Effects of tiaprofenic acid on the concentration and metabolism of proteoglycans in normal and degenerating canine articular cartilage.

The effects of tiaprofenic acid (TPA), a nonsteroidal antiinflammatory drug with high potency as a cyclooxygenase inhibitor, on the metabolism of normal and degenerating articular cartilage were examined. When present in the culture medium in clinically relevant concentrations encompassing those achieved in synovial fluid of patients treated with the drug, TPA had no significant effects on net proteoglycan synthesis in organ cultures of normal, osteoarthritic or atrophic canine articular cartilage. When fed to dogs for 8 weeks in a daily dose of 100 mg, TPA had no apparent effect on cartilage water content or uronic acid concentration. The suppression of net cartilage proteoglycan synthesis caused by immobilization was not affected by administration of TPA nor did the drug affect the proportion of newly synthesized glycosaminoglycans recovered from the spent culture medium, suggesting that it did not increase proteoglycan catabolism or affect the integrity of the cartilage matrix.