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An antithrombotic is a medication that addresses or prevents blood clots, and there are three classes of drugs that may be described as having antithrombotic properties. These are thrombolytic drugs, antiplatelet drugs and anticoagulants. Each of these groups works on preventing or ending blood clotting in different ways, and sometimes two or more of the groups will be used for maximum effectiveness in treatment, especially if a blood clot has already formed.
Thrombolytic drugs are usually those given when a person already has a severe blood clot and could be suffering its lasting effects by having stroke, pulmonary embolus, heart attack, or other conditions where a blood clot is present and dangerous, like deep vein thrombosis (DVT). This type of antithrombotic differs from other types because it’s most used in emergency settings and not used over long-term periods. It’s also important that the several drugs in this class are used as close as possible to the blood clot forming, with optimum results achieved in the first hour after diagnosis.
Generally, thrombolytics are most used in hospital settings and they must be used with great care because they can cause excessive bleeding. Any blood clot in the brain must be assessed to make sure it is not resulting in hemorrhage, as adding thrombolytics to this situation could result in severe physical problems.
Another form of the antithrombotic is the antiplatelet drug, which includes several common forms of these like aspirin and Plavix®. Antiplatelet drugs work to prevent thrombosis in a number of ways. Some act on platelet production, reducing its total so that platelets are less likely to collect or aggregate. Others work on the way platelets perform, causing them to fail to collect together, as they might do otherwise. These medicines are often part of long-term therapy for things like heart disease and atherosclerosis. Many of these drugs are used daily as a means of stopping blood clots before they are able to form.
A third group of antithrombotic drugs is anticoagulants, which also have a preventative effect on blood clot formation. Sometimes this group is known as blood thinners and the two most commonly used drugs in it are warfarin (Coumadin®) and heparin. These work in different ways, warfarin on vitamin K, and heparin on an agent that blocks thrombin, to make it much less likely that blood clots will form. People on these medicines, especially warfarin, need close blood monitoring to make certain blood clotting (pro-thrombin) time doesn’t sink below a particular level, which can cause excess bleeding. Given appropriate vigilance, drugs like warfarin can be highly effective in reducing the likelihood of blood clots occurring.
The appropriate antithrombotic is determined by a medical assessment of an individual. Certain conditions like the actual presence of a large clot may need the quickest treatment possible, in which case thrombolytics are recommended. Other conditions that pose risk for blood clots developing are better treated with antiplatelet or anticoagulant medications.