But only in the last few decades have we understood how aspirin works, and how it might be improved. Prostaglandins As you might expect from a drug with such diverse actions, aspirin blocks a central process in the body. Aspirin blocks the production of prostaglandins, key hormones that are used to carry local messages. Unlike most hormones, which are produced in specialized glands and then delivered throughout the body by the blood, prostaglandins are created by cells and then act only in the surrounding area before they are broken down. Prostaglandins control many of these neighborhood processes, including the constriction of muscle cells around blood vessels, aggregation of platelets during blood clotting, and constriction of the uterus during labor.
Prostaglandins also deliver and strengthen pain signals and induce inflammation.
These many different processes are all controlled by different prostaglandins, but all created from a common precursor molecule. It adds two oxygen molecules to arachidonic acid, beginning a set of reactions that will ultimately create a host of unusual molecules. Aspirin blocks the binding of arachidonic acid in the cyclooxygenase active site. The normal messages are not delivered, so we don't feel the pain and don't launch an inflammation response. COX-1 is built in many different cells to create prostaglandins used for basic housekeeping messages throughout the body.