized to give intramuscular tranexamic acid in the pre-hospital setting. In Japan, pre-hospital administration by emergency life-saving technicians is not yet authorized, despite the fact that tranexamic acid was invented by Japanese scientists. In Japan, the need for the pre-hospital administration of tranexamic acid has been raised on several occasions, where a patient died from traumatic bleeding prior to hospital admission. This paper summarizes the evidence on the use of tranexamic acid in patients with traumatic bleeding, including new evidence on the intramuscular route.

Should pre-hospital intramuscular tranexamic acid be given to trauma patients at risk of significant haemorrhage?

There are situations in the pre-hospital setting where gaining intravenous or intraosseous access is impossible or delayed. This can delay the administration of tranexamic acid to bleeding trauma patients, which may reduce its effectiveness. We sought to investigate whether some patients would benefit from early administration of tranexamic acid via the intramuscular route. Relevant observational and interventional studies were identified and summarised using a BestBET format. The current evidence supports clinicians considering intramuscular tranexamic acid in trauma patients at risk of haemorrhage when there may be significant delay in administration via intravenous or intraosseous routes.

Major haemorrhage: past, present and future

Major haemorrhage is a leading cause of morbidity and mortality worldwide. Successful treatment requires early recognition, planned responses, readily available resources (such as blood products) and rapid access to surgery or interventional radiology. Major haemorrhage is often accompanied by volume loss, haemodilution, acidaemia, hypothermia and coagulopathy (factor consumption and fibrinolysis). Management of major haemorrhage over the past decade has evolved to now deliver a 'package' of haemostatic resuscitation including: surgical or radiological control of bleeding; regular monitoring of haemostasis; advanced critical care support; and avoidance of the lethal triad of hypothermia, acidaemia and coagulopathy. Recent trial data advocate for a more personalised approach depending on the clinical scenario. Fresh frozen plasma should be given as early as possible in major trauma in a 1:1 ratio with red blood cells until the results of coagulation tests are available. Tranexamic acid is a cheap, life-saving drug and is advocated in major trauma, postpartum haemorrhage and surgery, but not in patients with gastrointestinal bleeding. Fibrinogen levels should be maintained > 2 g.l-1 in postpartum haemorrhage and > 1.5 g.l-1 in other haemorrhage. Improving outcomes after major traumatic haemorrhage is now driving research to include extending blood-product resuscitation into prehospital care.

Intramuscular Tranexamic Acid Administration on the Battlefield

Background

Tranexamic acid (TXA) is routinely administered intravenously (IV) and intraosseously (IO) in response to exsanguination.

Case

This report describes a patient who sustained multiple high-powered rifle gunshot wounds that received battlefield-environment intramuscular (IM) administration of TXA due to inability to obtain IV / IO access. This case represents the unlikely positive outcome in the setting of multiple remarkable obstacles, which may have been ameliorated by novel administration of TXA.

Conclusion

Cases of IM TXA administration as a primary intervention are not well represented in the current body of medical literature. This case report highlights a clinical scenario where IM TXA was utilized as part of first-line treatment that led to a positive clinical outcome. Although IM TXA is not yet endorsed by current trauma guidelines, this case suggests that IM route administration of TXA should be further investigated. If indeed IM administration of TXA proves just as efficacious as alternative routes, this would hold considerable advantageous implications for austere situations were sterility and IV / IO placement are impractical. This would also represent another avenue by which to decrease the time-to-TXA for patients, allowing sooner correction of hemorrhage and trauma-associated coagulopathy.

Antifibrinolytics in the treatment of traumatic brain injury

PURPOSE OF REVIEW

Traumatic brain injury (TBI) is a leading cause of trauma-related deaths, and pharmacologic interventions to limit intracranial bleeding should improve outcomes. Tranexamic acid reduces mortality in injured patients with major systemic bleeding, but the effects of antifibrinolytic drugs on outcomes after TBI are less clear. We therefore summarize recent evidence to guide clinicians on when (not) to use antifibrinolytic drugs in TBI patients.

RECENT FINDINGS

Tranexamic acid is the only antifibrinolytic drug that has been studied in patients with TBI. Several recent studies failed to conclusively demonstrate a benefit on survival or neurologic outcome. A large trial with more than 12 000 patients found no significant effect of tranexamic acid on head-injury related death, all-cause mortality or disability across the overall study population, but observed benefit in patients with mild to moderate TBI. Observational evidence signals potential harm in patients with isolated severe TBI.

SUMMARY

Given that the effect of tranexamic acid likely depends on a variety of factors, it is unlikely that a 'one size fits all' approach of administering antifibrinolytics to all patients will be helpful. Tranexamic acid should be strongly considered in patients with mild to moderate TBI and should be avoided in isolated severe TBI.

