1.What anticoagulant drugs are available? How to choose? A: There are many kinds of anticoagulant drugs in clinical application, which can be grouped into two major categories: parenteral anticoagulant drugs and oral (enteral) anticoagulant drugs. The most classic and longest used parenteral anticoagulants are common heparin, which cannot be absorbed in the digestive tract and is usually administered by subcutaneous injection or continuous intravenous drip, with an immediate onset of action and a half-life of 90 min. Therefore, heparin therapy can be monitored by the activated partial thromboplastin time (APTT), which is 2-3 times longer when the heparin level reaches the therapeutic amount. To overcome the shortcomings of regular heparin, people have researched low-molecular heparin, which is also the drug that needs to be injected. Low-molecular heparin is the breakdown of ordinary heparin into smaller molecules, but the efficacy is more stable, the half-life is prolonged, up to 3-4h, subcutaneous injection 1-2 times a day is sufficient, no monitoring is required, and it has now become the anticoagulant of choice in clinical practice. In addition, there are some parenteral anticoagulants such as sulforaphane sodium and argatroban. Theoretically, they have more controllable efficacy and better safety and efficacy, one better than the other, but also more expensive than the other. The most classic oral (enteral) anticoagulant is warfarin. Warfarin is now also the most widely used drug in clinical practice and is the standard for all new anticoagulant drugs when comparing their efficacy. The advantages of warfarin are that it is both economical and inexpensive, and easy to take. The disadvantages are the same as for regular heparin: too small a dose is not therapeutic, too large a dose may cause bleeding and other risks, and the International Normalized Ratio (INR) needs to be monitored to control the dose of warfarin. Warfarin achieves a therapeutic effect when the INR is between 2 and 3. In addition to warfarin, there are several oral anticoagulants, such as rivaroxaban and dabigatran, which can both prevent and treat blood clots. They have a fast onset of action and a short half-life, and do not require monitoring of coagulation when given in fixed doses daily, making them more convenient to use than warfarin, but of course more expensive. In conclusion, whichever drug is chosen will depend on the patient’s specific situation, which is largely determined by the doctor’s experience. However, it must be emphasized that if anticoagulation therapy is needed, then the therapeutic dose of the drug and the adequate duration of treatment must be achieved, otherwise the therapeutic effect will be affected. 2.Why is heparin often chosen for short-term anticoagulation therapy, while warfarin is chosen for long-term anticoagulation therapy A: According to different treatment periods and purposes, anticoagulation therapy can be divided into short-term anticoagulation and long-term anticoagulation. The purpose of anticoagulation is to prevent thrombosis or to prevent the continued spread of an already formed thrombus. The most clinically used short-term anticoagulant drug is heparin, which is characterized by short half-life (90min), immediate onset of action after injection, and rapid disappearance of anticoagulant effect after discontinuation of the drug. However, in many cases, the risk factors for thrombosis and treatment are difficult to eliminate completely in the short term, and long-term anticoagulation therapy is accordingly required. Regular heparin is ineffective when taken orally, and its necessity for injection or intravenous drip makes it difficult to adhere to long-term use. Warfarin, on the other hand, is both economical and inexpensive, and the advantage of easy administration has become the first choice for long-term anticoagulation therapy in clinical practice. Because the half-life of warfarin is long (36h), it takes 2-3 days to take effect, so clinically first 3-5 days with heparin, while oral warfarin, stop using heparin, just when warfarin play anticoagulant effect, at this time can be completely changed to warfarin to maintain the efficacy. 3.What do I need to pay attention to in the process of anticoagulation therapy? How long is the treatment cycle? A: For general patients with lower extremity DVT, ACCP recommends long-term anticoagulation for 3 to 6 months. For some patients with abnormal coagulation mechanism and other high-risk factors, lifelong anticoagulation is recommended. In the course of anticoagulation therapy, patients should follow the doctor’s instructions to take the medication on time, have regular follow-up examinations and laboratory tests on coagulation function to understand the effect of anticoagulation and adjust the dose of medication in a timely manner; pay attention to avoid strenuous activities and collisions in general, and go to the hospital immediately if you find any phenomena such as blood in stool, bleeding from gums, nosebleed, hemoptysis, vomiting blood, black stool, subcutaneous hematoma, etc.; consult the doctor if you need to take other medications in combination with other diseases to avoid abnormal drug effects due to drug interaction. The interaction of drugs to avoid abnormal drug effects (such as aspirin, sulfonamides, painkillers, azithromycin, ofloxacin, cephalosporin antibiotics, vitamin C, vitamin K, laxatives, acidophilus, corticosteroids, digitalis, estrogen, oral contraceptives, etc.); foods containing high vitamin K may affect the efficacy of anticoagulant drugs, including spinach, mustard, broccoli, carrots, seaweed, nori, kelp, green tea, etc. The above-mentioned foods should be eaten sparingly or in fixed portions in the usual diet.