Warfarin is an oral anticoagulant drug that 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 taking warfarin often need to be extra careful, because more dosage may easily lead to bleeding; less dosage may not achieve the purpose of preventing the occurrence of thrombosis. Therefore, INR values need to be monitored regularly. However, INR values are affected by many factors and are prone to fluctuations. When taking warfarin, it is important to pay attention to those factors that may cause INR fluctuations, so as not to affect the safety and effectiveness of warfarin.
Monitoring INR
On the way to anticoagulation, patients need to periodically review (PT) prothrombin time, the results of which will give an International Normalized Ratio (INR), according to which warfarin dosing is adjusted. During this period, attention should be paid to.
1, follow the doctor’s instructions to take warfarin, in the absence of prothrombin determination conditions, do not blindly take this drug.
2. Due to individual differences, the doctor needs to closely observe the patient’s condition during treatment and adjust the dosage according to the prothrombin time INR value.
3. If mild bleeding occurs, or if the prothrombin time has been significantly prolonged to more than 2.5 times normal, the dosage should be appropriately reduced or discontinued under the guidance of the doctor. The doctor will take appropriate measures according to the patient’s condition, such as: severe bleeding can be injected with vitamin Kl to control bleeding, and if necessary, whole blood, plasma or prothrombin complex can be transfused.
4.Because of the relatively long half-life of warfarin, the efficacy of the drug is usually stabilized only after 5-7 days of administration, therefore, the doctor needs to observe 5-7 days to make a conclusion whether the maintenance amount is sufficient or not.
Adverse reactions
1. Overdose of warfarin may cause various kinds of bleeding, especially when the amount taken at one time is too large.
2.Early manifestations during drug administration include petechiae p purpura p gum bleeding p epistaxis p wound bleeding for a long time, excessive menstrual flow, etc.
3. Bleeding can usually occur at any site, especially in the urinary and digestive tracts. Intestinal wall hematoma can cause subacute intestinal obstruction, and subdural intracranial hematoma and puncture site hematoma can also be seen.
4, Occasional adverse reactions include nausea, vomiting, diarrhea, pruritic rash, allergic reactions and skin necrosis.
5. Bilateral breast necrosis, microangiopathy or hemolytic anemia, and extensive skin gangrene may even occur when large amounts are taken orally.
Avoid other drug effects
1.The drugs that can enhance the anticoagulant effect of warfarin are: aspirin, sodium salicylate, glucagon, quinidine, indomethacin, pautazone, quinine, diuretic acid, methylsulfonylurea, metronidazole, allopurinol, erythromycin, chloramphenicol, certain aminoglycoside antibiotics, cephalosporins, beniodarone, cimetidine, clofibrate, dextromethorphan, acetaminophen, etc.
2, can reduce the anticoagulant effect of warfarin are: phenytoin sodium, barbiturates, oral contraceptives, estrogen, clofentezine, rifampin, vitamin K, chlorthalidone, spironolactone, paracetamol, corticosteroids, etc.
3, usually can not be combined with warfarin drugs are: epinephrine hydrochloride, amikacin, vitamin B12, methotrexate, indocin, chlorpromazine hydrochloride, vancomycin hydrochloride, etc.
4.Warfarin combined with chloral hydrate, its efficacy and toxicity are enhanced, should be used with caution in reduced doses under the guidance of a doctor. Impaired absorption or decreased synthesis of vitamin K can also affect the anticoagulant effect of warfarin.
As can be seen, many drugs can affect the efficacy of warfarin, so patients taking warfarin need to avoid self-medication if they have uncomfortable symptoms, and to inform their doctors promptly when they are taking warfarin. Under the guidance of the doctor, add or stop other drugs and adjust the dosage of warfarin, etc.
Maintain a balanced diet
Patients taking warfarin should try to maintain a balanced diet. Do not blindly change the structure of food, add nutrients, or consume too much of a single food at a time. In addition, do not eat large amounts of foods rich in vitamin K, such as leeks, carrots, spinach, tomatoes, animal liver, etc.
Doctor’s tips
1, patients need to check INR regularly at the hospital while taking warfarin.
2, patients taking warfarin should maintain good medication habits and try to take the medication at the same time of day, for example, if they take it early they all get up early.
3, in general, coagulation laboratory tests do not require fasting and can be done throughout the day, so patients do not need to be hungry and queue up early in the morning to do the tests at the hospital.
4.Warrant manufacturers are different and the dosage forms are different, so you should try to take the same manufacturer’s drug for a long time. If a different manufacturer’s drug needs to be replaced, the dose should be readjusted under the guidance of a doctor.
5, if the occasional missed dose during the dosing period, do not blindly take the same day and the previous missed dose superimposed together, it is recommended to maintain the previous dose first, go to the hospital to complete the relevant laboratory tests, and follow the doctor’s instructions to adjust will be safer.