Rat adjuvant arthritis as a model to test potential antirheumatic agents.

Adjuvant arthritis was induced in male Sprague-Dawley rats by a subcutaneous injection of Mycobacterium tuberculosis in sterile paraffine oil into the base of the tail. The effects of the immunomodulating drugs N-(2-carboxyphenyl)-4-chloroanthranilic acid disodium (CCA), d-penicillamine and thiabendazole were compared to those of the anti-inflammatory drugs indomethacin, tolfenamic acid and prednisolone. All the anti-inflammatory drugs were highly protective. Of the immunomodulating drugs thiabendazole also showed dose-related inhibitory effect. CCA had only a negligible effect and d-penicillamine enhanced the activity of the arthritic syndrome. An aggravation of the arthritis also occurred after pretreatment with d-penicillamine for 30 days before the induction of arthritis. The complement inhibiting agents epsilon aminocaproic acid and heparin enhanced the symptoms of the adjuvant arthritis as did d-penicillamine. We suggest that the effects of the immunomodulating drugs are dependent on the dose used and the stage of the disease at the beginning of treatment.