Malignant pheochromocytoma. Effect of oral alpha-methyl-p-tyrosine upon catecholamine metabolism.

In a patient with malignant pheochromocytoma treated unsuccessfully with propranolol and phenoxybenzamine the additional therapy with alpha-methyl-p-tyrosine resulted in a substantial decrease of the blood pressure to almost normal values. His general condition improved considerably. During therapy the urinary excretion rates of catecholamines and all their metabolites dropped to about 50% of control values. O-Hydroxylation of alpha-methyl-p-tyrosine could be demonstrated by the isolation of alpha-methyldopa and alpha-methylnormetanephrine. After discontinuation of treatment with alpha-methyl-p-tyrosine blood pressure and catecholamines returned to control values within two days.