[summary]
Blood coagulation is a complex chain reaction of protein hydrolysis activation, which eventually turns soluble fibrinogen into stable, insoluble fibrin and blood cells as blood clot. Anticoagulant drugs (anticoagulants) are drugs that interfere with coagulation factors and prevent blood clotting.
[main variety]
Heparin, coumarin, Hua Faling
[clinical application]
It is mainly used for prevention and treatment of thromboembolic diseases.
[adverse reaction]
It can cause menorrhagia and even hemorrhage. Menstrual period should be avoided, such as coumarin, heparin, thrombolytic agent, etc.
Thrombolytic drug
[summary]
Fibrinolysis system is called fibrinolytic system. Its main physiological function is to restrict the increase of blood clot and remove fibrin from wound healing. Thrombolytic agents are used to activate fibrinolytic system so that thrombus can be dissolved and can effectively treat thromboembolism. The first generation of thrombolytic drugs is streptokinase and urokinase. The second generation of thrombolytic drugs is t PA and SCU PA.
Thrombolytic drugs are fibrinolytic drugs, which can activate fibrinolytic enzymes, promote fibrinolysis, and have dissolved thrombolytic effects. Therefore, it is known as thrombolytic drugs: streptokinase, urokinase, tissue fibrinolytic activator, snake venom thrombolytic enzyme.
[action characteristics]
In 1959, streptokinase (SK) has been used to treat myocardial infarction. The thrombolytic drugs that can be used before 80s are SK and urokinase (UK). Since 80s, there have been recombinant tissue type plasminogen activator (rt-PA) and its mutants, TNKt-PA pre urokinase (Pro-UK) and staphylokinase (SAK). To date, the basic pharmacology of all thrombolytic drugs is to convert plasminogen to fibrinolytic enzyme, fibrinogen, fibrin (an important component of thrombus), coagulation factor V, VIII, IX, supplement, complement, growth hormone and so on. "Ideal" thrombolytic drugs should have the following characteristics: rapid thrombolysis; specific fibrin, low body response only to thrombus; lasting effect; low risk of bleeding; no systemic side reaction, antigenicity, avoidance of systemic fibrinolysis; low price and so on.
The first generation of thrombolytic drugs (SK, UK) and the second generation of thrombolytic drugs (rtPA) were developed in order to achieve the ideal thrombolytic drugs. The main drawback of the first generation of thrombolytic drugs, SK and UK, is that it is easy to cause systemic fibrinolysis and increase the risk of bleeding. However, the cost is low, especially UK is still widely used in our country.
The second generation of thrombolytic drugs is (rtPA) high specificity for fibrin, so its systemic fibrinolytic reaction is low, but its cost is high. In recent years, thrombolytic drugs such as Pro-UK, TNK-tPA and so on have been improved in the half lives of blood drugs. They can be intravenously injected without intravenous drip. In recent years, some chimeras have been developed, such as chimeric tPA with the active center of UK, increasing the half-life of blood.
The characteristic of thrombus is an important factor affecting thrombolytic effect. Thrombosis is different from blood clots in the tube. In the body, thrombus will develop into connective tissue after thrombosis, and the "susceptibility" to thrombolytic drugs depends on the size of the thrombus, the area of the thrombus and the surrounding blood vessels, the degree of cross-linking of fibrin; the new and old degree of thrombus and the degree of infiltration of collagen and fibroblasts; the location of the thrombus and the nature of the blood vessel; the part of the thrombus; The velocity of blood flow.
In general observation of the efficacy of new thrombolytic drugs, the selected myocardial infarction patients should be within 6 hours, and the gold indicator to determine whether the thrombolysis is dissolved should be angiography, only by the improvement of the electrocardiogram (myocardial infarction) or paralyzed limb activity (cerebral infarction) can not confirm whether the thrombus dissolves, only reflecting the local blood circulation. This improvement may be due to the improvement of collateral circulation and hemorheology, rather than the penetration of embolized blood vessels.
At present, a number of drugs through media advertising have claimed to have thrombolytic factors, but they have no strong evidence, which may cause some patients to miss the right time for thrombolytic.
The biggest risk of thrombolytic drugs is bleeding, but the advantages and disadvantages should be properly used in the case of strict indications and contraindications. The use of thrombolytic drugs reduces the mortality of patients, and can be administered by catheter in the thrombus. It not only improves the curative effect, but also reduces the dosage, and has little effect on the side effects of the whole body, especially the administration of SK and UK by catheter is better than intravenous drip.
When thrombolytic drugs are used, fibrinogen level, anti fibrinolytic enzyme, fibrin degradation products and other indicators should be measured, which are useful to judge the whole body reaction and adjust the dosage of the drug. At present, large hospitals in China already have the necessary equipment to measure these indicators, but they have not attracted the attention of clinicians.
[precautions]
Thrombolytic drugs are a relatively complex and special drug, which is generally not suitable for storing at home.
First, the use of thrombolytic drugs is complicated, and generally requires professional medical equipment. For example, some thrombolytic drugs should be intravenously injected by professional doctors, which is difficult to achieve in general patients' homes.
Second, the time of medication for thrombolytic drugs is strictly limited, and the condition of cardiovascular and cerebrovascular diseases and coronary heart disease is complex. It is difficult to determine the frequency and use of the drugs.
Third, the preservation methods of thrombolytic drugs are special, not only in low temperature, but also in the setting of specific temperature. It is difficult to achieve such conditions at home.
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