Anticoagulants (Anticoagulantia; from the Greek. anti - against and lat. coagulatio - fold) - substances which inhibit the activity of the blood coagulation system. Anticoagulants are used in clinical and experimental practice for the prevention of thrombosis, thromboembolism, and a quick stop further thrombosis and growth of a thrombus in cases where it has already occurred.
Anticoagulants is conventionally divided into the following groups. 1. The anti-self: heparin (see) and geparinoida - substances, acting like heparin, but differ in chemical structure. A. this group inhibit the clotting of blood as in the organism and in vitro. When intravenous effect occurs immediately and lasts for 4 - 6 hours. Less effective introduction of the skin and intramuscularly. 2. A. indirect action: derivatives of 4-oksikumarina - dikumarina (see), neodikumarin (see), or plantan, warfarin, singular, Naharin (see) and others, and derivative indandion - fenilin (see), omifin (see) and others. A. These inhibit the clotting of blood only in the body. Apply through the mouth, rarely rectal and intravenously (in the form of soluble salts).
The effect occurs within 24 to 72 hours. and continues to several days, and therefore these anticoagulants more convenient for long-term treatment. Anticoagulants are also salt rare-earth metals: trombozam (salt neodymium and sulfosalicylic acid), heliodon (salt neodymium, praseodymium and P-acetylamino acid), and other intravenous in the form of aqueous solutions of effect occurs in 5-15 minutes, reaches through 1-1 .5 hours and lasts about a day. In the USSR these preparations application is not found. Salt of lemon and oxalic acids (citrate and oxalate sodium) are used in laboratory practice for the prevention of blood clotting in vitro. Translating ions CA (IV coagulation factor) in multiscaleimage connection, they delay the clotting of blood.
The mechanism of action. In the pathogenesis of thrombosis along with the change in the activity of the blood coagulation system play an important role violations in anticoagulative system of the body (fibrinolytic enzymes, antitrombina, antitrombogenny, heparin and other), the status of the walls of blood vessels, blood flow and functional status of platelets and other body functions.
Inhibiting the activity of the blood coagulation system, anticoagulants to reduce the possibility of blood clots. However, the use of anticoagulants is not the only way of struggle with brain. The most successful prevention and treatment of thrombosis may be simultaneous effect on different stages of pathogenesis of thrombosis. When already raised blood clot important addition to A. are fibrinolytic funds (fibrinolizin, streptokinase, urokinase, trypsin and other).
The anticoagulant effect of heparin and geparinoidam due antitrombinom (antitrombogenny), antitrombinom, antitrombinom the influence; they inhibit the formation of fibrin, prevent agglutination of blood platelets. Heparin - physiological A. formed in the body; it is part of the physiological anticoagulative system.
Anticoagulants of indirect action are also vitamin K antagonists and in sufficient dosage violate biosynthesis of clotting factors [II (prothrombin), VII (proconvertin), IX (Christmas-factor), X (Stewart-prayer factor or factor Koller)], metabolism of which is connected with participation of vitamin K. From dikumarina, warfarin, Navarin, marcumar effect occurs slowly, but continues the long-term; these substances have a more pronounced cumulative effect. Singular and neodikumarin act faster, but shorter.
The reaction of patients to A. has individual differences in terms of quick onset of action, and the degree of influence. It is of some significance and character of the diet in patients receiving A. it is Experimentally shown that the effect of anticoagulants is sharper and their toxic dose is lower when you eat foods with a low content of fat. The relatively large latent period, characteristic A. indirect action, making it appropriate on the first day of treatment to combine them with heparin, geparinoidam or drugs rare-earth metals. Salts of rare-earth metals inhibit the activity II, VII and X of blood clotting factors. A. these combine fast acting peculiar to heparin, with a duration of effect, approaching that of A. indirect action. Rare earth metals than heparin.
Along with the impact on blood clotting anticoagulants have other side-effects: reduction of the resistance of the capillaries, spasmolytic effect, the expansion of the coronary vessels of the heart, lowering cholesterol and p-lipoproteins in the blood and other Conflicting reports about their impact on fibrinolytic activity of blood.
The readings. The major indication for the use of A. - tromboobrazovania warning or increase an already existing clot (see below - Clinical application A.).
Anticoagulants, in particular heparin may be used and instrumental examination of vessels, vehicles, surface which is in contact with blood, in laboratory practice.
Contraindications for application of anti - see Clinical application A.
Side effects, possible complications and their treatment. Application A. requires strict laboratory control for blood clotting. Treatment A. appointed in sufficient number, inefficient, and an overdose can be accompanied by the development of complications, including hemorrhagic associated with a decrease not only in blood clotting, but resistance capillaries, increase their permeability. Such complications may occur in the form of mikrogematuria, capillary bleeding from gums and nose; "bruises on the skin case of a minor injury, bleeding with small cuts (for example, when shaving, in places injection); macrohematuria, uterine and stomach bleeding.
Very rare complications may phenomenon drug intolerance: dyspepsia, vomiting, allergic reactions, lakopenia, hair loss, feelings of dizziness. At occurrence of the first signs of hemorrhagic diathesis in connection with the treatment A. indirect action and salts of rare-earth metals, these tools should be immediately abolished. The person is given a vitamin K (menadione), means that increase the resistance of the capillaries (vitamin e, ascorbic acid and others). If this therapy are not enough, possible blood transfusion. In cases of hair loss has a favorable impact vitamin D2.
When bleeding in connection with the use of heparin and geparinoidam appoint his antagonist - proteins.what (5 ml of 1% solution intravenously once or repeated every 15 minutes). Antagonists of heparin are also basic dyes - trepinoy blue, toluidine blue, azure And etc.