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.