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.

Tranexamic acid for the prevention of postpartum bleeding in women with anaemia: Statistical analysis plan for the WOMAN-2 trial: an international, randomised, placebo-controlled trial.

Background: Postpartum haemorrhage (PPH) is responsible for over 50,000 maternal deaths every year. Most of these deaths are in low- and middle-income countries. Tranexamic acid (TXA) reduces bleeding by inhibiting the enzymatic breakdown of fibrin blood clots. TXA decreases surgical bleeding and reduces deaths from bleeding after traumatic injury. When given within three hours of birth, TXA reduces deaths from bleeding in women with PPH. However, for many women, treatment of PPH is too late to prevent death. World-wide, over one-third of pregnant women are anaemic and many are severely anaemic. These women have an increased risk of PPH and are more likely to die if PPH occurs. There is an urgent need to identify ways to prevent severe postpartum bleeding in anaemic women. The WOMAN-2 trial will quantify the effects of TXA on postpartum bleeding in women with anaemia. Results: This statistical analysis plan (version 1.0; dated 22 February 2023) has been written based on information in the WOMAN-2 Trial protocol version 2.0, dated 30 June 2022. The primary outcome of the WOMAN-2 trial is the proportion of women with a clinical diagnosis of primary PPH. Secondary outcomes are maternal blood loss and its consequences (estimated blood loss, haemoglobin, haemodynamic instability, blood transfusion, signs of shock, use of interventions to control bleeding); maternal health and wellbeing (fatigue, headache, dizziness, palpitations, breathlessness, exercise tolerance, ability to care for her baby, health related quality of life, breastfeeding); and other health outcomes (deaths, vascular occlusive events, organ dysfunction, sepsis, side effects, time spent in higher level facility, length of hospital stay, and status of the baby). Conclusions: WOMAN-2 will provide reliable evidence about the effects of TXA in women with anaemia. Registration: WOMAN-2 was prospectively registered at the International Standard Randomised Controlled Trials registry ( ISRCTN62396133) on 07/12/2017 and ClinicalTrials.gov on 23/03/2018 ( NCT03475342).

Tranexamic acid for the prevention of postpartum bleeding: Protocol for a systematic review and individual patient data meta-analysis.

BACKGROUND: Tranexamic acid (TXA) reduces the risk of death and is recommended as a treatment for women with severe postpartum bleeding. There is hope that giving TXA shortly before or immediately after birth could prevent postpartum bleeding. Extending the use of TXA to prevent harmful postpartum bleeding could improve outcomes for millions of women; however we must carefully consider the balance of benefits and potential harms. This article describes the protocol for a systematic review and individual patient data (IPD) meta-analysis to assess the effectiveness and safety of TXA for preventing postpartum bleeding in all women giving birth, and to explore how the effects vary by underlying risk and other patient characteristics.   Methods: We will search for prospectively registered, randomised controlled trials involving 500 patients or more assessing the effects of TXA in women giving birth. Two authors will extract data and assess risk of bias. IPD data will be sought from eligible trials. Primary outcomes will be life-threatening bleeding and thromboembolic events. We will use a one-stage model to analyse the data. Subgroup analyses will be conducted to explore whether the effectiveness and safety of TXA varies by underlying risk, type birth, maternal haemoglobin (Hb), and timing of TXA. This protocol is registered on PROSPERO (CRD42022345775).  Conclusions: This systematic review and IPD meta-analysis will address important clinical questions about the effectiveness and safety of the use of TXA for the prevention of postpartum bleeding that cannot be answered reliably using aggregate data and will inform the decision of who to treat.   PROSPERO registration: CRD42022345775  Keywords   Anti-fibrinolytics; Tranexamic acid; childbirth; postpartum haemorrhage; meta-analysis.

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.

Tranexamic acid for gastrointestinal bleeding: can a reduction in the risk of death be discounted? A systematic review and meta-analysis of individual patient data from 64 724 bleeding patients.

