**6. Tranexamic acid**

Initially, its use was limited to the treatment of obstetric hemorrhages and hemophiliac patients. Subsequently, it was progressively extended to cardiac surgery and the rest of its current indications [16].

Aminocaproic acid are lysine analogs that reversibly inhibit fibrinolysis by binding to lysine binding sites on plasminogen, limiting plasmin activation, which cleaves fibrin strands [17].

A Cochrane review of the effectiveness and safety of tranexamic acid (TXA), which identified 51 studies of antifibrinolytics, found that TXA produced an RR of RBC transfusion of 0·61 (95 percent ci 0·53 to 0·70) and concluded that "lysine analogues are effective in reducing blood loss during and after surgery, and appear to be free of serious adverse effects" [17].

Dosage and dosing schedules vary depending on the clinical setting, but a 1 g dose is sufficient for most adults, with no evidence to support the use of high doses [16]. CRASH-2 (Clinical Randomization Trial of an Antifibrinolytic in significant bleeding) showed that early administration of 1 g of tranexamic acid (within 3 hours of traumatic injury) followed by a 1 g infusion over 8 hours significantly reduced the risk of death from bleeding and all-cause mortality in traumatic bleeding [17].

In cardiac interventions, the dose range was 2.5 mg/kg to 100 mg/kg, and for the maintenance dose, it was 0.25 mg/kg/h to 4.0 mg/kg/h, over 1 to 12 hours. These variations were also observed in non-cardiac surgery [18].

A meta-analysis showed that TXA significantly reduced blood loss compared with placebo; of the studies that reported the number of transfusions, administration of tranexamic acid was reported to reduce an average of 1.12 units compared with placebo and was not associated with an increase in morbidity or mortality [18].

Based on the CRASH 2 trial, CRASH 3 trial and WOMAN trial results TXA is the first choice for antifibrinolytic therapy in any hemorrhagic scenario due it effectiveness and cost/benefits evaluation [18].

The 2017 WHO recommendation on tranexamic acid for the treatment of obstetric hemorrhage states that tranexamic acid should be recognized as a life-saving intervention and readily available for the management of PPH in settings where emergency obstetric care is provided, regardless of the level of medical care system resources [19].

A meta-analysis of two trials showed that immediate treatment improved survival by >70%, and thereafter, the survival benefit decreased by 10% for each 15 min delay in treatment until 3 h, after which there was no benefit [20].

In an effort to administer TXA as early as possible, in a pre-hospital setting, its use is now supported by UK ambulance services, current research is evaluating alternative dosages and formulations, including intramuscular TXA, which appears more feasible for timely administration in emergencies [20].
