The transsynovial distribution of oxaprozin

Oxaprozin (Wy-21743) is a novel and unique compound among NSAIDs: it bears an aliphatic propionic acid function as a side chain in contrast to the large group of acetic acids and profens. The transsynovial distribution was studied in 18 RA-patients, who required articular surgery. Following a wash-out period of 7 days they were treated with 2 x 600 mg of oxaprozin. The patients were assigned to four different groups representing different treatment duration (2, 3, 4 and 5 days). 12 hours after the last dose during surgery synovial fluid and synovial tissue specimen were removed. Blood samples were taken simultaneously and analysed for oxaprozin employing HPLC. In the synovial tissue samples concentrations of 27 micrograms/g were detected. The concentrations were considerably higher than blood (10-17 micrograms/ml) or synovial fluid (4.9-7.6 micrograms/ml) levels. Oxaprozin shows a different pattern of transsynovial distribution and tissue affinity as compared to other NSAIDs.