Preemptive analgesic effect of diclofenac: experimental study in rats.

BACKGROUND Preemptive analgesia is an antinociceptive treatment that prevents central sensitization. Antinociceptive effects of diclofenac are well-known. The aim of this study was to investigate preemptive analgesic effects of intraperitoneally administrated diclofenac, before and after acute and inflammatory induced pain in rat model. METHODS Forty eight male Sprague Dawley rats were included in the study. The rats are divided in five groups (n=8 per each group); Group A, diclofenac at 10 mg/kg given ip, 30 min before the nociceptive stimulus realized with hot plate test; Group B, diclofenac at 10 mg/kg given ip, 5 min after the nociceptive stimulus, realized with hot plate test; Group C, diclofenac at 10 mg/kg given ip, 30 min before the nociceptive stimulus realized with formalin test, and; Group D, diclofenac at 10 mg/kg given ip, 5 min after the nociceptive stimulus, realized with formalin test. Saline was used as a control. Paw movements in response to induced pain with hot plate test and formalin test were measured during 60 minutes. RESULTS Preemptive analgesic effect was significant in both groups when diclofenac was administrated before the pain stimuli (P < 0.01 and P < 0.001). The significant decrease in paw movements started in 15 min after pain stimuli in group A and in 25 min, in group C. CONCLUSION Intraperitoneally administered diclofenac had preemptive analgesic effects on acute thermal, and inflammatory induced pain in rats. Our results contain the preemptive analgesic effect of systematically administrated diclofenac.