A single dose of preoperative gabapentin for pain reduction and requirement of morphine after total mastectomy and axillary dissection: randomized placebo-controlled double-blind trial.

BACKGROUND: Gabapentin has been recently found to be useful for reducing acute postoperative pain when administered preoperatively. Although various dose regimens have been tried in different surgical settings, the minimum effective dose is not established.

AIMS: We aimed to evaluate the analgesic efficacy of single low dose gabapentin in patients undergoing total mastectomy and axillary dissection.

SETTINGS AND DESIGN: Prospective randomized placebo-controlled double-blind trial in a tertiary care teaching hospital.

MATERIALS AND METHODS: Fifty women scheduled for total mastectomy and axillary dissection were randomized to receive either gabapentin 600 mg or placebo orally 1 h preoperatively. The intraoperative and postoperative management was standardized. Postoperative pain was assessed at rest and on movement for 12 h using the numerical rating scale (NRS). Morphine was administered if NRS exceeded 30. Primary outcome measure was total morphine consumption.

STATISTICAL ANALYSIS: The morphine consumption was compared using independent t test while pain and sedation scores were analyzed using Mann-Whitney U test.

RESULTS: Forty-six patients completed the trial. The postoperative morphine consumption was significantly less (5.8 +/- 4.2 vs. 11.0 +/- 3.4 mg; P 0.001) and the median [IQR] time to first analgesic was significantly longer (90 [37.5-120] vs. 0 [0-90] min; P 0.001) in the gabapentin group than in the placebo group. The incidence of side effects was similar in the two groups.

CONCLUSIONS: A single low dose of 600 mg gabapentin administered 1 h prior to surgery produced effective and significant postoperative analgesia after total mastectomy and axillary dissection without significant side effects.