The Effect of Subcutaneous Injection of Metoclopramide, Pethidine, and Ketamine on Postoperative Pain after Inguinal Hernia Repair under General Anesthesia

Background: The aim of this study was to investigate the effect of subcutaneous injection of metoclopramide, pethidine, and ketamine on postoperative pain after inguinal hernia repair under general anesthesia compared to control group. Methods: In this clinical trial study, 104 patients were selected and randomly divided into four groups of 26 patients. The patients received subcutaneous injection of each drug at the incision site. In the first group, 0.5 mg/kg ketamine, in the second group, 0.75 mg/kg pethidine, in the third group, 0.1 mg/kg metoclopramide, and in the control group, normal saline were administered. We evaluated the pain intensity [by visual analog scale (VAS)], hemodynamic parameters, extubation and recovery time, drug complications, total rescue analgesic consumption, time to first analgesic request, and satisfaction score for the initial 24 hours after entrance to recovery. Findings: The mean of VAS at the most of measuring times (P < 0.050) and the mean of total rescue analgesic consumption (P = 0.007) were significantly lower in the ketamine and pethidine groups compared to metoclopramide and control groups. The satisfaction score for postoperative analgesia in pethidine group was significantly higher than the other groups (P < 0.001). Conclusion: Pethidine and ketamine have equal effects on postoperative pain; but the patients were more satisfied with pethidine. The effect of metoclopramide on the postoperative pain was lower than the other two drugs; moreover, its effect was equal to the placebo and was associated with more adverse reactions.