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 250–300 g. procedures- animals were randomly divided into eight groups to receive pre- or post-incisional (tail skin incision) saline (1 ml/kg, ip), morphine (4 mg/kg, ip), tramadol (12.5 mg/kg, ip), or meloxicam (1 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 120 minutes, while pre- or post-incisional administration of tramadol prevented hyperalgesia for 90 and 120 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.