I. Historical Review
II. Mechanism of Action
III. Recognized Indications for Aspirin and Dose
IV. Perspective
GLOSSARY
atheroma same as atherosclerosis, raised plaques filled with cholesterol, calcium, and other substances on the inner wall of arteries that obstruct the lumen and the flow of blood; the plaque of atheroma hardens the artery, hence the term atherosclerosis (sclerosis ¼ hardening).
myocardial infarction death of an area of heart muscle caused by blockage of a coronary artery by blood clot and atheroma; medical term for heart attack or coronary thrombosis.
platelets very small disk-like particles that circulate in the blood along with red blood cells initiating the formation of blood clots; platelets clump and form little plugs called platelet aggregation, thus causing bleeding to stop.

• I. HISTORICAL REVIEW
  You do not have to believe in Adam and Eve to recognize the significance of an apple. The old saying ‘‘an apple a day keeps the doctor away’’ has been changed to ‘‘an aspirin a day keeps the doctor away’’ (see Fig. 1).
• II. Mechanism of Action
  Acetylsalicylic acid irreversibly acetylates the enzyme cyclooxygenase found in platelets. This enzyme is necessary for the conversion of platelet arachidonic acid to throm-boxane A2. The latter is a powerful platelet-aggregating agent and vasoconstrictor. The conversion to thromboxane A2 and platelet aggregation can be initiated by several substances, especially those released following the inter¬action of catecholamine or platelets with subendothelial collagen. Endothelial and smooth muscle cells, when stimulated by physical or chemical injury, cause cyclooxy-genase to convert membrane arachidonic acid to prosta-cyclin which is then released. Prostacyclin is a powerful inhibitor of platelet aggregation as well as a potent vaso¬dilator. Aspirin reduces the formation of prostacyclin in the vessel wall and its undesirable effects. Low-dose aspirin inhibits thromboxane A2 synthesis and platelet aggrega¬tion, but does not appear to inhibit prostacyclin produc¬tion significantly.
• III. RECOGNIZED INDICATIONS FOR ASPIRIN AND DOSE
  A. Life-Saving Measures
• IV. PERSPECTIVE
  Many individuals who fall into the above categories are not treated with aspirin by their physicians. In particular,
• BIBLIOGRAPHY
  Cairns, J. A., Gent, M., Singer, J. et al. Aspirin and sulfinpyrazone or both in unstable angina. N. Engl. J. Med., 313:1369, 1986.

Drawing spare parts catalogue lastly