Adult Dosing
Treatment of pheochromocytoma
- 250 mg PO qid; may increase the dose by 250 mg to 500 mg everyday to a max of 4000 mg/day in divided doses
Notes:- Administer the dose for at least 5-7 days when used for preoperative preparation
- Optimally effective dosages range between 2000 and 3000 mg/day; titrate the dose individually by monitoring clinical symptoms and catecholamine excretion
- In hypertensive patients, dosage should be titrated to achieve normalization of blood pressure and control of clinical symptoms
- In normotensive patients, dosage should be titrated to reduce urinary metanephrines and/or vanillylmandelic acid by 50% or more
- If adequate control of symptoms is not achieved, add an alpha-adrenergic blocking agent to the regimen
Pediatric Dosing
Treatment of pheochromocytoma
Below 12 yrs
- Safety and effectiveness in pediatric patients <12 yrs have not been established
Above 12 yrs
- 250 mg PO qid; may increase the dose by 250 mg to 500 mg everyday to a maximum of 4000 mg/day in divided doses
Notes:- Administer the dose for at least 5-7 days when used for preoperative preparation
- Optimally effective dosages range between 2000 and 3000 mg/day; titrate the dose individually by monitoring clinical symptoms and catecholamine excretion
- In hypertensive patients, dosage should be titrated to achieve normalization of blood pressure and control of clinical symptoms
- In normotensive patients, dosage should be titrated to reduce urinary metanephrines and/or vanillylmandelic acid by 50% or more
- If adequate control of symptoms is not achieved, add an alpha-adrenergic blocking agent to the regimen
[Outline]
See Supplemental Patient Information
- When metyrosine is used pre-operatively, maintain adequate intravascular volume during and after surgery to avoid the risk of hypotension and reduced perfusion of vital organs due to vasodilatation and expanded volume capacity
- Blood pressure and electrocardiogram should be monitored continuously during surgery
- Large amounts of plasma may be needed to maintain blood pressure and central venous pressure within normal range after tumor removal
- Life-threatening arrhythmias may occur during anesthesia and surgery, which may require treatment with a beta-blocker or lidocaine
- The risk of hypertensive crises or arrhythmias during manipulation of the tumor is not eliminated by metyrosine; use of alpha-adrenergic blocking agent (phentolamine) may be indicated
- Metyrosine may potentiate the sedative effects of alcohol and other CNS depressants such as sedatives, hypnotics, and tranquilizers
- Crystalluria has been reported in certain patients treated with metyrosine. Maintain adequate water intake sufficient to achieve a daily urine volume of 2 liters or more, especially when doses of metyrosine >2000 mg/day are given
- If crystalluria persists even after increasing the fluid intake, consider reducing the dose or discontinuing therapy
- Suitable laboratory evaluations should be performed periodically in patients treated with metyrosine for prolonged periods
- Because metyrosine may cause sedation, patients should be cautioned to avoid performing hazardous tasks that require mental alertness and motor coordination such as driving or operating machinery
Cautions: Use cautiously in
- Renal impairment
- Hepatic impairment
- Elderly patients
Supplemental Patient Information
- Advice patients to refrain from performing tasks that require mental alertness and motor coordination such as driving or operating machinery
- Instruct patients to maintain a liberal fluid intake
Pregnancy Category:C
Breastfeeding: Safety unknown. As many drugs are excreted in human milk, manufacturer advises caution while administering to nursing mothers.
Drug Name: Demser 250 MG Oral Capsule
Ingredient(s): Metyrosine
Imprint: MSD;690;Demser
Color(s): Blue
Shape: Capsule
Size (mm): 22.00
Score: 1
Inactive Ingredient(s): colloidal silicon dioxide / gelatin / hydroxypropyl cellulose / magnesium stearate / titanium dioxide / fd&c blue 2
Drug Label Author:
Aton Pharma, Inc.
DEA Schedule:
Non-Scheduled
Drug Name: Demser 250 MG Oral Capsule
Ingredient(s): Metyrosine
Imprint: MSD;690;DEMSER
Color(s): Blue
Shape: Capsule
Size (mm): 21.00
Score: 1
Inactive Ingredient(s): colloidal silicon dioxide / fd&c blue 2 / gelatin / hydroxypropyl cellulose / magnesium stearate / titanium dioxide
Drug Label Author:
Merck & Co., Inc.
DEA Schedule:
Non-Scheduled
