Aspirin

Aspirin, an ester of salicylic acid, is a drug that has the ability to decrease pain (analgesic properties), to lower body temperature (anti-inflammtory properties), It is most frequently taken in tablet form, and the tablet usually contains 325 mg of aspirin held together with an inert starch binder.

After ingestion, some aspirin undergoes hydrolysis to produce salycylic acid and acetic acid.

Salicylic acid is the active ingredient of aspirin -- the substance that has analgesic, antipyretic, and anti-inflammatory effects.

Salicylic acid is capable of irritating the lining of the stomach, inducing a small amount of bleeding. Breaking (or chewing) an aspirin tablet, rather than taking it whole,reduces the chance of bleeding by eliminating drug concentration on one part of the stomach lining, Buffered aspirin products contain alkaline chemicals (such as aluminium glycerate or aluminium hydroxide) to neutalize the acidity of the aspirin when it contains the stomach lining.

Aspirin inhibits the synthesis of a class of hormones called prostaglandins. When present in higher-than-normal levels in the bloodstream, these hormones cause pain, fever, and inflammtion.

Aspirin increases the time it takes blood to coagulate (clot). For blood to coagulate, platelets must first be able to aggregate, and prostaglandings (which aspirin inhibits) appear to be necessary for platelet aggregation to occur. One study suggests that healthy men can cut their risk of heart attacks nearly in half by taking one aspirin tablet everyother day. Aspirin acts by making the blood less likely to clot. Heart attacks usually occur when clots form in the coronary arteries, cutting off blood supply to the heart.