Gabapentin decreases acute nociceptive pain in animal and human studies when given before surgical incision. Various doses of gabapentin have been used (300-1,200 mg) to measure this preemptive effect. Here, we evaluated the optimal dose of gabapentin for reducing fentanyl consumption and the adverse effects of gabapentin following gynecologic surgery.

We recruited 100 patients who underwent laparotomy for gynecologic surgery. Patients were randomly divided into 4 groups and received a placebo (control), gabapentin 300 mg (G 300), gabapentin 600 mg (G 600), or gabapentin 1,200 mg (G 1200) 2 h before surgery. Postoperatively, patients received fentanyl via an intravenous patient controlled analgesia device. The cumulative fentanyl doses were recorded 2, 6, 12, 24 h, and 48 h postoperatively, and the sedation scale was recorded in the post anesthetic care unit (PACU).

The postoperative fentanyl requirement was lower with gabapentin treatment, but there was no significant differences for the different doses. PACU sedation scores were not different in any group.

Gabapentin has a preemptive effect in gynecologic surgery, but there were no additional fentanyl-sparing benefits at doses above 300 mg. Thus, 300 mg is an optimal dose for decreasing fentanyl consumption following gynecologic surgery.