Aspirin, also known as acetylsalicylic acid, is a nonsteroidal anti-inflammatory drug NSAID that works to relieve pain and reduce inflammation at the molecular level by inhibiting the production of prostaglandins.Prostaglandins are hormone-like substances that play a crucial role in the inflammatory response, pain perception, and regulation of blood flow. They are synthesized from arachidonic acid by the enzyme cyclooxygenase COX . There are two main isoforms of COX: COX-1 and COX-2. COX-1 is constitutively expressed and involved in maintaining normal physiological functions, while COX-2 is induced during inflammation and is responsible for the production of prostaglandins that cause pain and inflammation.Aspirin works by irreversibly inhibiting both COX-1 and COX-2 enzymes. It does this by acetylating a serine residue Ser-530 in the active site of the enzyme, which prevents the binding of arachidonic acid and, in turn, the production of prostaglandins. This inhibition of prostaglandin synthesis results in reduced inflammation, pain, and fever.In addition to its anti-inflammatory and analgesic effects, aspirin has also been shown to have antithrombotic properties. This is because it inhibits the production of thromboxane A2, a prostaglandin that promotes platelet aggregation and vasoconstriction. By inhibiting thromboxane A2 synthesis, aspirin reduces the risk of blood clot formation, making it useful for the prevention of heart attacks and strokes.In summary, aspirin works at the molecular level by irreversibly inhibiting the COX enzymes, which leads to a decrease in the production of prostaglandins. This results in reduced inflammation, pain, and fever, as well as antithrombotic effects.