Myotoxicity of amine metabolites from brown FK

Summary Amines derived from Brown FK and from its two myotoxic components, 2,4-diamino-5-( p -sulphophenylazo)toluene and 1,3-diamino-4-( p -sulphophenylazo)benzene, were injected intravenously into rats in single doses of 3·13-25 mg/kg. The mixture of amines from Brown FK was also injected into mice in the same range of doses. Cardiac and muscular lesions were produced by the amines in both species. These amines are thought to be the toxic metabolites of Brown FK produced by microbiological degradation in the intestine. The finding that orally administered Brown FK is myotoxic in rats but not in mice is probably due to differences in the intestinal flora in the two species.