Preemptive Use of Gabapentin in Abdominal Hysterectomy

Opioids relieve posthysterectomy pain, but their use is limited by their inherent dose-related adverse effects and other shortcomings. Therefore, an additional nonopioid agent is often required to lower the dose of the opioid. One such agent is gabapentin, a third-generation antiepileptic drug. Several randomized studies have evaluated the effectiveness of preemptive gabapentin before surgical incision for hysterectomy as well as combined use of preemptive and postoperative gabapentin. This meta-analysis and systematic review examined the evidence for preemptive use of gabapentin in abdominal hysterectomy. A search for articles published between 2004 and 2013 was conducted using the following electronic databases: PubMed, EMBASE, Ovid MEDLINE, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trials. The search was performed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) statement. Medical search subject heading terms, keywords, and their combinations used included “postoperative pain,” “hysterectomy,” “gynecologic surgical procedures,” “gabapentin,” “preemptive analgesia,” and “preemptive anesthesia.” A manual search of the reference lists in identified studies was conducted. Articles included were double-blind randomized controlled trials of women who underwent a total abdominal hysterectomy (with or without bilateral salpingo-oophorectomy), under general anesthesia using a preoperative dose of gabapentin. Of the 46 articles initially identified, only14 met inclusion criteria. Data were pooled for 448 cases in the gabapentin group and 443 others in the control group. Study outcomes assessed were cumulative narcotic consumption during the first 24 hours, visual analog scale (VAS) pain scores 24 hours postoperatively, and adverse effects of treatment. A significant decrease in morphine consumption at 24 hours occurred both when gabapentin was administered before surgery (from 24.3–55.9 mg to 13.2–42.7 mg; standardized mean difference, −0.69 mg) and before and after surgery (from 25.7–80 mg to 20.3–55 mg; standardized mean difference, −1.45 mg). With meta-regression analysis, however, the effect of gabapentin in reducing morphine consumption (compared with placebo) was stronger at 24 hours in the preoperative only group than in the combined preoperative and postoperative group. Preemptive gabapentin decreased VAS pain scores from 9–42.7 to 2–25.3 (standardized mean difference, −1.03 [95% confidence interval, −1.36 to −0.71]), whereas combined preoperative and postoperative gabapentin had no significant effect on VAS scores. The rate of nausea in the gabapentin group (11.6%–70%) was less than in the control group (16.1%–96.7%); the relative risk was 0.76, with a 95% confidence interval of 0.66 to 0.88. These data show that preemptive administration of gabapentin is effective in decreasing postoperative pain scores and narcotic consumption at 24 hours, as well as nausea. Preemptive doses ranged from 300 to 1200 mg given 1 to 2 hours preoperatively.