OBJECTIVES: HALT-IT was an international, randomised trial which assessed the effects of tranexamic acid (TXA) in 12 009 patients with gastrointestinal (GI) bleeding. The results found no evidence that TXA reduces death. It is widely accepted that results of trials should be interpreted in the context of other relevant evidence. We conducted a systematic review and individual patient data (IPD) meta-analysis to assess if the results of HALT-IT are compatible with evidence for TXA in other bleeding conditions. DESIGN: Systematic review and IPD meta-analysis of randomised trials involving ≥5000 patients assessing TXA for bleeding. We searched our Antifibrinolytics Trials Register on 1 November 2022. Two authors extracted data and assessed risk of bias. DATA SYNTHESIS: We used a one-stage model to analyse IPD in a regression model stratified by trial. We assessed heterogeneity of the effect of TXA on death within 24 hours and vascular occlusive events (VOEs). RESULTS: We included IPD for 64 724 patients from four trials involving patients with traumatic, obstetric and GI bleeding. Risk of bias was low. There was no evidence for heterogeneity between trials for the effect of TXA on death or for the effect of TXA on VOEs. TXA reduced the odds of death by 16% (OR=0.84, 95% CI: 0.78 to 0.91, p<0.0001; p-heterogeneity=0.40). In patients treated within 3 hours of bleeding onset, TXA reduced the odds of death by 20% (0.80, 0.73 to 0.88, p<0.0001; p-heterogeneity=0.16). TXA did not increase the odds of VOEs (0.94, 0.81 to 1.08, p for effect=0.36; p-heterogeneity=0.27). CONCLUSIONS: There is no evidence for statistical heterogeneity between trials assessing the effect of TXA on death or VOEs in different bleeding conditions. When the HALT-IT results are considered in the context of other evidence, a reduction in the risk of death cannot be discounted. TRIAL REGISTRATION NUMBER: PROSPERO CRD42019128260.Cite Now.

Tranexamic acid for bleeding: Much more than a treatment for postpartum hemorrhage.

The evidence that early tranexamic acid treatment reduces postpartum hemorrhage deaths has major implications for obstetrical care worldwide. Tranexamic acid may also have a role in the prevention of postpartum hemorrhage, but more evidence is needed on the balance of risks and benefits. Most deaths from postpartum hemorrhage are in low- and middle-income countries where tranexamic acid treatment is often unavailable. Several maternal health organizations including the Reproductive Health Supplies Coalition, Clinton Health Access Initiative, Concept Foundation, International Federation of Gynecology and Obstetrics, and Unitaid are working to increase access. However, a wider view of the evidence on tranexamic acid and bleeding shows that it can improve maternal health in many other ways. An appreciation of these other health benefits could facilitate efforts to increase access. By reducing heavy menstrual bleeding, tranexamic acid could reduce the prevalence of maternal anemia, a common and important risk factor for postpartum hemorrhage and other maternal and neonatal outcomes. Further clinical trials of tranexamic acid for the treatment of menstrual bleeding are needed. By reducing surgical bleeding and the need for blood transfusion, tranexamic acid would increase the availability of blood in countries where there is blood shortage so that more blood is available for use in life-threatening bleeding including postpartum hemorrhage. In countries where there is no blood shortage, tranexamic acid use would reduce healthcare costs and prevent transfusion-transmitted infections and reactions. Trauma affects women and men, and violence is a leading cause of death in pregnancy. Increased use of tranexamic acid in trauma would significantly reduce trauma deaths. Efforts to increase the availability and use of tranexamic acid for obstetrical hemorrhage should acknowledge its other health benefits and aim to increase its use across health services more generally.

Tranexamic acid at cesarean delivery: drug-error deaths.

The use of tranexamic acid for postpartum hemorrhage has entered obstetrical practice globally with the evidence-based expectation of saving lives. This improvement in the care of women with postpartum hemorrhage has come at a price. For the anesthetist, having tranexamic acid ampoules close at hand would seem an obvious strategy to facilitate its use during cesarean delivery, an important setting for severe hemorrhage. Tragically, we have identified a number of recent instances of inadvertent intrathecal administration of tranexamic acid instead of local anesthetic for spinal anesthesia. Reported cases of this catastrophic error seem to be increasing. The profound neurotoxicity of tranexamic acid causes rapid-onset convulsions, with mortality of 50%. How can these tragic errors be averted? Drug safety alerts have been issued by the US Food and Drug Administration and the World Health Organization, but that is not enough. We recommend extensive dissemination of information to raise awareness of this potential hazard, and local hospital protocols to ensure that tranexamic acid is stored separately from anesthetic drugs, preferably outside the operating room and with an auxiliary warning label. Implementation of safety strategies on a very large scale will be needed to ensure that the life-saving potential of tranexamic acid is not eclipsed by drug-error mortality.

Tranexamic acid at cesarean delivery: Drug-error deaths.

