Effects of tiaprofenic acid and indomethacin on proteoglycans in the degenerating porcine intervertebral disc

Eighteen pigs were stabbed with a scalpel in the anterior part of the anulus fibrosus of a lumbar disc. After surgery, the pigs received either tiaprofenic acid or indomethacin daily, and a third group did not receive any medication. Nonsteroidal anti-inflammatory agents are widely used in the treatment of low back patients, but their long-term effects on the matrix molecules in the degenerate disc are unknown. Several in vitro and in vivo studies on articular cartilage have suggested that tiaprofenic acid may not have adverse effects on matrix metabolism, whereas indomethacin probably does. Uronic acid, DNA, and water contents were determined from five different locations in each injured disc. Transport and incorporation of sulfate were examined by in vivo radioactive tracer analysis, and proteoglycan structures were analyzed by gel electrophoresis. Morphologically, there were no differences between the treatments. Tiaprofenic acid maintained a higher uronic acid content in the nucleus pulposus and outer anulus compared with that of the nonmedicated animals. Tiaprofenic acid decreased the incorporation of sulfate in the injured area and the water content at most sites. Indomethacin had no adverse effects compared with the nonmedicated group, and it increased water content in the posterior anulus fibrosus. Long-term administration of tiaprofenic acid and indomethacin did not have harmful effects on matrix metabolism after disc injury. On the contrary, tiaprofenic acid may slightly protect proteoglycans in the degenerating disc.