Discovered in 1897, aspirin (acetylsalicylic acid) was the most important and most widely used anti-inflammatory drug , analgesic and przeciwgoršczkowym in the twentieth century. Aspirin and its analogues called a common nonsteroidal antiinflammatory drugs ( NSAIDs) through a common mechanism działajš based on the ability to inhibit the enzyme cyclooxygenase . Cyclooxygenase istniejš in at least two varieties: constitutive (COX -1) and inducible (COX -2). Aspirin and other NSAIDs inhibit both isoforms invol COX . Since prostaglandins are produced as a result of the catalytic activity of COX- 1 ochraniajš śluzowš gastrointestinal membrane thus inhibition of its activity leads to ulceration of the stomach and duodenum. In order to prevent the development of ulcers , drugs can be administered simultaneously osłaniajšce gastrointestinal mucosa , NSAIDs and to replace their counterparts bšdź uwalniajšce połšczone nitric oxide amphipathic phospholipids . Recent studies have allowed a selective COX- 2 inhibitors , which involve only the inhibition of COX- 2 is responsible for the symptoms of inflammation and pain reactions . A new generation of NSAIDs characterized by a raised safety although it is not free from side effects. These effects are A consequence of constitutive expression of COX -2 in the kidney , gojšcych to ulcers and reproductive system . More and more reports indicate the existence of a third isoform of COX (COX -3 ) , including the study of paracetamol . The mechanism of action of this drug has so far been unknown. Paracetamol ability to inhibit pain and inflammation but fever , with low selectivity for COX -1 and COX -2 seems to confirm this hypothesis. This discovery changed the position of aspirin in the XXI century. It is now recommended in small doses , as an anticoagulant in adds the wyłšcznš obecnościš COX -1 in platelets .