PURPOSE: Although non-selective non-steroidal anti-inflammatory drugs (nsNSAIDs) and opioids are effective treatments for acute renal colic, they are associated with adverse events (AEs). As cyclooxygenase-2 selective NSAIDs may provide a safer alternative, we compared the efficacy and safety of parecoxib versus an nsNSAID in subjects with acute renal colic. MATERIALS AND METHODS: Phase IV., multicenter, double-blind, noninferiority, active-controlled study: 338 subjects with acute renal colic were randomized to parecoxib 40 mg i.v. plus placebo (n = 174) or ketoprofen 100 mg IV plus placebo (n = 164). 338 subjects with acute renal colic were randomized to parecoxib 40 mg IV (n = 174) or ketoprofen 100 mg IV(n = 164) plus placebo. Subjects were evaluated 15, 30, 45, 60, 90 and 120 minutes after treatment start and 24 hours after discharge. Primary endpoint was the mean pain intensity difference (PID) at 30 minutes by visual analog scale (VAS) (per-protocol population). An ANCOVA model was used with treatment group, country, and baseline score as covariates. Non-inferiority of parecoxib to ketoprofen was declared if the lower bound of the 95% confidence interval (CI) for the difference between the two groups excluded the pre-established margin of 10 mm for the primary endpoint. RESULTS: Baseline demographics were similar. The mean (SD) mPID30 min was 33.84 (24.61) and 35.16 (26.01) for parecoxib and ketoprofen, respectively. For treatment difference (parecoxib-ketoprofen) the lower bound of the 95% CI was 6.53. The mean change from baseline in VAS 30 minutes after study medication was ~43 mm; AEs were comparable between treatments. CONCLUSIONS: Parecoxib is as effective as ketoprofen in the treatment of pain due to acute renal colic, is well tolerated, and has a comparable safety profile.