COMPARATIVE EFFECT OF ANTIRHEUMATIC DRUGS ON ADJUVANT-INDUCED POLYARTHRITIS IN RATS

¹ Department of Medicine, University of Utah Medical Center, Salt Lake City, Utah

The effect of several clinically useful antiarthritic drugs on adjuvant-induced polyarthritis in rats is compared with that of indomethacin. The drugs were given daily, either orally or by intraperitoneal injection, beginning on the day of adjuvant injection. The doses used were comparable to the commonly used human doses, given in milligrams per kilogram. Adjuvant containing 6.0 mg of Mycobacterium butyricum per milliliter of heavy mineral oil was given by intradermal injection into a hind foot pad. Swelling occurred at the adjuvant depot site within 24 hr, and disseminated arthritis appeared in 10 to 14 days. Each joint and the injection site were scored daily for swelling and redness. Indomethacin, prednisolone and phenylbutazone were shown to decrease the swelling at the injection site and to suppress the generalized arthritis. Aspirin was only effective in suppressing the inflammation at the injection site. Chloroquine and hydroxychloroquine were without demonstrable activity. Because the doses of all drugs were within the range used for treating patients, adjuvant arthritis of rats is established as an experimental model for testing antiartliritic drugs. It is suggested that this model would be more useful for drug evaluation with improved techniques for measuring joint swelling and tenderness.