The use of tranexamic acid for postpartum hemorrhage has entered obstetrical practice globally with the evidence-based expectation of saving lives. This improvement in the care of women with postpartum hemorrhage has come at a price. For the anesthetist, having tranexamic acid ampoules close at hand would seem an obvious strategy to facilitate its use during cesarean delivery, an important setting for severe hemorrhage. Tragically, we have identified a number of recent instances of inadvertent intrathecal administration of tranexamic acid instead of local anesthetic for spinal anesthesia. Reported cases of this catastrophic error seem to be increasing. The profound neurotoxicity of tranexamic acid causes rapid-onset convulsions, with mortality of 50%. How can these tragic errors be averted? Drug safety alerts have been issued by the US Food and Drug Administration and the World Health Organization, but that is not enough. We recommend extensive dissemination of information to raise awareness of this potential hazard, and local hospital protocols to ensure that tranexamic acid is stored separately from anesthetic drugs, preferably outside the operating room and with an auxiliary warning label. Implementation of safety strategies on a very large scale will be needed to ensure that the life-saving potential of tranexamic acid is not eclipsed by drug-error mortality.

Tranexamic acid at cesarean delivery: drug-error deaths.

The use of tranexamic acid for postpartum hemorrhage has entered obstetrical practice globally with the evidence-based expectation of saving lives. This improvement in the care of women with postpartum hemorrhage has come at a price. For the anesthetist, having tranexamic acid ampoules close at hand would seem an obvious strategy to facilitate its use during cesarean delivery, an important setting for severe hemorrhage. Tragically, we have identified a number of recent instances of inadvertent intrathecal administration of tranexamic acid instead of local anesthetic for spinal anesthesia. Reported cases of this catastrophic error seem to be increasing. The profound neurotoxicity of tranexamic acid causes rapid-onset convulsions, with mortality of 50%. How can these tragic errors be averted? Drug safety alerts have been issued by the US Food and Drug Administration and the World Health Organization, but that is not enough. We recommend extensive dissemination of information to raise awareness of this potential hazard, and local hospital protocols to ensure that tranexamic acid is stored separately from anesthetic drugs, preferably outside the operating room and with an auxiliary warning label. Implementation of safety strategies on a very large scale will be needed to ensure that the life-saving potential of tranexamic acid is not eclipsed by drug-error mortality.

Tranexamic acid at cesarean delivery: drug-error deaths.

The use of tranexamic acid for postpartum hemorrhage has entered obstetrical practice globally with the evidence-based expectation of saving lives. This improvement in the care of women with postpartum hemorrhage has come at a price. For the anesthetist, having tranexamic acid ampoules close at hand would seem an obvious strategy to facilitate its use during cesarean delivery, an important setting for severe hemorrhage. Tragically, we have identified a number of recent instances of inadvertent intrathecal administration of tranexamic acid instead of local anesthetic for spinal anesthesia. Reported cases of this catastrophic error seem to be increasing. The profound neurotoxicity of tranexamic acid causes rapid-onset convulsions, with mortality of 50%. How can these tragic errors be averted? Drug safety alerts have been issued by the US Food and Drug Administration and the World Health Organization, but that is not enough. We recommend extensive dissemination of information to raise awareness of this potential hazard, and local hospital protocols to ensure that tranexamic acid is stored separately from anesthetic drugs, preferably outside the operating room and with an auxiliary warning label. Implementation of safety strategies on a very large scale will be needed to ensure that the life-saving potential of tranexamic acid is not eclipsed by drug-error mortality.

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.

A cost-effectiveness and value of information analysis to inform future research of tranexamic acid for older adults experiencing mild traumatic brain injury.

BACKGROUND: Tranexamic acid reduces head injury deaths in patients with CT scan evidence of intracranial bleeding after mild traumatic brain injury (TBI). However, the cost-effectiveness of tranexamic acid for people with mild TBI in the pre-hospital setting, prior to CT scanning, is uncertain. A large randomised controlled trial (CRASH-4) is planned to address this issue, but the economic justification for it has not been established. The aim of the analysis was to estimate the likelihood of tranexamic acid being cost-effective given current evidence, the treatment effects required for cost-effectiveness, and the expected value of performing further research. METHODS: An early economic decision model compared usual care for mild TBI with and without tranexamic acid, for adults aged 70 and above. The evaluation was performed from a UK healthcare perspective over a lifetime time horizon, with costs reported in 2020 pounds (GBP) and outcomes reported as quality-adjusted life years (QALYs). All analyses used a £20,000 per QALY cost-effectiveness threshold. RESULTS: In the base case analysis, tranexamic acid was associated with an incremental cost-effectiveness ratio of £4885 per QALY gained, but the likelihood of it being cost-effective was highly dependent on the all-cause mortality treatment effect. The value of perfect information was £22.4 million, and the value of perfect information for parameters that could be collected in a trial was £21.9 million. The all-cause mortality risk ratio for tranexamic acid and the functional outcomes following TBI had the most impact on cost-effectiveness. CONCLUSIONS: There is a high degree of uncertainty in the cost-effectiveness of tranexamic acid for older adults experiencing mild TBI, meaning there is a high value of performing future research in the UK. The value in a global context is likely to be far higher.

