Evaluating the effect of preoperative oral gabapentin on postoperative pain in patients receiving spinal anaesthesia for lower limb surgery

Abstract

Background: Gabapentin has been used successfully as a non-opioid analgesic adjuvant for postoperative pain management. We hypothesised that gabapentin might be a useful adjuvant for postoperative analgesia in patients undergoing lower extremity surgery under subarachnoid block. Method: Ninety male patients undergoing lower extremity surgery under subarachnoid block were randomly divided into three groups. Group I (n = 30) patients received oral gabapentin 1 200 mg one hour prior to surgery. Group II (n = 30) patients received oral gabapentin 600 mg one hour prior to surgery. Group III (n = 30) patients received an oral placebo one hour prior to surgery. Lumbar puncture was done with 23G Quincke’s spinal needle and 2.5 mL of 0.5% heavy bupivacaine was administered intrathecally. Patients were monitored at 0, 1, 3, 5, 8, 12 and 24 hours for assessment of pain and side effects. Patients having pain scores ≥5 received rescue analgesia in the form of intravenous tramadol 0.5 mg.kg-1. If the pain score persisted at ≥5 after ten minutes, 0.25 mg.kg-1 tramadol was repeated. Results: Pain scores at zero hour were statistically significantly lower in patients receiving 1 200 mg of gabapentin (group I) when compared with the other two groups. The total rescue analgesia (tramadol) requirement over the study period was also at the minimum in patients receiving 1 200 mg of gabapentin as compared to patients receiving 600 mg of gabapentin or placebo. However, sedation scores were significantly higher in patients receiving gabapentin 1 200 mg or 600 mg than placebo. Conclusion: Preoperative gabapentin, when administered one hour prior to surgery in a dose of 1 200 mg, decreases postoperative pain scores at zero hour and the rescue analgesia requirement significantly over a period of 24 hours in patients undergoing lower limb surgery under spinal anaesthesia.

Keywords: gabapentin; postoperative; pain; rescue analgesia