April 28, 1997

Metyrosine and Pheochromocytoma

Author Affiliations

From the Sections of Endocrinology and Nutrition and Cardiology, Department of Medicine, The Medical College of Georgia (Drs Steinsapir, Prisant, and Bransome), and Circulatory Disease Center, Augusta Preventive Cardiology Inc (Dr Carr), Augusta, Ga. Dr Steinsapir is now with the Brigham and Women's Hospital, Havard Medical School, Boston, Mass.

Arch Intern Med. 1997;157(8):901-906. doi:10.1001/archinte.1997.00440290087009

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 (α-methyl-p-tyrosine), a catecholamine synthesis inhibitor, and α-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 result of hypertensive crisis.

Conclusions:  The combination of α-metyrosine and α-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 α-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.Arch Intern Med. 1997;157:901-906