The fate of N-nitrosodiethanolamine after oral and topical administration to rats.

14C-labelled N-nitrosodiethanolamine ([14C]NDELA) was given to Osborne-Mendel rats at two dose levels, 0.5 or 50 mg/kg, by oral or topical administration. The excreta and tissues were analysed at various times from 4 hr to 1 wk after administration to determine the distribution of radioactivity. After oral administration, [14C]NDELA was rapidly absorbed from the gastro-intestinal tract, distributed throughout all organs and tissues, and then excreted, mainly via the kidneys. The tissue concentration reached a peak at 8 hr, but some activity remained after 1 wk. After topical application NDELA was slowly absorbed percutaneously, but once absorbed was distributed as in the orally dosed rats. Metabolic profiles of urine and bile samples from both the orally and topically dosed rats were identical, although the quantities varied. In addition to unchanged NDELA, one metabolite was present. The dose level had little effect on the quantities of unchanged NDELA or the metabolite present.

The metabolism of saccharin in animals.

Rats given oral doses of [3-14C] saccharin excreted 56-87% of the labeled dose in the urine and 10-40% in the feces during 7 days. Distribution studies showed that the highest levels of 14C were in the kidneys and bladders. The bile was not a significant route of excretion. The presence of labeled CO2 in expired air indicated that saccharin was decarbosylated to a slight degree. DEAE chromatographic separation and isolation of labeled compounds from urine samples showed that more than 99% of the urinary 14C was unchanged saccharin. Up to 1.0% of the 14C was a metabolite identified as 0-sulfamoylbenzoic acid. Comparative metabolic profiles of a dog, rabbit, guinea pig and hamster indicated that there was little difference in the pattern due to animal species or dose level.