BACKGROUND: The sensation of pain arises from both central and peripheral sites, and inflammation may be one of its underlying causes. Combination therapy with analgesic agents having multimodal mechanisms of action and complementary pharmacokinetic properties enhances pain relief by addressing the different pathways of pain while limiting individual drug doses and, therefore, the potential for adverse effects caused by any single agent. Oxycodone and ibuprofen each have been used effectively as monotherapy and in other combinations for the treatment of acute pain; a fixed combination of these analgesics may improve pain relief in the setting of abdominal or pelvic surgery, where trauma and any resultant inflammation may be present at the same time. OBJECTIVE: This study evaluated and compared the analgesic efficacy and tolerability of a single-dose combination tablet containing oxycodone 5 mg/ibuprofen 400 mg with either agent alone and with placebo in women who had undergone abdominal or pelvic surgery. METHODS: In this multicenter, randomized, double-blind,placebo- and active-controlled, parallel-group trial, women experiencing moderate to severe pain between 14 and 48 hours after surgery were randomized per protocol to receive a single dose of study medication in a 3:3:1:1 ratio (combination oxycodone/ibuprofen, ibuprofen, oxycodone, and placebo, in that order). Over a 6-hour study period, patients recorded their assessments of pain intensity (100-mm visual analog scale and 4-point scale), relief from starting pain, and overall evaluation of study drug based on prespecified definitions and rating scales. Based on these data, the following primary efficacy end points were determined: total pain relief 6 hours after dosing (TOTPAR6) and sum of pain intensity differences 6 hours after dosing (SPID6). Other end points included the time to onset of pain relief, time to use of rescue medication, and patient's global rating of analgesic effectiveness. Tolerability was evaluated on the basis of observed and patient-reported adverse events and findings on physical examination. RESULTS: Four hundred fifty-six women participated in the study. They were primarily white and had a mean age of 41.6 years and a mean body weight of 171.5 pounds. Combination treatment was associated with significantly better TOTPAR6 and SPID6 scores compared with ibuprofen alone (P < 0.02 and P < 0.015, respectively), oxycodone alone (P < 0.009 and P < 0.001), or placebo (both, P < 0.001). Fewer patients receiving combination treatment required rescue medication, and the time to use of rescue medication was significantly longer in the combination-treatment group compared with the other groups (P < 0.05). Patients' global ratings of analgesic efficacy were significantly higher in the combination-treatment group compared with all other groups (P < 0.044 vs ibuprofen alone; P < 0.001 vs oxycodone alone and placebo). The onset of pain relief occurred within 15 minutes of dosing with all 4 regimens. Nausea was the most frequently reported treatment-emergent adverse event in all 4 groups. The incidence of treatment-emergent adverse events was highest with placebo (55.0%), followed by oxycodone alone (44.2%), ibuprofen alone (42.3%), and combination treatment (40.8%). CONCLUSIONS: In this population of women who had undergone abdominal or pelvic surgery, the combination of oxycodone 5 mg/ibuprofen 400 mg was significantly more effective than either agent alone or placebo in the treatment of moderate to severe postoperative pain.