Metyrosine (Demser) - Uses, Dose, Side effects, MOA, Brands

Metyrosine (Demser) inhibits the enzyme tyrosine hydroxylase that is required for the synthesis of catecholamines (adrenaline, nor-adrenaline, and dopamine). It is used in patients with pheochromocytoma preoperatively and for long-term maintenance treatment in patients who are not fit to undergo surgery.

Metyrosine (Demser) Uses:

  • Pheochromocytoma:

    • Pheochromocytoma should be treated temporarily before surgery as an adjuvant to other anti-hypertensive drugs such as alpha-blockers.
    • When surgery is not an option or there is a persistent malignant pheochromocytoma, long-term care for pheochromocytoma is necessary.

Note: Usually, simultaneous alpha- and beta-adrenergic inhibition is only used for those who cannot tolerate it.

Metyrosine Dose in Adults:

Metyrosine (Demser) Dose in the treatment of Pheochromocytoma:

  • Oral: start with 250 mg four times per day, then increase by 250 to 500 mg per day up to 4 g per day in four evenly spaced dosages.
  • In hypertensive patients titrate until blood pressure is controlled and symptoms resolve.
  • For preoperative preparation, administer optimum effective dosage for 5 to 7 days.
  • In patients without hypertension titrate to decrease catecholamines by ≥50%.
  • The usual maintenance dose is: 2 to 3 g/day in 4 divided doses


  • It may be given combined with alpha-adrenergic receptor inhibitors (eg, phenoxybenzamine) to increase intraoperative hemodynamic stability;
  • Use 2 g/day, higher doses may potentially cause intraoperative hemodynamic instability.

Use in Children:

Refer to adults' dosing.

Pregnancy Risk Factor C

  • No animal reproduction studies

Metyrosine use during breastfeeding:

  • Use cautiously in lactating women.

Dose in Kidney Disease:

No dose adjustment is needed.

Dose in Liver disease:

No dose adjustment is needed.

Side Effects of Metyrosine (Demser):

  • Cardiovascular:

    • Peripheral edema
  • Central nervous system:

    • Hallucination
    • Headache
    • Extrapyramidal reactions
    • Parkinson’s disease
    • Sedation
    • Depression
    • Disorientation
    • Overstimulation (after withdrawal)
    • Anxiety
    • Confusion
  • Dermatologic:

    • Urticaria
  • Endocrine & metabolic:

    • Galactorrhea
  • Hematologic & oncologic:

    • Anemia
    • Thrombocythemia
    • Thrombocytopenia
    • Eosinophilia
  • Gastrointestinal:

    • Diarrhea
    • Abdominal pain
    • Nausea
    • Vomiting
    • Xerostomia
  • Genitourinary:

    • Dysuria
    • Hematuria
    • Breast swelling
    • Crystalluria
    • Impotence
    • Ejaculatory disorder
  • Hepatic:

    • Increased serum AST
  • Hypersensitivity:

    • Hypersensitivity reaction
  • Respiratory:

    • Nasal congestion
    • Pharyngeal edema

Contraindication to Metyrosine (Demser):

Sensitivity to any ingredient in the mix, including metyrosine

Warnings and precautions

  • CNS depression:

    • CNS depression
    • Reduced mental alertness
  • Crystalluria

    • Crystalluria can be avoided by hydrating enough to produce urine output >=2L, especially if you take more than 2 g per day.
    • If crystalluria occurs, adjust the dosage or discontinue use
  • Hepatic impairment

    • Patients with liver disease should be cautious.
  • Renal impairment

    • Patients with impaired kidney function should be cautious.

Metyrosine: Drug Interaction

Risk Factor C (Monitor therapy)

Alcohol (Ethyl)

May intensify metyrosine's sedative effects.

Antipsychotic Agents

The negative/toxic effects of antipsychotic agents may be amplified by metyroSINE.

CNS Depressants

May intensify metyrosine's sedative effects.


MetyroSINE may intensify Droperidol's harmful or hazardous effects.


Promethazine's negative/toxic effects may be exacerbated by metyroSINE.

Selective Serotonin Reuptake Inhibitors

Selective Serotonin Reuptake Inhibitors may have a negative or toxic impact that metyroSINE may amplify.


Tetrabenazine's harmful or hazardous effects may be amplified by metyroSINE.

Tricyclic Antidepressants

Tricyclic antidepressants may have a worsened or more toxic effect when taken with metyroSINE.

Risk Factor D (Consider therapy modification)


The negative or hazardous effects of metoclopramide may be increased by metyroSINE. Management: When feasible, look for alternatives for this combination. Observe patients receiving metyrosine and metoclopramide for the emergence of extrapyramidal symptoms.

Risk Factor X (Avoid combination)


MetyroSINE may enhance the adverse/toxic effect of Bromopride.


Monitoring parameters:

  • blood pressure
  • ECG during surgery
  • urinalysis
  • urine output ≥2000 mL recommended especially with doses >2 g/day)

How to administer Metyrosine (Demser)?

Administer with or without food.

Mechanism of action of Metyrosine (Demser):

  • Inhibits tyrosine hydroxylase required for conversion of tyrosine to dihydroxyphenylalanine, needed for catecholamine synthesis.
  • Use the recommended dose to reduce catecholamine biosynthesis by between 35% and 80%

Half-life elimination:

  • ~3-4 hours


  • Well absorbed


  • Primarily urine (53% to 88% as unchanged drug)

International Brand Names of Metyrosine:

  • Demser

Metyrosine Brand Names in Pakistan:

No Brands Available in Pakistan.


NO Comments Found

Related Posts

No Related Post