A comparison of effect of preemptive use of oral gabapentin and pregabalin for acute post-operative pain after surgery under spinal anesthesia

BACKGROUND AND AIMS: Preemptive analgesia is an antinociceptive treatment that prevents establishment of altered processing of afferent input. Pregabalin has been claimed to be more effective in preventing neuropathic component of acute nociceptive pain of surgery. We conducted a study to compare the effect of oral gabapentin and pregabalin with control group for post-operative analgesia MATERIALS AND METHODS: A total of 90 ASA grade I and II patients posted for elective gynecological surgeries were randomized into 3 groups (group A, B and C of 30 patients each). One hour before entering into the operation theatre the blinded drug selected for the study was given with a sip of water. Group A- received identical placebo capsule, Group B- received 600mg of gabapentin capsule and Group C — received 150 mg of pregabalin capsule. Spinal anesthesia was performed at L3-L4 interspace and a volume of 3.5 ml of 0.5% bupivacaine heavy injected over 30sec through a 25 G spinal needle. VAS score at first rescue analgesia, mean time of onset of analgesia, level of sensory block at 5min and 10 min interval, onset of motor block, total duration of analgesia and total requirement of rescue analgesia were observed as primary outcome. Hemodynamics and side effects were recorded as secondary outcome in all patients. RESULTS: A significantly longer mean duration of effective analgesia in group C was observed compared with other groups (P < 0.001). The mean duration of effective analgesia in group C was 535.16 ± 32.86 min versus 151.83 ± 16.21 minutes in group A and 302.00 ± 24.26 minutes in group B. The mean numbers of doses of rescue analgesia in the first 24 hours in group A, B and C was 4.7 ± 0.65, 4.1 ±0.66 and 3.9±0.614. (P value <0.001). CONCLUSION: We conclude that preemptive use of gabapentin 600mg and pregabalin 150 mg orally significantly reduces the postoperative rescue analgesic requirement and increases the duration of postoperative analgesia in patients undergoing elective gynecological surgeries under spinal anesthesia