Pain relief model for a COX-2 inhibitor in patients with postoperative dental pain.

AIM: To develop a pain relief model for a cyclooxygenase (COX)-2 inhibitor, CS-706, that permits prediction of doses for acute pain relief in Japanese and Western populations. METHODS: A categorical response model was developed to describe the probability of pain relief (PR) over time for a Phase 2a study. Models were also developed to describe patient's use of rescue medication and onset of pain relief. RESULTS: The placebo response was described by a first-order increase in PR that achieved a stable response after 4 h. The effect of CS-706 on PR was described using an E(max) model; the plasma concentration of CS-706 producing 50% of the maximum response was estimated to be 87 ng ml(-1), the median peak plasma concentration achieved after a 50-mg oral dose. The probability of rescue medication (REMD) decreased over time and was a function of the last observed PR score. This probability was < 16% for patients with a PR score > or =2. The probability of experiencing meaningful PR was 98% in patients who did not require REMD and 47% in those who required REMD. For patients who did not require REMD, the median onset time of meaningful pain relief (TMPR) decreased with increasing doses. In patients who required REMD, there was a saturable decline in TMPR, with the greatest improvement occurring from placebo to 50-mg doses. CONCLUSIONS: The set of models developed permitted compilation of multiple dose-response curves for dose selection of CS-706 in Westerners and facilitated scaling of doses to a Japanese population.

A randomized, double-blind, celecoxib- and placebo-controlled study of the effectiveness of CS-706 in acute postoperative dental pain.

BACKGROUND: CS-706 is a cyclooxygenase-2 (COX-2)-selective inhibitor with an in vitro selectivity ratio (COX-1:COX-2) similar to that of celecoxib. It has exhibited analgesic, anti-inflammatory, and antitumor properties in animal models. OBJECTIVES: This study evaluated the tolerability of single doses of CS-706 and compared the analgesic efficacy of CS-706 with that of celecoxib and placebo in the dental pain model. METHODS: This was a randomized, double-blind, double-dummy, active- and placebo-controlled study. Healthy male and female subjects with moderate to severe pain intensity (PI) after dental surgery were randomized ( approximately 50 per group) to receive a single oral dose of CS-706 10, 50, 100, or 200 mg; celecoxib 400 mg; or placebo. PI and pain relief (PR) were measured on categorical and visual analog scales through 24 hours after the dose. The primary efficacy variable was the time-weighted sum of PR scores at 4 hours after the dose (TOPAR4). The onset of analgesia was assessed by calculating the pain intensity difference (PID). Perceptible and meaningful pain relief were assessed using a 2-stopwatch method. RESULTS: The majority of subjects were female (62.0%) and white (59.5%). Subjects' mean (SD) age was 22.6 (3.9) years, and their mean body mass index was 25.3 (5.1) kg/m(2). All doses of CS-706 were associated with significant analgesic efficacy compared with placebo based on the primary end point, TOPAR4 (P<0.001), and on all secondary end points (P<0.05, comparisons of all CS-706 doses vs placebo) with the exception of time to 100% PR for CS-706 10 mg. Single 50-, 100-, and 200-mg doses of CS-706 also were significantly more effective than celecoxib for TOPAR4 (P=0.036, P=0.004, and P=0.006, respectively). The onset of analgesia (PID >or= 1) for all CS-706 doses occurred within 1 hour after dosing (P<0.001 vs placebo). The median duration of analgesia, measured as the time to administration of rescue medication, was significantly greater for all doses of CS-706 compared with placebo (5.7 hours for CS-706 10 mg, >24 hours for CS-706 50, 100, and 200 mg, and 1.7 hours for placebo; P<0.001 for CS-706 50, 100, and 200 mg). These data suggest that once-daily administration of CS-706 may be effective in providing relief of acute pain. The incidence of adverse events was similar among all treatment groups. Adverse events occurring in >or= 5 % of subjects in any treatment group were nausea, vomiting, dry socket, dizziness, headache, and paresthesia. CONCLUSION: Single doses of CS-706 had significant analgesic efficacy compared with celecoxib and placebo in the relief of postoperative dental pain in the healthy subjects enrolled in this study.