Routes of elimination of hexamethylmelamine and pentamethylmelamine in the rat

Abstract

1. In the rat 40% of a dose of 25 mg/kg of hexamethylmelamine or pentamethylmelamine was excreted in the urine as metabolites, more than 95% of which were N₂N₄-dimethylmelamine and monomethylmelamine.

2. Biliary excretion of hexamethylmelamine or pentamethylmelamine and their N-demethylated metabolites accounted for less than 2% of the administered dose. Only 0.3% was excreted with the faeces, suggesting that there is intestinal reabsorption of a portion of the methylmelamines passing into the bile.

3. Conjugates of methylmelamines with glucuronic acid or sulphate were found only in minute quantities in the urine or bile of rats treated with hexamethylmelamine or pentamethylmelamine. However a conjugation product of pentamethylmelamine, of as yet unknown nature, is a major metabolite after pentamethylmelamine treatment.