Biodehalogenation and metabolism of 125[I]-4-iodobiphenyl

[125I]-4-Iodobiphenyl has been used as a model compound to investigate the in vivo metabolism of iodinated aromatic compounds in the rat. Material balance studies showed that 57.6% of the injected dose was excreted via feces and 41.2% via urine. Distribution studies indicated uptake of inorganic iodide in the thyroid. In the feces, 2.2% of the dose was unmetabolized iodobiphenyl, 2.6% was 2-hydroxy-4'-iodobiphenyl, 21.9% was 4-hydroxy-4'-iodobipheny, and 20.9% was a polar fraction of which only 10.3% could by silylated. In urine, 1.6% of the dose was 2-hydroxy-4'-iodobiphenyl, 4.9% was 4-hydroxy-4'-iodobiphenyl, 1.9% was 2-hydroxy-4'-iodobiphenyl, 17.7% was 4-hydroxy-4'-iodobiphenyl glucuronide and sulfate conjugates, and 8.2% was inorganic iodide. About 3.0% of the dose in the urine polar fraction could be methylated.