Blood concentrations peak 90 minutes after oral administration of warfarin.The half-life of warfarin in the racemic form is 36-42h, and it is mainly bound to albumin in plasma.The anticoagulant effect generally occurs within 24 hours after administration, but may extend to 72-96h. Anticoagulation generally occurs within 24h after administration, but the peak of anticoagulation may be extended to 72-96h.The antitethering effect of warfarin depends on the decrease of thrombospondin (II), whose half-life is 72h.Due to the short half-life of factor VII and protein C (6-8h), the level of factor VII and protein C decreases very quickly after application of warfarin, and the INR measured at this time mainly reflects the level of factor VII and other proteins, and the INR measured at this time mainly reflects the level of factor VII. The INR measured at this time mainly reflects the level of factor VII, and the decline of other coagulation factors (e.g., factor II, i.e., prothrombin) is delayed for 24-48 h, before which there is a transient hypercoagulability (due to the decline of protein C), and the effective decline of the coagulation factors takes 3-4 days, so Warfarin should not be used for acute antitethering. The use of an initial shock dose of warfarin is not recommended after valve replacement, otherwise it may cause a decrease in protein C activity, resulting in a transient hypercoagulable state and even leading to thrombotic comorbidities.1 Lifelong oral administration of warfarin after surgery for those who have had a mechanical valve replaced (try to use the same manufacturer’s drug); six months of oral administration of warfarin after surgery for those who have had a biological valve replaced.2. Time of the start of the application of warfarin: generally, the first afternoon of the first day of the postoperative period to start the oral administration of warfarin. If the patient has bleeding tendency (drainage flow or active bleeding), then delay the application. If the patient can not eat orally, heparin anticoagulation can be applied intravenously. 3. The initial dose of warfarin is usually 3.0-5.0mg, and the initial shock dose is not recommended. The maintenance dose of Warfarin is usually around 3mg (2.5mg for most women in the south), which is adjusted according to the INR. 4. The international normative ratio (INR) or prothrombin activity is obtained by blood sampling, and the oral dosage of Warfarin is adjusted according to the results of anticoagulant laboratory tests. The aim is to keep the INR between 1.8-2.2. When the INR is >2.2, reduce the oral dose of warfarin. When the INR is 2.5, stop taking warfarin on the same day, and then go to the hospital the next day for anticoagulation tests, and then decide on the oral dose of warfarin according to the results. 3. The patients who go abroad can return to the local hospital after they have mastered the method of adjusting the oral dose of warfarin, and they should be reviewed regularly after discharge. After discharge, the coagulation status should be rechecked regularly. 4. Control of laboratory time; gradually extend the interval between laboratory tests as follows: check the anticoagulation every other day after discharge, adjust the dosage according to the above method, and extend the interval between laboratory tests when the INR stabilizes at 1.8-2.2. ———- check the anticoagulation twice a week, adjust the dosage according to the above method, and adjust the dosage according to the above method, and increase the interval between laboratory tests when the INR stabilizes at 1.8-2.2. When the INR is stable at 1.8-2.2, the laboratory interval can be extended ———— weekly ———- stable ———– every two weeks ——– stable ——— once a month. Stable is defined as three to four consecutive INR lab results between 1.8-2.2 without increasing or decreasing the oral dose of warfarin.5 Each lab result and oral dose of warfarin should be recorded in the table.6 Any bleeding or clotting complications after discharge should be seen at the local hospital. A full workup, including echocardiogram, chest X-ray, and electrocardiogram, should be done at 3 months after discharge.7. Effect of food: Vitamin K-rich foods can diminish the efficacy of the drug. Vitamin K content per 100g of dry food (mg): spinach (4.40), cabbage (3.20), cauliflower (3.00), peas (2.80), carrots (0.80), tomatoes (0.40 – 0.80), potatoes (0.16), pig’s liver (0.80), eggs (0.80), cow’s milk (trace). Long-term consumption of large quantities of the above foods should be adjusted by timely laboratory tests of the dosage of farin.