Relevant factors affecting the anticoagulant effect of warfarin
Warfarin is a widely used oral anticoagulant for the prevention and treatment of deep vein thrombosis, pulmonary embolism, cardiac
valve replacement and atrial fibrillation, and to reduce the risk of recurrent myocardial infarction and post-infarction thromboembolic death.
The risk of thrombotic death after myocardial infarction is reduced. However, the therapeutic window of warfarin is narrow, and underdose may lead to thromboembolism and failure of anticoagulation therapy.
Overdose leads to bleeding, which can be life-threatening in severe cases. At the same time, the individual differences of warfarin dosing are great, and to achieve the
To achieve the same effect, the difference between high and low doses can be more than 10 times. Therefore, clinical monitoring of prothrombin time [based on international standardized ratio (intern
Therefore, clinical monitoring of prothrombin time [based on the international normalizedratio (INR), abbreviated as INR value] is used to individualize the dosing of patients and maintain the appropriate dose in order to
The dose of warfarin should be maintained at an appropriate level to achieve the desired therapeutic effect.
1, the influence of genetic factors on the anticoagulant effect of warfarin
2, the effect of disease on the anticoagulant effect of warfarin
Low liver function: patients with impaired liver function are more likely to bleed after taking warfarin, excessive alcohol consumption leads to liver damage and severe
Patients with severe liver disease have higher INR values after taking warfarin.
Abnormal thyroid function: Patients with hyperthyroidism have increased sensitivity to warfarin. Hypothyroidism, resulting in insensitivity to
Warfarin insensitivity, and warfarin dose needs to be increased.
Congestive heart failure: Patients with congestive heart failure that worsens with hepatic congestion or edema may have an increased response to warfarin.
The response to warfarin may be enhanced, so caution should be exercised when administering the drug.
Malnutrition: In malnutrition, the surface area of gastric juice secretion and absorption may be altered in patients, resulting in altered absorption of warfarin.
Or the protein binding rate of warfarin may be changed due to the decrease of albumin synthesis by the liver, which in turn affects the distribution in the body.
3, the effect of drugs on the action of warfarin
Many drugs can interact with warfarin, which results in lower or higher INR values.
(1) Vitamin K preparations can directly antagonize warfarin and weaken its anticoagulant effect.
(2) Oral contraceptives increase the synthesis of coagulation factors, which can reduce the effect of warfarin.
(3) Aspirin, indomethacin and other non-steroidal anti-inflammatory drugs, prostacyclin, clopidogrel and other drugs that affect platelets
can enhance the anticoagulant effect of warfarin and increase the INR value.
(4) Various broad-spectrum antibiotics such as erythromycin and clarithromycin enhance the effect of warfarin.
The main mechanisms that reduce the anticoagulant effect of warfarin drugs are: (1) affect the absorption of warfarin, such as lipid-lowering drugs (cauleenamine), the
(2) hepatic enzyme inducers such as antituberculosis drugs (rifampicin, rifapentine), corticosteroid inhibitors (amiloride), and (3) hepatitis B.
(2) hepatic enzyme inducers such as antituberculosis drugs (rifampin, rifapentine), corticosteroid inhibitors (amiloride, mitotane, bosentan) and antiepileptic drugs (carbamazepine) can promote the metabolism of warfarin in the body.
4, the effect of natural drugs and food on the anticoagulant effect of warfarin