Metabolic disposition of radioactive phenothiazine in calves: a balance study.

Three Charolais calves were treated orally with [14C] phenothiazine. The amount of radioactivity excreted in the urine and feces was measured. The average quantity of the excreted dose recovered was divided equally between the urine and the feces. The radioactivity found in the feces and gastrointestinal tract was variable between the animals, but the urinary radioactivity was constant. Only a small amount of the administered dose was retained by selected organs, with the liver and kidneys accounting for most of that amount. These organs also had tissue-to-blood ratios of radioactivity greater than unity, whereas the other tissues had ratios close to unity. Essentially complete recovery of the administered radioactive dose was achieved.