The effect of oral gabapentin as an adjuvant to post operative epidural analgesia for lower abdominal surgeries. A randomized placebo controlled double blind trial

Abstract

Background and objectives: ABSTRACT To determine whether adjuvanting epidural analgesia with gabapentin can alter first analgesic requirement time, Postoperative epidural fentanyl consumption, and Postoperative pain scores in the first 24 hrs after surgery. Methodology: 66 ASA grade I and II patients, of either sex, aged 18 to 65 yrs, scheduled for lower abdominal surgery under epidural anaesthesia were included in the study. All were allocated randomly by computer generated randomization sheet into two groups of 33 each. Participants in the study were administered 2 capsules ( either gabapentin or placebo) one hour before surgery with sips of water. A compound solution containing 0.5% bupivacaine and 2% lignocaine was prepared and administered into epidural space through 20 gauge epidural catheter. The volume of the drug was calculated based on the patient’s body weight and age. Pain was assessed postoperatively using visual analogue scale. Inj. Fentanyl 20 g was administered as rescue analgesic. The data were analyzed using Mann-Whitney ‘U’ test and unpaired student ‘t’ test. Results: The time at which rescue analgesic was administered in the control group was 2.62±0.82 hrs and in the study group 4.27±1.24 hrs. The time at which rescue analgesics were required in the study group was significantly prolonged ( p<0.0001) . The amount of Inj. fentanyl required as rescue analgesic in the control group ( 103.03  15.91g ) and in study group ( 69.09  12.34 g ) . This was statistically significant ( p<0.0001) . IX Conclusion and interpretation: We conclude that the preemptive administration of 800mg oral gabapentin as an adjuvant to postoperative epidural analgesia for lower abdominal surgeries significantly prolongs the time at which patient requires rescue analgesic and the amount of rescue analgesic needed was also significantly reduced in the study group as compared to control.