High levels of post operative pain and anxiety increases patient discomfort and post operative morbidity. Anxiolytic and analgesic effects of melatonin improves control of post operative pain by controlling higher anxiety that accompanies surgical intervention. This study compares antinociceptive effects of both melatonin and gabapentin premedication on post operative pain and analgesic requirement.

Methods: Ninety female patients undergoing modified radical mastectomy were randomly divided into three groups of 30 each where Group G given Gabapentin 600 mg, Group M given Melatonin 6 mg, Group C given placebo tablet 90 minutes before surgery. Post operative pain, sedation scores and post operative analgesic consumption was assessed for 24 hrs.

Results: Visual analogue scale (VAS) score were lower in the group G and group M as compared to group C. Sedation score recorded highest in Group M followed by Group G and least in Group C. Time to first analgesic requirement was 16.58±4.47 hrs in Group G, 6.09±5.12 hrs in Group M and 2.80±0.83 hr in Group C (p<0.0001). Total 24 hr post operative diclofenac requirement in Group G (96.77±34.60) was significantly lower than Group C (166.93±31.87) and M (142.74±44.81) (p<0.0001).

Conclusion: Both melatonin and gabapentin reduced post operative pain and analgesic consumption. Gabapentin had higher analgesic effect while melatonin was more sedative. Administration of melatonin before surgery may accelerate the resynchronization of circardian rhythm in the post operative period suggesting better recovery quality.