STUDY OF ANTINOCICEPTIVE EFFECT OF MELATONIN ALONE AND IN COMBINATION WITH PETHIDINE IN SWISS ALBINO MICE

Pain is the most common reason for physician consultation. Among the currently available analgesic drugs, opioids are the most efficacious but have many unacceptable adverse effects. Melatonin has been found to have antinociceptive potential in many animal and clinical studies that need further evaluation. The study aimed to assess the antinociceptive effect of melatonin alone and in combination with pethidine. Twenty Swiss albino mice were divided into four groups, each containing five animals receiving respective drugs. Tail flick and tail clip methods were used to assess antinociceptive effect of the drug. The reaction time of each animal in each group was taken at 0 min, 30 min, 60 min, 90 min and 120 min and the experiment was conducted on day 0, day 7, day 14 and day 28. Mean reaction time averaged over day 0, day 7, day 14 and day 28 was used to make inter-group comparisons. The mean reaction time increased in all groups except group I, in both tail flick and tail clip methods suggesting an antinociceptive effect of melatonin. The mean reaction time of a combination of melatonin and pethidine was much higher than that of either pethidine alone or melatonin alone, suggesting that melatonin potentiated the effect of pethidine. The antinociceptive effect of melatonin in the dose used in the present study was comparable to that of melatonin, and melatonin potentiated antinociceptive effect of pethidine.