Evaluation of Antinociceptive Efficacy of pre Versus post-Incisional Morphine, Tramadol or Meloxicam in Rats

Objective- To evaluate antinociceptive efficacy of pre- versus post-incisional morphine, tramadol and meloxicam using tail-flick test in an incisional model of pain in rats. Design- Prospective, randomized experimental study. Animals- Eighty, adult, male Wistar rats weighing ۲۵۰–۳۰۰ g. Procedures- Animals were randomly divided into eight groups to receive pre- or post-incisional (tail skin incision) saline (۱ mL/kg, IP), morphine (۴ mg/kg, IP), tramadol (۱۲.۵ mg/kg, IP), or meloxicam (۱ mg/kg, IP). Antinociceptive effect of drugs was assessed using tail-flick latency (TFL) test following exposure to radiant heat. Results- Morphine injection before or after incision prevented hyperalgesia for ۱۲۰ minutes, while pre- or post-incisional administration of tramadol prevented hyperalgesia for ۹۰ and ۱۲۰ minutes, respectively. There was no significant difference between pre- or post-incisional administration of morphine or tramadol. Meloxicam, given either before or after skin incision, did not prevent hyperalgesia as compared with saline control group. Conclusion and Clinical Relevance- The timing of treatment had no significant effects on post-operative nociception. Both morphine and tramadol were effective in reducing post-operative hyperalgesia and can be used for the control of early postoperative nociception in rats.

Keywords:

Tail flick , Morphine , Tramadol , Meloxicam , Rat