Absorption, metabolism, and excretion of 14C-tosifen in the dog and rat.

14C-tosifen [N-2-(1-phenylpropyl)-N'-p-tolyl sulfonylurea] was readily absorbed in both rats and dogs. The rates of absorption, metabolism, and urinary excretion were higher in the rat than in the dog. More of the drug was excreted via the feces than in the urine of the rat, whereas in the dog, the drug was primarily excreted into the urine. The parent drug was the major radioactive component in the plasma of both species. In the urine, however, only a negligible amount of tosifen was found. The major urinary metabolite was a hydroxymethyl derivative which accounted for about 60% and 40% of the total radioactivity in the urine of the dog and rat, respectively.