Ibuprofen is typical of the class of nonsteroidal anti-inflammatory drugs and has anti-inflammatory, analgesic and antipyretic activities. In the early stages of the development of the acute inflammation there is increased vascular permeability and mast cell degranulation with accompanying release of histamine and 5-hydroxytryptamine within 10–15 min. The initial phase of inflammation induced by subplantar injection of carrageenan results only in a small degree of footpad swelling due to accumulation of fluid. The acute anti-inflammatory effects of ibuprofen in the carrageenan paw oedema model show that this drug is appreciably more potent than aspirin and phenylbutazone, but less so than indomethacin. Plasma iron concentrations usually decline in adjuvant arthritis as part of the systemic acute-phase response to the disease. Intrathecal ibuprofen has been shown to be 1.4 times more potent as an analgesic than aspirin and 10 times less so than indomethacin.