The main drugs used in the treatment of various thrombotic disorders are: antiplatelet agents, heparins, long-acting anticoagulants and fibrinolytic and thrombolytic agents. Among them, long-acting anticoagulants are the main drugs used to maintain anticoagulation therapy, especially for the treatment of venous thrombotic diseases. Long-acting anticoagulants, which are oral anticoagulants, are also known as vitamin K antagonists. There are two classes: coumarins and indanediones. Indandione class has dumb indandione, anisodindione and dumb indandione, its anticoagulant effect is the same as coumarin class, and the amount is different, but the toxicity of indandione class drugs than indandione class, so rarely used. Coumarin class has double coumarin dumb pro-coumarin and warfarin. Warfarin is currently commonly used in China, but also the only clinically used vitamin K antagonist. It varies widely among individuals and is also a drug that needs to be adjusted at any time according to laboratory indicators. Warfarin should not be used without laboratory conditions related to prothrombin time. Otherwise, serious consequences will occur. Pharmacological action and usage It mainly interferes with the synthesis of coagulation factors II, VII, IX and X by the liver, which depends on vitamin K, thus inhibiting blood coagulation. It is an indirect anticoagulant drug and is only effective in vivo. The half-lives of coagulation factors II, VII, IX and X are 6, 20-30, 45-72 and >60hrs respectively, so it takes 36-48hrs after oral administration of Warfarin or even after intravenous injection for the anticoagulant effect to take effect. After discontinuation of the drug, it takes many days for the coagulation to resume with the synthesis of each of the above coagulation factors. 1.Dosage Initial dose: 5~20mg Maintenance dose: 2.5~7.5mg 2.Use Start to combine with heparin or low molecular heparin, and then stop using heparin or low molecular heparin after Warfarin takes effect. Indicators for adjustment of Warfarin dose: prothrombin time prolonged by 50%, activity reduced to 20%-30%, international standard ratio (INR) maintained at 2-3. During the start of Warfarin, prothrombin time should be tested daily and the dose should be adjusted according to the daily test results, after reaching the test index, the number of tests can be reduced, and if the test index reaches and maintains the required index, the test interval can be gradually changed to 3 days. The test interval can be gradually changed to 3 days, 1 week, 2 weeks, 4 weeks. In the case of stable indicators, at least once a month. International standard ratio (INR): INR is called international standardized ratio in Chinese INR is derived from the prothrombin time (PT) and the international sensitivity index (ISI) of the assay reagent. The use of INR makes the PT measured by different laboratories and different reagents comparable and facilitates the unification of medication standards. Its normal value ranges from 0.8 to 1.2.