The metabolism of (+-)-methylephedrine in rat and man.

1. Urinary metabolites of methylephedrine and their excretion after oral administration to rat and human volunteers have been studied. 2. The unchanged drug, ephedrine, norephedrine, their aromatic hydroxylated compounds and methylephedrine N-oxide were found in rat urine. The same metabolites, except the p-hydroxylated metabolites, were detected in human urine. The most abundant metabolite in rat urine was methylephedrine N-oxide, and in human urine was the unchanged drug. 3. Metabolites excreted in three days after administration of the drug to rat amounted to about 54% of the dose and those after administration to man, 70-72%.