metyrosine (Demser)
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Introduction
Tradename: Demser.
Indications
- treatment of malignant pheochromocytoma
- perioperative treatment of patients with pheochromocytoma
Contraindications
- use in children < 12 years of age NOT recommended
- hypersensitivity to metyrosine
Dosage
- start 250 mg PO QID
- increase by 250-500 mg QD
- maximum 4 g/day
- maintain sufficient fluid intake to provide > 2 liters of urine/day
(may be combined with alpha-blockers)
Dosage adjustment in renal failure
- yes; but no specific recommendations available
Pharmacokinetics
- oral dose well absorbed
- elimination
- 12-47% metabolized by liver
- remainder eliminated unchanged in the urine
- elimination 1/2life: 3.4-7.2 hours (determined in 3 patients)
elimination via kidney
1/2life = 3.4-7.2 hours
Adverse effects
- sedation (common)
- diarrhea
- crystalluria
- dysuria
- drooling
- tremor
- speech difficulty
- parkinsonism (occasional)
- oculogyric crisis (1 case)
Drug interactions
- additive effects with other CNS depressants
Test interactions
- may interfere with determination of urinary catecholamines
Mechanism of action
- inhibits tyrosine 3-hydroxylase
- inhibits catecholamine synthesis
More general terms
Additional terms
- pheochromocytoma; paroxysmal hypertension; adrenal medullary paraganglioma; chromoffinoma
- tyrosine 3-hydroxylase (tyrosine 3-monooxygenase, TH, TYH)