Pheochromocytomas are catecholamine-releasing endocrine tumors of chromaffin cells.1-3 The secretion of catecholamines typically results in hypertension, either continuous or paroxysmal.3,4 Pheochromocytoma patients are at high risk for developing hypertensive crisis (an acute increase in blood pressure with systolic blood pressure exceeding 180 mm Hg and diastolic pressure exceeding 120 mm Hg).1,3 Severe cases (hypertensive emergencies) may be associated with visual disturbances, palpitations, encephalopathy, acute myocardial infarction, congestive heart failure, or cerebrovascular accidents; in cases of multisystem crisis, patients often develop pulmonary edema, cardiac arrhythmias, and acute renal failure.1,3,5 Pheochromocytoma-associated hypertension may respond inadequately to conventional antihypertensive therapy.3,6

Severe hemodynamic instability may occur during surgery to resect pheochromocytoma.3 DEMSER® (metyrosine) is a therapy employed to help manage the hypertension of patients with pheochromocytoma in preparation for surgery, among other uses.7


DEMSER® (metyrosine) capsules are indicated in the treatment of patients with pheochromocytoma for: preoperative preparation of patients for surgery, management of patients when surgery is contraindicated, and/or chronic treatment of patients with malignant pheochromocytoma. DEMSER is not recommended for the control of essential hypertension.


  • DEMSER is contraindicated in persons known to be hypersensitive to this compound.
  • Maintain adequate intravascular volume intraoperatively (especially after tumor removal) and postoperatively to avoid hypotension and decreased perfusion of vital organs resulting from vasodilatation and expanded volume capacity.
  • Life-threatening arrhythmias may occur during anesthesia and surgery. Monitor blood pressure and electrocardiogram continuously during surgery.
  • DEMSER does not eliminate the danger of hypertensive crises or arrhythmias during manipulation of the tumor, and the alpha-adrenergic blocking drug, phentolamine, may be needed.
  • DEMSER may add to the sedative effects of alcohol and other CNS depressants, e.g., hypnotics, sedatives, and tranquilizers.
  • To minimize the risk of crystalluria, patients should be urged to maintain water intake sufficient to achieve a daily urine volume of 2000 mL or more, particularly when doses greater than 2 g per day are given. Routine examination of the urine should be carried out. If metyrosine crystalluria occurs, fluid intake should be increased further. If crystalluria persists, the dosage should be reduced or the drug discontinued.
  • Observe caution in patients with impaired hepatic or renal function.
  • Warn patients about engaging in activities requiring mental alertness and motor coordination, such as driving a motor vehicle or operating machinery.
  • Advise patients to maintain liberal fluid intake.
  • Use caution in administering DEMSER to patients receiving phenothiazines or haloperidol because the extrapyramidal effects of these drugs can be expected to be potentiated by inhibition of catecholamine synthesis.
  • The most common adverse reaction to DEMSER is moderate to severe sedation. Other commonly reported adverse reactions are extrapyramidal signs such as drooling, speech difficulty and tremor in approximately 10 percent of patients, occasionally accompanied by trismus and frank Parkinsonism. Anxiety and psychic disturbances such as depression, hallucinations, disorientation, and confusion may occur. Diarrhea occurs in about 10 percent of patients and may be severe.

To report SUSPECTED ADVERSE REACTIONS, contact Bausch Health Customer Service at 1-800-321-4576 or FDA at 1-800-FDA-1088 or


References: 1. Canu L, Parenti G, De Filpo G, Mannelli M. Pheochromocytomas and paragangliomas as causes of endocrine hypertension. Front Endocrinol. 2019;10:333. doi:10.3389/fendo.2019.00333 2. Aygun N, Uludag M. Pheochromocytoma and paraganglioma: from treatment to follow-up. Med Bull Sisli Etfal Hosp. 2020;54(4):391-398. 3. Fang F, Ding L, He Q, Liu M. Preoperative management of pheochromocytoma and paraganglioma. Front Endocrinol. 2020;11:586795. doi:10.3389/fendo.2020.586795 4. Y-Hassan S, Falhammar H. Cardiovascular manifestations and complications of pheochromocytomas and paragangliomas. J Clin Med. 2020;9:2435. doi:10.3390/jcm9082435 5. Prejbisz A, Lenders JW, Eisenhofer G, Januszewicz A. Cardiovascular manifestations of phaeochromocytoma. J Hypertens. 2011;29(11):2049-2060. 6. Kometani M, Yoneda T, Maeda Y, et al. Pheochromocytoma crisis with cyclic fluctuation in blood pressure mimics acute coronary syndrome. Endocrinol Diabetes Metab Case Rep. 2020; 2020:20-0115. doi:10.1530/EDM-20-0115 7. Demser. Package insert. Bausch Health US, LLC; 2020.