1, anticoagulants and their use.
(1) The current anticoagulants are mainly warfarin. Warfarin oral anticoagulation, 60kg weight patients, generally need about 3mg of warfarin once a day (domestic 2, 5mg per tablet, imported 3mg per tablet). However, the sensitivity of anticoagulants varies from patient to patient, so regular blood sampling for prothrombin time and activity is required. (Note: Imported warfarin is easy for patients and family members to divide by themselves).
(2) Warfarin is absorbed through the gastrointestinal tract, and more than 90% is bound to plasma proteins and metabolized by the liver, which starts to work 12 hours after taking the drug and reaches its peak effect in 48 hours, with a plasma half-life of 44 hours. The plasma half-life is 44 hours. It takes 5-7 days for the anticoagulant to reach steady state after taking once a day, so the maintenance dose should be changed every 5-7 days. The prothrombin time returns to normal 5-6 days after discontinuation of the drug.
In severe bleeding, vitamin K may be used to counteract the effects of warfarin. The prothrombin time returns to normal after 12-24 hours after oral vitamin K. The prothrombin time returns to normal after only 3-5 hours after intravenous vitamin K.
(3) Warfarin should be used for the first time 24-48 hours after the removal of pericardial and mediastinal drains, generally the first dose is 1 tablet (3mg), and later the dose is adjusted according to the dynamic changes of prothrombin time and activity.
(4) The WHO (World Health Organization) now advocates an international standard for oral anticoagulant testing, the International Standard Ratio (INR). After valve replacement, the mechanical mitral valve INR should be controlled 1,8-2,5 (normal human values 0,8-1,2), Pt value 18-24 seconds (normal value 11-14 seconds); mechanical aortic valve INR 1,5-2,0 (normal human values 0,8-1, Pt value 14-18 seconds (normal value 11-14 seconds)).
(5) If the prothrombin time is more than 2 times normal or the activity is less than 30%, the dosage can be reduced by 1/4 or 1/8; if the activity is less than 25% or the prothrombin time is higher than 30 seconds, the dosage can be stopped once and adjusted after laboratory tests the next day. Prothrombin time or activity should be measured 4-5 days after each dose adjustment.
(6) If the dose of medicine is too high, pay attention to close observation. If there are signs of bleeding such as nasal obstruction, bleeding from teeth and eyes, hematuria, black stool, intra-abdominal bleeding manifestation (abdominal pain), intracranial bleeding manifestation (coma), etc., go to the hospital immediately for laboratory tests, reduce the dose or stop taking warfarin, and if necessary, inject vitamin K against, or transfuse blood, plasma, platelets, etc.
(7) If there is blunted valve tone, heart failure, hemiplegia, aphasia, painful arterial embolism in the limbs, etc., review the prothrombin time and activity, and increase the anticoagulant dose if thrombosis is confirmed.
(8) The general maintenance dose of warfarin is around 3mg, but individual differences are great, if the use of 6mg warfarin still can not achieve satisfactory anticoagulation effect indicates that the patient is not sensitive to warfarin, you can go to our hospital to perform warfarin antibody test to guide the use of drugs.
(9) heart valve disease patients during hospitalization, according to the need to determine the time or activity of prothrombin by the doctor, after a period of time to find the appropriate amount of maintenance, can be changed to 3-5 days to measure 1 time; if the measurement is still stable after 3-4 times, can be changed to 1 time per week; if 3-4 times to determine very stable, can be extended to 1 time per half month. By analogy, it can be changed to 1 month, 3 months or half a year. Even if the conditions are poor, it should be measured once every six months to prevent thromboembolism or bleeding phenomenon. If the dose is adjusted, it should be measured again within 4-5 days until it is stable, and then the interval of measurement should be extended appropriately.
2, the effect of food, drugs and other diseases on the anticoagulant effect.
(1) The effect of food: foods rich in vitamin k can reduce the effect of anticoagulants. The following foods rich in vitamin K. The content of vitamin K per 100 g of dry food is: spinach 4,4 mg, cabbage 3,2 mg, cauliflower 3,0 mg, peas 2,8 mg, carrots 0,8 mg, tomatoes 0,6 mg, potatoes 0,16 mg, pig liver 0,8 mg, eggs 0,8 mg. Although the above foods are rich in vitamin K, as long as a balanced diet, regular and Regular measurement of prothrombin time and activity, it is possible to adjust the dose of anticoagulants, there is no need to deliberately favor or prohibit a certain food.
(2) The influence of drugs: drugs that enhance the effect of anticoagulant drugs are.
① broad-spectrum antibiotics that reduce the intestinal production of vitamin K;
(2) Aspirin, Antomin, sulforaphane and propofol can compete with warfarin for plasma protein binding sites, increasing the free blood concentration of the latter;
③Liquid paraffin can reduce the absorption of vitamin K;
④Chloramphenicol, metronidazole, methohexital, and ethanol can inhibit the enzymes that degrade warfarin, resulting in a relative increase in warfarin concentration;
⑤ Phenytoin sodium, toluene, and sulfobutylurea have the same metabolic pathway;
(6) Aspirin and acetaminophen have anticoagulant synergistic effects;
(7) Salicylic acid, botrytisine, chlorpromazine, and benadryl have the effect of interfering with platelet function.
Drugs that reduce the anticoagulant effect.
①Deglutamine can bind to anticoagulants in the intestine;
(ii) Hypnotics, rifampin and ashwagandha have the effect of increasing the activity of enzymes in the liver and accelerating the metabolism of warfarin;
(3) Estrogen and oral contraceptives can increase the level of coagulation factors in the blood.
(3) Effects of other diseases.
Diarrhea, vomiting can affect drug absorption, heart failure or primary liver disease can reduce vitamin K synthesis, while reducing the metabolic rate of warfarin, the dosage of warfarin should be reduced.