Oxaprozin: kinetic and dynamic profile in the treatment of pain

Oxaprozin (4,5-diphenyl-2-oxazolepropionic acid) is a non-steroidal anti-inflammatory drug (NSAID) which is effective in models of inflammation, pain and pyrexia. It is effective and well tolerated in the clinical management of adult rheumatoid arthritis (RA), osteoarthritis (OA), ankylosing spondylitis, soft tissue disorders and post operative dental pain. Oxaprozin has a high oral bioavailability (95%), with peak plasma concentrations at 3 to 5 hours after dosing. It is metabolised in the liver by oxidative and conjugative pathways and readily eliminated by the renal and faecal routes. Oxaprozin's strong analgesic qualities are particularly useful in painful musculoskeletal conditions such as periarthritis of the shoulder, since it exhibits actions such as inhibition of COX-1 and COX-2 isoenzymes, inhibition of nuclear translocation of NF-kappaB and of metalloproteases, and modulates the endogenous cannabinoid system. This editorial addresses the accompanying paper by Barbara Heller and Rosanna Tarricone on the management of shoulder periarthritis pain, in which they studied the efficacy and safety of oxaprozin compared to the comparator drug diclofenac over a 15 day period. Both oxaprozin and diclofenac compared well in the primary study endpoint of reduction in shoulder pain. Oxaprozin and diclofenac were well tolerated and oxaprozin showed better improvement in shoulder function and in the mental health item of the SF-36 quality of life component. The study by Heller and Tarricone is an addition to the large number of clinical trials which demonstrate that oxaprozin has equal efficacy in comparison with standard doses of commonly used anti-rheumatic agents such as aspirin, diclofenac, ibuprofen, indomethacin etc. in several different painful musculoskeletal conditions.