Oral bioavailability, urinary excretion and organ distribution of melamine in Sprague-Dawley rats by high-performance liquid chromatography with tandem mass spectrometry.

High-performance liquid chromatography with tandem mass spectrometry (HPLC/MS/MS) was used to determine melamine oral bioavailability (BA) and urinary excretion. Organ distribution after a 14-day consecutive oral melamine administration (100 mg/kg/day, once a day) was also evaluated. A noncompartmental model was utilized to obtain pharmacokinetic parameters. According to the results, the BA of melamine was estimated to be 98.1%. Approximately 63% of administered melamine was recovered in urine within 96 h after a single oral administration (100 mg/kg). The bladder had the highest melamine concentration of all the organs after a 14-day consecutive oral administration of melamine, and almost no melamine was found in the rat brain. This result indicated that the oral absorption of melamine was almost complete and urinary excretion was the major route for its elimination. Repeated exposure to high-dose melamine may result in only slight accumulation in organs.