title: Pheochromocytoma resistant to alpha-adrenergic blockade.
abstract: In a 54-year-old man with a norepinephrine-secreting pheochromocytoma, resistance developed to the alpha-adrenergic blocking agent, phenoxybenzamine hydrochloride. Dosages of 240 mg/day were ineffective. Intravenous phentolamine mesylate reduced his BP at first, but resistance developed to this also. Therapy with alpha-methylparatyrosine, an inhibitor of catecholamine biosynthesis, finally controlled his BP, and the tumor was removed.
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000188:drug therapy*; D000317:Adrenergic alpha-Antagonists / Q000627:therapeutic use*; D004351:Drug Resistance; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D008297:Male; D008781:Methyltyrosines / Q000627:therapeutic use; D008875:Middle Aged; D010643:Phenoxybenzamine / Q000627:therapeutic use; D010646:Phentolamine / Q000627:therapeutic use; D010673:Pheochromocytoma / Q000188:drug therapy*; D014446:Tyrosine 3-Monooxygenase / Q000037:antagonists & inhibitors; D019805:alpha-Methyltyrosine
chemical_list: D000317:Adrenergic alpha-Antagonists; D008781:Methyltyrosines; D010643:Phenoxybenzamine; D019805:alpha-Methyltyrosine; D014446:Tyrosine 3-Monooxygenase; D010646:Phentolamine