Neomycin metabolism in calves.

Disposition of oral neomycin in calves was determined using 14C-labeled neomycin. The influences of age, diet, and method of administration were observed. All calves were killed 96 h after a single oral dose of [14C]neomycin (approximately 30 mg/kg) and the distribution of 14C in excreta and tissues was determined.

Evidence for involvement of non-biliary excretion into the intestines in the formation of methylsulphonyl-containing metabolites of 2-chloro-N-isopropylacetanilide (propachlor) by swine and rats.

1. Radiolabelled metabolites excreted in the urine of swine after an oral dose of 14C-propachlor were similar to those previously reported with rats and included methylsulphonyl (CH3SO2-)-containing metabolites. 2.

Mass spectra of aniline glucuronides.

Mass spectra of TMS derivatives of aniline glucuronide and pentachloroaniline glucuronide are presented, and the fragmentation of these derivatives is compared with that of TMS aryl-O-glucuronides. Fragmentation yielding ions entirely from the glycone moiety was sufficiently similar to establish these N-glucuronides as TMS glucuronides in the same manner used for TMS-O-glucuronides; however, differences observed may be diagnostic for TMS-N-glucuronides.