Cartilage stimulatory and antiproteolytic activity is present in sera of dogs treated with a chondroprotective agent

Chondroprotective agents are widely prescribed in veterinary medicine for t he treatment of degenerative joint disease. These agents exert multiple eff ects on articular cartilage but the avascular nature of cartilagenous tissu e clouds the mechanism(s) whereby such agents are presented to joint surfac es. We explored whether the active agents comprising the chondroprotective agent Cosequin(R) circulate in serum at levels which may have beneficial ef fects On maintaining cartilage integrity. Cosequin(R), a mixture of sodium chondroitin Sulfate, glucosamine HCl and manganese ascorbate was given oral ly to normal canines for 30 days. The biosynthetic and degradative response s of bovine cartilage exposed to canine serum were monitored with standard radiolabeling methods. Metabolic responses were assessed by comparison with serum samples taken prior to dosing. The median level of serum glycosamino glycan (GAG) levels at 30 days was increased by 42% (P< 0.005) with little change 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 GAG bi osynthesis (P < 0.02) while median proteolytic degradation was reduced by 5 9% (P < 0.055). The data suggests that Cosequin(R) given orally over extend ed periods of time elevates levels of circulating agents which stimulate ca rtilage metabolism while inhibiting cartilage degradation.