Appraising the use of tranexamic acid in traumatic and non-traumatic intracranial hemorrhage: A narrative review

Recently there has been increasing interest and debate on the use of tranexamic acid (TXA), an antifibrinolytic drug, in both traumatic and non-traumatic intracranial hemorrhage. In this review we aim to discuss recent investigations looking at TXA in traumatic brain injury (TBI) and different categories of spontaneous intracranial hemorrhage. We also discuss differences between setting (hospital vs pre-hospital), dosing and timing strategies, and other logistical challenges surrounding optimal use of TXA for isolated intracranial hemorrhage. Last, we hope to provide guidance for clinicians when considering the use of TXA in a patient with traumatic or non-traumatic intracranial hemorrhage based on appraisal of the available literature as well as some potential ideas for future research in this area.

Effects of tranexamic acid treatment in severely and non-severely injured trauma patients

BACKGROUND

Urgent treatment with tranexamic acid (TXA) reduces bleeding deaths but there is disagreement about which patients should be treated. We examine the effects of TXA treatment in severely and non-severely injured trauma patients.

STUDY DESIGN AND METHODS

We did an individual patient data meta-analysis of randomized trials with over 1000 trauma patients that assessed the effects of TXA on survival. We defined the severity of injury according to characteristics at first assessment: systolic blood pressure of less than 90 mm Hg and a heart rate greater than 120 beats per minute or Glasgow Coma Scale score of less than nine or any GCS with one or more fixed dilated pupils. The primary measure was survival on the day of the injury. We examined the effect of TXA on survival in severely and non-severely injured patients and how these effects vary with the time from injury to treatment.

RESULTS

We obtained data for 32,944 patients from two randomized trials. Tranexamic acid significantly increased survival on the day of the injury (OR = 1.22, 95% CI 1.11-1.34; p < .01). The effect of tranexamic acid on survival in non-severely injured patients (OR = 1.25, 1.03-1.50) was similar to that in severely injured patients (OR = 1.22, 1.09-1.37) with no significant heterogeneity (p = .87). In severely and non-severely injured pateints, treatment within the first hour after injury was the most effective.

DISCUSSION

Early tranexamic acid treatment improves survival in both severely and non-severely injured trauma patients. Its use should not be restricted to the severely injured.

Alternative routes to intravenous tranexamic acid for postpartum hemorrhage: A systematic search and narrative review

OBJECTIVE

To review available data on tranexamic acid (TXA) plasma concentration needed to inhibit fibrinolysis and the time to achieve this concentration when giving TXA by different routes in humans. To identify ongoing trials assessing alternatives to intravenous TXA administration.

METHODS

We updated two previous systematic reviews by searching MEDLINE, EMBASE, OviSP, and ISI Web of Science from database inception to July 2021. We also searched the WHO International Clinical Trials Registry Platform for ongoing trials to July 2021. Titles and abstracts were screened for relevant trials. Two reviewers independently reviewed and agreed the trials to be included.

RESULTS

Plasma TXA concentrations over 10 mg/L provide near maximal inhibition of fibrinolysis, with concentrations over 5 mg/L providing partial inhibition. Oral TXA tablets take about 1 h to reach a plasma concentration of 5 mg/L in postpartum women. Studies in healthy volunteers and shocked trauma patients show that intramuscular TXA achieves a plasma level of over 10 mg/L within 15 min. One trial is ongoing to determine the pharmacokinetics of intramuscular and oral solution TXA in pregnant women.

CONCLUSION

Intramuscular TXA in healthy volunteers and shocked trauma patients reaches therapeutic concentration rapidly. Oral TXA tablets take too long to reach the minimum therapeutic concentration in postpartum women.

Pharmacokinetics of tranexamic acid after intravenous, intramuscular, and oral routes: a prospective, randomised, crossover trial in healthy volunteers

BACKGROUND

In response to the World Health Organization call for research on alternative routes for tranexamic acid (TXA) administration in women with postpartum haemorrhage, we examined the pharmacokinetics of TXA after i.v., i.m., or oral administration.

METHODS

We conducted a randomised, open-label, crossover trial in 15 healthy volunteers who received i.v. TXA 1 g, i.m. TXA 1 g, or oral TXA solution 2 g. Blood samples were drawn up to 24 h after administration. Tranexamic acid concentration was measured with liquid chromatography-mass spectrometry, and the parameters of the pharmacokinetic models were estimated using population pharmacokinetics.

