(S)-alpha-Methyltyrosine
(S)-alpha-Methyltyrosine Uses, Dosage, Side Effects, Food Interaction and all others data.
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)
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.
| Trade Name | (S)-alpha-Methyltyrosine |
| Availability | Prescription only |
| Generic | Metyrosine |
| Metyrosine Other Names | (S)-alpha-Methyltyrosine, Methyltyrosine, Metirosin, Metirosina, Metirosine, Métirosine, Metirosinum, Metyrosine |
| Related Drugs | propranolol, labetalol, Inderal, phenoxybenzamine, phentolamine, Normodyne |
| Type | |
| Formula | C10H13NO3 |
| Weight | Average: 195.2151 Monoisotopic: 195.089543287 |
| Groups | Approved |
| Therapeutic Class | |
| Manufacturer | |
| Available Country | |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
(S)-alpha-Methyltyrosine is a tyrosine 3-monooxygenase inhibitor used to treat excessive sympathetic stimulation in pheochromocytoma.
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.
(S)-alpha-Methyltyrosine is also used to associated treatment for these conditions: Pheochromocytomas
How (S)-alpha-Methyltyrosine works
(S)-alpha-Methyltyrosine 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 and their synthesis. This consequently, depletes the levels of the catecholamines dopamine, adrenaline and noradrenaline in the body,usually measured as decreased urinary excretion of catecholamines and their metabolites. One main end result of the catecholamine depletion is a decrease in blood presure.
Toxicity
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.
Food Interaction
- Avoid alcohol. Ingesting alcohol may increase the sedative and CNS depressant effects of metyrosine.
(S)-alpha-Methyltyrosine Alcohol interaction
[Moderate]
(S)-alpha-Methyltyrosine, when coadministered with other CNS depressants including alcoholic beverages, may lead to excessive somnolence and other forms of nervous system depression.
The patient should be informed to use caution if these agents are coadministered, especially if performing hazardous tasks such as driving or operating machinery.
(S)-alpha-Methyltyrosine Drug Interaction
Moderate: diphenhydramine, diphenhydramine, duloxetine, duloxetine, melatonin, melatoninUnknown: amphetamine / dextroamphetamine, amphetamine / dextroamphetamine, fluticasone / salmeterol, fluticasone / salmeterol, ubiquinone, ubiquinone, omega-3 polyunsaturated fatty acids, omega-3 polyunsaturated fatty acids, levothyroxine, levothyroxine, ascorbic acid, ascorbic acid, cholecalciferol, cholecalciferol
(S)-alpha-Methyltyrosine Disease Interaction
Moderate: extrapyramidal symptoms, psychoses and emotional disturbances, renal dysfunction
Elimination Route
Well absorbed from the gastrointestinal tract.
Half Life
3.4 to 3.7 hours
Elimination Route
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.
Innovators Monograph
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