Hi Jane,
This is what I found on the Anticoagulants. Hope this helps you.
ANTICOAGULANTS
Blood clotting is good when we cut ourselves or get into an accident. However, a lot of cardiovascular problems arise from blood clotting inappropriately in blood vessels or the chambers of the heart. Doctors use blood thinning agent to prevent this inappropriate clotting without causing excessive bleeding as a side effect. There are 2 systems in the blood that promote clotting, platelets and the coagulation system.
The coagulation system consists of a large number of protein molecules that circulate in the blood. Anticoagulants interfere with any one of a number of these proteins to produce powerful blood thinning effects. They help prevent blood clots from forming and help stabilize and slowly dissolve those that have already formed. Clot dissolving agents (thrombolytic agents) rapidly dissolve blood clots.
Intravenous heparin achieves an immediate anticoagulant effect and is useful for treating and stabilizing patients with blood clots on the legs (phlebitis) or the lung (pulmonary embolus) as well as patients with unstable angina or a heart attack. These latter 2 conditions are contributed to by blood clots in the coronary arteries. Heparin is also used to prevent blood clotting during procedures such as cardiac catheterizations, angioplasties and open heart surgery.
Heparin can also be used a substitute for oral anticoagulants in patients who are unable to take medication orally. The only oral anticoagulant, coumadin, cannot be given to pregnant women during certain parts of their pregnancy (particularly the first trimester) as it can cause birth defects. Heparin can be used in its place as heparin has not been associated with birth defects. Use of intravenous heparin must be monitored closely by blood tests. Lower doses of heparin are used subcutaneously to prevent blood clots from forming in leg veins when hospitalized patients are unable to walk.
There are new medicines available called low molecular weight heparins. These include enoxaparin (Lovenox), dalteparin (Fragmin), ardeparin (Normiflo), nadroparin (Fraxiparine), reviparin (Clivarine) and tinzaparin (Innohep). These are usually administered subcutaneously and appear to be at least as effective and safe as heparin. Unlike heparin, they do not require blood tests for monitoring.
Another substance, known as a heparinoid, goes by the name of danaproid (Orgaran). This has been used to treat a rare side effect of heparin, called heparin-induced thrombocytopenia (HIT).
And finally, there is a medicine called lepirudin (Refludan). This is related to the substance secreted by the leeches (Hirudo medicinalis) used by physicians in the past to bleed patients. It too inhibits the coagulation system. You will be relieved to know this medicine can now be administered without applying a leech to your body! It is produced using recombinant DNA technology and administered intravenously. It is currently indicated to treat HIT and is being investigated for other cardiovascular uses as well. A related medicine, bivalirudin (Angiomax) can be used as a blood thinner in place of heparin during angioplasty procedures.
An amino acid derivative, argatroban, can also be used to treat HIT. Argatroban is also being investigated for use in cardiac procedures and in the treatment of acute myocardial infarctions and HIT.
The only oral anticoagulant is coumadin. This is given for several months after a person has had a blood clot in a leg vein or the lung and sometimes after a heart attack as well. People with mechanical heart valves and many patients with atrial fibrillation or blood clots in their heart chambers must remain on coumadin chronically to prevent strokes. Some people have unusually thick blood due to abnormal coagulation proteins and also must remain on coumadin permanently.
Treatment with coumadin requires periodic monitoring with blood tests. Doctors used to measure something called the prothrombin time or "pro-time" but we now measure a more accurate indicator of blood thinning called the International Normalized Ratio (INR). The main side effect with coumadin is an increased risk of bleeding.
Many medications interact with coumadin. It is prudent to check the INR more frequently when other medications are added or withdrawn.
Coumadin works by interfering with the effect of vitamin K. Vitamin K is used by the liver to make some of the coagulation proteins. Excess vitamin K will offset the effect of coumadin. However, contrary to popular belief, people on coumadin do not have to avoid foods with vitamin K. The dose of coumadin can be adjusted for any level of dietary vitamin K intake. However, it is important to eat the same amount of vitamin K containing foods all the time so that the level of blood thinning remains stable. Vitamin K is found in vegetables, particularly the green leafy vegetables.
Christina
