Absorption, Distribution and Excretion
Rapidly absorbed following oral administration. The peak plasma concentrations of the prodrug, desglymidodrine, is reached about half an hour following drug administration. The metabolites reach their peak plasma concentrations at about 1 to 2 hours following drug administration. The absolute bioavailability of midodrine (measured as desglymidodrine) is 93% and is not affected by food. As desglymidodrine displays poor diffusibility across the blood-brain barrier, it is expected to have minimal effects on the central nervous system.
Renal cl=385 mL/minute
Renal elimination of midodrine is insignificant. The renal clearance of desglymidodrine is of the order of 385 mL/minute, most, about 80%, by active renal secretion. The actual mechanism of active secretion has not been studied, but it is possible that it occurs by the base-secreting pathway responsible for the secretion of several other drugs that are bases.
Midodrine hydrochloride is a prodrug, i.e., the therapeutic effect of orally administered midodrine is due to the major metabolite desglymidodrine, formed by deglycination of midodrine. After oral administration, midodrine hydrochloride is rapidly absorbed. The plasma levels of the prodrug peak after about half an hour and decline with a half-life of approximately 25 minutes, while the metabolite reaches peak blood concentrations about 1 to 2 hours after a dose of midodrine and has a half-life of about 3 to 4 hours. The absolute bioavailability of midodrine (measured as desglymidodrine) is 93%. The bioavailability of desglymidodrine is not affected by food. Approximately the same amount of desglymidodrine is formed after intravenous and oral administration of midodrine. Neither midodrine nor desglymidodrine is bound to plasma proteins to any significant extent.
Midodrine is an oral drug for orthostatic hypotension. This drug is almost completely absorbed after oral administration and converted into its active form, 1-(2',5'-dimethoxyphenyl)-2-aminoethanol) (DMAE), by the cleavage of a glycine residue. The intestinal H+-coupled peptide transporter 1 (PEPT1) transports various peptide-like drugs and has been used as a target molecule for improving the intestinal absorption of poorly absorbed drugs through amino acid modifications. Because midodrine meets these requirements, we examined whether midodrine can be a substrate for PEPT1. The uptake of midodrine, but not DMAE, was markedly increased in PEPT1-expressing oocytes compared with water-injected oocytes. Midodrine uptake by Caco-2 cells was saturable and was inhibited by various PEPT1 substrates. Midodrine absorption from the rat intestine was very rapid and was significantly inhibited by the high-affinity PEPT1 substrate cyclacillin, assessed by the alteration of the area under the blood concentration-time curve for 30 min and the maximal concentration. Some amino acid derivatives of DMAE were transported by PEPT1, and their transport was dependent on the amino acids modified. In contrast to neutral substrates, cationic midodrine was taken up extensively at alkaline pH, and this pH profile was reproduced by a 14-state model of PEPT1, which we recently reported. These findings indicate that PEPT1 can transport midodrine and contributes to the high bioavailability of this drug and that Gly modification of DMAE is desirable for a prodrug of DMAE.

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Metabolism / Metabolites
Thorough metabolic studies have not been conducted, but it appears that deglycination of midodrine to desglymidodrine takes place in many tissues, and both compounds are metabolized in part by the liver.
The human cytochrome P450 (CYP) isoforms catalyzing the oxidation metabolism of desglymidodrine (DMAE), an active metabolite of midodrine, were studied. Recombinant human CYP2D6, 1A2 and 2C19 exhibited appreciable catalytic activity with respect to the 5'-O-demethylation of DMAE. The O-demethylase activity by the recombinant CYP2D6 was much higher than that of other CYP isoforms. Quinidine (a selective inhibitor of CYP2D6) inhibited the O-demethylation of DMAE in pooled human microsomes by 86%, while selective inhibitors for other forms of CYP did not show any appreciable effect. Although the activity of CYP2D6 was almost negligible in the PM microsomes, the O-demethylase activity of DMAE was found to be maintained by about 25% of the pooled microsomes. Furafylline (a selective inhibitor of CYP1A2) inhibited the M-2 formation in the PM microsomes by 57%. The treatment of pooled microsomes with an antibody against CYP2D6 inhibited the formation of M-2 by about 75%, whereas that of the PM microsomes did not show drastic inhibition. In contrast, the antibody against CYP1A2 suppressed the activity by 40 to 50% in the PM microsomes. These findings suggest that CYP2D6 have the highest catalytic activity of DMAE 5'-O-demethylation in human liver microsomes, followed by CYP1A2 to a small extent.
Thorough metabolic studies have not been conducted, but it appears that deglycination of midodrine to desglymidodrine takes place in many tissues and both compounds are metabolized in part by the liver. Neither midodrine nor desglymidodrine is a substrate for monoamine oxidase.

