Midodrine

254.28

254.28

255-945-3

DTXSID0023321

C - Cardiovascular system

2924299090

93.8

-0.5

Solid

1.204±0.06 g/cm3(Predicted)

200 - 203 °C

H2O: soluble

Store in tight container as defined in the USP-NF. This material should be handled and stored per label instructions to ensure product integrity.

2.63X10-10 mm Hg at 25 deg C (est)

Specific optical rotation = +138.5 deg at 20 °C/D (concentration = 0.5 in chloroform)

7.8None

Henry's Law constant = 6.91X10-19 atm-cu m/mol at 25 °C (est)

7.8|pKa = 7.8 (0.3% aqueous solution); pH 3.5 to 5.5 (5% aqueous solution) /Midodrine hydrochloirde/

White to off-white /Midodrine hydrochloride/|Hydroxyl radical reaction rate constant = 9.2X10-11 cu cm/molec-sec at 25 °C (est)

SRP: Expired or waste pharmaceuticals shall carefully take into consideration applicable DEA, EPA, and FDA regulations. It is not appropriate to dispose by flushing the pharmaceutical down the toilet or discarding to trash. If possible return the pharmaceutical to the manufacturer for proper disposal being careful to properly label and securely package the material. Alternatively, the waste pharmaceutical shall be labeled, securely packaged and transported by a state licensed medical waste contractor to dispose by burial in a licensed hazardous or toxic waste landfill or incinerator.|SRP: At the time of review, regulatory criteria for small quantity disposal are subject to significant revision, however, household quantities of waste pharmaceuticals may be managed as follows: Mix with wet cat litter or coffee grounds, double bag in plastic, discard in trash.

The Approved Drug Products with Therapeutic Equivalence Evaluations List identifies currently marketed prescription drug products, including midodrine hydrochloride, approved on the basis of safety and effectiveness by FDA under sections 505 of the Federal Food, Drug, and Cosmetic Act. /Midodrine hydrochloride/

For handling of laboratory scale quantities, a cloth lab coat is recommended. Where significant quantities are handled, work clothing may be necessary to prevent take-home contamination.|Safety glasses with sideshields are recommended. Face shields or goggles may be required if splash potential exists or if corrosive materials are present. Approved eye protection (eg, bearing the ANSI Z87 or CAS stamp) is preferred. Maintain eyewash facilities in the work area.|Where respirators are deemed necessary to reduce or control occupational exposures, use NIOSH-approved respiratory protection and have an effective respirator program in place.

Water spray, dry chemical, carbon dioxide, or foam as appropriate for surrounding fire and materials. ... As with all fires, evacuate personnel to a safe area. firefighters should use self-contained breathing equipment and protective clothing.

Wear approved respiratory protection, chemically compatible gloves, and protective clothing. Wipe up spillage or collect spillage using a high- efficiency vacuum cleaner. Avoid breathing dust. Place spillage in appropriately labeled container for disposal. Wash spill site.

Airborne exposure should be controlled primarily by engineering controls such as general dilution ventilation, local exhaust ventilation, or process enclosure. Local exhaust ventilation is generally preferred to general exhaust because it can control the contaminant at its source, preventing dispersion into the work area. An industrial hygiene survey involving air monitoring may be used to determine the effectiveness of engineering controls. Effectiveness of engineering controls intended for use with highly potent materials should be assessed by use of nontoxic surrogate materials. local exhaust ventilation such as a laboratory fume hood or other vented enclosure is recommended, particularly for grinding, crushing, weighing, or other dust-generating procedures.|This material is assumed to be combustible. As with all dry powders, it is advisable to ground mechanical equipment in contact with dry material to dissipate the potential buildup of static electricity.|As a general rule, when handling USP Reference Standards, avoid all contact and inhalation of dust, mists, and/or vapors associated with the material. Wash thoroughly after handling.|SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.|For more Preventive Measures (Complete) data for Midodrine (7 total), please visit the HSDB record page.

