Parecoxib versus dipyrone (metamizole) for postoperative pain relief after hysterectomy : a prospective, single-centre, randomized, double-blind trial.

BACKGROUND AND OBJECTIVE: Selective cyclo-oxygenase-2 (COX-2) inhibitors provide postoperative pain relief similar to conventional NSAIDs. However, many of these non-opioid analgesics are available only for oral administration, and are therefore ineffective in patients experiencing postoperative nausea or vomiting. The aim of this study was to compare the analgesic efficacy of the COX-2 inhibitor parecoxib with that of dipyrone (metamizole) administered intravenously for 48 hours after vaginal hysterectomy.

METHODS: Fifty women undergoing vaginal hysterectomy under general anaesthesia were randomly assigned to two groups: the parecoxib group, who received intravenous parecoxib 40 mg intraoperatively and every 12 hours after surgery over a period of 48 hours, and the dipyrone group, who received intravenous dipyrone 2.5 g injected intraoperatively, followed by dipyrone 1 g every 6 hours after surgery over a period of 48 hours. Because of the double-blinded study protocol, patients in the parecoxib groups were required to receive placebo infusions 6, 18, 30 and 42 hours after the operation. Visual analogue scale (VAS [scale 0-10]) scores were recorded 0.5, 1, 2, 3, 4, 6, 9, 12, 15, 18, 24, 36 and 48 hours after surgery. To assess the cumulative opioid administration, all patients were fitted with an intravenous patient-controlled analgesia (PCA) device containing the opioid piritramide. An alpha value of 0.05 was considered statistically significant.

RESULTS: VAS scores did not differ between groups with one exception: VAS scores were lower in the parecoxib group 12 hours after surgery than in the dipyrone group (1 and 2, respectively; p < 0.05). No significant differences in cumulative piritramide administration were measured between groups 1 hour or 24 hours after surgery (parecoxib 14.7 [+/- SD 4.4] and 30.6 [+/- 12.8] mg, respectively; dipyrone 11.8 [+/- 4.9] and 36.5 [+/- 10.7] mg, respectively).

CONCLUSIONS: Parecoxib 40 mg twice daily provides postoperative pain relief equivalent to that of dipyrone 4 g daily during the first 48 hours in patients after hysterectomy.