Ketorolac tromethamine is a highly potent member of a class of compounds having both analgesic and antiinflammatory activity. In animal pain models using underlying inflammation, ketorolac markedly inhibited the pain response and increased the pain threshold; it did not exhibit any narcotic or central nervous system depressant effects. It was also active in rat models of acute and chronic inflammation and pyresis. These activities are mediated primarily by potent prostaglandin cyclooxygenase inhibitory activity. Mild central nervous system and cardiovascular effects occurred only at doses far greater than those required for analgesic and antiinflammatory activity. Solutions of ketorolac tromethamine are not irritating. When given intramuscularly to rabbits (0.31-5% solutions), no drug-related irritation or changes in serum creatine phosphokinase were seen. The agent was not irritating when applied to the skin or eyes (less than or equal to 0.5% solutions) of animals.