ChEBI: Ibuprofen is a monocarboxylic acid that is propionic acid in which one of the hydrogens at position 2 is substituted by a 4-(2-methylpropyl)phenyl group. It has a role as a non-steroidal anti-inflammatory drug, a non-narcotic analgesic, a cyclooxygenase 2 inhibitor, a cyclooxygenase 1 inhibitor, an antipyretic, a xenobiotic, an environmental contaminant, a radical scavenger and a drug allergen. It derives from a propionic acid. It is a conjugate acid of an ibuprofen(1-).NCI Thesaurus (NCIt): Ibuprofen is a propionic acid derivate and nonsteroidal anti-inflammatory drug (NSAID) with anti-inflammatory, analgesic, and antipyretic effects. Ibuprofen inhibits the activity of cyclo-oxygenase I and II, resulting in a decreased formation of precursors of prostaglandins and thromboxanes. This leads to decreased prostaglandin synthesis, by prostaglandin synthase, the main physiologic effect of ibuprofen. Ibuprofen also causes a decrease in the formation of thromboxane A2 synthesis, by thromboxane synthase, thereby inhibiting platelet aggregation. (NCI05)