because such drugs would induce the potentially highly dangerous hyperphenylalaninemia or phenylketonuria. Tyrosine hydroxylase inhibitors like metirosine, which is used in the treatment of pheochromocytoma as a sympatholytic or antihypertensive agent. Aromatic L-amino acid decarboxylase or DOPA decarboxylase inhibitors including benserazide, carbidopa, and methyldopa, which are used in the treatment of Parkinson's disease in augmentation of L-DOPA to block the peripheral conversion of dopamine, thereby inhibiting undesirable side-effects, and as sympatholytic or antihypertensive agents. Others such as hyperforin and adhyperforin (both found in Hypericum perforatum St. John's Wort), L-theanine (found in Camellia sinensis, the tea plant), and S-adenosyl-L-methionine (SAMe) See also Adrenergic Cholinergic Cocaine and amphetamine regulated transcript (CART) GABAergic Histaminergic Serotonergic References Dopamine