Tyrosine hydroxylase enzyme

Metyrosine induces sleep by blocking tyrosine kinases, which releases stored catecholamines [2].
Metyrosine is a methylated tyrosine, a catecholamine synthesis antagonist with antihypertensive property. Metyrosine competitively inhibits tyrosine 3-monooxygenase, an enzyme that activates molecular oxygen to catalyze the hydroxylation of tyrosine to dihydroxyphenylalanine (Dopa), an intermediate to catecholamine (dopamine, norepinephrine, and epinephrine) production. This agent reduces the elevated levels of catecholamines associated with pheochromocytoma, thereby preventing hypertension.

Carrageenan modulator is lowered by metyrosine (50–200 mg/kg; ip) [1]. Male albino Wistar rats with carrageenan-induced rat paw edema are the animal model of resistance to the anti-activity of metyrosine (50–200 mg/kg; ip) at dosages of 50, 100, and 200 mg/kg [2].

Animal/Disease Models: Male albino Wistar rats (carrageenan-induced rat paw edema)[2]
Doses: 50, 100 or 200 mg/kg
Route of Administration: I.p.
Experimental Results: diminished carrageenan inflammation at 50, 100 and 200 mg/kg doses (40%, 67% and 87%, respectively, at 4 h).

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In this study, the anti-inflammatory and anti-ulcerative effects of metyrosine, a selective tyrosine hydroxylase enzyme inhibitor, were investigated in rats. For ulcer experiments, indomethacin-induced gastric ulcer tests and ethanol-induced gastric ulcer tests were used. For these experiments, rats were fasted for 24 h. Different doses of metyrosine and 25 mg/kg doses of ranitidine were administered to rats, followed by indomethacin at 25 mg/kg for the indomethacin-induced ulcer test, or 50% ethanol for the ethanol-induced test. Results have shown that at all of the doses used (50, 100 and 200 mg/kg), metyrosine had significant anti-ulcerative effects in both indomethacin and ethanol-induced ulcer tests. Metyrosine doses of 100 and 200 mg/kg (especially the 200 mg/kg dose) also inhibited carrageenan-induced paw inflammation even more effectively than indomethacin. In addition, to characterize the anti-inflammatory mechanism of metyrosine we investigated its effects on cyclooxygenase (COX) activity in inflammatory tissue (rat paw). The results showed that all doses of metyrosine significantly inhibited high COX-2 activity. The degree of COX-2 inhibition correlated with the increase in anti-inflammatory activity. In conclusion, we found that metyrosine has more anti-inflammatory effects than indomethacin and that these effects can be attributed to the selective inhibition of COX-2 enzymes by metyrosine. We also found that adrenalin levels are reduced upon metyrosine treatment, which may be the cause of the observed gastro-protective effects of this compound.[1]

Absorption, Distribution and Excretion
Well absorbed from the gastrointestinal tract.
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.

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Metabolism / Metabolites
Little biotransformation, with catechol metabolites accounting for less than 1% of the administered dose.

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Biological Half-Life
3.4 to 3.7 hours

[1]. Gastric anti-ulcerative and anti-inflammatory activity of metyrosine in rats. Pharmacol Rep. 2010;62(1):113‐119.

[2]. Medical management of pheochromocytoma: Role of the endocrinologist. Indian J Endocrinol Metab. 2011;15 Suppl 4(Suppl4):S329‐S336.

Alpha-methyl-L-tyrosine is an L-tyrosine derivative that consists of L-tyrosine bearing an additional methyl substituent at position 2. 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. It has a role as an antihypertensive agent and an EC 1.14.16.2 (tyrosine 3-monooxygenase) inhibitor. It is a L-tyrosine derivative and a non-proteinogenic L-alpha-amino acid.
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)
Metyrosine is a Catecholamine Synthesis Inhibitor. The mechanism of action of metyrosine is as a Catecholamine Synthesis Inhibitor.
Metyrosine is a methylated tyrosine, a catecholamine synthesis antagonist with antihypertensive property. Metyrosine competitively inhibits tyrosine 3-monooxygenase, an enzyme that activates molecular oxygen to catalyze the hydroxylation of tyrosine to dihydroxyphenylalanine (Dopa), an intermediate to catecholamine (dopamine, norepinephrine, and epinephrine) production. This agent reduces the elevated levels of catecholamines associated with pheochromocytoma, thereby preventing hypertension.
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)

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Drug Indication
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.

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Mechanism of Action
Metyrosine 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.

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Pharmacodynamics
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.

C10H13NO3

195.2151

195.09

672-87-7

Metyrosine-13C9,15N,d7;1994331-23-5

441350

White to off-white solid powder

1.283g/cm3

383.7ºC at 760 mmHg

320-340°C dec.

185.9ºC

1.599

1.437

3

4

3

14

211

1

C[C@](CC1=CC=C(C=C1)O)(C(=O)O)N

NHTGHBARYWONDQ-JTQLQIEISA-N

InChI=1S/C10H13NO3/c1-10(11,9(13)14)6-7-2-4-8(12)5-3-7/h2-5,12H,6,11H2,1H3,(H,13,14)/t10-/m0/s1

(S)-2-amino-3-(4-hydroxyphenyl)-2-methylpropanoic acid

Demser; Metirosine; Racemetirosine; METYROSINE; 672-87-7; alpha-Methyl-L-tyrosine; Metirosine; Demser; Methyltyrosine; (S)-alpha-Methyltyrosine; (S)-2-Amino-3-(4-hydroxyphenyl)-2-methylpropanoic acid; α-Methyltyrosine

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~5 mg/mL (~25.61 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)