Non-steroidal antiinflammatory drugs (NSAIDs) are a heterogeneous group of agents classified together due to their ability to inhibit the cyclooxygenase pathway of arachidonic acid metabolism. Cyclooxygenase (COX) products include the "classic" prostaglandins such as PGE2 and PGF2D, prostacyclin (PGI2) and thromboxane A2(TxA2). Lipoxygenase products include pro-inflammatory leukotrienes, such as the neutrophil chemoattractant LTB4 and the bronchoconstrictors LTC4 and LTD4. These products, while playing a role in inflammation and pain transmission, participate in a number of key physiologic functions, including those underlying inflammation and pain transmission. The particular final product formed depends on the cell type being stimulated, the stimulus, and the presence of specific PG synthases within that cell. For example, the primary product of platelet stimulation is TxA2, a potent platelet aggregator and vasoconstrictor, while the primary product of the endothelial cell is PGI2, which has opposing actions to TxA2. In this way, these products form a series of "checks and balances" and participate in many normal day to day physiologic responses.
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