Metabolism of methocarbamol (robaxin) in the isolated perfused rat liver and identification of glucuronides.

1. Permethylation and g.l.c.-mass spectrometric analysis of bile from an isolated rat liver perfusion to which methocarmol was added showed seven components not present in control bile: methocarbamol, glucuronides of methocarbamol and desmethyl-methocarbamol, and four glucuronides of hydroxylated methocarbamol metabolites. 2. An interesting rearrangement of a methyl group has been found in the mass spectrum of 3-(2-methoxyphenyloxy)-1,2-dimethoxypropane, the permethylation product from methocarbamol.