The Comparison Effects of Analgesics Flunixin Meglumine and Ketoprofen in Pain induced by Peroxynitrite in Guinea-Pigs

Background and objectives: Non steroidal anti inflammatory drugs (NSAIDs) are widely used to reduce inflammation, pain and fever. The present study was organized to induce an experimental inflammation in an animal model, using a putative biological oxidant, Peroxynitrite (ONOO-) and to study the effects of Flunixin meglumine and Ketoprofen on the pressure-induced pain. Materials and Methods: For this purpose, ۲۴ male guinea pigs were divided into ۴ groups each consisting of ۶ animals. Three groups (groups ۲, ۳ and۴) were injected Peroxynitrite and one group (the first: control) received physiological salt solution subcutaneously in the paw. After induction of a local inflammatory response, Flunixin meglumine (۱mg/kg) and Ketoprofen (۲ mg/kg) were injected to the second and third groups, ۵ times with ۱۲h intervals. The first and the fourth groups were injected saline solution in the same manner. Pressure analgesiometry was performed before and ۱ hour after injections. Result: The animals in all ۳ groups treated with Peroxynitrite demonstrated an increased sensitivity to painful pressure (P<۰.۰۵). Both NSAIDs decreased the pain sensation dramatically after the ۱st and the ۲nd injections but, not after the ۳rd, ۴th and the ۵th injections. Conclusion: The study suggested that NSAIDs may be helpful in reducing pressure-induced pain in animal model in early hours of the treatment, whereas the effect subsides over time and ends up after a few days. This effect may be of importance in humans who receive these kinds of drugs for a long period as they may not be effective in reducing pain after a while.