[Comparison of the effects of preemptive gabapentin and dextromethorphan on the postoperative pain after open prostatectomy]

ABSTRACT

Preemptive administration of gabapentin and dextromethorphan has been shown to be effective for reduction of postoperative pain; but the effect of these two drugs has not yet been compared. The aim of the present study was to compare the effects of administration of gabapentin and dextromethorphan on the postoperative pain after open prostatectomy. In a randomized clinical trial, 80 adult males with ASA class of I, II and III who were candidate for open prostatectomy under spinal anesthesia in Shahid Hasheminejad Educational Center [in Tehran] were enrolled and randomly allocated to two groups of gabapentin [n=40] and dextromethorphan [n=40]. In dextromethorphan group, 60 mg of dextromethorphan syrup and in gabapentin group, 300 mg of gabapentin syrup were administered 2 hours preoperatively. During operation, the maximum height of block was determined at 5, 10 and 15 minutes after spinal anesthesia establishment. In postoperative period, at 1, 2, 12, and 24 hours, the pain intensity was measured through Visual Analogue Pain Scale [VAS]; and, overall opioid consumption and the time to first analgesic request were recorded as well. While the pain intensity in all the measurements was comparable between groups, at the 2nd hour, the pain was significantly lesser in gabapentin group [2.70 +/- 1.51 vs. 3.74 +/- 1.77, P=0.006]. Also, the time for the first analgesic request was comparable between study groups; however, the total dose of postoperative opioid consumption was lesser in gabapentin group [45.0 +/- 39.32 vs. 64.45 +/- 32.12 mg, P=0.018]. Moreover, the height of block showed no significant difference. Preemptive oral administration of 300 mg of gabapentin syrup in patients undergoing open prostatectomy under spinal anesthesia significantly lessens the pain intensity and the total dose of opioid consumption compared with 60 mg of dextromethorphan syrup. Meanwhile, the level of spinal anesthesia and the time for the first analgesic request were comparable between groups