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In a randomized study we compared postoperative pain and analgesic requirement in patients who underwent elective cesarean section under general anesthesia induced with Thiopental 4 mg/kg (N=25) or Ketamin 1 mg/kg (N=25). Anesthesia was maintained with N2O and Halothane. Postoperative pain was measured with OPS scale and analgesia was provided with Morphine. Median time to first need of analgesic was greater in Ketamine group compared with Thiopental group. Median Morphine consumption over 24 hour was less in Ketamine group compared with Thiopental group. No patient had recall of intraoperative events in Ketamine group however in Thiopental group 12% of patients had such recalls. Apgar score was similar between groups. Induction of anesthesia for cesarean section using Ketamine is associated with a lower postoperative analgesic requirement compared with Thiopental. Patients who had anesthesia for cesarean section induced with Ketamine required less analgesic drugs in the first 24 hours postoperative period compared with patients who received Thiopental. Ketamin unlike Thiopental has analgesic properties that may reduce sensitization of pain pathways and extend into post-operative period.

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Background & Objective: Black pepper is frequently used in Iranian traditional medicine as an analgesic (E.g, for toothache). This investigation was conducted to evaluate the response of mice to pain induced by hot-plate and Formalin test either with or without Piperine (One of the active substances of the pepper). Materials & Methods: This randomized experimental study was performed on mice. Hot-plate and Formalin tests were planned to pain measurement. The mice were divided into 2 groups in each arm of study (Hot-plate and Formalin test group). The data of control (Saline) and drug (Piperine) groups were separately compared in each arm of study with student t-test and ANOVA. The difference between each point of data was considered significant at P-value under 0.05. Results: There was not a significant difference in tolerance time of subjects between hot-plate and saline groups. Piperine (25, 50 and 75 mg/kg) along with Morphine (10 mg/kg) causes significant increase to saline group in tolerance time and also significant increase to Morphine group, but in Formalin test Piperine could have significant effect in decreasing the pain induced by of Formalin on mice. These effects are comparable with Morphine. In Formalin test, pain has 2 phases. The first phase is acute and the 2nd one is chronic that begins from 15-20 minutes. Acute pain has central effect and chronic pain has peripheral pathway and Piperine causes decreasing response to Formalin test at the first phase of pain. Naloxone can prevent these effects in all groups. In Formalin test and hot-plate, the effect of Piperine were dose dependent. Conclusion: Piperine can centrally act on the nociception pathway and its effect on Opioid system exhibits as an enhancement Opioid effect. The effects are dose dependent and will be inhibited by Opioid antagonist.

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Background and Objective: Appropriate analgesia after surgery helps patients feel more comfortable and increase the mobility of them. The purpose of this study was to compare the effect of subcutaneous injection of Ketamine and Lidocaine in reducing postoperative pain in patients undergoing elective inguinal hernia surgery under general anesthesia.
Methods: This double blinded, randomized clinical trial study was done on 60 patients undergoing elective inguinal hernia under general anesthesia. Subjects were randomly assigned into three groups including control, Ketamine and Lidocaine groups. Subjects in Ketamine group were received infiltration of subcutaneous Ketamine 0.5 mg/kg/bw after closure of surgical incision. Subjects in Lidocaine group were received infiltration of subcutaneous Lidocaine 1 mg/kg/bw at the time of wound suturing. Subjects in control group did not receive Ketamine and Lidocaine. The visual analogue scale (VAS) of pain and vital signs were continuously assessed. If VAS≥3, 100 mg diclofenac suppository was administered and if there were no response, 30 mg intravenous pethidine was also administered. The complications, including hallucination, nystagmus, nausea, vomiting and drowsiness in patients were also recorded.
Results: The mean VAS at 1, 2 hours after surgery were significantly lower in the Ketamine and Lidocaine group in compared to control group (P<0.05). No significant adverse effect was observed in the Ketamine group.
Conclusion: For reduction of pain, administration of subcutaneous Ketamine is recommended due to no adverse effect and anti analgesic effect of Ketamine is similar to Lidocaine.