title: Metyrosine and pheochromocytoma.
abstract: BACKGROUND
  Severe hemodynamic instability may occur during surgery for removal of pheochromocytoma, unless there is preoperative pharmacological treatment.
  
  
  OBJECTIVE
  To evaluate the effects of metyrosine (alpha-methyl-p-tyrosine), a catecholamine synthesis inhibitor, and alpha-blockade with prazosin or phenoxybenzamine on cardiovascular morbidity during surgery for pheochromocytoma.
  
  
  METHODS
  A retrospective analysis was made of patients followed up at the Medical College of Georgia, Augusta, during 28 years who received metyrosine and prazosin (n = 6), metyrosine and phenoxybenzamine alone (n = 14), phenoxybenzamine alone (n = 6), or no medication (n = 7) during 3 weeks before tumor removal. The percentage of patients not requiring pressors or phentolamine during the intraoperative period as well as the perioperative peak systolic pressures and peak heart rates were estimated in each group.
  
  
  RESULTS
  There was a significant (P < .05) increase in intraoperative peak systolic pressures without preoperative treatment (mean +/- SD, 243 +/- 40 mm Hg) vs metyrosine (mean +/- SD, 168 +/- 27 mm Hg). Ninety-five percent of patients who received metyrosine did not require pressors intraoperatively vs 50% with phenoxybenzamine alone. Eighty-one percent of patients pretreated with metyrosine did not require intraoperative phentolamine vs 33% with phenoxybenzamine alone and 29% without medications. Two patients in the no medication group died as a results of hypertensive crisis.
  
  
  CONCLUSIONS
  The combination of alpha-metyrosine and alpha-blockade results in better blood pressure control and less need for use of antihypertensive medication or pressors during surgery, compared with the classical method of single-agent adrenergic blockade. Preoperative treatment with metyrosine along with an alpha-blocker is a useful strategy for decreasing the surgical morbidity in patients with pheochromocytoma and assumes greater importance as long as the availability of phentolamine for intraoperative use is a problem.
authors.affiliation: Department of Medicine, Medical College of Georgia, Augusta, USA.
authors.forename: J
authors.initials: J
authors.lastname: Steinsapir
authors.forename: A A
authors.initials: AA
authors.lastname: Carr
authors.forename: L M
authors.initials: LM
authors.lastname: Prisant
authors.forename: E D
authors.initials: ED
authors.lastname: Bransome
mesh_terms: D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000503:physiopathology / Q000601:surgery*; D000316:Adrenergic alpha-Agonists / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002395:Catecholamines / Q000378:metabolism; D002648:Child; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D007431:Intraoperative Complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D008781:Methyltyrosines / Q000627:therapeutic use*; D008875:Middle Aged; D010643:Phenoxybenzamine / Q000627:therapeutic use*; D010673:Pheochromocytoma / Q000503:physiopathology / Q000601:surgery*; D011224:Prazosin / Q000627:therapeutic use*; D012189:Retrospective Studies; D016896:Treatment Outcome; D019805:alpha-Methyltyrosine
chemical_list: D000316:Adrenergic alpha-Agonists; D002395:Catecholamines; D004791:Enzyme Inhibitors; D008781:Methyltyrosines; D010643:Phenoxybenzamine; D019805:alpha-Methyltyrosine; D011224:Prazosin