Use of tranexamic acid in major trauma: a sex-disaggregated analysis of the Clinical Randomisation of an Antifibrinolytic in Significant Haemorrhage (CRASH-2 and CRASH-3) trials and UK trauma registry (Trauma and Audit Research Network) data.

BACKGROUND: Women are less likely than men to receive some emergency treatments. This study examines whether the effect of tranexamic acid (TXA) on mortality in trauma patients varies by sex and whether the receipt of TXA by trauma patients varies by sex. METHODS: First, we conducted a sex-disaggregated analysis of data from the Clinical Randomisation of an Antifibrinolytic in Significant Haemorrhage (CRASH)-2 and CRASH-3 trials. We used interaction tests to determine whether the treatment effect varied by sex. Second, we examined data from the Trauma and Audit Research Network (TARN) to explore sex differences in the receipt of TXA. We used logistic regression models to estimate the odds ratio for receipt of TXA in females compared with males. Results are reported as n (%), risk ratios (RR), and odds ratios (OR) with 95% confidence intervals. RESULTS: Overall, 20 211 polytrauma patients (CRASH-2) and 12 737 patients with traumatic brain injuries (CRASH-3) were included in our analysis. TXA reduced the risk of death in females (RR=0.69 [0.52-0.91]) and in males (RR=0.80 [0.71-0.90]) with no significant heterogeneity by sex (P=0.34). We examined TARN data for 216 364 patients aged ≥16 yr with an Injury Severity Score ≥9 with 98 879 (46%) females and 117 485 (54%) males. TXA was received by 7198 (7.3% [7.1-7.4%]) of the females and 19 697 (16.8% [16.6-17.0%]) of the males (OR=0.39 [0.38-0.40]). The sex difference in the receipt of TXA increased with increasing age. CONCLUSIONS: Administration of TXA to patients with bleeding trauma reduces mortality to a similar extent in women and men, but women are substantially less likely to be treated with TXA.

Postpartum haemorrhage in anaemic women: assessing outcome measures for clinical trials.

BACKGROUND: Postpartum haemorrhage (PPH) is a leading cause of maternal mortality worldwide. Maternal anaemia greatly increases the risk of PPH, and over a third of all pregnant women are anaemic. Because anaemia reduces the oxygen-carrying capacity of the blood, anaemic women cannot tolerate the same volume of blood loss as healthy women. Yet the same blood loss threshold is used to define PPH in all women. The lack of an established PPH definition in anaemic women means the most appropriate outcome measures for use in clinical trials are open to question. We used data from the WOMAN-2 trial to examine different definitions of PPH in anaemic women and consider their appropriateness as clinical trial outcome measures. MAIN BODY: The WOMAN-2 trial is assessing tranexamic acid (TXA) for PPH prevention in women with moderate or severe anaemia at baseline. To obtain an accurate, precise estimate of the treatment effect, outcome measures should be highly specific and reasonably sensitive. Some outcome misclassification is inevitable. Low sensitivity reduces precision, but low specificity biases the effect estimate towards the null. Outcomes should also be related to how patients feel, function, or survive. The primary outcome in the WOMAN-2 trial, a 'clinical diagnosis of PPH', is defined as estimated blood loss > 500 ml or any blood loss within 24 h sufficient to compromise haemodynamic stability. To explore the utility of several PPH outcome measures, we analysed blinded data from 4521 participants. For each outcome, we assessed its: (1) frequency, (2) specificity for significant bleeding defined as shock index ≥1.0 and (3) association with fatigue (modified fatigue symptom inventory [MFSI]), physical endurance (six-minute walk test) and breathlessness. A clinical diagnosis of PPH was sufficiently frequent (7%), highly specific for clinical signs of early shock (95% specificity for shock index ≥1) and associated with worse maternal functioning after childbirth. CONCLUSION: Outcome measures in clinical trials of interventions for PPH prevention should facilitate valid and precise estimation of the treatment effect and be important to women. A clinical diagnosis of PPH appears to meet these criteria, making it an appropriate primary outcome for the WOMAN-2 trial. TRIAL REGISTRATION: ClinicalTrials.gov NCT03475342, registered on 23 March 2018; ISRCTN62396133, registered on 7 December 2017; Pan African Clinical Trial Registry PACTR201909735842379, registered on 18 September 2019.

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.

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.