Ambivalent properties of gold drugs in adjuvant induced polyarthritis in rats.

We evaluated the antiarthritic activity of gold sodium aurothiomalate (GSTM) and auranofin (AF) against experimental polyarthritis induced in 3 rat strains using 3 different adjuvants. These 2 gold drugs were found to either stimulate, inhibit or have no effect upon the development of arthritis, dependent upon the rat strain and/or the adjuvant used. The ambivalent antiarthritic activities of GSTM and AF did not appear to be associated with any variations in serum gold levels. These results highlight the need for caution in studying gold drugs using the adjuvant polyarthritic model in the rat and, if used, the need to define clearly the strain/adjuvant/gold drug combination. Within these constraints however, our findings support the concept that GSTM and AF have different mechanisms of action.