586954-09-8

3-O-Methyldopa-d3 (3-OMD isotopic standart), 3-Methoxy-L-tyrosine, is a metabolite of L-dioxyphenylalanine (DOPA, L-DOPA, the drug levadopa), which is formed by the action of catechol-O-methyltransferase (COMT). 3-Methoxy-L-tyrosine competitively inhibits the pharmacodynamics of L-DOPA and dopamine. 3-Methoxy-L-tyrosine is an important marker for screening Parkinson's disease patients taking the drug levadopa. 3-Methoxy-L-tyrosine is also a major biochemical marker of aromatic L-amino acid decarboxylase deficiency (AADC, EC 4.1.1.28), an inborn error of metabolism that affects serotonin and dopamine biosynthesis.