Preoperative use of gabapentin decreases the anesthetic and analgesic requirements in patients undergoing radical mastectomy

Background/aim
Gabapentin is an anticonvulsant drug that is safe and effective for the treatment of neuropathic pain syndrome, as well as postoperative pain with good results. This prospective randomized study was done to evaluate the effects of preoperative administration of oral gabapentin (1200 mg) on the intraoperative fentanyl and isoflurane consumption, postoperative analgesic requirements and postoperative pain in patients undergoing radical mastectomy.
Methods
Sixty ASA I and II patients were randomly allocated into two equal groups to receive oral gabapentin 1200 mg, 2 h before surgery (G group) or control (C group). General anesthesia was induced and maintained at bispectral index value between 40 and 60. During surgery the end-tidal isoflurane concentrations required to maintain adequate depth of anesthesia and the required incremental doses of intraoperative fentanyl were recorded. Postoperative pain was assessed using visual analogue scale (VAS) at rest for 24 h. Postoperatively, whenever visual analogue scale (VAS) was more than 5 or on patients’ demand, analgesia in both groups was provided with diclofenac sodium (1 mg/kg IM) or tramadol hydrochloride (1 mg/kg IV) as needed. VAS, analgesics requirements, and side-effects were assessed for 24 h postoperatively.
Results
Intraoperative fentanyl and postoperative analgesic consumption were significantly lower in G group than C group ( < 0.001). Patients in the G group had significantly lower end-tidal concentrations of isoflurane required to maintain adequate depth of anesthesia ( < 0.05). VAS was significantly lower in G group than C group at the first three measurement times ( < 0.01). The incidence of postoperative nausea and vomiting was significantly lower in G group than C group (30% versus 60% of patients, respectively,  < 0.05). The incidence of dizziness was significantly higher in the G group than C group (26% versus 3.3% of patients, respectively,  < 0.05).
Conclusion
Gabapentin (1200 mg) administered orally 2 h before surgery decreased the intraoperative fentanyl and isoflurane consumption, postoperative analgesic requirements, postoperative pain, and the incidence of postoperative nausea and vomiting, but increased dizziness.