Absorption, Distribution and Excretion
Metaraminol takes effect 1-2 minutes after intravenous injection, 10 minutes after intramuscular injection, and 5-20 minutes after subcutaneous injection. It is absorbed orally. Following a single intravenous injection, metaraminol absorption is detectable in the rabbit heart for at least 8 days. Metaraminol is widely distributed in the heart, lungs, liver, kidneys, and skeletal muscle, with less distribution in the spleen, brain, fat, and stomach. Except for the brain, peripherally administered metaraminol is well distributed in rats. Organs containing large amounts of norepinephrine (NE) storage vesicles, such as the heart, spleen, and adrenal glands, absorb relatively more AMT and retain it for a longer time than the liver, lungs, and kidneys. Metaraminol is absorbed orally; however, to achieve the same effect, the oral dose must be 5 to 6 times the intramuscular or intravenous dose. Following an intramuscular injection of 5 mg, the pressor effect lasts approximately 1.5 hours.

---

Metabolism/Metabolites
Hepatum
The fact that metaraminol (1-(m-hydroxynorephedrine)) remains unchanged and binds to tissues for 1-2 weeks after ingestion has prompted in vitro studies. Studies have shown that this drug can resist the biotransformation by liver enzymes, which typically metabolize structure-related compounds. /Mammalian species not listed in the source/

Protein Binding
Approximately 45% Interactions Monoamine oxidase inhibitors… may interact with metaraminol by inhibiting the oxidative deamination of sympathomimetic amines. The result may be increased storage of norepinephrine in tissues, leading to an enhanced hypertensive response secondary to the indirect effects of metaraminol. /Biotartrate/ Guanethidine, toxapine, and methyldopa affect postganglionic neural activity by reducing norepinephrine storage or promoting its release. Therefore, these drugs interfere with the indirect release of norepinephrine by metaraminol and may limit its efficacy. /Potassium Tartrate/ Cardiac output increases significantly when atropine prevents bradycardia.
The antibacterial effect of furazolidone is accompanied by progressive and generalized inhibition of monoamine oxidase; concurrent or subsequent administration of metaraminol may lead to hypertensive crisis. /Tartrate/ For more complete data on interactions of resorcinols (20 in total), please visit the HSDB record page.

---

Non-human toxicity values
Oral LD50 in rats: 240 mg/kg
Intraperitoneal LD50 in rats: 41 mg/kg
Subcutaneous LD50 in rats: 117 mg/kg
Oral LD50 in mice: 99 mg/kg
For more complete non-human toxicity data on resorcinol (6 types in total), please visit the HSDB record page.

Metarhamnol belongs to the phenylethanolamine class of compounds. Its structure is 2-amino-1-phenylethanol, with a methyl group at the 2-position and a phenolic hydroxyl group at the 1-position. It is a sympathomimetic drug used to treat hypotension. Metarhamnol has a triple effect as an alpha-adrenergic agonist, a sympathomimetic drug, and a vasoconstrictor. Metarhamnol is an adrenergic agonist, primarily acting on alpha-adrenergic receptors and stimulating the release of norepinephrine. It is mainly used as a vasoconstrictor to treat hypotension. Metarhamnol is a sympathomimetic drug, primarily acting on alpha-1 adrenergic receptors. It is mainly used as a vasoconstrictor to treat hypotension. Drug Indications Used for the treatment and prevention of hypotension caused by hemorrhage, spinal anesthesia, and brain injury-related shock.

---

Mechanism of Action
Metaraminol, as a pure α1-adrenergic receptor agonist, causes peripheral vasoconstriction, thereby increasing blood pressure (both systolic and diastolic). Its action is thought to be related to the inhibition of adenylate cyclase, which in turn inhibits cAMP production. Another effect of metaraminol is the indirect release of norepinephrine from its storage site.
Through direct action on α-adrenergic receptors and indirect release of norepinephrine from its storage site, metaraminol causes vasoconstriction and increased peripheral vascular resistance, leading to elevated blood pressure. Reflex bradycardia is usually present, and renal and cerebral blood flow is reduced. /Tartrate/
Myocardial contractility is enhanced, but not as significantly as with norepinephrine; cardiac output remains unchanged or may decrease slightly in cases of bradycardia. Metaraminol can cause partial β-adrenergic-mediated vasodilation, but the α-adrenergic effect is dominant. /Dihydrotartrate/
After intravenous injection of 1.5 mg/kg into rabbits, plasma drug concentration was positively correlated with its vasopressor effect. This drug is clearly a direct-acting sympathomimetic amine, and its effect may terminate due to dilution in body fluids and tissue absorption.

---

Therapeutic Uses
Adrenergic α-agonist; Adrenergic drug; Sympathomimetic drug; Vasodilator
Drug (Veterinary): Used to treat hypotension in dogs, such as endotoxin shock or hypotension caused by barbiturate anesthesia. Previously used in combination with phenylephrine or amphetamines. May be indicated for shock associated with myocardial infarction.
...For...certain acute hypotensive conditions, such as anaphylactic shock (after initial epinephrine treatment) or shock secondary to myocardial infarction, trauma, sepsis, Gram-negative bacterial endotoxins, and adverse drug reactions. Potassium hydrogen tartrate (abbreviated as "potassium hydrogen tartrate") is almost exclusively used to treat hypotensive conditions. It has both direct and indirect effects, and its overall efficacy is similar to norepinephrine, but its potency is much lower and its duration of action is longer. It does not have a central nervous system stimulant effect.
For more complete data on the therapeutic uses of metaraminol (12 in total), please visit the HSDB record page.

---

Drug Warnings
Veterinarians: Continued use may deplete norepinephrine reserves.
Not recommended for hypovolemic shock.Potassium tartrate/
…Prolonged infusion of metaraminol can cause shock, and some authorities are reluctant to use metaraminol in any type of shock other than anaphylactic shock. Extravasation of metaraminol can lead to tissue necrosis. Potassium tartrate/
Subcutaneous injection should be avoided as tissue necrosis may occur.
For more complete data on the drug warnings of metaraminol (14 in total), please visit the HSDB record page.

---

Pharmacodynamics
Metaraminol is a potent sympathomimetic amine that can raise blood pressure. It is indicated for the prevention and treatment of acute hypotension induced by spinal anesthesia. It can also be used as adjunctive therapy for hypotension caused by bleeding, drug reactions, surgical complications, and shock associated with trauma or tumor-related brain injury. Metaraminol acts on α1-adrenergic receptors but appears to have no effect on β-adrenergic receptors. Its mechanism of action is through enhancing cardiac pumping capacity and constricting peripheral blood vessels.

C9H13NO2

167.207

167.095

54-49-9

33402-03-8 (tartrate);

5906

Typically exists as solid at room temperature

1.198g/cm3

357.9ºC at 760mmHg

107.5°C

170.3ºC

1.4760 (estimate)

1.473

3

3

2

12

141

2

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

WXFIGDLSSYIKKV-RCOVLWMOSA-N

InChI=1S/C9H13NO2/c1-6(10)9(12)7-3-2-4-8(11)5-7/h2-6,9,11-12H,10H2,1H3/t6-,9-/m0/s1

3-[(1R,2S)-2-amino-1-hydroxypropyl]phenol

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)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

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.

---

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).

View More

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)

---

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).

View More

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

---

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.

---

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