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Maintain Fluid Volume During and After Surgery
When DEMSER (metyrosine) 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.
While the preoperative use of DEMSER (metyrosine) in patients with pheochromocytoma is thought to decrease intraoperative problems with blood pressure control, DEMSER (metyrosine) 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 (metyrosine) may add to the sedative effects of alcohol and other CNS depressants, e.g., hypnotics, sedatives, and tranquilizers. (See PRECAUTIONS: Information for Patients and DRUG INTERACTIONS.)
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 (metyrosine) and caution should be observed in patients with impaired hepatic or renal function.
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 Category C. Animal reproduction studies have not been conducted with DEMSER (metyrosine) . It is also not known whether DEMSER (metyrosine) can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. DEMSER (metyrosine) should be given to a pregnant woman only if clearly needed.
It is not known whether DEMSER (metyrosine) is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when DEMSER (metyrosine) is administered to a nursing woman.
Safety and effectiveness in pediatric patients below the age of 12 years have not been established.
Clinical studies of DEMSER (metyrosine) did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 11/20/2008
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