RESULTS

The median time to reach a concentration of 10 mg L^-1 was 3.5 min for the i.m. route and 66 min for the oral route, although with the oral route the target concentration was reached in only 11 patients. Median peak concentrations were 57.5, 34.4, and 12.8 mg L^-1 for i.v., i.m., and oral routes, respectively. A two-compartment open model with body weight as the main covariate best fitted the data. For a 70 kg volunteer, the population estimates were 10.1 L h^-1 for elimination clearance, 15.6 L h^-1 for intercompartmental clearance, 7.7 L for the volume of central compartment, and 10.8 L for the volume of the peripheral compartment. Intramuscular and oral bioavailabilities were 1.0 and 0.47, respectively, showing that i.m. absorption is fast and complete. Adverse events were mild and transient, mainly local reactions and low-intensity pain.

CONCLUSIONS

The i.m. (but not oral) route appears to be an efficient alternative to i.v. tranexamic acid. Studies in pregnant women are needed to examine the impact of pregnancy on the pharmacokinetics.

CLINICAL TRIAL REGISTRATION

EudraCT 2019-000285-38; NCT03777488.

Intramuscular uptake of tranexamic acid during haemorrhagic shock in a swine model

Background

Tranexamic acid (TXA) reduce mortality in bleeding trauma patients, with greater effect if administered early. Serum concentrations above 10 µg/mL are considered sufficient to inhibit fibrinolysis. Normally administered intravenously (i.v.), TXA can also be administered intramuscularly (i.m.). This could be advantageous in low resource and military settings, if sufficient serum concentrations can be reached in shocked patients with reduced muscular blood perfusion. Accordingly, we aimed to: (1) Determine the impact of shock on the pharmacokinetics of i.m. TXA, and (2) Compare the pharmacokinetics of i.v. versus i.m. TXA in ongoing shock.

Materials and methods

In a prospective experimental study, N = 18 Norwegian landrace pigs (40–50 kg), utilised in a surgical course in haemostatic emergency surgery, were subjected to various abdominal and thoracic trauma. After 1 h of surgery the animals were given 15 mg/kg TXA either i.v. or i.m. A control group without injury, or surgery, received intramuscular TXA. Blood samples were drawn at 0, 5, 15, 25, 35, 45, 60 and 85 min. The samples were centrifuged and analysed with liquid chromatography–tandem mass spectrometry (LC–MS/MS) for TXA serum-concentrations.

Results

In shocked pigs, i.m. administration resulted in a mean maximum serum concentration (C_max) of 20.9 µg/mL, and i.v. administration a C_max of 48.1 µg/mL. C_max occurred 15 min after i.m. administration and 5 min after i.v. administration. In non-shocked swine, i.m. administration resulted in a C_max of 36.9 µg/mL after 15 min. In all groups, mean TXA serum concentrations stayed above 10 µg/mL from administration to end of experiments.

Conclusions

I.m. administration of TXA in shocked pigs provides serum concentrations associated with inhibition of fibrinolysis. It may be an alternative to i.v. and intraosseous administration during stabilisation and transport of trauma patients to advanced medical care.

Clinical Validation of a Volumetric Absorptive Micro-Sampling Device for Pharmacokinetic Studies With Tranexamic Acid

We assessed the accuracy of tranexamic acid (TXA) concentrations measured in capillary whole blood using volumetric absorptive micro-sampling (VAMS) devices. Paired venous and VAMS capillary blood samples were collected from 15 healthy volunteers participating in a pharmacokinetic study of alternative routes (oral, IM and IV) of administering TXA. To assess accuracy across a range of concentrations, blood was drawn at different times after TXA administration. We measured TXA concentrations in plasma, whole blood from samples collected by venepuncture and whole blood from venous and capillary samples collected using VAMS devices. TXA was measured using a validated high sensitivity liquid chromatography - mass spectrometry method. We used Bland-Altman plots to describe the agreement between the TXA concentrations obtained with the different methods. In the 42 matched samples, the mean plasma TXA concentration was 14.0 mg/L (range 2.6-36.5 mg/L) whereas the corresponding whole blood TXA concentration was 7.7 mg/L (range 1.6-17.5 mg/L). When comparing TXA concentrations in VAMS samples of venous and capillary whole blood, the average bias was 0.07 mg/L (lower and upper 95% limits of agreement: -2.1 and 2.2 mg/L respectively). When comparing TXA concentrations in venous whole blood and VAMS capillary whole blood, the average bias was 0.7 mg/L (limits of agreement: -2.7 and 4.0 mg/L). Volumetric absorptive micro-sampling devices are sufficiently accurate for use in pharmacokinetic studies of tranexamic acid treatment in the range of plasma concentrations relevant for the assessment of fibrinolysis inhibition.

