Acetylation of sulphanilamide in four marsupials and a monotreme.

1. The urinary metabolites of sulphanilamide (100 mg/kg, i.p.) have been studied in four marsupials (the Tasmanian devil, brushtail possum, pademelon and barred bandicoot), a monotreme (the echidna) and a eutherian (the rat). 2. All species excreted some unchanged sulphanilamide (20-30% of dose in 24 h). The major urinary metabolite in the devil, possum and pademelon was N4-acetylsulphanilamide (6-17%). This was less than that excreted by the rat (40%). These three marsupials and the rat also excreted small amounts of N1-acetyl and N1, N4-diacetylsulphanilamide. 3. The bandicoot and echidna were virtually unable to acetylate sulphanilamide, unlike the 16 other species of animals and birds in which this has been studied. The reason for this metabolic defect is unknown.