ANTIPLATELET AGENTS

DISCLAIMER: THIS PAGE CONTAINS A GENERAL EDUCATIONAL DISCUSSION ON THE ABOVE TOPIC. IT IS NOT HEALTH ADVICE AND SHOULD NOT BE CONSTRUED AS SUCH. YOU SHOULD NEVER RELY UPON THE INFORMATION GIVEN HERE. YOUR PARTICULAR CIRCUMSTANCES MAY WELL REQUIRE AN ENTIRELY DIFFERENT APPROACH. YOU SHOULD NOT MAKE ANY CHANGES IN YOUR MEDICATIONS, DIET, ACTIVITY, LIFESTYLE, ETC. WITHOUT FIRST CONSULTING A LICENSED PHYSICIAN IN YOUR AREA.

CHEMICAL NAME	BRAND NAME(S)
CYCLOOXYGENASE INHIBITORS
ACETYLSALICYLIC ACID	ASPIRIN, AGGRENOX (in combination with dipyridimole)
ADP INHIBITORS
CLOPIDOGREL	PLAVIX
TICLOPDIPINE	TICLID
PHOSPHODIESTERASE III INHIBITORS
CILOSTAZOL	PLETAL
GLYCOPROTEIN IIB/IIIA INHIBITORS
ABCIXIMAB	RHEOPRO
EPTIFIBATIDE	INTEGRILIN
TIROFIBAN	AGGRASTAT
ADENOSINE REUPTAKE INHIBITORS
DIPYRIDIMOLE	PERSANTINE, AGGRENOX (in combination with aspirin)

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.

Platelets are small particles of cells in the blood stream which promote clotting. They can be inhibited by aspirin (acetylsalicylic acid), Ticlid (ticlodipine), Plavix (clopidogrel), Pletal (cilostazol), Persantine (dipyridamole), Anturane (sulfinpyrazone), and 3 intravenous agents called Rheopro (abciximab), Integrilin (eptifibatide) and Aggrastat (tirofiban). All of these agents affect platelets in different ways to achieve their effect. Nitrates, Vitamin E and Gingko Biloba also have mild antiplatelet effects. Platelet inhibition is a mild form of blood thinning.

Aspirin is the most commonly used of the antiplatelet agents. It is quite effective for preventing recurrent cardiovascular events such as heart attacks and strokes in patients with known cardiovascular disease. It is an important component of the treatment of patients with unstable angina and heart attacks as well as stable coronary patients. It prolongs the survival of heart attack victims. It reduces the risk of recurrent stroke in people who have had a stroke or ministroke. The appropriate dose is anywhere from 81 to 325 milligrams per day. It is generally recommended that it be taken in an "enteric coated" form so that it does not dissolve until it reaches the intestine. This decreases the risk of it causing an upset stomach or an ulcer. The effect of aspirin on platelets lasts 10 days so if a patient needs a surgical procedure, aspirin may need to be stopped as early as 10 days before.

Ticlodipine (Ticlid) is used if a person has a stroke despite already being on aspirin. It is also used for one month after a coronary stent has been placed. Patients with coronary stents should generally remain on aspirin as well, even while they are taking Ticlid. The main side effect of Ticlid is a low white blood cell count. Therefore, blood counts are monitored during its use.

Clopidogrel (Plavix) works in a fashion similar to Ticlid but with less side effects. Studies on it suggest that it may be therapeutically superior to aspirin as well. It appears less likely to cause an upset stomach or an ulcer than aspirin. Plavix is used combination with aspirin for one month after placement of a coronary stent. It is also used in combination with aspirin in patients who have developed a severe form of angina, called unstable angina, and in patients suffering from a certain type of heart attack.

Aspirin, ticlodipine and clopridogrel are also effective for the inflammatory process in blood vessels that promotes athersclerosis.

Aggrenox is a combination of aspirin and extended-release dipyridimole that may be more effective than aspirin alone for the prevention of strokes in patients at risk.

Cilostazol (Pletal) is an antiplatelet agent that also dilates blood vessels. It is used to treat symptoms resulting from blocked leg arteries and may also help prevent restenosis after coronary angioplasty.

Abciximab (Rheopro), eptifibatide (Integrilin) and tirofiban (Aggrastat) are in a class of agents called glycoprotein 2b/3a inhibitors. Glycoprotein 2b/3a inhibitors are the most potent antiplatelet agents developed to date. They are given intravenously during angioplasty and related procedures to improve the outcome of the procedure and they help stabilize patients admitted with unstable angina. They may also prove useful in the treatment of acute heart attack victims. Oral glycoprotein 2b/3a inhibitors (orbofiban, sibrafiban, xemlofiban, and Klerval-PM) were investigated for chronic use but were not found to be beneficial.