Maintain Fluid Volume During and After Surgery

When DEMSER is used preoperatively, alone or especially in combination with alpha-adrenergic blocking drugs, adequate intravascular volume must be maintained intraoperatively (especially after tumor removal) and postoperatively to avoid hypotension and decreased perfusion of vital organs resulting from vasodilatation and expanded volume capacity. Following tumor removal, large volumes of plasma may be needed to maintain blood pressure and central venous pressure within the normal range.

In addition, life-threatening arrhythmias may occur during anesthesia and surgery, and may require treatment with a beta blocker or lidocaine. During surgery, patients should have continuous monitoring of blood pressure and electrocardiogram.

Intraoperative Effects

While the preoperative use of DEMSER in patients with pheochromocytoma is thought to decrease intraoperative problems with blood pressure control, 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.

Interaction with Alcohol

DEMSER may add to the sedative effects of alcohol and other CNS depressants, e.g., hypnotics, sedatives, and tranquilizers. (See

PRECAUTIONS

General

Metyrosine Crystalluria:   Crystalluria and urolithiasis have been found in dogs treated with DEMSER (Metyrosine) at doses similar to those used in humans, and crystalluria has also been observed in a few patients. 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. Metyrosine will crystallize as needles or rods. If metyrosine crystalluria occurs, fluid intake should be increased further. If crystalluria persists, the dosage should be reduced or the drug discontinued.

Relatively Little Data Regarding Long-term Use:   The total human experience with the drug is quite limited and few patients have been studied long-term. Chronic animal studies have not been carried out. Therefore, suitable laboratory tests should be carried out periodically in patients requiring prolonged use of DEMSER and caution should be observed in patients with impaired hepatic or renal function.

Information for Patients

When receiving DEMSER, patients should be warned about engaging in activities requiring mental alertness and motor coordination, such as driving a motor vehicle or operating machinery. DEMSER may have additive sedative effects with alcohol and other CNS depressants, e.g., hypnotics, sedatives, and tranquilizers.

Patients should be advised to maintain a liberal fluid intake. (See

PRECAUTIONS

Drug Interactions

Caution should be observed 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.

Concurrent use of DEMSER with alcohol or other CNS depressants can increase their sedative effects. (See

WARNINGS

Laboratory Test Interference

Spurious increases in urinary catecholamines may be observed in patients receiving DEMSER due to the presence of metabolites of the drug.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long-term carcinogenic studies in animals and studies on mutagenesis and impairment of fertility have not been performed with metyrosine.

Pregnancy

Pregnancy Category C. Animal reproduction studies have not been conducted with DEMSER. It is also not known whether DEMSER can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. DEMSER should be given to a pregnant woman only if clearly needed.

Nursing Mothers

It is not known whether DEMSER is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when DEMSER is administered to a nursing woman.

Pediatric Use

Safety and effectiveness in pediatric patients below the age of 12 years have not been established.

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