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metyrosine (Demser)
Tradename: Demser.
Indications:
1) treatment of malignant pheochromocytoma
2) perioperative treatment of patients with pheochromocytoma
Contraindications:
1) use in children < 12 years of age NOT recommended
2) hypersensitivity to metyrosine
Dosage:
1) start 250 mg PO QID
2) increase by 250-500 mg QD
3) maximum 4 g/day
4) maintain sufficient fluid intake to provide > 2 liters of urine/day
(may be combined with alpha-blockers)
Dosage adjustment for renal insufficiency:
- yes; but no specific recommendations available
Pharmacokinetics:
1) oral dose well absorbed
2) elimination
a) 12-47% metabolized by liver
b) remainder eliminated unchanged in the urine
2) elimination 1/2life: 3.4-7.2 hours (determined in 3 patients)
Adverse effects:
1) sedation (common)
2) diarrhea
3) crystalluria
4) dysuria
5) drooling
6) tremor
7) speech difficulty
8) parkinsonism (occasional)
9) oculogyric crisis (1 case)
Drug interactions:
-> additive effects with other CNS depressants
Test interactions:
-> may interfere with determination of urinary catecholamines
Mechanism of action:
1) inhibits tyrosine 3-hydroxlase
2) inhibits catecholamine synthesis
Related
pheochromocytoma; paroxysmal hypertension; adrenal medullary paraganglioma; chromoffinoma
tyrosine 3-hydroxylase (tyrosine 3-monooxygenase, TH, TYH)
General
alpha-amino acid
antineoplastic agent (chemotherapeutic agent)
enzyme inhibitor
Properties
INHIBITS: tyrosine 3-hydroxylase
MISC-INFO: elimination route KIDNEY
1/2life 3.4-7.2 HOURS
pregnancy-category C
safety in lactation ?
Database Correlations
PUBCHEM correlations
References
- Micromedix
- Medical Knowledge Self Assessment Program (MKSAP) 11, American
College of Physicians, Philadelphia 1998