Single Dose Preoperative Gabapentin Use in Minimally Invasive Hysterectomy for Acute Pain Management

Multimodal postoperative analgesia after a hysterectomy has been mainly based on a combination of nonsteroidal anti-inflammatory drugs and opioids. However, adverse effects including nausea, vomiting, sedation, and pruritus may limit use of opioids. As the side effects are dose related, minimizing opioid exposure may significantly reduce these risks. Thus, there has been an interest in evaluating preemptive as well as post-operative administration of non-opioids. Additional regimens have been suggested to minimize opioid use and its associated adverse effects including injection of local anesthetics, epidural analgesia, and anticonvulsants, such as gabapentin or pregabalin.

Gabapentin, a widely used anticonvulsant used for treatment of neuropathic pain, has recently been suggested to improve postoperative analgesia and reduce opioid requirements. Gabapentin is thought to modulate calcium channels on the presynaptic nociceptive neurons, which in turn modulate or inhibit the release of excitatory neurotransmitters from activated nociceptors. In addition to inhibiting pain transmission, gabapentin may exert an analgesic effect by activating descending inhibitory noradrenergic pathways.

Many studies have demonstrated the safety and efficacy of gabapentin for perioperative use in a variety of procedures across disciplines including thoracotomy, laparoscopic cholecystectomy, tonsillectomy, major orthopedic surgery, cesarean sections, and abdominal hysterectomy. Several randomized trials have evaluated the effects of gabapentin administered preoperatively only as well as given pre- and postoperatively for hysterectomy. In a systematic review of 14 studies conducted between 2004 and 2013, with samples ranging from 40 to 200, investigators identified 8 trials in which gabapentin was administered only preoperatively to reduce pain associated with abdominal hysterectomy surgery. Analysis of those data clearly demonstrates that preemptive gabapentin reduced the postoperative visual analog scale (VAS) pain score by approximately 50% and postoperative use of morphine by approximately 37%. The incidence of pruritus and dry mouth in those receiving preemptive gabapentin appeared similar to those receiving placebo, however there was a higher rate of reported dizziness (not statistically significant) associated with gabapentin. In contrast, multiple postoperative doses of gabapentin in addition to the preoperative dose was found to have no significant effect on VAS scores at 24 hours, thus favoring a single preoperative dose.

Although initial results have been encouraging, uptake of gabapentin in routine clinical use remains limited due to mixed results and variability between gabapentin protocols, including dosing and duration. Christiana Care Health System (CCHS) plans to implement the Enhanced Recovery After Surgery (ERAS) protocol which administers preoperative medications to reduce postoperative pain, including acetaminophen, celecoxib, dexamethasone, and gabapentin. Therefore the aim of this study is to assess the efficacy of a single dose of preoperative gabapentin protocol to reduce acute postoperative pain in women undergoing a minimally invasive hysterectomy.