4-nitro-2-phenoxymethanesulfonanilide (R-805): a chemically novel anti-inflammatory agent.

The anti-inflammatory activity of the sulfonanilide, 4-nitro-2-phenoxymethanesulfonanilide (R-805) has been demonstrated in conventional models (carrageenan-induced edema of the rat's paw, UV-induced erythema of guinea-pig skin, adjuvant-induced arthritis of the rat). R-805 differs from most currently available acidic anti-inflammatory drugs in that its functional acidic group is not carboxyl. The relative anti-inflammatory potency of R-805 is comparable to indomethacin. Calculation of acute therapeutic indices (LD50/ED50) for 8 acidic anti-inflammatory drugs show R-805 to possess a more favourable index than the other drugs examined.