Ketorolac is a nonsteroidal anti-inflammatory drug (NSAID) chemically related to indomethacin and tolmetin. Ketorolac tromethamine is a racemic mixture of [-]S- and [+]R-enantiomeric forms, with the S-form having analgesic activity. Most NSAIDs, including ketorolac, are non-selective prostaglandin G/H synthase (better known as cyclooxygenase or COX) inhibitors that act on both prostaglandin G/H synthase 1 and 2 (COX-1 and -2). Prostaglandin G/H synthase catalyzes the conversion of arachidonic acid to prostaglandin G2 and prostaglandin G2 to prostaglandin H2. Prostaglandin H2 is the precursor of a number of prostaglandins involved in fever, pain, swelling and inflammation (e.g. PGE2). Ketorolac antagonizes COX by binding to the upper portion of the active site, preventing its substrate, arachidonic acid, from entering the active site. The analgesic, antipyretic and anti-inflammatory effects of ketorolac occur as a result of decreased prostaglandin synthesis. Ocular administration of ketorolac reduces prostaglandin E2 levels in aqueous humor.
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