PTGS2 and rheumatoid arthritis: Celecoxib, 4-[5-(4-methylphenyl)-3-(trifluoromethyl)pyrazol-1-yl]benzenesulfonamide, is a poorly water-soluble drug belonging to the class of selective cyclooxygenase-2 (COX-2) inhibitors and is clinically used in the treatment of acute pain, rheumatoid arthritis, and osteoarthritis [1].