The Anti-inflammatory Effect of Ketorolac Propyl Ester and Pentyl Ester in Guinea Pigs

Abstract

In order to develop long-acting nonsteroidal antiinflammatory drugs for clinical use, we carried out two studies in guinea pigs to evaluate the antiinflammatory effects of the depots of two ketorolac esters-propyl ester and pentyl ester-and to see whether they had a long-acting effect. In study 1, the dose response study of the antiinflammatory effect of intramuscular ketorolac tromethamine in saline was carried out. In study 2, the dose response studies of the antiinflammatory effect of intramuscular ketorolac propyl ester and pentyl ester in oil were made. We found that both the traditional dosage form of ketorolac tromethamine in saline and the novel dosage forms of ketorolac esters in oil produced significant dose-related antiinflammatory effects but with different durations of action. Under the given doses of 80 and 160mmol/kg, the durations of action of ketorolac tromethamine, ketorolac propyl ester, and pentyl ester were 8- and 10-h, 52- and 56-h, and 80- and 96-h, respectively. In conclusion, intramuscular injection of novel depots of ketorolac propyl ester and pentyl ester in guinea pigs produced a long-acting effect. These evidences are valuable for the development of long-acting depots of ketorolac esters.