Nitromide (3,5-dinitrobenzamide) is reduced to monoamino- and diamino-metabolites in vitro on anaerobic incubation with rat intestinal microflora. This conversion is suppressed by the antibiotics neomycin, tetracycline and bacitracin. 2. Nitromide is also in part reduced to monoamino but not diamino metabolites when incubated aerobically with homogenates of rat liver. 3. Pretreatment of rats with the antibiotics did not decrease their ability to form monoamino metabolites from nitromide, although formation of diamino metabolites was suppressed. 4. An antibiotic regime shown to suppress the methaemoglobinaemia resulting from the administration of nitrobenzene did not significantly reduce the methaemoglobinaemia resulting from the administration of nitromide.