Eye, skin, ... and/or respiratory tract irritation.

Symptoms of overdose could include hypertension, piloerection (goosebumps), a sensation of coldness and urinary retention. The single doses that would be associated with symptoms of overdosage or would be potentially life- threatening are unknown. The oral LD50 is approximately 30 to 50 mg/kg in rats, 675 mg/kg in mice, and 125 to 160 mg/kg in dogs. Desglymidodrine is dialyzable.

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.

LD50 Mouse oral 675 mg/kg|LD50 Rat oral 30 to 50 mg/kg|LD50 Dog oral 125-160 mg/kg

Midodrine hydrochloride is contraindicated in patients with severe organic heart disease, acute renal disease, urinary retention, pheochromocytoma or thyrotoxicosis. Midodrine hydrochloride should not be used in patients with persistent and excessive supine hypertension.

For the treatment of symptomatic orthostatic hypotension (OH).

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/

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.

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.

Drugs that mimic the effects of stimulating postganglionic adrenergic sympathetic nerves. Included here are drugs that directly stimulate adrenergic receptors and drugs that act indirectly by provoking the release of adrenergic transmitters. (See all compounds classified as Sympathomimetics.)|Drugs used to cause constriction of the blood vessels. (See all compounds classified as Vasoconstrictor Agents.)|Compounds that bind to and activate ADRENERGIC ALPHA-1 RECEPTORS. (See all compounds classified as Adrenergic alpha-1 Receptor Agonists.)

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.

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.

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.

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.

Recommended general treatment, based on the pharmacology of the drug, includes ... administration of alpha-sympatholytic drugs (e.g., phentolamine).|/SRP:/ Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Poisons A and B/|/SRP:/ Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 mL of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poisons A and B/|/SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poisons A and B/

/SIGNS AND SYMPTOMS/ Symptoms of overdose could include hypertension, piloerection (goosebumps), a sensation of coldness and urinary retention.|/CASE REPORTS/ A 42-year-old female had suffered from repeated syncope. She had vasovagal syncope with convulsions from vasodilatation and cardiac standstill which lasted for 9.8 sec. The 60 degrees head-up tilt test, nitroglycerin injection and isoproterenol infusion provoked vasovagal reaction. Although a beta blocker was not effective in preventing tilt-induced hypotension and bradycardia, midodrine hydrochloride (alpha-1 stimulant) or atropine prevented it. In this patient, insufficient constriction of capacitance vessels might have played an important role in activation of an inhibitory reflex from cardiopulmonary mechanoreceptors which caused hypotension and bradycardia.|/CASE REPORTS/ There are 2 reported cases of overdosage with midodrine hydrochloride, both in young males. One patient ingested midodrine hydrochloride drops, 250 mg, experienced systolic blood pressure greater than 200 mm Hg, was treated with an IV injection of 20 mg of phentolamine and was discharged the same night without any complaints. The other patient ingested 205 mg of midodrine hydrochloride (41 5-mg tablets) and was found lethargic and unable to talk, unresponsive to voice but responsive to painful stimuli, hypertensive and bradycardic. Gastric lavage was performed and the patient recovered fully by the next day without sequelae. The single doses that would be associated with symptoms of overdosage or would be potentially life-threatening are unknown.|/CASE REPORTS/ Midodrine is an alpha-agonist that causes peripheral vasoconstriction, resulting in increased blood pressure. It has been reported to be safe and effective in patients with end stage renal disease (ESRD) and is widely used for hemodialysis-associated hypotension. We report a case report of midodrine-induced ischemia in a patient on hemodialysis and review the literature relating to the safety of midodrine in patients with end stage renal disease.|For more Human Toxicity Excerpts (Complete) data for Midodrine (8 total), please visit the HSDB record page.

Amatine

Table: Midodrine Hydrochloride Preparations [Table#7602]

Human Drugs -> FDA Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book) -> Active Ingredients|Pharmaceuticals