What are Antiplatelet Drugs?

wiseGEEK Writer

An antiplatelet drug is a medicine that acts on the body’s platelets to prevent them from clotting or clumping together abnormally, as might occur during a heart attack, if people have had heart surgery, and especially for things like stent placement, or when people have narrowed blood vessels from conditions like atherosclerosis. These drugs don’t discriminate between normal platelet clotting, which occurs when people a get a cut, and abnormal clotting, when blood clots form where they shouldn’t. This means antiplatelet drugs can be slightly risky to take, though that risk factor is outweighed by their potential benefits.

Antiplatelet drugs help prevent blood clot formation.
Antiplatelet drugs help prevent blood clot formation.

Platelets are an important constituent of human blood, and when present in appropriate supply, they aggregate or clump together to stop bleeding. This includes bleeding under the skin or injury in the blood vessels. Forming blood clots in blood vessels is a highly undesirable state. Large clots can either stem the flow of blood or they may pass into the heart, brain, or lungs creating heart attack, stroke or pulmonary embolus. Blood clots can also form in areas like the legs, causing deep vein thrombosis.

Aspirin is sometimes used to prevent platelet aggregation.
Aspirin is sometimes used to prevent platelet aggregation.

Antiplatelet drugs cannot break down a clot, for the most part, but they can interfere with the clot forming. Depending on type of need, doctors could use one of three kinds of antiplatelet drugs to try to stop platelet aggregation. These types are aspirin, thienopyradines, and glycoprotein 2a/2b inhibitors.

Aspirin may be one of the best known of the antiplatelet drugs. It usually has to be taken in low dose or child strengths on a consistent basis to work, though a whole aspirin taken during a heart attack has been shown to reduce mortality by about 20%. It provides some heart attack and stroke prevention, but is not always the drug of choice. It is associated with gastrointestinal upset in some users and should not be taken by pregnant or breastfeeding women.

Thienopyradines include the drugs Plavix® and Ticlid®, and work in a slightly different methods than aspirin. They block receptors on platelets for a naturally produced chemical called adenosine diphosphate. In the absence of platelets receiving this, they may not clump or aggregate as they ordinarily would. In some cases, doctors double up and prescribe Plavix® and aspirin concurrently.

The third type of antiplatelet drugs are generally only used during the treatment of heart attacks or possibly strokes. Unlike Plavix® or aspirin, glycoprotein 2a/2b inhibitors are administered intravenously, and are usually taken for short spans of time. People on aspirin or thienopyradines may take them for life.

People taking antiplatelet drugs should always inform doctors of this if they’ll have medical or dental procedures. Extensive surgeries might require not taking the drugs for a few weeks to minimize risk of excess bleeding. It should also be noted that these are not the only medicines that are anti-coagulants and that help to prevent blood from clumping together. Medicines like warfarin may be more appropriate for long term treatment than are antiplatelet drugs, with certain heart conditions.

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