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Ten milligrams [14C]NTA in gelatin capsules was given (p.o.) to 8 male subjects. Blood samples were taken, and samples of urine and feces were collected. In addition, expired CO2 was collected in 4 of the subjects. NTA is poorly absorbed since approximately 12% of the dose appeared in the urine. The compound is rapidly excreted in the urine since 87 % of the absorbed dose was excreted within the first 24 hr post dosing. The blood concentration peak occurred 1-2 hr after dosing. Reverse isotope dilution and thin-layer chromatography showed the urinary radioactivity to be unchanged NTA, and therefore no biotransformation had occurred. These results closely resemble the rat and dog metabolic data except that rats and dogs absorb 4 times more NTA than humans. The metabolic similarities among rats, dogs and humans lends some confidence to the extrapolation of the results derived from rat and dog toxicity tests for the purpose of estimating human safety.

Literature: Budny, J.A. and Arnold, J.D. (1973). Human Metabolism and its Importance in the Total Safety Evaluation Program. Tox. Appl. Pharmacol. 25, 48 - 53 (cited in MAK documentation 2008).