The effect of dextromethorphan, alone or in combination with ibuprofen, onpostoperative pain after minor gynaecological surgery

Background: Experimental studies have demonstrated that peripheral tissue i njury may lead to hyperexcitability of nociceptive neurones in the dorsal h orn, in part mediated by N-methyl-D-aspartate (NMDA)-receptor mechanisms. S ensitisation of dorsal horn neurones may be an important contributor to pos toperative pain. The aim of the present study was to investigate the effect of the NMDA-receptor antagonist dextromethorphan on pain after minor gynae cological surgery, and to evaluate a potential additive effect with ibuprof en. Methods: In a double-blind, placebo-controlled study, 100 patients schedule d for elective termination of pregnancy were randomised to receive placebo, oral ibuprofen 400 mg, oral dextromethorphan 120 mg, or a combination of i buprofen 400 mg and dextromethorphan 120 mg, 1 h before surgery. Pain and a nalgesic requirements were assessed 0.5, 1 and 2 h after operation. Results: We observed no effect of dextromethorphan on visual analogue scale (VAS) pain scores or analgesic consumption, and no additive or synergistic analgesic effects between ibuprofen and dextromethorphan. Ibuprofen reduce d pain scores compared with placebo, and analgesic consumption compared wit h both placebo and dextromethorphan. The combination of ibuprofen and dextr omethorphan increased preoperative nausea compared with both placebo and ib uprofen, whereas no statistically significant side effects were observed wi th dextromethorphan alone. Conclusion: No analgesic effects of oral dextromethorphan 120 mg on pain af ter surgical termination of labour, and no additive analgesic effects when combined with ibuprofen 400 mg, were observed. Ibuprofen reduced both VAS p ain scores and analgesic consumption compared with placebo.