Effect of celecoxib, a cyclooxygenase-2 inhibitor, on the pathophysiology of adjuvant arthritis in rat

We investigated the efficacy of celecoxib, a specific cyclooxygenase (COX)-2 inhibitor, on arthritic pathophysiology and confirmed its gastric safety in adjuvant-induced arthritis rats. Results were compared with those for loxoprofen, a non-selective COX inhibitor. Arthritis was induced by injection of 1 mg of Mycobacterium butyricum in 50 μl of liquid paraffin into the left footpad of Lewis rats. The drugs were given by twice daily oral administration for 10 days beginning 15 days after adjuvant injection, with celecoxib at 0.01-3 mg/kg/day and loxoprofen at 0.01-3 mg/kg/day. Celecoxib significantly inhibited paw swelling, hyperalgesic response, and joint destruction (radiographic and histopathological findings) in these arthritic rats. These effects of celecoxib were superior to those of loxoprofen. Further, the administration of loxoprofen (3 mg/kg/day) caused significant gastric lesions, whereas celecoxib at the same dose did not. These results suggest that COX-2-mediated prostaglandins may play an important role in the progression of pathophysiology in this model and that celecoxib may be a useful therapeutic agent for the treatment of rheumatoid arthritis, with greater safety than non-selective COX inhibitors.