Role of Preemptive Gabapentin on Postoperative Analgesia After Infraumbilical Surgeries Under Subarachnoid Block-A Randomized, Placebo-Controlled, Double-Blind Study

Abstract

Background: Preemptive use of gabapentin might accelerate recovery by reducing acute post-inguinal herniorrhaphy pain and opioid requirement being an analgesic.

Study question: Assessing efficacy of three different doses of oral gabapentin premedication for postoperative pain management after inguinal herniorrhaphy under spinal anesthesia.

Study design: This prospective, randomized, placebo controlled study was performed on 120 male patients (ASA I/II) undergoing inguinal herniorrhaphy under subarachnoid block. Patients were divided into 4 groups of 30 patients each to receive placebo (group A) or gabapentin 400 mg (B) or 800 mg (C) or 1200 mg (D), administered orally 2 hours before surgery. Assessment of postoperative pain was made on the basis of the visual analog score (VAS), where 0 cm "no pain" and 10 cm "worst pain imaginable." Patients received IV fentanyl 0.5 μg/kg bolus when VAS >3.

Measures and outcomes: VAS score at regular intervals, the first analgesic requirement and total opioid consumption within 24 hours after surgery along with side/adverse effect (s) of study drug in perioperative period.

Results: The VAS of the study groups B, C, D were significantly lower than placebo group (A) at 0, 1, 2, 4, 8, 12, 16, 20, and 24-hour intervals after surgery (P < 0.05). The first analgesic need and total opioid consumption within 24 hours after surgery of study groups were significantly lower than placebo group (P < 0.005) while within study groups difference was not significant. Dizziness and somnolence were seen maximally in group D patients (P = 0.01). However, pruritus, nausea and vomiting though maximally reported among group (A) patients but statistically non-significant.

Conclusion: Preemptive gabapentin is opioid sparing to control postoperative pain with anxiolysis and sedation. We found the optimal dose to be 400 mg for gabapentin. However, increasing dose from 400 to 1200 mg does not increase its efficacy as analgesic but with higher adverse effects.