Ibuprofen and acetaminophen are two commonly prescribed pain medications that belong to different classes of drugs. Ibuprofen is a nonsteroidal anti-inflammatory drug NSAID , while acetaminophen also known as paracetamol is an analgesic and antipyretic drug. Both drugs are used to treat mild to moderate pain and reduce fever, but they have different chemical structures and modes of action in the body.Chemical Structures:1. Ibuprofen: The chemical structure of ibuprofen is C13H18O2, and it is derived from propionic acid. It has a chiral carbon atom, which means it exists in two enantiomeric forms S and R . The S-enantiomer is the active form responsible for the drug's therapeutic effects.2. Acetaminophen: The chemical structure of acetaminophen is C8H9NO2, and it is derived from aniline. It does not have a chiral carbon atom, so it does not exist in enantiomeric forms.Modes of Action:1. Ibuprofen: The primary mode of action of ibuprofen is the inhibition of cyclooxygenase COX enzymes, specifically COX-1 and COX-2. These enzymes are responsible for the conversion of arachidonic acid to prostaglandins, which are involved in inflammation, pain, and fever. By inhibiting COX enzymes, ibuprofen reduces the production of prostaglandins, thereby alleviating pain, inflammation, and fever. Additionally, ibuprofen has a mild antiplatelet effect due to its inhibition of COX-1, which can reduce blood clot formation.2. Acetaminophen: The exact mode of action of acetaminophen is not entirely understood, but it is believed to involve the inhibition of COX enzymes, particularly a variant called COX-3, which is found mainly in the central nervous system. This inhibition leads to a decrease in prostaglandin synthesis, resulting in pain relief and fever reduction. Unlike ibuprofen, acetaminophen does not have significant anti-inflammatory effects and does not inhibit COX-1 or COX-2 in peripheral tissues, which is why it does not cause gastrointestinal side effects or affect platelet function.In summary, ibuprofen and acetaminophen are both effective pain relievers and fever reducers, but they have different chemical structures and modes of action. Ibuprofen is an NSAID that primarily works by inhibiting COX-1 and COX-2 enzymes, providing pain relief, fever reduction, and anti-inflammatory effects. Acetaminophen, on the other hand, is an analgesic and antipyretic drug that is believed to inhibit the COX-3 enzyme, providing pain relief and fever reduction without significant anti-inflammatory effects or gastrointestinal side effects.