CARTILAGE STIMULATORY AND ANTIPROTEOLYTIC ACTIVITY IS PRESENT IN SERAOF DOGS TREATED WITH A CHONDROPROTECTIVE AGENT

Chondroprotective agents are widely prescribed in veterinary medicine for the treatment of degenerative joint disease. The agents exert mult iple effects on articular cartilage but the avascular nature of cartil agenous tissue clouds the mechanism(s) whereby such agents are present ed to joint surfaces. We explored whether the active agents comprising the chondroprotective agent Cosequin(R) circulate in serum at levels which may have beneficial effects on maintaining cartilage integrity. Cosequin(R), a mixture of sodium chondroitin sulfate, glucosamine HCl and manganese ascorbate, was given orally to normal canines for 30 day s. The biosynthetic and degradative responses of bovine cartilage expo sed to canine serum were monitored with standard radiolabeling methods . Metabolic responses were assessed by comparison with serum samples t aken prior to dosing. The median level of serum glycosaminoglycan (GAG ) levels at 30 days was increased by 42% (P < 0.005) with little chang e in free or bound hexosamine levels. Cartilage segments cultured in a 1:1 mixture of canine serum. Ham's F-12 media had a 50% increase in G AG biosynthesis (P < 0.02) while median proteolytic degradation was re duced by 59% (P < 0.055). The data suggests that Cosequin(R) given ora lly over extended periods of time elevates levels of circulating agent s which stimulate cartilage metabolism while inhibiting cartilage degr adation.