Metabolism of methyl methacrylate: evidence for metabolism by the valine pathway of catabolism in rat and in man.

1. Evidence to support the suggestion that methyl methacrylate is metabolized by the normal pathway of valine catabolism has been obtained by the administration of methyl [Me-14C]methacrylate to rats. 2. Of the administered dose, 80% was respired as 14CO2 as predicted, and methylmalonic acid, specifically labelled with 14C in a manner consistent with the proposed pathway of metabolism, was excreted (0.22%) dose). 3. Following administration of sodium [Me-2H3]methacrylate to a human subject, [Me-2H3]methylmalonic acid was detected in the urine by g.l.c.-mass spectrometry.