WOMAN-PharmacoTXA trial: Study protocol for a randomised controlled trial to assess the pharmacokinetics and pharmacodynamics of intramuscular, intravenous and oral administration of tranexamic acid in women giving birth by caesarean section

Background: Intravenous tranexamic acid (TXA) within 3 hours of birth significantly reduces death due to bleeding in women with postpartum haemorrhage (PPH). Most PPH deaths occur in the first hours after giving birth and treatment delay decreases survival.  One barrier to rapid TXA treatment is the need for intravenous injection. Intramuscular injection and oral solution of TXA would be easier and faster to administer and would require less training. However, the pharmacokinetics (PK), pharmacodynamics and safety of TXA administered by different routes in pregnant women have not been established. The main aim of this study is to ascertain whether IM and oral solution of TXA will be absorbed at levels sufficient to inhibit fibrinolysis in pregnant women.

Methods: WOMAN-PharmacoTXA is a prospective, randomised, open label trial to be conducted in Zambia and Pakistan.  Adult women undergoing caesarean section with at least one risk factor for PPH will be included.  Women will be randomised to receive one of the following about 1 hour prior to caesarean section: 1-gram TXA IV, 1-gram TXA IM, 4-grams TXA oral solution or no TXA. Randomisation will continue until 120 participants with at least six post randomisation PK samples are included. TXA concentration in maternal blood samples will be measured at baseline and at different time points during 24 hours after receipt of intervention. Blood TXA concentration will be measured from the umbilical cord and neonate.

The primary endpoint is maternal blood TXA concentrations over time. Secondary outcomes include umbilical cord and neonate TXA concentration D-dimer concentration, blood loss and clinical diagnosis of PPH, injection site reactions and maternal and neonate adverse events.

Discussion: The WOMAN-PharmacoTXA trial will provide important data on pharmacokinetics, pharmacodynamics and safety of TXA after IV, intramuscular and oral administration in women giving birth by caesarean section.

Trial registration: ClincalTrials.gov, NCT04274335 (18/02/2020).

Tranexamic Acid Treatment for Trauma Victims

Worldwide, traumatic injury is responsible for over 5 million deaths per year, the majority due to exsanguination and head injury. The antifibrinolytic drug tranexamic acid is the only drug proven to reduce deaths after traumatic injury. Several large randomized controlled trials have provided high-quality evidence of its effectiveness and safety in trauma patients. Early tranexamic acid reduces deaths on the day of the injury in polytrauma patients and patients with isolated traumatic brain injury by around 20%. Treatment is time critical; for patients to benefit, tranexamic acid must be given as soon as possible after injury. Intramuscular administration is well tolerated and rapidly absorbed, with the potential to reduce time to treatment. Because the proportional reduction in bleeding death with tranexamic acid does not vary by baseline risk, a wide range of trauma patients stands to benefit. There are far more low-risk trauma patients than high-risk patients, with a substantial proportion of bleeding deaths in the low-risk group. As such, treatment should not be limited to patients with severe traumatic hemorrhage. We must give paramedics and physicians the confidence to treat a far wider range of trauma patients while emphasizing the importance of early treatment.

Validation of the BATT score for prehospital risk stratification of traumatic haemorrhagic death: usefulness for tranexamic acid treatment criteria

BACKGROUND

Tranexamic acid reduces surgical blood loss and reduces deaths from bleeding in trauma patients. Tranexamic acid must be given urgently, preferably by paramedics at the scene of the injury or in the ambulance. We developed a simple score (Bleeding Audit Triage Trauma score) to predict death from bleeding.

METHODS

We conducted an external validation of the BATT score using data from the UK Trauma Audit Research Network (TARN) from 1st January 2017 to 31st December 2018. We evaluated the impact of tranexamic acid treatment thresholds in trauma patients.

RESULTS

We included 104,862 trauma patients with an injury severity score of 9 or above. Tranexamic acid was administered to 9915 (9%) patients. Of these 5185 (52%) received prehospital tranexamic acid. The BATT score had good accuracy (Brier score = 6%) and good discrimination (C-statistic 0.90; 95% CI 0.89-0.91). Calibration in the large showed no substantial difference between predicted and observed death due to bleeding (1.15% versus 1.16%, P = 0.81). Pre-hospital tranexamic acid treatment of trauma patients with a BATT score of 2 or more would avoid 210 bleeding deaths by treating 61,598 patients instead of avoiding 55 deaths by treating 9915 as currently.

CONCLUSION

The BATT score identifies trauma patient at risk of significant haemorrhage. A score of 2 or more would be an appropriate threshold for pre-hospital tranexamic acid treatment.