Assessment of comparative pain relief and tolerability of SK1306X compared with celecoxib in patients with rheumatoid arthritis: A 6-week, multicenter, randomized, double-blind, double-dummy, phase III, noninferiority clinical trial

Background: SK1306X, which consists of biologically active ingredients from Clematis mandshurica, Trichosanthes kirilowii, and Prunella vulgaris, was developed and tested in preclinical trials in Korea. Those studies found that SK1306X was associated with an anti-inflammatory and analgesic effect, and that it can delay the destruction of cartilage in rheumatoid arthritis (RA). Objective: The aim of this study was to compare the pain relief and tolerability of SK1306X and celecoxib in patients with RA. Methods: This study was a 6-week, multicenter, randomized, double-blind, double-dummy, Phase III, noninferiority clinical trial. Eligible patients were aged 18 to 80 years, had a history of RA with a disease duration of >= 3 months, and were functional American College of Rheumatology (ACR) class I, II, or III before entry. After a washout period of 2 weeks, patients were randomized to SK1306X 200 mg TID or celecoxib 200 mg BID for 6 weeks. The primary end point was a change in patient assessment of pain intensity using a visual analog scale (VAS). The secondary end points were a 20% improvement in response rate as defined by the ACR (ACR20) and the frequency of rescue medication use. Results after 3 and 6 weeks of treatment were compared with baseline and between treatment groups, and all patients were assessed for adverse events (AEs), clinical laboratory data, and vital signs. AEs were identified based on spontaneous reports by patients during interviews conducted by the investigators and the study coordinator. Results: Two hundred twenty-two Korean patients from 7 medical centers were assessed and 183 were enrolled and randomized to 1 of 2 treatment groups. Ninety-one patients (10 male, 81 female; mean [SD] age, 52.13 [12.64] years; mean [SD] duration of RA, 9.08 [10.23] years; no. [%] of ACR class I, II, and III, 13 [14.29], 44 [48.35] and 34 [37.36] patients, respectively) received SK1306X 200 mg TID and 92 patients (10 male, 82 female; mean [SD] age, 51.78 [10.94] years; mean [SD] duration of RA, 8.78 [7.78] years; no. [%] of ACR class I, II, and III, 14 [15.22], 44 [47.83], and 34 [36.96] patients, respectively) received celecoxib 200 mg BID. An analysis of the change in reported pain intensity as determined by VAS (mm) score between baseline and week 3 (mean [SD], 13.64 [16.62] vs 14.45 [15.89]), and between baseline and week 6 (18.4 [20.8] vs 17.9 [19.1], respectively) suggested that SK1306X was not inferior to celecoxib. The number of patients who achieved ACR20 response rate was not significantly different between the SK1306X group and the celecoxib group at week 3 (16/87 [18.4%] vs 24/87 [27.6%], respectively) and at week 6 (29/87 [33.3%] vs 29/87 [33.3%]). The frequency of rescue medication use was not significantly different between the SK1306X group and celecoxib group at week 3 (54/87 [62.1%] vs 47/87 [54.0%], respectively) or week 6 (57/87 [65.5%] vs 49/87 [56.3%]). Drug-related AEs were reported by 27 (29.7%) patients in the SK1306X group and 22 (23.9%) patients in the celecoxib group. The most frequent drug-related AEs were epigastric pain (9/91 [9.9%]) in the SK1306X group and glutamyltranferase elevation (4/92 [4.3%]) in the celecoxib group. No significant between-group differences were observed in the prevalence of drug-related clinical- or laboratory-determined AEs. Conclusion: The results of this study suggest that SK1306X was generally well tolerated and not inferior to celecoxib in regard to pain relief in these Korean patients with RA.