Inhibitory effects of anti-inflammatory drugs on type II collagen induced arthritis in rats.

The effects of steroidal and non-steroidal anti-inflammatory drugs on the established lesion of type II collagen induced arthritis in rats were evaluated by measuring the hind paw oedema and anti-type II collagen antibody titre. Dexamethasone, a steroidal anti-inflammatory drug, reduced the anti-type II collagen antibody titre and markedly suppressed the established lesion of type II collagen induced arthritis in rats. A rebound of the arthritis, i.e., a rapid recovery of the hind paw swelling took place after withdrawal of the treatment with steroidal anti-inflammatory drugs, including dexamethasone, prednisolone, and hydrocortisone. On the other hand, indomethacin, benoxaprofen, piroxicam, and tiflamizole, which are cyclo-oxygenase inhibitors in prostaglandin synthesis, had no effect on anti-type II collagen antibody titre, but suppressed the established lesion of the arthritis without causing an apparent rebound of the arthritis after withdrawal of the drug treatment. These results suggest that the level of anti-type II collagen antibodies has no relation to the intensity of hind paw swelling in the established lesion of the arthritis, though the antibodies contribute to the incidence of the arthritis. It also indicates that non-steroidal anti-inflammatory drugs having inhibitory action on cyclo-oxygenase are useful antiarthritic drugs without causing the rebound phenomenon, an untoward side effect after withdrawal of steroidal anti-inflammatory drugs.