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 thrombi.
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 biological valve replacement or 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 new thrombosis and maintain the application for a period of time after the acute period to reduce the recurrence of thrombosis.
3.How to take warfarin?
Take it once a day, preferably in the afternoon or evening at the same time, before or after meals, do not miss it; you should take it according to the dose recommended by your doctor or pharmacist, do not stop or adjust the dose casually; please make up the dose within 4 hours after you forget to take it, do not make up the dose 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 forget to take it. In order 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 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. Therefore, regular monitoring of INR is required to ensure the safety and efficacy of your warfarin application.
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; the interval of blood check can be extended after the INR value is continuously stabilized in the target range, and it is recommended that the maximum interval should not exceed 1 month; in the process of your long-term warfarin use, if there is the addition of other drugs, new diseases, warfarin dosage adjustment, the frequency of blood check should be increased. In the process of your long-term use of warfarin, if there is the addition of other drugs, new diseases, warfarin dose adjustment, you need to increase the frequency of blood checks, there are signs of bleeding or embolism need to promptly go to the hospital to recheck INR value.
5.What factors can affect warfarin test results and how to deal with them?
Food.
When you take warfarin orally, you should try to maintain a balanced diet structure, do not blindly change the food structure, add nutrients, and monitor the INR value regularly. Foods containing large amounts of vitamin K (green vegetables, animal liver, soybean oil, etc.) can reduce the efficacy of warfarin. Certain foods such as mangoes, 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 have an enhancing/weakening effect on the efficacy of warfarin. If you are unwell, try to avoid self-medication. 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, timetan, etc.
Proprietary Chinese medicines.
Proprietary Chinese medicines and herbs have the potential to 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 herbal 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 (3-5 days after starting) in order to know if drug interactions occur and to adjust the warfarin dosage if necessary.
Effect 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 liver 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 the warfarin dose
Please adjust warfarin dose with the assistance of doctors and pharmacists. INR within the target range does not require dose adjustment; INR continuous measurement results outside the target range before starting to adjust the dose, an increase or decrease does not need to be anxious to change the dose, but should be looking for the cause of INR fluctuations; when adjusting the dose, generally each increase or decrease the dose by 1/4 tablet, after adjusting the dose, pay attention to strengthen monitoring; INR abnormal increase and Hemorrhage is closely related, INR>3 should be discontinued warfarin, and to the hospital by the doctor for treatment.
7.What are the adverse effects of warfarin?
A common complication of warfarin is bleeding. Minor bleeding symptoms are gum bleeding, nasal bleeding, menstrual bleeding, skin petechiae, etc. Warfarin dose can be adjusted according to the test results; serious bleeding symptoms are hematuria, hematochezia, hemoptysis, vomiting blood, intracranial hemorrhage, etc. Warfarin should be discontinued immediately, and immediately go to the hospital. After applying warfarin, if the amount of menstruation increases significantly, 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 living habits, you can do appropriate exercise, such as walking, swimming, etc.. You should pay attention to safety and avoid participating in activities or sports that are prone to 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 solubility can vary from manufacturer to manufacturer due to different preparation processes, so try to take the same manufacturer’s drugs and pay attention to them when purchasing; if you change the drug manufacturer, you should also monitor the INR value more.
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 an individualized dosing regimen based on the test results and with reference to the FDA’s recommended dose.