1.What is warfarin?
Warfarin is an oral anticoagulant drug, which can inhibit the synthesis of vitamin K-dependent coagulation factors, change the hypercoagulable state of blood, prevent thrombosis, and limit the further expansion and extension of existing thrombosis.
2.Warfarin indications and course of treatment
Warfarin is widely used for long-term anticoagulation treatment and prevention of thrombotic high-risk diseases such as post-prosthetic valve replacement, atrial fibrillation, deep vein thrombosis, and pulmonary embolism. Patients after mechanical valve replacement need lifelong anticoagulation, and patients with biological valve replacement or alone placed in the forming ring need anticoagulation for 3-6 months; patients with atrial fibrillation long-term oral warfarin can reduce the incidence of stroke in patients with atrial fibrillation; patients with deep vein thrombosis and pulmonary embolism apply warfarin to inhibit the formation of new thrombosis, and still need to maintain the application for a period of time after the acute period to reduce the recurrence of thrombosis.
3.How to take warfarin
Take warfarin once a day, preferably in the afternoon or evening at the same time, before and after meals, do not miss the dose; you should take the dose as recommended by your doctor or pharmacist, do not stop or adjust the dose casually; 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 of forgetting to take the dose. 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 blood needs to be drawn when taking warfarin
Patients taking warfarin need to have their blood drawn regularly to check the coagulation index, i.e. the International Normalized Ratio (INR) of prothrombin time. the INR value is affected by many factors and is prone to fluctuations.
(1) If your INR value is too low, it indicates that the anticoagulation is not up to standard and there is a risk of clot formation.
(2) And an INR that is too high indicates excessive anticoagulation and a risk of bleeding.
Therefore, you need to monitor your INR regularly 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. 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
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 augmenting/diminishing effects on the efficacy of warfarin. When visiting the hospital, tell your doctor that you are taking warfarin, and if you are adding or stopping other medications, take care to monitor your INR closely under your doctor’s supervision and adjust your warfarin dosage 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 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 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 (3-5 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 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 the warfarin dose
Please adjust the warfarin dose with the assistance of your doctor and pharmacist; 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 in the dose does not need to be anxious to change the dose, but should look for the cause of INR fluctuations; when adjusting the dose, in general, each time 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 reactions 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 examination results; serious bleeding symptoms are hematuria, hematochezia, hemoptysis, vomiting blood, intracranial hemorrhage, etc. Warfarin should be discontinued immediately, and go to the hospital immediately. 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 to pay attention to when taking warfarin
Oral anticoagulation therapy does not affect your normal lifestyle 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, or surgery 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 you need to use other drugs instead.