BACKGROUND Pain following extraction of an impacted third molar is widely used to assess analgesic efficacy, especially that of a single dose of a drug. The analgesic activity of conventional nimesulide (CN) has been documented in a variety of types of acute and chronic pain. Beta-cyclodextrin nimesulide (BN) is a new formulation in which nimesulide is included in a cyclodextrin molecule, which increases its solubility in water and its dilution rate, allowing extended, rapid absorption of the drug. OBJECTIVE The aim of this study was to assess the efficacy and tolerability of a single dose of BN compared with CN in patients with pain following extraction of an impacted third molar. METHODS This was a prospective, randomized, double-blind, double-dummy study conducted at 3 dentistry centers in Venezuela. The patients were randomized to 1 of 2 groups. One group received a single dose of BN (400-mg tablet, equivalent to 100 mg of nimesulide); the other group received a single dose of CN (100-mg tablet). Both groups also received a placebo. The efficacy variables were (1) pain intensity (PI), assessed on a visual analog scale (VAS) at the following times: 0, 5, 10, 15, 30, and 45 minutes and 1, 2, 4, 6, 8, 10, and 12 hours after drug administration; (2) time to first measurable difference in PI from baseline (PID) (PID ≥1 cm on the VAS; ie, the beginning of analgesic action); (3) maximum PID (max PID); (4) sum of PIDs in the 12-hour observation period; (5) pain relief (PR), as rated on a 5-point scale; (6) maximum PR; and (7) sum of the PR scores in the 12-hour observation period (ie, total PR). For the tolerability analysis, all adverse events (AEs) were to be recorded, and the investigators were to assess whether each AE was drug related. RESULTS Seventy-two patients were enrolled in the study. Of these, 62 patients (40 women, 22 men; mean [SD] age, 20.1 [5.9] years) were assessed; 35 were treated with BN and 27 with CN. PI reduction was more rapid and greater in the BN group. The first measurable change in PI (PID ≥1 on the VAS) was reached within 5 minutes by 39% and 15% of the patients in the BN and CN groups, respectively, and within 10 minutes by 52% and 30% of the patients in the BN and CN groups, respectively. The max PID was reached <1 hour in 32% and 15% of patients in the BN and CN groups, respectively. No AEs were reported. CONCLUSIONS In this study population, both BN and CN were similarly effective in relieving pain after extraction of an impacted third molar, and both drugs were well tolerated. PI changes were statistically significantly more rapid and greater with BN than CN.