1.What is warfarin? Warfarin is an oral anticoagulant drug that inhibits the synthesis of vitamin K-dependent coagulation factors, changes the hypercoagulable state of blood, prevents thrombosis, and limits the further expansion and extension of existing blood clots. 2.Why should I take warfarin and the course of treatment? Warfarin is widely used for long-term anticoagulation therapy and prevention of thrombotic high-risk diseases such as post-prosthetic valve replacement, atrial fibrillation, deep vein thrombosis, and pulmonary embolism. Patients with mechanical valve replacement need lifelong anticoagulation, and patients with bioprosthetic valve replacement or a forming ring alone need anticoagulation for 3-6 months; patients with atrial fibrillation need long-term oral warfarin to reduce the incidence of stroke in patients with atrial fibrillation; patients with deep vein thrombosis and pulmonary embolism need warfarin to inhibit the formation of new thrombosis and maintain the application for a period of time after the acute phase to reduce the recurrence of thrombosis. 3. How to take warfarin? Take warfarin once a day, preferably in the afternoon or at the same time in the evening, before or after meals, do not miss the dose; you should take the dose recommended by your doctor or pharmacist, do not stop or make dose adjustment; please make up the dose within 4 hours after forgetting to take the dose, do not make up the dose after more than 4 hours, continue to take the dose normally on the second day, do not double the dose on the second day because you forgot to take the dose. To facilitate monitoring, please record in the warfarin anticoagulation record sheet each time you test INR, adjust warfarin dose, increase or decrease medication, and bring the anticoagulation record sheet with you when you visit the clinic. 4. Why and when do I need to have blood drawn when taking warfarin? Patients taking warfarin need to have their blood drawn regularly to check the coagulation index, i.e. International Normalized Ratio (INR) of prothrombin time. INR value is affected by many factors and can fluctuate easily. You need to monitor your INR regularly to ensure the safety and efficacy of your warfarin. The frequency of blood check is usually decided according to the doctor’s or pharmacist’s recommendation during the initial application of warfarin, and it is not recommended to adjust the dosage by yourself. If you are taking warfarin for a long period of time, you need to increase the frequency of blood check, and if you have bleeding or embolism signs, you need to go to the hospital to review the INR value in time. 5.What factors can affect warfarin test results and how to deal with them? Food: When you take warfarin orally, try to maintain a balanced diet, do not blindly change the food structure, add nutrients, and regularly monitor the INR value. Foods containing large amounts of vitamin K (green vegetables, animal liver, soybean oil, etc.) can reduce the efficacy of warfarin. Certain foods such as mango, grapefruit, garlic, and ginger can enhance the efficacy of warfarin. If you occasionally consume large amounts of these foods, they may cause your INR to fluctuate. You should be careful to eat a balanced diet and not deliberately favor or abstain from certain foods. Medications: Many medications can potentiate/decrease the effectiveness of warfarin, so avoid self-medication if you are unwell. Tell your doctor that you are taking warfarin at the time of your hospital visit. If you add or discontinue other medications, you should monitor your INR closely under your doctor’s supervision and adjust the dosage of warfarin if necessary. Common drugs that enhance the efficacy of warfarin include metronidazole, fluconazole, levofloxacin, amiodarone, simvastatin, acetaminophen, citalopram, omeprazole, etc.; common drugs that weaken the efficacy of warfarin include ribavirin, carbamazepine, bosentan, temsifloxacin, etc. Proprietary Chinese medicines: Proprietary Chinese medicines and herbs may affect the efficacy of warfarin. For example, salvia, angelica and wolfberry may enhance the efficacy of warfarin, and ginseng products may reduce the efficacy of warfarin. If you must take Chinese medicine, also let the doctor who prescribes it know that you are taking warfarin. The INR should be monitored for a shorter period of time after starting (3 to 5 days after starting) to see if drug interactions occur and to adjust warfarin dosage if necessary. Effects of disease/physical condition: Certain diseases and changes in physical condition have an effect on the anticoagulant effect of warfarin. For example, prolonged diarrhea or vomiting, hyperthyroidism, prolonged fever, impaired hepatic function, and congestive heart failure may enhance the effect of warfarin, and hypothyroidism may reduce the effect of warfarin. Smoking and alcohol consumption will accelerate the metabolism of warfarin, patients should try to quit smoking and avoid alcohol abuse. 6. learn to simply adjust warfarin dose Please adjust warfarin dose with the assistance of your doctor and pharmacist. no need to adjust dose when INR is within the target range; INR continuous measurement results outside the target range before starting to adjust the dose, a rise or fall need not be urgent to change the dose, but should look for the cause of INR fluctuations; when adjusting the dose, generally increase or decrease the dose by 1/4 tablet each time, after adjusting the dose, pay attention to When adjusting the dose, generally reduce the dose by 1/4 tablet each time, and pay attention to monitoring after adjusting the dose; abnormally high INR and bleeding are closely related, and warfarin should be stopped when INR > 3 and handled by a doctor in hospital. 7. What are the adverse effects of warfarin? A common complication of warfarin is bleeding. Minor bleeding symptoms include gum bleeding, nasal bleeding, heavy menstrual bleeding, petechiae on the skin, etc. Warfarin dose can be adjusted according to the examination results; serious bleeding symptoms include hematuria, bloody stool, hemoptysis, vomiting blood, intracranial hemorrhage, etc. Warfarin should be discontinued immediately and the patient should go to the hospital immediately. If there is a significant increase in menstrual flow after the application of warfarin, the warfarin dose can be reduced by 1/4 tablet or more, and then restored to the original dose after the end of the period. 8. What do I need to pay attention to when taking warfarin? Oral anticoagulation therapy does not affect your normal life habits. You can do appropriate exercises, such as walking and swimming. You should pay attention to safety and avoid participating in activities or sports that may cause injury. If you need to have a tooth extraction, gastroscopy, surgery, etc. while taking warfarin, you should tell your doctor that you are taking warfarin and follow his or her instructions to decide whether to stop taking it or whether to replace it with other medications. Warfarin dissolution may vary from manufacturer to manufacturer due to different preparation processes, so try to take the same manufacturer’s drug and pay attention to it when you buy it; if you change the drug manufacturer, you should also monitor the INR value more often. 9. Genetic testing of warfarin In addition, patients with high suspicion of warfarin resistance or sensitivity are recommended to undergo warfarin-related pharmacogenomic testing and develop individualized dosing regimens based on the test results and with reference to the FDA recommended doses.