Demser
Demser - General Information
An inhibitor of the enzyme tyrosine 3-monooxygenase, and consequently of the synthesis of catecholamines. It is used to control the symptoms of excessive sympathetic stimulation in patients with pheochromocytoma. (Martindale, The Extra Pharmacopoeia, 30th ed)
Pharmacology of Demser
In patients with pheochromocytoma, who produce excessive amounts of norepinephrine and epinephrine, administration of one to four grams of metyrosine per day has reduced catecholamine biosynthesis from about 35 to 80 percent as measured by the total excretion of catecholamines and their metabolites (metanephrine and vanillylmandelic acid). The maximum biochemical effect usually occurs within two to three days, and the urinary concentration of catecholamines and their metabolites usually returns to pretreatment levels within three to four days after metyrosine is discontinued. Most patients with pheochromocytoma treated with metyrosine experience decreased frequency and severity of hypertensive attacks with their associated headache, nausea, sweating, and tachycardia. In patients who respond, blood pressure decreases progressively during the first two days of therapy with metyrosine; after withdrawal, blood pressure usually increases gradually to pretreatment values within two to three days.
Demser 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 also be advised to maintain a liberal fluid intake.
Demser 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.
Demser Contraindications
DEMSER is contraindicated in persons known to be hypersensitive to this compound.
Additional information about Demser
Demser Indication: For use in the treatment of patients with pheochromocytoma for preoperative preparation of patients for surgery, management of patients when surgery is contraindicated, and chronic treatment of patients with malignant pheochromocytoma.
Mechanism Of Action: Demser inhibits tyrosine hydroxylase, which catalyzes the first transformation in catecholamine biosynthesis, i.e., the conversion of tyrosine to dihydroxyphenylalanine (DOPA). Because the first step is also the rate-limiting step, blockade of tyrosine hydroxylase activity results in decreased endogenous levels of catecholamines, usually measured as decreased urinary excretion of catecholamines and their metabolites, resulting in reduced blood pressure.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Metyrosine
Synonyms: Metirosine; Methyltyrosine
Drug Category: Enzyme Inhibitors
Drug Type: Small Molecule; Approved
Other Brand Names containing Metyrosine: Demser;
Absorption: Well absorbed from the gastrointestinal tract.
Toxicity (Overdose): Signs of metyrosine overdosage include those central nervous system effects observed in some patients even at low dosages. At doses exceeding 2000 mg/day, some degree of sedation or feeling of fatigue may persist. Doses of 2000-4000 mg/day can result in anxiety or agitated depression, neuromuscular effects (including fine tremor of the hands, gross tremor of the trunk, tightening of the jaw with trismus), diarrhea, and decreased salivation with dry mouth. The acute toxicity of metyrosine was 442 mg/kg and 752 mg/kg in the female mouse and rat respectively.
Protein Binding: Not Available
Biotransformation: Little biotransformation, with catechol metabolites accounting for less than 1% of the administered dose.
Half Life: 3.4 to 3.7 hours
Dosage Forms of Demser: Capsule Oral
Chemical IUPAC Name: (2S)-2-amino-3-(4-hydroxyphenyl)-2-methylpropanoic acid
Chemical Formula: C10H13NO3
Metyrosine on Wikipedia: Not Available
Organisms Affected: Humans and other mammals