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Biological Half-Life
The metabolites display a half-life of about 3 to 4 hours.
The plasma levels of the prodrug peak after about half an hour and decline with a half-life of approximately 25 minutes, while the metabolite reaches peak blood concentrations about 1 to 2 hours after a dose of midodrine and has a half-life of about 3 to 4 hours.

Interactions
It appears possible, although there is no supporting experimental evidence, that the high renal clearance of desglymidodrine (a base) is due to active tubular secretion by the base-secreting system also responsible for the secretion of such drugs as metformin, cimetidine, ranitidine, procainamide, triamterene, flecainide and quinidine. Thus there may be a potential for drug-drug interaction with these drugs.
Midodrine hydrochloride has been used in patients concomitantly treated with salt-retaining steroid therapy (i.e., fludrocortisone acetate), with or without salt supplementation. The potential for supine hypertension should be carefully monitored in these patients and may be minimized by either reducing the dose of fludrocortisone acetate or decreasing the salt intake prior to initiation of treatment with midodrine hydrochloride. Alpha-adrenergic blocking agents, such as prazosin, terazosin and doxazosin, can antagonize the effects of midodrine hydrochloride.
The use of drugs that stimulate alpha-adrenergic receptors (e.g., phenylephrine, pseudoephedrine, ephedrine, phenylpropanolamine or dihydroergotamine) may enhance or potentiate the pressor effects of midodrine hydrochloride. Therefore, caution should be used when midodrine hydrochloride is administered concomitantly with agents that cause vasoconstriction.
When administered concomitantly with midodrine hydrochloride, cardiac glycosides may enhance or precipitate bradycardia, A.V. block or arrhythmia.
An episode of transient, severe hypertension occurring within 2 minutes of injection of 1% lidocaine with 1:100,000 U of epinephrine in a patient taking midodrine for orthostatic hypotension /is reported/. /It was/ hypothesize that the patient's autonomic nervous system was dangerously susceptible to the effect of local anesthetic when combined with the vasoactive systemic effect of midodrine. Surgeons should minimize the use of vasoconstrictors in patients treated with midodrine to avoid hypertensive complications.

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Non-Human Toxicity Values
LD50 Mouse oral 675 mg/kg
LD50 Rat oral 30 to 50 mg/kg
LD50 Dog oral 125-160 mg/kg

Midodrine is an aromatic ether that is 1,4-dimethoxybenzene which is substituted at position 2 by a 2-(glycylamino)-1-hydroxyethyl group. A direct-acting sympathomimetic with selective alpha-adrenergic agonist activity, it is used (generally as its hydrochloride salt) as a peripheral vasoconstrictor in the treatment of certain hypotensive states. The main active moiety is its major metabolite, deglymidodrine. It has a role as a prodrug, an alpha-adrenergic agonist, a sympathomimetic agent and a vasoconstrictor agent. It is a secondary alcohol, an amino acid amide and an aromatic ether. It is functionally related to a glycinamide and a deglymidodrine. It is a conjugate base of a midodrine(1+).
An ethanolamine derivative that is an adrenergic alpha agonist. It is used as a vasoconstrictor agent in the treatment of hypotension.
Midodrine is an alpha-Adrenergic Agonist. The mechanism of action of midodrine is as an Adrenergic alpha-Agonist.
Midodrine is a direct-acting prodrug and sympathomimetic agent with antihypotensive properties. Midodrine is converted to its active metabolite, desglymidodrine by deglycination reaction. Desglymidodrine selectively binds to and activates alpha-1-adrenergic receptors of the arteriolar and venous vasculature. This causes smooth muscle contraction and leads to an elevation of blood pressure. Desglymidodrine diffuses poorly across the blood-brain barrier, and is therefore not associated with effects on the central nervous system (CNS).
An ethanolamine derivative that is an adrenergic alpha-1 agonist. It is used as a vasoconstrictor agent in the treatment of HYPOTENSION.
See also: Midodrine Hydrochloride (has salt form).

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Drug Indication
For the treatment of symptomatic orthostatic hypotension (OH).

