Hemostatics (hemostatic agents of local action) are bio-surgical materials that have a hemostatic effect in direct contact with damaged tissues of the body.
Normally, the human body has two balanced systems: coagulation and anti-coagulation. The first prevents prolonged profuse bleeding, the second prevents the formation of blood clots. The ability of blood to clot is an important defense mechanism that prevents death from blood loss. But he does not always cope with the task. Therefore, hemostatics are irreplaceable agents used in surgery, traumatology, disaster medicine, etc.
А group of drugs, the mechanism of action of which is aimed at accelerating blood clotting. These drugs can affect the patient's body both locally, reducing blood flow in the affected area or accelerating thrombus formation in it, and systemically, increasing the activity of thrombus formation in the entire bloodstream as a whole.
The basis for the use of drugs is the development of pathological conditions in the patient, fraught with the possibility of bleeding. A number of such drugs are used for congenital pathologies of the blood coagulation system, for example, in hemophilia.
Hemostatic drugs are drugs that help stop bleeding. All hemostatics, depending on the mechanism of action, are divided into three large groups:
fibrinolysis inhibitors (antifibrinolytics);
drugs that enhance blood clotting (coagulants);
agents that reduce vascular permeability.
In clinical practice, two groups of drugs of fibrinolysis inhibitors are widely used: natural inhibitors of fibrinolysis (aprotinin and its analogs) and synthetic inhibitors of fibrinolysis (aminocaproic acid, aminomethylbenzoic acid, tranexamic acid).
Aprotinin is a polypeptide derived from the lungs, pancreas and parotid glands of cattle, which acts similarly to α2-antiplasmin. Aprotinin destroys free plasmin, practically does not interact with bound plasmin, and also inhibits platelet activation. Being a serine protease, aprotinin blocks the kallikrein-kinin system by destroying kallikrein, reduces the activity of certain proteolytic enzymes, such as trypsin, chymotrypsin, kininogenase. Initially, the drug was included in the recommendations for the treatment of acute pancreatitis and pancreatic necrosis, but did not confirm its effectiveness, and the indications for its use were revised. [1]
Aminocaproic acid - 6-aminohexanoic acid is a synthetic derivative of lysine. By joining the lysine-binding site of plasminogen, aminocaproic acid reversibly blocks the process of fibrinolysis, reduces the activity of streptokinase, urokinase, tissue kinases, kallikrein, trypsin and hyaluronidase. A derivative of aminocaproic acid, aminomethyl benzoic acid, has a similar pharmacological effect, which is characterized by improved pharmacokinetics. Aminocaproic acid reduces the activity of thrombolytic drugs and can be used to neutralize their effect.
Tranexamic acid - trans-4- (aminomethyl) -cyclohexanecarboxylic acid - reversibly blocks the effect of plasminogen, the adhesion of leukocytes and platelets to the thrombus surface due to competitive inhibition of the plasminogen activator. It has antiallergic and anti-inflammatory effect by suppressing the formation of kinins and other active peptides involved in allergic and inflammatory reactions. In terms of the power of antifibrinolytic action, tranexamic acid is significantly superior to aminocaproic acid. The activity of the drug in plasma lasts for 7-8 hours, in tissues - up to 17 hours.
In patients with a high risk of massive blood loss in elective surgery (cardiovascular surgery, traumatology and orthopedics, transplantology), the use of fibrinolysis inhibitors reduces intraoperative blood loss and reduces the need for donor blood transfusion. Over the past 20 years, many studies have been carried out, the results of which were ambiguous: opinions were inclined in favor of aprotinin, then in favor of synthetic lysine derivatives.