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Mechanism of Action
Midodrine undergoes metabolism to form its pharmacologically active metabolite, desglymidodrine. Desglymidodrine acts as an agonist at the alpha₁-adrenergic receptors expressed in the arteriolar and venous vasculature. Activation of alpha₁-adrenergic receptor signaling pathways lead to an increase in the vascular tone and elevation of blood pressure. Desglymidodrine is reported to have negligible effect on the cardiac beta-adrenergic receptors.
Midodrine hydrochloride forms an active metabolite, desglymidodrine, that is an alpha1-agonist and exerts its actions via activation of the alpha-adrenergic receptors of the arteriolar and venous vasculature, producing an increase in vascular tone and elevation of blood pressure. Desglymidodrine does not stimulate cardiac beta-adrenergic receptors. Desglymidodrine diffuses poorly across the blood-brain barrier and is therefore not associated with effects on the central nervous system.

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Therapeutic Uses
FDA proposed to withdraw approval of the drug midodrine hydrochloride, used to treat the low blood pressure condition, orthostatic hypotension, because required post-approval studies that verify the clinical benefit of the drug have not been done. To date, neither the original manufacturer nor any generic manufacturer has demonstrated the drug's clinical benefit, for example, by showing that use of the drug improved a patient's ability to perform life activities.
...used as a vasoconstrictor agent in the treatment of hypotension
Midodrine hydrochloride is used in the management of symptomatic orthostatic hypotension; the drug is designated an orphan drug by the US Food and Drug Administration (FDA) for such use. /Included in US product label/

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Drug Warnings
WARNING: Because midodrine hydrochloride tablets can cause marked elevation of supine blood pressure, it should be used in patients whose lives are considerably impaired despite standard clinical care. The indication for use of midodrine hydrochloride tablets in the treatment of symptomatic orthostatic hypotension is based primarily on a change in a surrogate marker of effectiveness, an increase in systolic blood pressure measured one minute after standing, a surrogate marker considered likely to correspond to a clinical benefit. At present, however, clinical benefits of midodrine hydrochloride tablets, principally improved ability to carry out activities of daily living, have not been verified.
The most potentially serious adverse reaction associated with midodrine hydrochloride therapy is marked elevation of supine arterial blood pressure (supine hypertension). Systolic pressure of about 200 mmHg was seen overall in about 13.4% of patients given 10 mg of midodrine hydrochloride. Systolic elevations of this degree were most likely to be observed in patients with relatively elevated pre-treatment systolic blood pressures (mean 170 mmHg). There is no experience in patients with initial supine systolic pressure above 180 mmHg, as those patients were excluded from the clinical trials. Use of midodrine hydrochloride in such patients is not recommended. Sitting blood pressures were also elevated by midodrine hydrochloride therapy. It is essential to monitor supine and sitting blood pressures in patients maintained on midodrine hydrochloride.
The potential for supine and sitting hypertension should be evaluated at the beginning of midodrine hydrochloride therapy. Supine hypertension can often be controlled by preventing the patient from becoming fully supine, i.e., sleeping with the head of the bed elevated. The patient should be cautioned to report symptoms of supine hypertension immediately. Symptoms may include cardiac awareness, pounding in the ears, headache, blurred vision, etc.
Midodrine hydrochloride use has not been studied in patients with hepatic impairment. Midodrine hydrochloride should be used with caution in patients with hepatic impairment, as the liver has a role in the metabolism of midodrine.
For more Drug Warnings (Complete) data for Midodrine (12 total), please visit the HSDB record page.

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Pharmacodynamics
Midodrine is a prodrug, i.e., the therapeutic effect of orally administered midodrine is due to the major metabolite desglymidodrine formed by deglycination of midodrine. Administration of midodrine results in a rise in standing, sitting, and supine systolic and diastolic blood pressure in patients with orthostatic hypotension of various etiologies. Standing systolic blood pressure is elevated by approximately 15 to 30 mmHg at 1 hour after a 10-mg dose of midodrine, with some effect persisting for 2 to 3 hours. Midodrine has no clinically significant effect on standing or supine pulse rates in patients with autonomic failure.

C12H18N2O4

254.286

254.127

42794-76-3

Midodrine hydrochloride;43218-56-0;Midodrine-d6 hydrochloride;1188265-43-1

4195

Typically exists as solid at room temperature

0.903

3

5

6

18

263

0

MGCQZNBCJBRZDT-PPHPATTJSA-N

InChI=1S/C12H18N2O4.ClH/c1-17-8-3-4-11(18-2)9(5-8)10(15)7-14-12(16)6-13/h3-5,10,15H,6-7,13H2,1-2H3,(H,14,16)1H/t10-/m0./s1

(R)-2-amino-N-[2-(2,5-dimethoxyphenyl)-2-hydroxyethyl]acetamide hydrochloride

St-1085 St1085 St 1085Amatine Pro-AmatineOrvaten

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.

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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.)